Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23) (Springer Proceedings in Materials, 32) 9819955661, 9789819955664

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Springer Proceedings in Materials

Sanjay Mavinkere Rangappa Suchart Siengchin   Editors

Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23)

Springer Proceedings in Materials Volume 32

Series Editors Arindam Ghosh, Department of Physics, Indian Institute of Science, Bangalore, India Daniel Chua, Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore Flavio Leandro de Souza, Universidade Federal do ABC, Sao Paulo, São Paulo, Brazil Oral Cenk Aktas, Institute of Material Science, Christian-Albrechts-Universität zu Kiel, Kiel, Schleswig-Holstein, Germany Yafang Han, Beijing Institute of Aeronautical Materials, Beijing, Beijing, China Jianghong Gong, School of Materials Science and Engineering, Tsinghua University, Beijing, Beijing, China Mohammad Jawaid , Laboratory of Biocomposite Technology, INTROP, Universiti Putra Malaysia, Serdang, Selangor, Malaysia

Springer Proceedings in Materials publishes the latest research in Materials Science and Engineering presented at high standard academic conferences and scientific meetings. It provides a platform for researchers, professionals and students to present their scientific findings and stay up-to-date with the development in Materials Science and Engineering. The scope is multidisciplinary and ranges from fundamental to applied research, including, but not limited to: • • • • • • • • •

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Sanjay Mavinkere Rangappa · Suchart Siengchin Editors

Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23)

Editors Sanjay Mavinkere Rangappa Natural Composites Research Group Lab Department of Materials and Production Engineering The Sirindhorn International Thai-German Graduate School of Engineering, King Mongkut’s University of Technology North Bangkok Bangkok, Thailand

Suchart Siengchin Natural Composites Research Group Lab Department of Materials and Production Engineering The Sirindhorn International Thai-German Graduate School of Engineering, King Mongkut’s University of Technology North Bangkok Bangkok, Thailand

ISSN 2662-3161 ISSN 2662-317X (electronic) Springer Proceedings in Materials ISBN 978-981-99-5566-4 ISBN 978-981-99-5567-1 (eBook) https://doi.org/10.1007/978-981-99-5567-1 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore Paper in this product is recyclable.

Organization

Editors Assoc. Prof. Dr. Sanjay Mavinkere Rangappa, KMUTNB, Thailand Prof. Dr.-Ing. habil. Suchart Siengchin, KMUTNB, Thailand

Co-editors Dr. Indran Suyambulingam, KMUTNB, Thailand Dr. Sathish Kumar Palaniappan, KMUTNB, Thailand Dr. Rajeshkumar Lakshminarasimhan, KMUTNB, Thailand

Organizing Committee Members Dr. Rapeeporn Srisuk, KMUTNB, Thailand Assoc. Prof. Dr. Laongdaw Techawinyutham, KMUTNB, Thailand Asst. Prof. Dr. Chakaphan Ngaowthong, KMUTNB, Thailand Asst. Prof. Dr. Jiratti Tengusthiwat, KMUTNB, Thailand Dr. Krittirash Yorseng, KMUTNB, Thailand Dr. Harikrishnan Pulikkalparambil, KMUTNB, Thailand Dr. Divya Divakaran, KMUTNB, Thailand Dr. Vijay Raghunathan, KMUTNB, Thailand Dr. Vinod Ayyappan, KMUTNB, Thailand

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Organization

Advisory Committee Dr. Alessandro Pegoretti, University of Trento, Italy Dr. Angel Romo-Uribe, Johnson and Johnson Vision Care, USA Dr. Anish Khan, King Abdulaziz University, Saudi Arabia Dr. V. Arul Mozhi Selvan, National Institute of Technology Tiruchirappalli, India Dr. Baijayantimala Garnaik, CSIR National Chemical Laboratory, India Dr. S. Basavarajappa, Indian Institute of Technology Dharwad, India Dr. P. Baskara Sethupathi, SRM Institute of Science and Technology, India Dr. S. S. Bhattacharya, Indian Institute of Technology Madras, India Dr. M. Bhuvaneshwaran, K. S. R. College of Engineering, India Dr. Carlo Santulli, Università degli studi di Camerino, Italy Dr. Christian Emeka Okafor, Nnamdi Azikiwe University, Awka, Nigeria Dr. Claudia Barile, Politecnico di Bari, Italy Dr. Danuta Matykiewicz, Pozna´n University of Technology, Poland Dr. Dayananda Pai, Manipal Institute of Technology, Manipal, India Dr. Dineshkumar Harursampath, Indian Institute of Science, Bengaluru, India Dr. R. Edwin Raj, National Rail and Transportation Institute, India Dr. Elammaran Jayamani, Swinburne University of Technology, Malaysia Dr. Gaurav Manik, Indian Institute of Technology Roorkee, India Dr. Gunda Yoganjaneyulu, National Institute of Technology Jamshedpur, India Dr. Haniyeh Rostamzad, University of Guilan, Iran Dr. Hao Wang, University of Southern Queensland, Australia Dr. Hasan Koruk, MEF University, Turkey Dr. Hom Dhakal, University of Portsmouth, UK Dr. Ibrahim M Alarifi, Majmaah University, Saudi Arabia Dr. Inamuddin, King Abdulaziz University, Saudi Arabia Dr. Ing Kong, La Trobe University, Australia Dr. Jayakrishna K, Vellore Institute of Technology Vellore, India Dr. Jayashree Bijwe, Indian Institute of Technology Delhi (Retd.), India Dr. Jürgen Pionteck, Leibniz-Institut für Polymerforschung Dresden e.V., Germany Dr. Jyotishkumar Parameswaranpillai, Alliance University, India Dr. K. Palanikumar, Sri Sairam Institute of Technology, India Dr. M. Kamaraj, Indian Institute of Technology Madras, India Dr. Karthik Aruchamy, Akshaya College of Engineering and Technology, India Dr. Kunigal Shivakumar, North Carolina A&T State University, USA Dr. Kuruvilla Joseph, Indian Institute of Space Science and Technology, India Dr. Lai Chin Wei, Universiti Malaya, Malaysia Dr. D. Lenin Singaravelu, National Institute of Technology Tiruchirappalli, India Dr. Libo Yan, TU Braunschweig & Fraunhofer WKI, Germany Dr. Lothar Kroll, Chemnitz University of Technology, Germany Dr. Malinee Sriariyanun, King Mongkut’s University of Technology North Bangkok, Thailand Dr. Mamilla Ravi Sankar, Indian Institute of Technology Tirupati, India

Organization

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Dr. P. Manimaran, Karpagam Institute of Technology, India Dr. S. Manoharan, Surya Engineering College, India Dr. Manoj Kumar Gupta, Motilal Nehru National Institute of Technology Allahabad, India Dr. Marta Maria Moure Cuadrado, University Carlos III de Madrid, Spain Dr. Michal Petru, Technical University Liberec, Czech Republic Dr. Mohammad Jawaid, Universiti Putra Malaysia, Malaysia Dr. Mrityunjay Doddamani, Indian Institute of Technology Mandi, India Dr. Munish Kumar Gupta, Opole University of Technology, Poland Dr. S. Nagarajan, National Institute of Technology Manipur, India Dr. Nayan Ranjan Singha, Government College of Engineering and Leather Technology (Post-graduate) and Maulana Abul Kalam Azad University of Technology, India Dr. Ozgur Seydibeyoglu, University of Maine, USA Dr. K. Padmanabhan, Vellore Institute of Technology, India Dr. Paulo Davim, University of Aveiro, Portugal Dr. Peerawatt Nunthavarawong, King Mongkut’s University of Technology North Bangkok, Thailand Dr. Philip Oladijo, Botswana International University of Science and Technology, Botswana Dr. S. Prashantha, Siddaganga Institute of Technology, India Dr. Rajasekar Rathanasamy, Kongu Engineering College, India Dr. M. Ramesh, KIT—Kalaignarkarunanidhi Institute of Technology, India Dr. Rapeephun Dangtunagee, Maejo University International College, Thailand Dr. C. R. Rejeesh, Federal Institute of Science and Technology, India Dr. Richard Spontak, North Carolina State University, USA Dr. Rokbi Mansour, Université de M’sila, Algeria Dr. Sabu Thomas, Mahatma Gandhi University, India Dr. S. M. Sapuan, Universiti Putra Malaysia, Malaysia Dr. Sarani Zakaria, Universiti Kebangsaan Malaysia, Malaysia Dr. S. S. Saravanakumar, Kamaraj College of Engineering and Technology, India Dr. Saroj Kumar Sarangi, National Institute of Technology Patna, India Dr. T. P. Sathishkumar, Kongu Engineering College, India Dr. Seeram Ramakrishna, National University of Singapore, Singapore Dr. Seno Jose, Government College Kottayam, India Dr. B. Senthil Kumar, The Gandhigram Rural Institute, India Dr. Sergey Gorbatyuk, National University of Science and Technology MISIS, Russia Dr. Sergio Alfonso Pérez García, Advanced Materials Research Center, SC (CIMAV), México Dr. Seyda Eyupoglu, Istanbul University, Turkey Dr. Shishir Sinha, Indian Institute of Technology Roorkee, India Dr. Sreedevi Upadhyayula, Indian Institute of Technology Delhi, India Dr. Steffen Fischer, Technical University Dresden, Germany Dr. Sudheer Kumar, Polymer Scientist, JC OrthoHeal Pvt. Ltd., Vadodara, India Dr. Sunny Zafar, Indian Institute of Technology Mandi, India

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Organization

Dr. Supakij Suttiruengwong, Silpakorn University, Thailand Dr. Sushanta Kumar Sahoo, CSIR—National Institute for Interdisciplinary Science and Technology, India Dr. Thomas Heinz, Fredrich Schiller University Jena, Germany Dr. Togay Ozbakkaloglu, Texas State University, USA Dr. M. Uthayakumar, Kalasalingam Academy of Research and Education, India Dr. A. Varada Rajulu, Council of Scientific and Industrial Research (Retd.), India Dr. G. B. Veeresh Kumar, National Institute of Technology Andhra Pradesh, India Dr. Vigneshwaran Shanmugam, Lulea University of Technology, Sweden Dr. Vincenzo Fiore, University of Palermo, Italy Dr. Vinod Kushvaha, Indian Institute of Technology Jammu, India Dr. Yamuna Munusamy, Universiti Tunku Abdul Rahman, Malaysia Dr. B. Yogesha, Malnad College of Engineering, India Dr. Yucheng Liu, Jilin University, China

Scientific Committee Dr. S. S. Abhilash, Sree Chitra Thirunal College of Engineering, India Dr. Ahmad Fudholi, Universiti Kebangsaan, Malaysia Dr. Akarsh Verma, University of Petroleum and Energy Studies, Dehradun, India Dr. Anagha M. Gopalan, Indian Institute of Technology Kharagpur, West Bengal, India Dr. Aswathy Jayakumar, Kyung Hee University, Seoul, South Korea Dr. C. Balaji Ayyanar, Coimbatore Institute of Technology, Coimbatore, India Dr. K. N. Bharath, GM Institute of Technology, Davangere, India Dr. J. S. Binoj, Sree Vidyanikethan Engineering College, Tirupati, India Dr. H. Cristina Vasconcelos, University of Azores, Portugal Dr. Dan Belosinschi, Universiti du Quebec, Canada Dr. Deepu Gopakumar, Universiti Putra Malaysia, Malaysia Dr. G. L. Devnani, Harcourt Butler Technical University, Kanpur, India Dr. Dipen Kumar Rajak, GH Raisoni Institute of Engineering and Business Management, India Dr. Edi Syafri, Politeknik Pertanian Negeri Payakumbuh, Indonesia Dr. Femiana Gapsari, University of Brawijaya, Indonesia Dr. Fitriani Kasim, Andalas University, Indonesia Dr. P. M. Gopal, Karpagam Academy of Higher Education, Coimbatore, India Dr. L. R. Gopinath, Vivekanandha College of Arts and Sciences for Women, India Dr. Hind Abdellaoui, Mohammed VI Polytechnic University, Morocco Dr. R. A. Ilyas, Universiti Teknologi Malaysia, Malaysia Dr. Jafrey Daniel James Dhilip, K. Ramakrishnan College of Engineering, India Dr. Jayaseelan Veerasundaram, Prathyusha Engineering College, India Dr. H. Jeevan Rao, Amity University, Punjab, India Dr. Jyoti Jain, Meerut Institute of Engineering and Technology, Meerut, India

Organization

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Dr. M. Kavimani, Karpagam Academy of Higher Education, Coimbatore, India Dr. Madhu Puttegowda, Malnad College of Engineering, Hassan, India Dr. Manoj Kumar Singh, University of Guelph, Canada Dr. Marttin Gundapalli Paulraj, University of Alberta, Canada Dr. Melbi Mahardika, National Research and Innovation Agency, West Java, Indonesia Dr. N. K. Mithun, Kamaraj College of Engineering and Technology, India Dr. C. D. Midhun Dominic, Sacred Heart College, Kerala, India Dr. Mochamad Asrofi, University of Jember, Indonesia Dr. Moganapriya Chinnasamy, Indian Institute of Technology Kharagpur, West Bengal, India Dr. Mohamed Amin Omri, University of Sfax, Tunisia Dr. T. P. Mohan, Durban University of Technology, South Africa Dr. H. Mohit, Alliance University, Bangalore, India Dr. Muthukumar Chandrasekar, Hindustan Institute of Technology and Science, India Dr. K. J. Nagarajan, Thiagarajar College of Engineering, Madurai, India Dr. Nasmi Herlina Sari, University of Mataram, Indonesia Dr. Naveen Jesu, VIT University, Vellore, India Dr. K. Naresh, University of Southern California, Los Angeles, USA Dr. Prakash Bhuyar, Maejo University, Thailand Dr. G. Rajesh Kumar, PSG Institute of Technology and Applied Research, India Dr. Rebeca Martinez Garcia, Universidad de Leon, Spain Dr. Sabarish Radoor, Jeonbuk National University, South Korea Dr. G. Saikrishnan, Rajalakshmi Institute of Technology, Chennai, India Dr. Sandhya Alice Varghese, Kasetsart University, Bangkok, Thailand Dr. Sanjay Remanan, Indian Institute of Technology Kharagpur, West Bengal, India Dr. Sara Abdullah Alqarni, University of Jeddah, Saudi Arabia Dr. A. Saravana Kumaar, Sethu Institute of Technology, Madurai, India Dr. T. Sathish, Saveetha School of Engineering, Chennai, India Dr. Senthil Kumar Krishnasamy, PSG Institute of Technology and Applied Research, India Dr. Senthil Muthu Kumar Thiagamani, Kalasalingam Academy of Research and Education, Krishnankovil, India Dr. Shubam Sharma, Amity University, Punjab, India Dr. Suganya Priyadharshini, Coimbatore Institute of Technology, Coimbatore, India Dr. K. R. Sumesh, Czech Technical University in Prague, Czech Republic Dr. B. Suryarajan, B. S. Abdur Rahman Crescent Institute of Science and Technology, India Dr. Tej Singh, Savaria Institute of Technology, Szombathely, Hungary Dr. Vinyas Mahesh, National Institute of Technology, Silchar, India Dr. Vishnu Prasad, University College, Ireland Dr. Widya Fatriasari, National Research and Innovation Agency, West Java, Indonesia Dr. Yashas Gowda Thyavihalli Girijappa, Malnad College of Engineering, Hassan, India Dr. Yashwant Munde, MKSSS’s Cummins College of Engineering for Women, India

Preface

This book is the Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23) that was held in Bangkok, Thailand, on 17 February 2023. The sole objective of this symposium is to bring together researchers in the fields of polymer chemistry, physics, and materials science from both academia and industry to share and discuss the latest findings from their research into cutting-edge and environmentally friendly polymers. The event was comprised of keynote addresses, plenary discussions, and oral presentations delivered by stalwarts in the field of polymer composites from all around the globe. This book consolidates the research and review articles authored with recent advancements in polymer science and technology especially emphasizing the potentiality of lightweight and sustainable polymeric materials. A total of 200 papers were received, and around 60 papers were selected for presentation from various countries including Germany, Japan, Italy, India, Indonesia, Maldives, Malaysia, Nigeria, Russia, Algeria, and Turkey. A total of 34 papers were selected for inclusion in the conference proceedings. More than 300 authors were involved in contributing their work to LSPM23 from various countries like South Africa, Netherlands, Thailand, USA, UK, Zambia, and Belarus in addition to the above countries. This symposium was conducted in three major cutting-edge themes: • Lightweight and Sustainable Materials • Manufacturing Technologies for Lightweight Polymer Materials • Design Optimization of Lightweight Polymeric Materials The editors would like to express their gratitude to all the international advisory committee members, scientific committee members, technical committee members, and organizing committee members for making this symposium proceedings a reality. Bangkok, Thailand

Assoc. Prof. Dr. Sanjay Mavinkere Rangappa Prof. Dr.-Ing. habil. Suchart Siengchin

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Contents

LSPM-MAT (Lightweight and Sustainable Materials) Extraction and Characterization of Natural Fiber from Herbaceous Residues of Orthosiphon aristatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chang Koon Wong, Nadia Adrus, Jamarosliza Jamaluddin, Woan Qian See, Nur Aina Farhana Mat Nasir, and Muhammad Aqil Mohd Farizal Morphology, Isothermal Crystallization Kinetics and Mechanical Properties of Polyvinyl Alcohol/Aloe Vera Electrospun Nanofibers . . . . . Siti Norasmah Surip, Jaka Fajar Fatriansyah, Khairunnadim Ahmad Sekak, Nur Areisman Mohd Salleh, Andreas Federico, and Nur Athirah Abdullah Shukry Electrospun Porous Carbon Nanofibers from PVDF Source . . . . . . . . . . . B. D. S. Deeraj, Karthika Menon, and Kuruvilla Joseph

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Thermal Insulation for Refrigeration Pipe Made of Polyurethane Reinforced Coconut Husk and Rice Husk . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. M. Khalid, M. Y. M. Zuhri, A. A. Hairuddin, and A. As’arry

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Vibro-acoustic Behavior of GFRP Curved Panel Under Non-uniform Thermal Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bhaskar Meesala, Pankaj Chaupal, and Prakash Rajendran

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Study the Mechanical Characteristics of NaOH & SLS Treated Cotton-Kenaf Fabric Reinforced Epoxy Composites Laminates . . . . . . . . . A. Karthik, M. Bhuvaneswaran, and P. S. Sampath

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Green Synthesis of Silver/Iron(Ag/Fe) and Copper/Iron(Cu/Fe) Nanoparticles for Cytotoxic Investigation on Henrietta Lacks(HeLa) Cancer Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. Raja Nandhini, H. Joy Prabu, Ebenezer Thaninayagam, R. R. Gopi, I. Johnson, and Arockiasamy Felix Sahayaraj

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LSPM-MAN (Manufacturing Technologies for Lightweight Polymeric Materials) Effect of Manufacturing Techniques on Mechanical Properties of Natural Fibers Reinforced Composites for Lightweight Products—A Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. Sasi Kumar, S. Sathish, M. Makeshkumar, S. Gokulkumar, and A. Naveenkumar

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Characterization of Muntingia calabura Fiber as a Composite Reinforcement with Bleaching Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Hastono Wijaya, Wirabbany Rukmana, Femiana Gapsari, Francisca G. U. Dewi, Putu Hadi Setyarini, Thesya M. Putri, and Clarissa Ratusima Arifi Bio-waste Composite Recycling Using 3d Printing: A Review . . . . . . . . . . 131 Shashwath Patil and T. Sathish Preparation of Transparent Thin Film from Cellulose Extracted from Oil Palm Empty Fruit Bunch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 See Woan Qian, Nadia Adrus, and Jamarosliza Jamaluddin Development and Characterization of Glycine Max Seed Powder Blended with Unidirectional Agave Fourcroydes Reinforced Epoxy Nanocomposite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 S. Gokulkumar, T. Kannan, N. Karthi, S. Sathish, L. Prabhu, M. Aravindh, and J. Alex Mechanical Properties and Abrasion Resistance of 3D Printed Lightweight CF-Reinforced PLA/ABS Composites Using Design of Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 B. Suresha, Vikas Hanamasagar, Imran M. Jamadar, S. L. Arvind, and H. M. Somashekar Tribological Characterization of Two Different Elastic Polymers Produced via FDM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 Enes Aslan and Gül¸sah Akincio˘glu Effect of Mixing Parameters on the Friction Performance of Non-asbestos Organic Based Automotive Brake Friction Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 G. Sathyamoorthy, R. Vijay, and D. Lenin Singaravelu Increasing the Lifetime of Mill Rolls by Applying Polymer Materials on Their Bodies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 S. I. Platov, D. V. Terentyev, E. Yu. Zvyagina, L. F. Kerimova, M. A. Levantsevich, A. Ya. Grigoriev, and V. L. Basiniuk Impregnation of Wood Derived Scaffolds with Cellulose Acetate . . . . . . . 223 Winfried A. Barth, Arndt Weiske, and Steffen Fischer

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Development of Cassava Starch-Based Biodegradable Plastic with PCC for Industrial Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Emekwisia C. Chukwudubem, Osita M. Chinazor, Ibeh T. Chukwuka, and Ezekwesili C. Chinecherem Identifying the Effect of Stacking Sequence on Water Absorption, Mechanical and Fracture Properties of Flax/Glass Hybrid Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 Yashwant Munde, Avinash Shinde, Prashant Anerao, and I. Siva LSPM-DES (Design Optimization of Lightweight Polymeric Materials) Rheological Properties of Polyacrylamide and Modified Polyacrylamide Under Specific Heating Effect and pH Effect Between Fann Viscometer and Marsh Funnel . . . . . . . . . . . . . . . . . . . . . . . . 267 Jin Kwei Koh, Chin Wei Lai, Mohd Rafie Johan, Sin Seng Gan, and Wei Wei Chua The Effect of Overlap Length on Adhesive Bonded Composite Joint Using Digital Image Correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 Avinash Thirunavukarasu and Rahul Singh Sikarwar Experimental Investigations on the Effect of Carbon Nanotubes and Nanoclay Additives on Thermo-Kinetics and Mechanical Characteristics of Acrylonitrile Butadiene Styrene (ABS) . . . . . . . . . . . . . 291 S. L. Aravind, H. P. Bharath, B. Suresha, B. Harshavardhan, Imran M. Jamadar, P. K. Samal, and A. Anand Molecular Energies of Lightweight Al, Cu and Alloys: Evaluation and Insights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 Aditya Kataria, Akarsh Verma, Sachin Sharma, Sanjay Mavinkere Rangappa, and Suchart Siengchin Impact of Different Parameters on Adhesively Bonded Composite Joint on Shear Strength—A Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321 Vinayak S. Hiremath, D. Mallikarjuna Reddy, Rajashekara Reddy Mutra, and Gopalan Venkatachalam Preparation and Characterization of Biodegradable Polyester-Based Shape-Memory Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 N. W. Mohd Rusli, N. Adrus, N. J. Jusoh, N. A. Hamidon, A. A. Bowo Leksano, J. Jamaluddin, and S. A. Samsudin Design and Development of Light Weight Antenna Using Polydimethylsiloxane (PDMS) for Biomedical Applications . . . . . . . . . . . . 351 T. A. Karthikeyan, M. Nesasudha, and S. Saranya

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Design Optimization of Kapton Polyimide Based Wearable Antenna for Biosensing Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363 S. Saranya and B. Sharmila Experimental Analysis on Mechanical Properties of Hemp/Rice Cereal Fibre Reinforced Hybrid Composites for Light Weight Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377 J. Venkatesh, M. Bhuvaneshwaran, and P. Jagadeesh Mechanical and Wear Behavior of Halloysite Nanotubes Filled Silk/Basalt Hybrid Composites Using Response Surface Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 S. M. Darshan, B. Suresha, B. Harshavardhan, Mohan B. Vanarotti, Sunil Waddar, Shijo Thomas, and L. Francis Xavier A Brief Review on Structural Applications of FRP Nanocomposites . . . . 403 S. S. Vinay Stealth Carbon Nano-tubes (S-CNTs): AI/ML Based Modeling of Nano-structured Composites for Attenuation and Shielding in Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425 Hemaraju Pollayi and Praveena Rao Design of Carbon Nano-tubes (CNTs) for Crack Prevention in Concrete of RCC Beam-Column Connections Subjected to Cyclic Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443 Praveena Rao and Hemaraju Pollayi Geopolymeric Cross-Linking Compressed Lateritic Soil-Based Bricks: An Innovative Eco-friendly Building Material with 60 Mpa of Compressive Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455 D. Ben Ghida Development and Proposal of Thermal Insulation Using Recycled Materials in Extreme Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469 Benoudjafer Ibtissam and Benoudjafer Imaneb

About the Editors

Assoc. Prof. Dr. Sanjay Mavinkere Rangappa is currently working as a Senior Research Scientist/Associate Professor and also ‘Advisor within the office of the President for University Promotion and Development towards International goals’ at King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand. He received the B.Engg. (Mechanical Engineering) in the year 2010, M.Tech. (Computational Analysis in Mechanical Sciences) in the year 2013, Ph.D. (Faculty of Mechanical Engineering Science) from Visvesvaraya Technological University, Belagavi, India in the year 2018 and Post Doctorate from King Mongkut’s University of Technology North Bangkok, Thailand, in the year 2019. He is a Life Member of Indian Society for Technical Education (ISTE) and an Associate Member of Institute of Engineers (India). He is an Associate Editor of Heliyon Elsevier (Materials Science) and Frontier Materials Journals. Also acting as a Board Member of various international journals in the fields of materials science and composites. He is a reviewer for more than 150 International Journals (for Nature, Elsevier, Springer, Sage, Taylor and Francis, Wiley, American Society for Testing and Materials, American Society of Agricultural and Biological Engineers, IOP, Hindawi, NC State University USA, ASM International, Emerald Group, Bentham Science Publishers, Universiti Putra, Malaysia), also a reviewer for book proposals, and international conferences. In addition, he has published more than 250 articles in high-quality international peerreviewed journals indexed by SCI/Scopus, nine editorial corners, 60 book chapters, one book, 32 books as an editor (Published by lead publishers such as Elsevier, Springer, Taylor and Francis, Wiley), and also presented research papers at national/ international conferences. His many articles got top-cited in various top journals (Journal of Cleaner Production, Carbohydrate Polymers, International Journal of Biological Macromolecules, Journal of Natural Fibers, Polymer Composites, Journal of Industrial Textiles). He is a lead editor of several special issues. Based on google scholar, the number of citations amounts to 13000+ and his present H-index is 60 with i10-Index of 196. In addition, one Thailand patent and two Indian patents are granted. He has delivered keynote and invited talks at various international conferences and workshops. His current research areas include Natural Fiber Composites, Polymer Composites, and Advanced Material Technology. He has received a ‘Top xvii

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About the Editors

Peer Reviewer 2019’ award, Global Peer Review Awards, Powered by Publons, Web of Science Group. The KMUTNB selected him for the ‘Outstanding Young Researcher’ Award 2020 and Outstanding Researcher’ Award 2021. He is recognized by Stanford University’s list of the world’s Top 2% of the Most-Cited Scientists in Single Year Citation Impact 2019 and also for the year 2020. In 2021, he is recognized by Stanford University’s list of the world’s Top 2% of the Most-Cited Scientists in Single Year Citation Impact and also in Career = long Citation impact. He is listed in ‘Top 100 Scientists’ in Thailand, by AD Scientific Index. Prof. Dr.-Ing. habil. Suchart Siengchin is President of King Mongkut’s University of Technology North Bangkok. He has received his Dipl.-Ing. in Mechanical Engineering from University of Applied Sciences Giessen/Friedberg, Hessen, Germany in 1999, M.Sc. in Polymer Technology from University of Applied Sciences Aalen, Baden-Wuerttemberg, Germany in 2002, M.Sc. in Material Science at the ErlangenNürnberg University, Bayern, Germany in 2004, Doctor of Philosophy in Engineering (Dr.-Ing.) from Institute for Composite Materials, University of Kaiserslautern, Rheinland-Pfalz, Germany in 2008 and Postdoctoral Research from Kaiserslautern University and School of Materials Engineering, Purdue University, USA. In 2016 he received the habilitation at the Chemnitz University in Sachen, Germany. He worked as a Lecturer for Production and Material Engineering Department at The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), KMUTNB. He has been full Professor at KMUTNB and became the President of KMUTNB. He won the Outstanding Researcher Award in 2010, 2012 and 2013 at KMUTNB and National Outstanding Researcher Award for the year 2021 in engineering and industrial research by National Research Council of Thailand (NRCT). His research interests in Polymer Processing and Composite Material. He is Editorin-Chief: KMUTNB International Journal of Applied Science and Technology and the author of morethan 400 peer-reviewed journal articles, 15 editorial corners, 80 book chapters, one book, and 35 books as an editor. He has participated with presentations in more than 45 International and National Conferences with respect to Materials Science and Engineering topics. He has recognized and ranked among the world’s top 2% scientists listed by prestigious Stanford University.

LSPM-MAT (Lightweight and Sustainable Materials)

Extraction and Characterization of Natural Fiber from Herbaceous Residues of Orthosiphon aristatus Chang Koon Wong , Nadia Adrus , Jamarosliza Jamaluddin , Woan Qian See , Nur Aina Farhana Mat Nasir , and Muhammad Aqil Mohd Farizal

Abstract Agricultural residues are rich sources of cellulose that have garnered research interests as one of the sustainable raw materials in composite manufacturing. Herbaceous residues from medicinal plants are promising sources of cellulose too, although they have not been well explored. This paper attempts to extract and characterize the novel cellulosic fibers from Orthosiphon aristatus stem fiber (OASF), then to evaluate its potential as natural filler. The quality enhancement of OASF has been processed through different pre-treatments like dewaxing, alkaline treatment, and bleaching. The fiber properties were investigated in terms of fiber yield, Fouriertransform-infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The findings from this study suggested that OASF pre-treatments could yield cellulosic fiber of about 25% with greater cellulose purity. The physical appearance and FTIR results revealed that the pre-treatments eliminated a significant amount of hemicellulose and lignin, resulting cellulose-rich fiber. The TGA results showed that degradation of hemicellulose and decomposition of cellulose started at Tonset = 295.53 °C, resulting in weight loss of 21.37% and 57.91%, respectively. Meanwhile, pre-treated OASF shows a maximum degradation temperature (Tmax = 329.25 °C), which is comparable with other plant fibers (Tmax ranges from 300 to 400 °C). This proves that pre-treated OASF has the potential to be employed as natural filler for reinforcing applications. Notably, this study can aid the pre-treatment of natural cellulosic fiber and the exploration of new sources from residues of herbaceous plants. Keywords Orthosiphon aristatus · Pre-treatment · Fiber extraction · Cellulose fiber · Natural fiber

C. K. Wong · N. Adrus (B) · J. Jamaluddin · W. Q. See · N. A. F. Mat Nasir · M. A. Mohd Farizal Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_1

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1 Introduction In recent years, researchers have been focusing on the production of natural polymers that can replace synthetic polymers. Due to their hydrophilicity, biodegradability and biocompatibility, natural polymers utilized in polymer industry have demonstrated potential for various applications. Cellulosic fiber is the most attractive source of natural polymer due to its abundance in nature and high biocompatibility [1]. Numerous studies have demonstrated the use of natural fibers as reinforcements in polymer matrices, specifically from plant fibers [2]. Hemp, sisal, banana, jute, ramie and pineapple leaf are often used for low and medium load structural and semistructural applications [2]. Furthermore, current estimates of future green, sustainable and renewable products indicate a substantial growth in the usage of natural cellulose fiber [3]. Agricultural waste is regarded as one of the most promising biomass resources globally. It is anticipated that by 2025, the production of agricultural waste in Malaysia would increase to 0.210 tonnes per year from the current 0.122 tonnes per year [4]. For instance, sugarcane and pineapple are yielded annually around 0.7 million metric tonnes and 0.36 million tonnes, respectively in Malaysia [3]. It is anticipated that these agricultural wastes would include significant amounts of cellulose, which might be utilised to produce value-added products. Generally, agricultural waste comprises of lignocellulosic biomass, which constituted mainly cellulose (35– 65%), hemicellulose (20–45%), and lignin (10–25%) [5]. Among them, cellulose is thought to be the most prevalent naturally-occurring organic molecule that makes up the majority of plant cell walls [6]. Nevertheless, as cellulose is the primary constituent of all plants, the cellulose content of herbaceous residue from medicinal plants must not be disregarded. As a tropical nation, Malaysia is recognised for its cultivation of various medicinal plants, such as Misai Kucing, also known as Orthosiphon aristatus (OA) [7]. According to Department of Agriculture Malaysia [8], Misai Kucing output has grown from 21.31 metric tonnes in 2018 to 41.15 metric tonnes in 2020 and projected to increase continually. In fact, the leaves of OA are favoured over the stems for phytochemical extraction because of their higher medicinal value [9]. Nonetheless, this residue has many undiscovered and underutilised potential, especially its stem fiber i.e., Orthosiphon aristatus stem fiber (OASF). Therefore, maximising the herbaceous residue’s usage by isolating its cellulose content could be used to produce value-added products and aid in the management of agricultural waste issues, simultaneously [10]. Up to now, the cellulose extraction from OASF has yet to be reported in literature. Natural fibers are usually pre-treated chemically to improve their properties due to their inherent drawbacks in terms of hydrophilicity, low or weak interfacial bonding with matrix, presence of lignin, wax and other carbohydrates [2]. Thus, an optimal cellulose extraction method of cellulose with maximum yield and purity is recommended. Chemical pre-treatment is among the effective approaches for isolating cellulose from herbaceous residue, which usually comprises of using alkaline [11] or bleaching [12]. In prior study, hemicellulose and lignin were eliminated via alkali

Extraction and Characterization of Natural Fiber from Herbaceous …

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treatment and bleaching, resulting in the extraction of cellulose [10, 13]. However, different natural fibers are extracted under distinct circumstances. Thus, establishing an efficient procedure for cellulose extraction from OASF is critical for maximizing the extraction and purification of cellulose. In this work, cellulose was extracted from OASF by a novel method which includes dewaxing, alkaline treatment and bleaching to eliminate amorphous components (hemicellulose and lignin). The physical, thermal, and chemical properties are determined during characterization. This work aims as a pioneer of establishing a solid foundation on the cellulose extraction from herbaceous residue in order to determine its possible applicability as a natural filler in polymer matrix.

2 Materials and Method 2.1 Materials OASF was obtained from HERBagus Trading (Malaysia), Johor. Ethanol (EtOH) and sodium hydroxide (NaOH) were purchased from QREC (Asia) Sdn. Bhd. Toluene was obtained from MERCK Sdn. Bhd. and hydrogen peroxide (H2 O2 ) was obtained from Solvay Interox Pty Ltd.

2.2 OASF Preparation The novel cellulose extraction from OASF was performed with modifications from various studies [12, 14–16]. At first, OASF were dewaxed in a 2:1 toluene/ethanol (v/v) mixture with a total volume of 600 mL at 80 °C for 4 h before being washed in distilled water at 50 °C for 2 h [14]. The dewaxed OASF was then alkaline treated for 3 h at 80 °C in 600 mL NaOH solution (5% w/v) [10]. Afterwards, a 300 mL H2 O2 solution (40% w/v) was used to bleach the OASF for 2 h at 90 °C, and this procedure was repeated for second time [12, 16]. After each treatment, OASF was filtered and rinsed until pH 7. The pre-treated OASF was then oven-dried at 50 °C for 24 h [10].

2.3 Determination of Fiber Yield Equation 1 was used to calculate the yield of fiber extracted from OASF, WU is the weight of untreated OASF and W E is the weight of treated OASF [11].

6

Derivative Weight (%/min)

TGA curve DTG curve

Weight (%)

Fig. 1 Scheme for the determination of the temperature of initial degradation (Tonset ), percentage of residues and temperature of maximum degradation (Tmax )

C. K. Wong et al.

Residue

Tonset

Tmax

Temperature (°C)

Yield =

WE × 100% WU

(1)

2.4 Thermogravimetric Analysis The fiber was first reduced to micro-size (about 1 mm). This characterisation was performed using a thermal gravimetric analyser (TGA-Model: TGA 7 Perkin Elmer Pyris). At the rate of 10 °C/min in a nitrogen gas (20 mL/min), OASF was heated from 25 to 700 °C [11]. As shown in Fig. 1, the temperature of initial degradation (Tonset ) was calculated by projecting the segments before (horizontal) and after (vertical) the TGA curves’ deflection point. Similarly, the percentage of residues was obtained by the curves’ final point. The temperature of maximum degradation (Tmax ) was determined using the DTG curves’ peaks [17].

2.5 Functional Group Analysis Using IRTracer-100 Fourier Transform Infrared Spectrophotometer (Shimadzu, Japan), the composition in OASF and functional group changes of the various chemical pre-treated cellulose samples were analysed. ATR (Attenuated Total Reflectance) mode spectra were acquired at room temperature with a resolution of 32 scans in the range of 4000–600 cm−1 [10].

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3 Results and Discussion 3.1 Determination of Fiber Yield Natural plant fibers consist mostly of cellulose, which is composed of helically wrapped microfibrils held together by an amorphous lignin matrix [18]. Lignin is important for regulating the transport of liquid in plants, defending against biological attack, and providing stems with resistance to gravity and wind [19, 20]. Moreover, it is hypothesised that the hemicellulose present in the natural fibers functions as a compatibilizer between cellulose and lignin. To boost the quality of cellulose in natural fibers, OASF was chemically pre-treated to isolate cellulose and eliminate the fiber impurities. The amorphous regions could be hydrolysed by the chemical treatment of cellulose microfibrils, leaving behind a crystalline residue [21]. As indicated in Fig. 2, the fiber yield of OASF after a series of treatments was around 25%. The weight loss after extraction was attributed to the degradation of hemicellulose and lignin via dewaxing, alkaline treatment, and multiple bleaching process [10]. The appearance of the acquired OASF was observed before and after treatment. The untreated OASF were naturally branching and dark brownish in colour, as shown in Fig. 3a. Due to the fact that dewaxing only eliminates the toluene-ethanol soluble content, but not the lignocellulosic constituents of the fiber, there was no noticeable change in colour or texture after dewaxing (Fig. 3b), as also reported by Liew et al. [14]. After alkaline treatment, the OASF looked lighter in colour and fluffier in

Fig. 2 Weight of untreated OASF, dewaxed OASF, alkaline-treated OASF, 1st bleached OASF, and 2nd bleached OASF, showing gradual decrease in weight

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Fig. 3 The physical appearance of a untreated OASF, b dewaxed OASF, c alkaline-treated OASF, d 1st bleached OASF and e 2nd bleached OASF, showing changes in colour and texture

texture (Fig. 3c). This difference can be attributed to the removal of hemicellulose and lignin after the alkaline treatment with NaOH [22]. Due to their random amorphous structure, hemicellulose and lignin are claimed to be more susceptible to chemical treatment [16]. After 1st bleaching, OASF becomes slightly yellowish in colour and fluffier (Fig. 3d). This is because bleaching involves removing the residual lignin from the fibers [12]. According to Owonubi et al. [16], multiple bleaching is needed to further remove the residual lignin. Thus, 2nd bleaching was undertaken, transforming OASF into a pure white cotton-like structure (Fig. 3e), indicating the majority of the hemicellulose and lignin had been removed [23].

3.2 Functional Group Analysis The difference between the functional groups of untreated OASF and pre-treated OASF was determined using FTIR analysis (Fig. 4). Table 1 presents an overview of band analysis. Peaks in the range of 2920–2850 cm−1 (asymmetric stretching of CH and CH2 in cellulose and hemicellulose) and around 1729 cm−1 (C=O stretching vibration linkage of the ester group in hemicellulose) were seen in untreated OASF (Fig. 4a) and were amplified after dewaxing. This is thought to be due to the increased

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(a) Untreated OASF

(b) Dewaxed OASF

(c) Alkaline Treated OASF

(d) 1st Bleached OASF

(e) 2nd Bleached OASF

4000 3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000

800

600

Wavelength (cm-1)

Fig. 4 FTIR spectra of a untreated OASF, b dewaxed OASF, c alkaline-treated OASF, d 1st bleached OASF and e 2nd bleached OASF

exposure of lignocellulosic components in OASF as surface wax is removed during dewaxing [24]. After alkaline treatment, peaks around 2920, 2850 and 1729 cm−1 that correspond to the presence of hemicellulose have diminished, which is also observed in Lai and colleagues’ work [10]. Similarly, peaks at 1620 and 1270 cm−1 , which indicate the presence of lignin also diminished. This demonstrates that alkaline treatment have eliminated a significant amount of hemicellulose and lignin from OASF [10, 22]. The broad absorption band in the range of 3500–3000 cm−1 indicates the presence of O–H groups in all samples. After multiple bleaching processes, peaks that confirm the presence of cellulose (3500–3000, 1373, 1316, 1100–1000, 902 and 897 cm−1 ) have enhanced. This may be related to the increased cellulose content along with the decreased hemicellulose and lignin content after bleaching treatments [23]. Therefore, these chemical pre-treatments have successfully eliminated the majority of hemicellulose and lignin from OASF, leaving a cellulose-rich fiber. This result is consistent with the pure white cotton-like appearance of the 2nd bleached OASF (Fig. 3c).

3.3 Thermogravimetric Analysis Figure 5 depicts the results of TGA and DTG, which were done to determine the thermal stability of the OASF over a range of temperatures. The initial stage of weight

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Table 1 Summary Interpretation of FTIR result of a untreated OASF, b dewaxed OASF, c alkaline treated OASF, d 1st bleached OASF, and e 2nd bleached OASF Wavelength (cm−1 )

(a)

(b)

(c)

(d)

(e)

Functional group

References

3000–3500

✓

✓

✓

↑

↑

O–H stretching vibration of a hydroxyl group of cellulose

[25]

2920, 2850

✓

↑

↓

↓

↓

C–H stretching vibration of cellulose and hemicellulose

[26]

1729

✓

↑

↓

↓

↓

Carbonyl C=O stretching of the acetyl group of hemicellulose

[22]

1620

✓

✓

↓

↓

↓

α-keto carboxylic acids in [27] lignin

1373

✓

✓

✓

↑

↑

CH2 and C–H groups of cellulose

[27]

1316

✓

✓

✓

↑

↑

C–O groups of the aromatic ring in polysaccharides

[27]

1270

✓

✓

↓

↓

↓

C–O stretching of the acetyl group of lignin

[10]

1000–1100

✓

✓

✓

↑

↑

C–O group of secondary alcohols and ethers functions of cellulose

[28]

902, 897

✓

✓

✓

↑

↑

β-glycosidic linkage [12] between monosaccharides in cellulose

loss in OASF began at ambient temperature to 147.53 °C and resulted in an 7.6% weight loss owing to the vaporisation of moisture content [13]. Next, degradation of hemicellulose and decomposition of cellulose occurred at Tonset = 295.53 °C, resulting in weight losses of 21.4% and 57.9%, respectively [11]. The fact that the percentage of residue is 0.56% shows that the lignin content has been successfully eliminated by the chemical pre-treatments. This is because cellulose is easily decomposed when lignin is removed from the fiber owing to its easier thermal accessibility. Hence, it is reported that the reduced lignin content will result in a lower residue yield value [29]. The DTG curves indicate that Tmax occurs at 329.25 °C. This is comparable to the Tmax of cellulose extracted from various plant fiber, ranges from 300 to 400 °C, as displayed in Table 2. More comparisons of findings are available in the research of Seki et al. [30]. In short, the Tmax proves that OASF is a viable source of high-quality cellulose that can be used in composite manufacturing for temperature applications greater than 250 °C [31].

Extraction and Characterization of Natural Fiber from Herbaceous …

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110

10

100 0

Weight (%)

80

-21.4%

70 -10

60 50 40

-57.9%

-20

30

Derivative Weight (%/min)

-7.6%

90

20 -30

10

-12.1%

329.25

0 0

100

200

300

400

500

600

700

Temperature (°C)

Fig. 5 TGA and DTG curve of the 2nd bleached OASF

Table 2 Initial (Tonset ) and maximum (Tmax ) thermal degradation comparison of OASF with other fiber sources Fiber source

Chemical pre-treatments

Tonset (°C) Tmax (°C) Reference

OASF

Dewaxed, alkaline treated, bleached

295.23

329.25

This study

214

329

[14]

Green bamboo Dewaxing, bleaching, alkaline treatment cellulose fiber Rice husk

Alkaline treatment, bleaching

277.3

329.4

[13]

Wheat Straw

Dewaxing, bleaching, alkaline treatment

254

304

[23]

Corn stalk

Alkaline-treated, silane-treated

180 - 300

327

[32]

Sugarcane bagasse

Alkali-catalysed hydrothermal treatment, 260.4 bleaching

351.3

[33]

Lemba leaves

Alkaline treatment

286

–

[11]

Kenaf

–

298

364

[34]

Jute

–

297

365

[34]

Sisal

–

291

347

[34]

4 Conclusion This study presents a novel cellulose extraction from herbaceous residues of OASF (dewaxing, alkaline treatment, and bleaching processes). The pure white cotton-like appearance and FTIR results indicate that high purity cellulose has been isolated from OASF via the elimination of lignin and hemicellulose, giving a yield of 25%. The Tonset of 295.23 °C and Tmax of 329.25 °C suggest that the thermal stability of

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pre-treated OASF is comparable to various treated plant fibers, showing OASF as a viable source of high-quality cellulose for the application of natural polymer-based composites. In the future, it is recommended to evaluate the crystallinity, tensile strength, and morphology to examine whether OASF could be used in polymer composites as a reinforcing material. In conclusion, this study is envisioned to help in the exploration of novel sources derived from herbaceous plant residues, which may have potential application for natural fiber-reinforced polymer composites. Acknowledgements This study was supported by the Fundamental Research Grant Scheme (FRGS/1/2021/TK0/UTM/02/2) by the Ministry of Higher Education Malaysia, and the Research University Grant (TDR Vote No. 07G02) funded by Universiti Teknologi Malaysia.

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Morphology, Isothermal Crystallization Kinetics and Mechanical Properties of Polyvinyl Alcohol/Aloe Vera Electrospun Nanofibers Siti Norasmah Surip , Jaka Fajar Fatriansyah , Khairunnadim Ahmad Sekak , Nur Areisman Mohd Salleh , Andreas Federico , and Nur Athirah Abdullah Shukry

Abstract The present research aims to determine the morphology, crystallization kinetic of PVA with the addition of aloe vera and its relation to mechanical behaviour. PVA/AV membranes were examined under a field emission scanning electron microscope (FESEM). Mechanical properties of PVA/Aloe vera blending systems were studied via tensile test and isothermal crystallization kinetics of PVA in the blends was investigated by means of differential scanning calorimetry (DSC). FESEM micrographs showed that all types of nanofibers produced were smooth, continuous, and free of beads. PVA + 10%AV produced finest fiber size at about 150 nm. The incorporation of Aloe vera into PVA has resulted in decreasing the tensile strength of the PVA/AV nanofibres. By incorporating 5% Aloe vera, the strength has reduced 49%, from 5.93 MPa to 3.01 MPa. Further increments of Aloe vera loading at 10% and 15% have reduced the strength to 2.02 MPa and 1.12 MPa, respectively. At 10 wt% of Aloe vera loading, however, elongation at break was improved. DSC results show that the Avrami equations are applicable to describe the isothermal crystallization kinetics of the PVA and the blend systems. The addition of Aloe vera generally reduces the Avrami index for all crystallization temperatures. Thus, Aloe vera acts as a promoting agent for the axial crystal growth direction by increasing the thermal gradient, however does not show linear correlation with mechanical properties. Keywords Electrospinning · Nanofibers · Polyvinyl alcohol · Aloe vera

S. N. Surip (B) · K. A. Sekak · N. A. Abdullah Shukry Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia e-mail: [email protected] J. F. Fatriansyah · A. Federico Department of Metallurgical and Materials Engineering, Faculty of Engineering, Universitas Indonesia, 16424 Depok, West Java, Indonesia N. A. M. Salleh Forest Research Institute Malaysia, 52109 Kepong, Selangor, Malaysia © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_2

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1 Introduction A popular technique for creating high-quality polymer nanofibers is electrospinning. It has been demonstrated that nanofibers can be successfully fabricated by this method from a variety of polymers, both bio-based and petroleum-based. Electrospun nanofibers have several outstanding properties, including a high surface area, less in weight, and high porosity [1] and make it suitable for the application in medical fields such as wound patch, tissue regeneration, drug delivery systems, and coating techniques [2]. PVA is a semi-crystalline polymer derived from the hydrolysis of polyvinyl acetate. PVA is also a polymer that is hydrophilic, non-toxic, biocompatible, and water soluble. As well as being chemically resistant and having good mechanical properties, PVA received high demand in industrial applications due to its mechanical properties and resistance to organic solvents [3]. In terms of antimicrobial activity, Aloe vera (AV) is a promising ingredient. Aloe vera has been used as a medicinal herb because of its ability to promote wound healing [4] and treat skin burns. It is made up of three components: structural, chemical, and polysaccharide. Salicylic acid, along with other chemicals and organic compounds, is the active ingredient in polysaccharides that promote wound healing [5]. The presence of Aloe vera was proven beneficial as scaffold in wound dressing application [6] and accelerating the wound healing process [7]. Additionally, the encapsulation of Aloe vera in PVA electrospun nanofibers exhibits a good biomaterial structure due to its biodegradability and biocompatibility. Incorporation of AV could enhance the antimicrobial ability and promote wound healing due to its chemical compound. However, the presence of AV could alter the molecular structure of PVA and influence its properties such as thermal stability and mechanical. Due to a lack of research reported on the tensile properties of PVA/AV electrospun nanofibers, and its relation to isothermal crystallisation kinetics, this research was focusing on these characteristics. By mixing PVA with different percentages of Aloe vera in distilled water, the solution was then electrospun to fabricate long and continuous nanofibers. The mechanical properties of nanofibers were tested with tensile test, the crystallization kinetics was studied using differential scanning calorimetry and morphology study was done by Field Emission Scanning Electron Microscope (FESEM).

2 Materials and Method 2.1 Materials Polyvinyl alcohol (PVA) was purchased from Sigma-Aldrich and Aloe vera powder extract purchased from A&T Ingredients.

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2.2 Sample Preparation The PVA powder was dissolved in 90 ml of distilled water at a 10% w/v concentration with about 10 g per 90 ml. An electromagnetic stirrer was used to stir the solution at 80 °C for 3 h to obtain a homogeneous solution. Aloe vera powder extract at 5, 10 and 15% were mixed with PVA solution and stirred directly using the same method as mentioned above. Before the electrospinning process, all solutions were cooled down at room temperature.

2.3 Functional Group Analysis PVA/AV nanofiber membranes were produced via electrospinning process. Electrospinning setup (Fig. 1) consists of a DC high-voltage power supply (Gamma BP series), syringe pump for non-medical purposes will ensure feeding capacity of 0– 60 ml/h, and a flatten needle-tip attached to the syringe was connected to the positive electrode. The negative counter electrode of the power supply was attached to the rotating drum acting as the nanofibers collector. The drums were wrapped with an aluminium foil where nanofibers mat can be easily taken out for sample variation. A varied concentration of AV in PVA (as in 2.2) were tested. The optimum conditions are obtained at 15 kV of voltage, feeding rate at 0.5 ml/h and the distance from needle to collector was fixed at 15 cm. The drum winder collector was fixed at 50 rpm. All samples were oven dried for more than 12 h for later stages of characterization and testing. The electrospinning process continued for 6–8 h until a fair amount of thick nanofiber membrane was collected. Fig. 1 Experiment setup of electrospinning

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Fig. 2 Experimental sample for tensile test

2.4 Tensile Test Nanofiber membranes produced are very thin and delicate, thus requiring special handling for tensile tests to avoid damage or slipping from the grips during testing. The samples were cut into 2 cm × 8 cm and paper frames were used in helping positioning the specimen as shown in Fig. 2. The paper frames were clamped between the grips, and the experiment was carried out at a crosshead speed of 5 mm min−1 . Tensile tests were performed in accordance with ASTM D882-97 using an Instron Universal Testing Machine.

2.5 Field Effect Scanning Electron Microscope (FESEM) Morphological structure analysis was carried out using the Field Effect Scanning Electron (FESEM) with a working voltage of 2 kV. Before FESEM analysis, all samples were gold-coated for 3 min to minimize any charging effects. The average diameter of the electrospun nanofibers were analysed via Image J software.

2.6 Thermal Analysis The isothermal crystallization kinetics experiment was conducted using Simultaneous thermal analyzer STA 6000, Perkin-Elmer. To erase their thermal history, the sample was heated from 30 to 200 °C at a scan rate of 10 °C/min. Furthermore, the sample was cooled to a crystallization temperature of 102.5, 105, 110, and 115 °C at a cooling rate of 30 °C/min and maintained for those crystallization temperatures for 30 min to be measured relative crystallinity. Avrami Eqs. (1) and (2) [8] were used to calculate the Avrami index (n), half crystallization time (t 1/2), and crystallization rate constant (k).

Morphology, Isothermal Crystallization Kinetics and Mechanical …

  X (t) = 1 − exp −kt n  t 21 =

ln 2 k

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(1)

 n1 (2)

where X (t) is the relative crystallization as a function of time, k is the crystallization rate, and n is the Avrami index. The value of X (t) can be extracted from STA results by calculating the relative change of heat flow with respect to the area under specific crystallization temperature.

3 Results and Discussion 3.1 Morphology Study All nanofibre samples with Aloe vera concentration (5, 10, 15%) and pure PVA were analyzed by FESEM for surface morphology analysis and their average diameter were calculated. Figure 3 illustrates that the fibers for all types were smooth, continuous, and free of beads. This beaded-free structure could be influenced by the presence of Aloe vera that decreases the membrane conductivity [1]. Figure 3a shows the surface structure of pure PVA with continuous, longitudinal and cylindrical shape of nanofibers. The average diameter of the nanofibers is recorded at 183 nm. The incorporation of 5% Aloe vera into PVA resulted in continuous, spindle-like fibre formation of the nanofiber structure as shown in Fig. 3b. Having continuous fibers without branching is one of the key properties of biomedical applications, especially for drug delivery. More importantly, there is no bead developed after the addition of Aloe vera and the fiber surface is still smooth. The smooth fiber formation indicates that Aloe Vera had been successfully encapsulated inside PVA solution. The average diameter for PVA + 5%AV is 185 nm, which means it is slightly bigger from pure PVA nanofiber membrane. Similar structure was observed for PVA + 10%AV nanofiber membrane as shown in Fig. 3c. The average fiber diameter is 150 nm which is the smallest fiber diameter among all types of membranes produced. According to Munir et al. [9], an increase of AV content will affect the electrostatic forces and coulombic forces. However, at 15% AV loading, the average size of nanofibers is 380 nm, which is about 2.5 times larger than PVA + 10%AV nanofibers. According to Solaberrieta et al. [10] mixing two different solutions resulted in heterogeneous fibre diameters at high AV loadings. By adding AV, certain changes in polymer solutions’ viscosity, rheological properties, and conductivity may occur, which influence the size and shape of electrospun nanofibers.

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Fig. 3 SEM micrographs and average diameter of PVA/AV electrospun membranes at different percentages of AV; a 0%, b 5%, c 10%, d 15%

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3.2 Mechanical Properties An important characteristic to determine the mechanical properties of nanofiber mats are by tensile strength and elongation at break [11]. According to Baghersad et al. [12] Aloe vera is commonly added in nano-membranes for skin substitutes, therefore it should have good mechanical properties to prevent tearing or damage when used on skin to guarantee the comfortness and efficiency of delivering active ingredients/drugs to cells. Figure 4 shows the tensile strength and elongation of PVA/ AV nanofibres. The incorporation of Aloe vera into PVA has resulted in decreasing the tensile strength of the PVA/AV nanofibres. By incorporating 5% Aloe vera, the strength has reduced 49%, from 5.93 MPa to 3.01 MPa. Further increments of Aloe vera loading at 10% and 15% have reduced the strength to 2.02 MPa and 1.12 MPa, respectively. This observation was different from Jegina et al. [11] who reported the increasing of tensile strength with the increment of Aloe vera percentage. Another research on PVA/AV electrospun nanofibers conducted by Sosiati et al. [13] found out that only low concentration of Aloe vera increased the tensile properties. At a high percentage (6% AV) the tensile strength and strain were decreased. On the other hand, a different observation was recorded for the elongation at 10% AV, the nanofibres become more flexible indicating high mobility of PVA chains as compared to nanofibre samples containing 5% AV and 15% AV. This result could be contributed by the fine fibers produced of PVA + 10%AV as discussed in Sect. 3.1. As reported by Maccaferri et al. [14] mechanical behavior of fibrous membrane type could be affected by two main reasons which are a variation of polymeric crystallinity, and the nanofibrous morphology, such as the number of nanofibers intersections. Smaller diameters of nanofiber lead to a higher number of intersections. The addition of AV concentration may also influence the degree of crystallinity, resulting in

Fig. 4 Tensile strength and elongation at break of PVA/AV nanofiber membranes

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changes of mechanical behaviour. Differential scanning calorimetry (DSC) analysis through the calculation on Avrami index was used to determine the crystallization kinetics of PVA/AV nanofibers, which will be discussed in the next section.

3.3 Isothermal Crystallization Kinetics Figure 5 shows the crystallization kinetics curve fitted using the Avrami Eq. (1). Table 1 summarizes the calculated kinetic parameters. A crystallization direction is indicated by the value of n. Axialites and spherulites of radial lamellae have n values of 2 and 3, respectively [15, 16]. Figure 6 shows the samples crystallization dimensions. Table 1 and Fig. 6 show that Aloe vera generally reduces the Avrami index for all crystallization temperatures. Crystal growth becomes more axialite as Aloe vera concentration increases. Thus, Aloe vera acts as a promoting agent for the axial crystal

Fig. 5 Crystallization kinetics curve fitted using Avrami equation at various percentages of AV; a 0%, b 5%, c 10%, d 15%

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Table 1 Avrami index, crystallization rate, half-crystallization time and percentage of crystallinity of all samples Samples

Temp. (°C)

Avrami index (n)

Crystallization rate (k)

Half-crystallization time t 1/2 (s)

Percentage of crystallinity (%)

Pure PVA

102.5

3.48

0.960

0.911

28.82

105

3.99

1.144

0.882

24.16

110

3.41

1.102

0.873

27.41

115

3.54

0.963

0.911

33.57

102.5

3.22

0.722

0.987

34.55

105

3.46

1.472

0.804

36.43

110

3.20

1.194

0.844

32.11

115

3.10

0.805

0.953

44.83

102.5

3.24

0.654

1.018

39.68

105

3.47

1.605

0.829

35.32

110

3.61

1.128

0.874

35.12

115

3.38

1.097

0.873

30.82

102.5

3.11

0.696

0.999

39.23

105

3.05

0.781

0.961

40.35

110

2.85

0.747

0.974

45.5

115

2.99

0.872

0.926

39.28

PVA + 5% AV

PVA + 10% AV

PVA + 15% AV

Fig. 6 Crystallization illustration of crystallization dimension of the samples

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growth direction by increasing the thermal gradient. The more axialite structure is associated with strong negative birefringence which may be useful in film application [17]. However according to Table 1, the addition of Aloe vera does not change the crystallization rate and half-time which means despite promoting growth in axial direction, Aloe vera does not act as a good nucleating agent. But by no means, the percentage of crystallinity Aloe vera added samples is generally higher than pure PVA as demonstrated in Table 1. However, this is contrary to the mechanical properties of PVA/Aloe vera where the tensile strength reduced as Aloe vera was added. This can be understood that the membranes are in a form of fibrous non-woven type. It would therefore be hard to predict a positive linear correlation between crystallinity and tensile strength as in a bulk material. Maccaferri et al. [14] found out that, DSC analysis does not show differences in glass transition temperature nor in degree of crystallinity on Nylon66 electrospun nanofibrous membranes, even the mechanical properties were increased.

4 Conclusion Nanofiber with Aloe vera in 5, 10 and 15 wt% added to PVA solution have successfully produced and their morphology, mechanical and isothermal crystallization kinetics were determined. Addition of aloe vera generally did not affect the surface structure of PVA nanofibers but at higher concentration (15%) has resulted in an increase of the size. Nanofiber diameters of PVA + 10%AV was observed as the finest fiber at about 150 nm and shows highest elongation at break. This result shows that 10%AV is the optimum percentage for PVA/AV nanofibers. The addition of Aloe vera generally reduces the Avrami index for all crystallization temperatures, making the crystal growth become more axialite as the AV concentration increases. There is no linear correlation between isothermal crystallization and mechanical properties of PVA/AV nanofibers membranes. That means, the reduction of mechanical properties of PVA after adding aloe vera were not associated with the crystallization behaviour of the polymer. This could be related to the membrane conditions that form thin fibrous non-woven and not in a bulk. Due to limited research findings, further study could be done for deep understanding of the factors that influence the mechanical behaviour of thin nanofiber membranes. Acknowledgements The authors would like to thank Universiti Teknologi MARA for providing matching grant (100-RMC 5/3/SRP 036/2021) and Universitas Indonesia for granted this research through BISA grant number NKB-679/ UN2.RST/HKP.05.00/2021.

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Electrospun Porous Carbon Nanofibers from PVDF Source B. D. S. Deeraj , Karthika Menon, and Kuruvilla Joseph

Abstract This work aims at preparing low-cost carbon fibers from polyvinylidene fluoride (PVDF) via the electrospinning route that have diverse array of applications across material science. Here, electrospinning—autoclave stabilization—carbonization way was used to achieve the required fibers by systematically optimizing the parameters. We successfully prepared porous carbons via this route and these fibers are proven to have good surface area. The use of autoclave stabilization proved to improve the porosity and surface area. To best of our knowledge, this is the first report that signifies the use of autoclave for stabilization and thereby carbonizing the fibers to convert them to porous carbon fibers. Keywords PVDF · Electrospinning · Electrospun porous carbon fibers

1 Introduction Porous carbon fibers are characterized by the existence of large number of pores in their fiber structure, unlike traditional solid carbon fibers [1]. The presence of these pores on the structure, makes these fibers potential candidates for vast array of applications like filtration, electrode materials, sensing, adsorption and catalysis. Usually, conventional carbon fibers were made from their precursor sources and then after by the step of activation (physical or chemical) pores are introduced or the width of pores are increased in case of carbon fibers. These activated carbon fibers are used in many applications, mainly adsorption. The process of preparation of activated carbon fibers are expensive as an additional step is needed for their preparation. These fibers can be made from different precursors like PAN, pitch, lignin, bio-based precursors etc. Researchers made activated carbon fibers and illustrated their performance [2–8]. In the case of polymers like B. D. S. Deeraj · K. Menon · K. Joseph (B) Department of Chemistry, Indian Institute of Space Science and Technology, Thiruvananthapuram, Kerala 695547, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_3

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polyvinylidene difluoride (PVDF) and polyvinylidene chloride (PVDC), the porous carbon fibers are observed to be produced during the carbonization process, without the need of additional activation step. One such work on PVDC based carbon fibers was reported by Xu et al. [9]. PVDF is semi-crystalline thermoplastic polymer that belongs to class of fluoropolymers, which have a carbon/fluorine bond in their structure [10]. Fluoropolymers are having advantages like chemical resistance, thermal stability, lightweight, ease of processing and high piezoelectric coefficients and more. PVDF consists of CF2 =CH2 monomer units. It will not dissolve readily in all solvents, for dissolving PVDF polar aprotic solvents needs to be used at sufficient heating conditions [11, 12]. PVDF can crystallize into α, β, γ and δ forms, while α phase is the most stable one. PVDF in fiber form have many potential applications in material science [13–15]. Electrospinning technique, is one of the widely used process to prepare continuous fibers [16, 17] these fibers are used for various applications. The conversion of polymer fibers to carbon fibers makes these fibers be used in advanced applications [18, 19]. Porous carbon fibers produced from electrospinning process has applications in gas sensor, photocatalysts, electrodes for EDLC, adsorption, bio-medical and more [20–25]. In case of PVDF based porous carbon fibers, the structural infusibility is developed from the dehydrofluorination process. In this process, PVDF is made to react with strong bases so that the bond structures changes removal of fluorine in the form of fluorides takes place. But, the hydrophobicity of PVDF will restrict the reaction with base, so a catalyst was employed to accelerate the reaction between PVDF and base. The initial report on PVDF dehydrofluorination was performed with NaOH, from all the catalyst they have used they found tetra butyl ammonium bromide (TBAB) to be the most effective catalyst [26]. The effectiveness of TBAB in dehydrofluorination is reported in another work [27]. Ross et al. studied the degradation mechanism in PVDF with and without catalyst [28, 29]. Yamashita et al. report the initial work on PVDF based carbon fibers and films where, 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) is used as base and carbonization was done at temperature of 1300 °C with a heating rate of 2 °C/min in nitrogen [30]. Yamashita et al. prepared PVDF based porous carbon fibers following the same way as done earlier and activated the fibers using carbon dioxide [31]. Conductive PVDF nanofiber composites were prepared with adding varying amounts of carbon nanotubes [32]. Chung et al. investigated the hydrogen storage capacity of PVDF based carbon fibers. They reported that the carbonization temperature has vital role in mesopores and micropore formation and found a linear relationship between hydrogen storage capacity and carbonization temperature [33]. The catalyst assisted carbonization for the PVDF nanofibers was done by Hong et al. [34]. They found the use of catalyst promotes the formation of ultra-micropores and used for hydrogen storage application. A highly porous electrode material was developed from PVDF fibers by Yang et al. [35]. Porous carbon fibers were obtained with a surface area of 380 m2 /g and found to have excellent performance in redox reaction. Hong et al. prepared porous carbon fibers from PVDF at low carbonization temperatures and used for carbon dioxide

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adsorption [36]. PAN/PVDF electrospun mats were converted to carbon adsorbents for CO2 capture by Heo et al. [37]. Lee et al. prepared porous carbon fibers with good surface area from PVDF and polyimide and used it for supercapacitor application [38]. In this work, PVDF is considered as the precursor polymer source and by the process of electrospinning—autoclave stabilization—carbonization, porous carbon fibers were prepared. the effect of electrospun parameters, stabilization parameters on the resultant fibers was investigated and reported. This work paves way in preparation of porous carbon fibers with high surface area that can be employed in multifunctional applications.

2 Experimental Section 2.1 Materials PVDF polymer (molecular weight: 275,000) used in this work is procured from Sigma Aldrich. DMF, Acetone (analytical reagent (AR) grade) were used as solvents. Sodium hydroxide and Potassium hydroxide used in this work is procured from Emparta and Tetra butyl ammonium hydroxide was procured from Sigma Aldrich.

2.2 Preparation of Porous Carbon Fibers The preparation of carbon fibers involve three steps, (1) electrospinning to produce fibers of PVDF, (2) stabilization step and finally, (3) the carbonization step to prepare the carbon fibers. The electrospinning was done in a ESPIN-NANO horizontal setup electrospinning apparatus. The stabilization was done in an autoclave and the carbonization is done in a high temperature furnace.

3 Results and Discussion 3.1 Electrospinning Step Morphology of electrospun fibers. PVDF used in this work was dissolved in a cosolvent system of DMF and acetone and electrospinning fibers was tried at different solvent ratios. From the optical images, the fibers produced at the ratio of 60:40 produced good fibers and this ratio was selected for the study. The optical image of fibers observed in optical microscope is presented in Fig. 1. Further at this solvent

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ratio, PVDF with 15 and 20 w% is electrospun at different flow rates and the data is presented in Table 1. From the table, we can observe both the polymer concentrations produced beadless fibers. The SEM images of the fibers produced at PVDF 20 w% with respect to different flow rates such as 0.25, 0.50, 0.75 and 1.00 ml/hr was studied. From the analysis, it was observed that the average diameter of the fibers increased with the increase in the flow rate. With increase in the amount of liquid ejecting from the needle, the average diameter of the spun fibers too increased. From this a flow rate of 0.25 ml/hr is considered for the further testing.

Fig. 1 Optical images of beadless PVDF fibers

Table 1 Electrospun parameters and remarks Polymer concentration (%)

DMF/acetone ratio

Voltage (KV)

Distance (cms)

Flow rate (ml/ hr)

Remarks

15

60:40

11

16

1

Beadless fibers

15

60:40

11

16

0.75

Beadless fibers

15

60:40

11

16

0.5

Beadless fibers

15

60:40

11

16

0.25

Beadless fibers

20

60:40

11

16

1

Beadless fibers

20

60:40

11

16

0.75

Beadless fibers

20

60:40

11

16

0.5

Beadless fibers

20

60:40

11

16

0.25

Beadless fibers

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Characterization of electrospun fibers. The FTIR spectrum of the prepared PVDF mats was presented in Fig. 2. From the figure, we can observe the peaks 840, 1275 and 1420 cm−1 , that corresponds to the β-phase of PVDF. During the spinning process, mechanical and electric field was applied to the PVDF and these results in the formation of β-phase. Usually, stretching and nanofillers are added to PVDF to get improvement in β-phase, but electrospun fibers readily have a β-phase, that can be used for piezoelectric applications. The water contact angle of the prepared PVDF fiber mat was investigated and a contact angle of ~ 130° was observed. As the surface roughness of the electrospun PVDF is more, enhanced hydrophobicity was observed. The XRD peaks of the prepared mats are presented in Fig. 3, from which the phase is observed. From the pattern, the sharp peak at 21°, signifies the presence of the β-phase and the small peak around 40° indicates the presence of α- phase in the electrospun PVDF mat. Fig. 2 FTIR spectrum of electrospun PVDF

Fig. 3 XRD spectrum of electrospun PVDF

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3.2 Stabilization Step The electrospun PVDF mats are subjected to thermal stabilization at 400 °C, at a heating rate of 5 °C/min in muffle furnace. The SEM micrographs of the samples after this step was observed and presented in Fig. 4. We can see that all the fibers got melted and thus the thermal stabilization method was not effective for PVDF, as the melting point of PVDF is around 170 °C. From the SEM Image it is very clear that the usually way of thermal stabilization used in case of PAN polymer is ineffective in case of PVDF. So, we used a dehydrofluorination mechanism for converting PVDF polymer to carbon. In literature, researchers tried with different strong bases and catalysts for this purpose. In our case, dehydrofluorination step in an autoclave, in presence of a phase change catalyst is found to be effective for making carbon fibers. For this strong bases Sodium hydroxide (NaOH) and potassium hydroxide (KOH) was used. The catalyst used here is Tetra butyl ammonium hydroxide (TBAH). The reaction between the inorganic and organic phase can be mediated by phase transfer catalyst. Usually, they are quarternary ammonium salts or quarternary phosphonium salts which can transfer anions between the inorganic salt and the organic phase. In the case of PVDF these catalysts are used for accelerating the reaction and to confirm the successful dehydrofluorination reaction. The conditions and remarks of the study are presented in Table 2. The reaction temperature, catalyst concentration, reaction time and base concentration have a significant effect on dehydrofluorination reaction. Hence, we have conducted a series of experiments for determining the same. From our observations, 4 M NaOH or 4 M KOH, 0.11 M Tetrabutyl ammoniumhydroxide at 70 °C for 1 h was found to be the optimum conditions for dehydrofluorination of the PVDF mat. The colour change from white to black/dark brown is an indication of dehydrofluorination. The FTIR spectra was used to confirm the successful dehydrofluorination Fig. 4 SEM Micrograph of electrospun PVDF mat after thermal stabilization

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Table 2 Different dehydrofluorinating conditions with surfactant and remarks Solvent

Surfactant (0.11 M)

Molarity of solvent (M)

Temperature (°C)

Time (h)

Remarks

NaOH

TBAH

20

70

1

Colour changed

KOH

TBAH

20

70

1

Colour changed

NaOH

TBAH

10

70

1

Colour changed

KOH

TBAH

10

70

1

Colour changed

NaOH

TBAH

1

70

1

No colour change

KOH

TBAH

1

70

1

No colour change

NaOH

TBAH

2

70

1

Slight colour change

KOH

TBAH

2

70

1

No colour change

NaOH

TBAH

3

70

1

Colour changed

KOH

TBAH

3

70

1

Slight colour change

NaOH

TBAH

4

70

1

Colour changed

KOH

TBAH

4

70

1

Colour changed

and presented in Fig. 5. In the figure, the peak corresponding to 1617 cm−1 confirms the partial dehydrofluorination. With the partial dehydrofluorination, small extent of the conjugated carbon double bonds was introduced in the structure and fluorine will be removed as fluorides. Fig. 5 FTIR of dehydrofluorinated fiber

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Fig. 6 SEM images of PVDF based carbon fibers

3.3 Carbonization Step The partially dehydrofluorinated fibers were washed with both methanol and distilled water many times and dried in air oven, then after subject to carbonization at 900 °C, at heating rate of 1 °C/min, in an inert atmosphere in presence of Argon. The SEM micrographs of the prepared carbon fibers are presented in Fig. 6. From the figure, the profiles of carbon fibers produced from PVDF mats at different flow rates are presented. For carbon fibers prepared from 1 ml/hr spun mats the mean diameter is 780.65 nm and the carbon content in the fiber was 75.84%. For carbon fibers prepared from 0.75 ml/hr spun mats the mean diameter is 616.7 nm and the carbon content in the fiber was 81.68%. For carbon fibers prepared from 0.5 ml/hr spun mats the mean diameter is 308.2 nm and the carbon content in the fiber was 80.33%. For carbon fibers prepared from 0.25 ml/hr spun mats the mean diameter is 313.3 nm and the carbon content in the fiber was 82.80%. For carbon fibers prepared from 0.15 ml/hr spun mats the mean diameter is 565.45 nm and the carbon content was 85.31%. The carbon fibers produced from NaOH/TBAH as dehydrofluorinating agent with DMF/Acetone in the ratio of 60/40 and with flow rate 0.25 ml/hr was found optimum and further testing was done on those samples. The surface area of the carbon fibers was studied by N2 adsorption-desorption isotherm. From the results, the carbon fibers are observed to have surface area of 1528.7 m2 /g and pore width of 3.61 nm. The analysis of pore size distribution signifies that the carbon fibers contains combination of micropores, mesopores and macropores with the majority of pores in the mesoporous domain. The carbon dioxide adsorption by the prepared carbon fibers were studied using the volumetric method.

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Fig. 7 XRD analysis of PVDF based carbon fiber

An adsorption of 3.68 mmol/g and 0.68 mmol/g were observed at temperature of 0 °C and 25 °C respectively. The XRD of the porous carbon fibers was confirmed by XRD and presented in Fig. 7. The broad peaks at 23° and 43° are characteristic peak of amorphous graphitic carbon.

4 Conclusions This work presents porous carbon fibers prepared from PVDF source at different electrospinning, defluorination conditions. From preparing good quality fibers a cosolvent system of DMF and Acetone and its composition of 60/40 was optimized. The use of TBAH catalyst and concentration of base in autoclave defluorination is optimized. The porous carbon produced from the 0.25 ml/hr spun fibers are found have good carbon content and nanometer dimensions. The surface area of fibers is found to be more than 1500 m2 /g, which makes them ideal for adsorption applications. This work systematically presents how PVDF can be used for porous carbon fiber mat preparation and the optimized conditions for successful preparation. The effect of flow rate on the carbon fiber diameter is also presented. When compared to the previous literature related to carbon fibers, this work presents fibers with more porosity even at less carbonization temperature of 900 °C, which is evident by the surface area. Acknowledgements The authors thank, Indian Institute of Space Science and Technology (IIST) for the financial assistance.

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Thermal Insulation for Refrigeration Pipe Made of Polyurethane Reinforced Coconut Husk and Rice Husk A. M. Khalid, M. Y. M. Zuhri, A. A. Hairuddin, and A. As’arry

Abstract The abstract should summarize It is well-known that the conductivity coefficient (K-value) of insulator is an important factor for the heat transfer process. Consequently, objective of this research is to investigate the capability of environmentally friendly thermal insulation based on natural fibre for refrigeration pipe. Here, coconut husk and rice husk are used as the reinforcement and using a mixing ratio of 1:1. Then, fibers are mixed into the flexible foam at a weight percentage anywhere from 5 to 25%. The samples are tested in terms of their thermal conductivity. It is observed that the results show acceptable value for the thermal conductivity coefficient, which is between 0.037 and 0.045 Wm−1 K−1 . Closer examination found that the conductivity coefficient value is increasing as the fibre content increased. The lowest value of t conductivity coefficient is obtained at 0.037 Wm−1 K−1 for the sample with 5%wt and 0.039 Wm−1 K−1 for the sample with 10%wt. Thus, these results are within the range of conventional thermal conductivity coefficients. Keywords Thermal conductivity · Flexible polyurethane foam · Thermal insulation

A. M. Khalid (B) · M. Y. M. Zuhri (B) Advanced Engineering Materials and Composites, Department of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia e-mail: [email protected] M. Y. M. Zuhri Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia A. A. Hairuddin · A. As’arry Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia e-mail: [email protected] A. As’arry e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_4

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1 Introduction One of the most popular air conditioning systems for providing thermal comfort to the inhabitants of the space in commercial and residential buildings are split air conditioning systems. It consists of external and internal units connected to each other by means of refrigerant pipes [1]. According to the numbers, air conditioners in business buildings account for over 50% of power costs while those in homes account for approximately 30%. Hence, air conditioning systems that have their pipelines insulated consume less energy [2]. On another hand, the researchers indicated that there are various ways to reduce on energy use, particularly in heating and cooling equipment. The best strategy to conserve energy may be to use proper insulation in the pipe network [3]. In other words, the insulator is used in air conditioning systems and other engineering applications, to avoid heat transfer when the refrigerant flows. Thus, increasing efficiency and reducing operating costs. Therefore, The conductivity coefficient of insulating materials is one of the primary parameters that characterizes their ability to insulate and resist heat transfer [4]. In recent decades, natural fibers are gaining interest as reinforcing components in polymer composites because of their many benefits, including excellent thermal and acoustic insulation. Furthermore, environmental difficulties are caused by the fact that synthetic fibres are neither biodegradable nor recyclable [5, 6]. Composites made from natural fibers are popular for usage in load-bearing applications due to their compatibility and high mechanical strength [7]. Besides, low density. Biodegradability and providing it at a cheaper cost. In addition, natural fibres for composite applications offer many advantages. For example, the damping capacity, high specific strength and stiffness strength. subsequently, improving the mechanical and thermal properties of the resulting composite [8]. On another hand, benefits of composites based on polymers are their durability, simplicity of production, and low cost. Their reinforcement might come in the form of fibers or unique forms produced from either natural or manmade materials [9]. Composites made from polymers are increasingly being used in place of more traditional materials like steel and aluminum. The transportation, energy, and automobile industries are just a few examples of where composites are seeing widespread application today [10]. The influence of hemp fibres on the characteristics of polyurethane at various loading rates (5, 10, 15, 20, and 25%) is investigated. The results demonstrated that thermal conductivity increases linearly with the density. In addition, the percentage of (15%) by weight contributes to a 40% improvement in strength. Therefore, hemp fibre reinforced polyurethane offers superior insulating characteristics in comparison to conventional insulation [11]. Researchers looked at how adding coconut husk and maize cob pulp altered the properties of polyurethane foams. As an example, by increasing the filler content from 5, 10, 15, 20 and 25%, they found that the density and compression test improved [12]. Slabs of coconut shells and bagasse were tested for heat conductivity. The values for conductivity coefficients ranged from 0.046 to 0.068 W/m K, which is comparable to those of conventional thermal insulation [13]. Thermal and mechanical properties of four types of agricultural waste were investigated wheat hulls, wood, textile scraps, and

Thermal Insulation for Refrigeration Pipe Made of Polyurethane …

41

rice husk. The results indicated that rice husks, with a density of 378 kg/m3 , had the lowest conductivity coefficient 0.08 W/m K. In addition, after 24 h of submersion of rice husks had lowest water absorption at 42% [14]. On another hand, Polyurethane is unparalleled in the polymer world due to its exceptional mechanical qualities. High elongation, high energy absorption, high resilience to harsh conditions, low cost, chemical resistance, product and application flexibility, ease of use, Thermal conductivity coefficient low [15]. To the best of our knowledge, the thermal conductivity and thermal resistance of flexible foam reinforced with coconut husks and rice husks have not been studied as a single compound. This study focuses on calculating the thermal conductivity (K-value) and thermal resistance of flexible polyurethane reinforced with rice husks and coconut husks, with a mixture ratio (1:1) of natural fibers, and weight ratios of 5, 10, 15, 20, and 25%, to be used as thermal insulation for refrigeration pipes.

2 Materials and Methods In this study, polyether polyol [Density: 1.05 ± 0.05 g/cm3 ; Dynamic viscosity: 800– 1000 mPa s (at 25 °C)] and polymeric methylene diisocyanate [viscosity: 150 mPa s at 25 °C, NCO content: 26.7%wt specific gravity: 1.19 at 25 °C] were taken from, Shandong INOV New Materials Co., Ltd, China. Coconut husks and rice husks were purchased. Malaysia farms. The process of preparing coconut husks and rice husks begins with rinsing with distilled water to remove dirt and dust. Then, it was sent for drying at a temperature of 60 °C. The drying process for fibers required 24 h. in the end, the washed natural fibers and polyol are mixed by a mixer electric for 30 s. After that, the polyisocyanate was added with a ratio of polyol/polyisocyanates of 100:60. Then, material was put into a mold that was 12 cm tall and 7 cm in diameter. Figure 1 composites were prepared for three samples coconut husks, rice husks, and Coconut husks mixed with rice husks in a mixing ratio (1:1). The mixing ratio was for each model (5%, 10%, 15%, 20% and 25%) wt. All preparations were performed under lab temperature.

3 Measurements and Characterizations 3.1 Thermal Conductivity Measurement Thermal conductivity coefficient of flexible polyurethane reinforced with natural fibers was measured for (rice husks with coconut husks) using KD2 Pro thermal properties analyzer manufactured by (Decagon Devices Inc. Pullman, WA) [16]. Where it uses the phenomenon of the heat source of the transient line to analyze

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Fig. 1 Specimen manufacture: a drying of rice husks and coconut husks: b mixing the fiber with the polymer using mixer electric: c specimen at laboratory temperature

the thermal properties of materials according to the criterion ASTM D5334-08. Using a sensor KS-1 as in Fig. 2 Thermal conductivity measurement of the test specimen using a thermal Property Analyzer. The tests were conducted to check the conductivity coefficients of the specimens at ambient temperature 30 °C ∓ 1 and for a period of 10 min for each measurement period and for three models for each mixing ratio.

Fig. 2 Experimental setup: a measurement of thermal conductivity using KD2 pro thermal properties analyzer: b thermal properties analyzer KD2 pro

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4 Results and Discussion 4.1 Thermal Conductivity The effectiveness of insulation mainly depends on determining the value of the conductivity coefficient (K-value) of the insulation material [17]. Thus, the conductivity coefficient depends on many parameters such as density, cell size, and homogeneous material [18]. Therefore, value of the conductivity coefficient is a function of the ability of insulation materials. On another hand, the conductivity coefficient of air is significantly lower than that of biocomposite, showing the greater contribution of conductive fibers to heat transfer [19]. In another word, all fibres have a great deal of air trapped inside their structure, and this air retention is one of the defining characteristics of fibres (conductivity coefficient for air 0.026 W/m−1 K−1 ) [20]. Figure 3 show the conductivity coefficient of each mixing ratio. It is noted that the conductivity coefficient of the reinforced foam increases with the loading of the natural fibers. The value of the conductivity coefficient according to the measured results was (0.037, 0.039, 0.041, 0.043, and 0.045) W/m K respectively. In other words, compared to pure polyurethane foam, composite (5%wt) has a lower coefficient of thermal conductivity by 4.3%. Furthermore, the coefficient of conductivity increased with the increase in loading ratios (10%, 15%, 20%, and 25%) wt, the amount of increase 1.03%, 3.6%, 11.3%, and 16.5% respectively. These results can be explained that the flexible polyurethane foam is significantly affected by the addition of coconut husks and rice husks. This indicates that the conductivity coefficient of coconut husks and rice husks is higher than that of the polyurethane matrix. These fibers appear to have a porous structure due to the formation of their cells that contain voids. In addition, the volume and nature of the gas trapped by the flexible polyurethane. Consequently, Introduction of coconut husks and rice husks increases the thermal conductivity coefficient. In contrast, several researchers have found that when reinforcement ratios of rice husks in the mix increase, the material’s thermal conductivity coefficient rises (0.242 W/m−1 K−1 –0.2756 W/m−1 K−1 ) [21]. In addition, these results are observed in other works of polyurethane foam with natural fibers [11]. Nevertheless, increasing natural fibre loading leads to higher thermal conductivity because of increased contact between fibre particles and reduced thermal resistance with polymer [22, 23]. In another word, the thermal conductivity was within acceptable values compared to commercial insulators. Hence, they can be used as pipe insulators for air conditioning and refrigeration equipment applications.

4.2 Comparison of Properties One of the most crucial factors to consider when picking thermal insulation is the material’s conductivity coefficient [24]. Table1: the results showed present study acceptable values compared to previous works. Researchers indicated that the thermal

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Thermal conductivity (W/m.K)

0.05

0.04

0.03

0.02

0.01

0.00 0% wt

5% wt

10% wt

15% wt

20% wt

25% wt

Sample

Fig. 3 Variance in thermal conductivity of five different composites with respect to the PUF_CR

conductivity of Pineapple leaf and Banana reinforced polyester composites increased with increasing temperatures. The measured results were for thermal conductivity 0.171–0.213 Wm−1 K−1 [25]. In addition, researchers indicated that the treatment of kenaf composites with 6% NaOH contributed to an increase in conductivity coefficient from 0.210–0.232 Wm−1 K−1 [26]. Results showed that thermal conductivity coefficient decreased for flexible polyurethane composites reinforced by 5% of artichoke stem percentage at 0.0499 Wm−1 K−1 . On another hand, thermal conductivity increased by 10% of the reinforced fibers at 0.0507 Wm−1 K−1 [27]. Using reinforced polyurethane foam with sugar beet pulp, the researchers noticed an increase in the conductivity coefficient of 0.027–0.035 Wm−1 K−1 with an increase in fiber content. Attributed to the agglomeration of the fiber granules inside the foam, which led to an increase in the conductivity coefficient. Consequently, it corresponds with the current study to increase the conductivity coefficient with an increase in the content of natural fibers [28]. Alongside, Table 2: Provides a comparison between the values of the conductivity coefficient of the current study with the conductivity coefficient of insulation that is currently used in HVAC applications obtained from previous studies. Therefore, the polyurethane foam reinforced by 5%wt and 10%wt rice husks and coconut husks has a thermal conductivity coefficient within the acceptable values as a thermal insulator for refrigeration pipes. Researchers presented interesting results for strengthening flexible and rigid polyurethane foam with fir wood sawdust using mixing ratio (0,35,40,45, and 50 wt%). The results showed an increase of thermal conductivity with increasing the sawdust in the rigid polyurethane matrix, the opposite of that with the flexible polyurethane foam. Different values of conductivity coefficient depended on the porosity of the sawdust. In addition, morphological composition of the flexible and rigid foams. Thus, interpretation is consistent with the current study.

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Table 1 Comparison of the thermal conductivity results with other studies Fiber

Matrix

Thermal conductivity, Wm−1 K−1

Reference

Pineapple leaf and banana

Polyester

0.171–0.231

[24]

Kenaf

Epoxy

0.210–0.232

[25]

Artichoke stem

Flexible polyurethane

0.210–0.232

[26]

Sugar beet pulp

Rigid Polyurethane

0.027–0.035

[28]

Fir Sawdust

Rigid/Flexible Polyurethane

0.045–0.0432 0.025–0.0433

[29]

Coconut husk and rice husk

Flexible polyurethane

0.037–0.045

Present study

Table 2 Comparison with commercial insulators Material

Thermal conductivity, Wm−1 K−1

Reference

Mineral wool

0.039

[27]

Expanded polystyrene (EPS)

0.036

[30]

Extruded polystyrene (XPS)

0.031

[30]

Flexible insulation foam

0.039

[1]

Polyurethane foam reinforced with coconut husk and rice husk (5%, 10%, 15%, 20% and 25%) wt

0.037, 0.039, 0.041, 0.043, 0.045

Present study

5 Conclusions In this work, flexible polyurethane foam strengthened with coconut husks and rice husks with a ratio of 1:1 was studied. Due to the fact that the obtained results appear to be satisfactory, thermal conductivity coefficient of polyurethane foam reinforced with coconut husk and rice husk complies with thermal insulation standards of commonly used in engineering applications HAVC, such as wood fibers, materials consisting of mineral wool, polystyrene foam, and flexible insulation foam. Accordingly, it is possible to prepare an alternative to traditional insulation materials for refrigeration pipe networks. This result can be supported based on the data obtained. The conductivity coefficient of the reinforcement ratio (5%, 10%, 15%, 20%, and 25%) was examined. The results showed that the reinforcement ratio of 5% and 10% had the best conductivity coefficient by 0.037 Wm−1 K−1 and 0.039 W/m−1 K−1 respectively. Through this study, it is possible to qualify composite materials with a proportion of 5 and 10% which creates competition for the development of an insulating material for refrigeration pipes of high quality and low cost. On another hand, the thermal

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conductivity coefficient can be enhanced by adjusting variables such as the fibre content of the polymer. Acknowledgements Gratitude given to the Ministry of Higher Education Malaysia for funding this work via the Fundamental Research Grant Scheme (FRGS/1/2021/TK0/UPM/02/21).

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Vibro-acoustic Behavior of GFRP Curved Panel Under Non-uniform Thermal Environment Bhaskar Meesala , Pankaj Chaupal , and Prakash Rajendran

Abstract Aeronautical engineers often use curved panels composed of glass fiberreinforced plastic (GFRP) to meet aerodynamic requirements for aircraft. However, these curved panels are exposed to heat loading which leads to poor acoustic comfort and structural integrity degradation. This study deals with the numerical investigation on vibro-acoustic characteristics of GFRP curved panel under non-uniform temperature. The curved panel of dimensions 500 * 500 * 3 mm and stacking sequence of order [0°/90°/0°/90°]4 is modelled using ANSYS workbench and placed in a closed enclosure of dimensions 1.5 * 1.5 * 1.5 m. The curved panel has fixed edges on all four sides, and a harmonic force with a unit amplitude is applied at the outer surface at its centre. Further, a non-uniform temperature gradient is applied on both outer and inner surfaces. Frequency responses are obtained under these conditions and acoustic analysis is carried out. There is evidence of a decline in natural frequency and amplitude remains constant with increase of temperature. It is also remarked that as amplitude of vibration increases when sound pressure level (SPL) increases. Furthermore, the sound absorption coefficient (SAC), which falls as temperature increases, is not significantly affected by temperature increases over ambient temperature.To understand the vibro-acoustic behaviour of GFRP curved panels under non-uniform temperature variation through numerical investigation and the GFRP stacking sequence is optimized in such a way to observe the maximum SAC. Keywords GFRP · Curved panel · Frequency response · Sound pressure level · Sound absorption coefficient.

B. Meesala · P. Chaupal · P. Rajendran (B) Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620015, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_5

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1 First Section The production of the aero plane fuselage, doors, ailerons, spoilers, and other aircraft components uses GFRP laminate composite on a large scale. Aerodynamic heating can cause temperature variations across the surfaces of thin cylinder shell structures used in high-speed aerospace vehicles, missiles, and airplanes [1–3]. These structural components are delicate to heat loads and thin in nature. The health indices of passengers and flight attendants are severely impacted by noise and vibration in the aircraft construction. To manage noise and vibration in aerospace constructions, it’s critical to understand the vibro-acoustic behavior of curved composite structures. Therefore, the creation of an optimum composite laminate geometry and stacking order with excellent damping is essential to removing noise and vibration [4–6]. Jeyaraj et al. [7] utilized ANSYS and SYSNOISE, which are widely recognized finite element programs in the industry, to perform a numerical simulation of the vibration and acoustic behaviour of a rectangular panel under varying temperature conditions. For all boundary conditions, it is discovered that the structure’s displacement response grows as temperature rises. Although the sound power levels may increase significantly as a panel nears its critical buckling point, the overall sound radiation of the panel only shows a minor increase with temperature. Baburaja et al. [8] conducted the comparison of silicon carbide and aluminum in lower frequencies for the vibroacoustic properties of metal matrix composites (MMC) of aluminum. It was found that both uniform and non-uniform temperature fields have a considerable impact on the acoustic response. It has been shown that high silicon carbide content leads to high rigidity in all areas, which lowers low-frequency sounds even in environments with varying temperatures. The results at lower frequencies also show that noise is reduced by around 5 to 15 dB for combinations of silicon carbide reinforcement in aluminum matrix with high stiffness. Li and Yu [9] examined the vibration and acoustic response of orthotropic sandwich panels to a concentrated harmonic load in a heated setting. The piecewise low order shear deformation theory is utilized to determine the inherent frequencies and associated modes of the panels under thermal loads. The results reveal that the natural frequencies of the sandwich panels decline with increasing temperature due to the material anisotropy, resulting in change in mode shapes. Furthermore, an increase in temperature causes an increase in displacement amplitude but a decrease in velocity. Reddy et al. [10] utilized ANSYS software to investigate the vibro-acoustic properties of doubly curved metallic foam panels. The research focused on the effect of porosity on panels, and it was observed that the difference in the sound power levels emitted by solid and porous doubly curved panels was not significant. Additionally, the addition of porosity had no discernible effect on the acoustic behavior of the panels. Furthermore, a 50% reduction in weight resulted in an 11.87% decrease in natural frequencies, and sound power increased by 5 dB over the entire frequency range. Li et al. [11] Utilizing NASTRAN, the first order shear deformation theory, the classical laminate theory, and Rayleigh integrals, researchers examined the analytical and numerical results of the clamped composite laminated panel’s buckling and vibroacoustic response to a concentrated

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harmonic force in a temperature environment. Naturally occurring frequencies fall off as temperature rises. While the panel’s radiation efficacy decreases as temperature increases, displacement and sound pressure also increase along with it. Bhagat et al. [12] analyzed using ANSYS software the buckling and free vibration behavior of cylindrical panels subjected to various non-uniform temperature fields. As temperature increases, the displacement response of the structure also increases, regardless of the boundary conditions. Although there is a significant rise in sound power levels, the overall sound radiation of the panel only slightly increases as the temperature approaches the critical buckling threshold, regardless of the boundary conditions. Madenci et al. [13] contrasted the findings of the buckling and free vibration studies of the pultruded GFRP laminated composites with analytical and experimental data using ABACUS software. The experimental, analytical, and finite element results were compared and found to be consistent despite using different methods. All experimental tests identified matrix cracks and mat damage as the initial damage, both of which appeared in the first layers of glass mat. During buckling tests, a sample measuring 250 * 25 * 6 mm was able to withstand a load of 8.3 kN before reaching a critical buckling displacement threshold of approximately 0.6 mm. Arunkumar et al. [14] studied the orthotropic panel behaviour under vibration and acoustics was examined, and it was found that increasing the composite’s stiffness decreased the vibration and acoustics’ features. Patil et al. [15] analyzed how porous metallic beams subjected to thermal load, buckling and vibration. According to their research, the structure’s ability to withstand heat grows as the porosity coefficient does. By accounting for the natural material damping of composite materials. Bhagat et al. [16] found that a functionally graded carbon nanotube (FG-CNT) reinforced composite cylindrical panel’s buckling and free vibration behaviour were affected by temperature-dependent properties and a non-uniform temperature field. It is implied that a panel with a smaller thickness and curvature ratio, or a panel that is stiffer, will experience a greater impact from temperature-dependent qualities on its buckling strength. Regardless of temperature fields, the functionally graded-X grading pattern for CNTs provides more buckling strength than the other pattern examined. Li et al. [17] investigated the vibro-acoustic behaviour of a fiber-reinforced polymer (FRP) laminates with a core of porous foam (PFC) and it is subjected to planar acoustic wave (PAW) excitation. The researchers employed theoretical and experimental analyses to investigate these properties. The results showed that as compared to plates without a porous core, the PFC-FRP plates exhibited decrease in resonant response as the porosity coefficient increases. Due to the interrelation between stiffness and damping properties, the sound transmission loss increases further. The researchers recommended selecting a core material with the highest feasible porosity coefficient to achieve effective vibro-acoustic suppression. Arunkumar et al. [18] aimed to enhance the acoustic performance of truss core sandwich panels. Researchers found that incorporating foam into the panels resulted in a substantial reduction in the overall sound power levels compared to unfilled truss panels. More specifically, filling the empty truss core space with polyurethane foam (PUF) resulted in significant reductions in both vibration and acoustic responses resonant amplitudes. Jeyaraj et al. [19] focused on analyzing the vibration and acoustic response properties of a viscoelastic sandwich

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plate consisting of multiple layers under varying temperatures, using numerical simulations. Results indicated that as the temperature increased, the resonant amplitudes of both the vibration and acoustic responses decreased. Moreover, as the uniform temperature approached the critical buckling temperature of the structure, the resonant amplitude also decreased. Additionally, an increase in the number of layers and core thickness led to an increase in the overall sound power level. Although the type of thermal environment had no significant impact on the overall sound power level, the type of core material used did influence it. Li et al. [20] examined the impact of partial bolt loosening on the vibration of fiber-reinforced composite cylindrical shells (FRCCSs) with bolted joint boundary conditions. Both theoretical and experimental approaches were used to analyze the system. The findings indicated that an increase in the number of loose bolts and the degree of bolt loosening caused natural frequencies to decline while modal damping ratios and resonant response amplitudes increased due to a reduction in boundary stiffness and an increase in boundary damping at the bolted constraint edges. The study also found that the natural frequencies and damping parameters of FRCCSs degraded with increasing excitation intensity, and the rates of resonant response amplitudes showed an upward trend. Several studies have been conducted in the field of vibro-acoustics to improve the comfort of individuals and reduce the risk of resonance in panels exposed to thermal environments. These studies have explored various factors, such as the type of materials used, the effect of porosity, the use of viscoelastic materials, and the impact of bolt loosening on the vibro-acoustic response of panels. Researchers have utilized numerical simulations as well as experimental studies to investigate these factors and have found that temperature changes can significantly impact the natural frequencies and resonant amplitudes of panels. The use of certain materials, such as foam filling, porous foam cores, and truss cores, has been found to decrease the total sound power level of panels. Additionally, the choice of core material has been observed to influence the overall sound power level of panels. Overall, these studies provide insights into improving the vibro-acoustic properties of panels subjected to thermal environments, which can enhance the comfort of individuals and reduce the risk of resonance. From summary of the literature review, most of the studies are conducted on the flat FRP plate and considered only uniform temperature condition of the plate. Only few studies are carried out under curved panels which creates a demand in aerospace and automobile industry. Hence, the novelty of work is to study the vibro-acoustic characteristics of GFRP curved panel under non-uniform temperature environment.

2 Methodology Methodology for the vibro-acoustic analysis of GFRP panel shown in Fig. 1. FEA is taken into consideration when analyzing the vibrating properties under thermal conditions. ANSYS, a widely used finite element solver, is selected to estimate the vibration and acoustic properties under various temperature patterns. The first task

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is to model the composite GFRP curved panel. E-glass and Resin epoxy are the materials required to make the composite using ACP Pre. In experimental part we used vacuum bagging method for manufacture of GFRP sheets. Making glass fiber sheets using vacuum, also known as vacuum bagging, is a common manufacturing process used to create composite materials with high strength-to-weight ratios. The first step is to prepare the mold that will be used to shape the glass fiber sheet. Here we used the wooden block having the required curvature. To make the mold smooth and non-porous it is covered with plastic on the top of block which has curvature. The mold should also be coated with a release agent to prevent the glass fibers from sticking to it. Cut the glass fiber fabric into the desired shape and size for the sheet. The glass fiber fabric can be cut using scissors or a rotary cutter. Apply a layer of epoxy resin onto the mold. The resin should be applied in a uniform layer using a brush or roller. Place the glass fiber fabric onto the resin-coated mold, making sure that it is properly aligned and wrinkle-free. Cover the glass fiber fabric with a vacuum bagging film and seal the edges of the bag to create an airtight seal. Connect the vacuum pump to the bag and turn it on to evacuate the air from the bag. Allow the resin to cure according to the manufacturer’s instructions. This typically involves applying heat to the mold and bagged fabric. Once the resin has cured, remove the vacuum bagging film, and carefully remove the glass fiber sheet from the mold. In finite element (FE) simulation, first step is to create the geometry in design modeler. The dimensions of the panel are 500 * 500 * 3 mm, and the radius of curvature is 318.31 mm. After that meshing was done using SHELL 181 from the ANSYS library. Then composite is made by specifying the thickness of each ply, ply angle, no of laminates and global drop off material i.e., resin epoxy. Figure 2 shows the composite panel made in the ANSYS, meshing the panel inside the enclosure for harmonic acoustics. Steady state thermal analysis is a numerical technique that is used to calculate the temperature distribution in a structure under steady state conditions. In this technique, the boundary conditions are specified as the temperatures at the outer and inner surfaces of the panel, and the heat transfer equation is solved to obtain the temperature distribution within the panel. The results of the steady state thermal analysis can be used to study the effect of temperature on the properties of the panel, such as the natural frequencies and damping ratios. The temperature distribution obtained from the thermal analysis can also be used as input to the subsequent vibro-acoustic analysis, which is used to predict the vibration and acoustic response of the panel under external excitation. Overall, the steady state thermal analysis is an essential step in the analysis of panels subjected to thermal environments, as it provides critical information about the temperature distribution within the panel that can have a significant impact on the structural and acoustic behavior of the panel. The analysis was performed for different cases, by varying the temperature outer surface and keeping the inner surface constant at 22 °C. Outer surface temperatures taken for analysis are − 50, 22, 50, 150, 250, 350 °C and achieving the non-uniform thermal load in thickness direction of the panel. These non-uniform thermal loads are imported for the static structural analysis. The static structural analysis was carried out to determine the stresses and deformations generated within the panel by fixing the edge surfaces of the panel as boundary

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Fig. 1 Methodology

Fig. 2 a Composite GFRP plate, b Meshed plate, c GFRP plate inside the enclosure

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condition and non-uniform thermal loads are imported from the steady state thermal analysis. Now the panel is under thermal stress. Since the panel is under thermal stress, now pre-stressed modal analysis was accomplished to the structure by specifying the no of modes. First six modes were considered for this analysis, because there is higher chance of resonance occurrence in the frequency range, and these are lowest frequencies with higher amplitudes. In the next step, harmonic response analysis was carried out to obtain the frequency response of panel by specifying the frequency range of 0–1200 Hz and harmonic load of unit amplitude at the centre of the panel. The obtained velocity of body is the input to the harmonic acoustics and is imported. Harmonic acoustics is the last step in which curved panel and enclosure of box with dimensions 1.5 * 1.5 * 1.5 m was designed for that acoustic analysis was done. The imported velocity is given to the panel and air is the filling medium of enclosure. The enclosure’s exterior surface is constructed with radiation boundary to guarantee non-reflective boundary requirements. We must give the port boundary condition to obtain the sound absorption coefficient. From this analysis we found out, sound pressure level (SPL) in the air medium at in the frequency range of 0–1200 Hz.

3 Results and Discussions This section discusses the result obtained by conducting the numerical simulation, such as thermal analysis, modal analysis, harmonic analysis, and harmonic acoustic analysis. In the modal analysis, natural frequencies and corresponding mode shape are obtained. Under harmonic analysis, the amplitude in terms of velocity obtained at different natural frequencies.

3.1 Thermal Analysis The thermal analysis was performed in ANSYS 2022 R2 with different outer surface temperature as boundary conditions and obtained temperature distribution within the panel. It is observed that decrease in temperature from outer surface to inner surface along the thickness. Thus, the non-uniform thermal load is obtained along the thickness. The cruising altitude of the majority of jet aircraft is between 9 and 12 km, where air temperatures range from 40 to 70 °F (40–57 °C). To shield pilots and passengers from cold air and gusts of wind, modern aircraft have sealed cabins and heaters. Maximum environment temperature ranges from 45 to 52 °C. Typical in-flight temperatures vary between 15 and 30 degrees centigrade (C°) and mostly 25 °C. By keeping in mind all these temperature range and non-uniform surface temperatures of the flight, the thermal boundary conditions to panel were given as − 50, 22, 50, 150, 250, 350 °C. The source of temperature on surface of the aircraft is radiation from the sun and aerodynamic heating of surface at high-speed of aircraft.

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Fig. 3 Temperature distribution within the panel along the thickness for various cases

For all these outer surface temperatures, thermal analysis was carried out. The results of thermal analysis are shown in Fig. 3. The variation of temperature along the thickness is slow this is because of low thermal conductivity of the composite i.e., 1.2 W/mK. Figure 4 clearly depicts the non-uniform thermal load. Glass fiber-reinforced polymer (GFRP) possesses high heat resistance, with 25% and 50% of its tensile strength retained even at temperatures of 480 °C and 370 °C, respectively. Its softening point and melting point are at 845 °C and 1135 °C, respectively. Furthermore, since glass fibers are mineral substances, they are naturally incombustible and do not contribute to the spread or continuation of flames. When exposed to heat, they also do not produce any hazardous substances or smoke. The large surface area to weight ratio of glass fibers makes them ideal thermal insulators and very useful in the construction industry. Additionally, GFRP exhibits good chemical resistance, making it highly durable against chemical attacks.

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Fig. 4 Thermal load for different cases

3.2 Pre-stressed Modal Analysis Thermal load is imported to static structural, and the fixed boundary condition is given to the edge surfaces and then modal analysis was performed up to six modes. Figure 5 show the deformation pattern at different modes i.e., modes shapes for nonuniform temperature of − 50 to 22 °C. From the modal analysis, first six modes are extracted. The panel first natural frequency was estimated about 649.45 Hz with three half waves along the width and one-half wave along the length, maximum amplitude observed at the centre. The modal analysis was performed for all the different cases and frequencies at all modes. The variation of frequency with different non-uniform thermal loads was shown in Fig. 6. From the modal analysis, it is inferred that by increasing the non-uniform thermal load, the frequency of vibration of GFRP curved panel decreases and vice-versa. This is because of lower stiffness and higher stiffness of the panel with increase and decrease of temperature. With increase of temperature, the compressive stresses are generated in the panel and with decrease of temperature the tensile stresses are generated in the panel. First mode of vibration is lower for hot panel; thus, the resonance will occur at lower frequency than the cold panel. A maximum frequency of 1084.1 Hz was obtained at − 55 °C. It is further observed that there is not much decrease in frequency with increasing temperature. At modes 4 and 5, there is clear difference in the frequencies. For all thermal loads, mode 1, 2 will fall under frequency range nearly 630–660 Hz, and mode 3, 4 will fall under the frequency range of 930–1000 Hz while mode 5, 6 will under the 960–1090 Hz. A component’s mode shape is the distortion it would have if it were vibrating at its natural frequency. Natural vibration shape and mode shape are terms used in structural dynamics. Its mode shape describes how a component would deform when vibrating at its natural frequency.

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Fig. 5 Mode shapes of GFRP curved plate for case (i)

Fig. 6 Variation of frequency under thermal load

3.3 Harmonic Response Analysis The analysis of pre-stressed modes is a crucial step in conducting harmonic response analysis, where the thermal environment is also taken into account. A harmonic load of unit amplitude is applied to the panel normal to its center, and the resulting frequency response is measured in terms of velocity, sound power level, and sound

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power. The study reveals that up to 600 Hz frequency range, the amplitude of vibration exhibits only a slight increase with the raise of thermal load. However, in the frequency range of 630–660 Hz, the trend shows an anomalous behavior where, at a temperature of 350 °C, a higher amplitude is observed at 150 °C instead of 250 °C, and at − 50 °C instead of 22 °C. Interest fact at mode 1 that the frequency response amplitude increases and frequency decreases as temperature of the panel increases. In hot condition, the stiffness of the panel decreases and induces more vibration as compared to mode 2 and 3. In the frequency range of 900–970 Hz highest amplitude obtained at − 55 °C followed by 350, 50, 250 °C. Sound power levels are also calculated different thermal loads and they are compared. In the frequency range of 630–660 Hz, SPL increases with increase in temperature. The highest SPL was found out in this range only with a value of 164.84 dB at frequency of 636 Hz and at 250 °C followed by 158.53 dB, 146.48 dB, 133.56 dB, 126.99 dB, 115.5 dB at 350 °C, 150 °C, 50 °C, − 55 °C, 22 °C respectively. The hot panel is vibrating at lower frequency than the colder panel to produce the same SPL in the frequency range of 630–660 Hz. In the frequency range 930– 1000 Hz and 960–1090 Hz, it is noticed that the highest SPL occurred at the − 55 °C, followed by the panel with 150 °C. Overall, it is observed that the frequencies other than modal frequencies or near to modal frequencies, there is no effect of temperature on the SPL. The frequency response, sound power level, sound powers were calculated under different thermal environment are shown in Figs. 7, 8 and 9. At modal frequencies or near to modal the there is significant effect of temperature on the Sound Power Level and at modal frequencies 1, 2 hot panel will generate more sound than the cold panel. At modal frequencies 3, 4, 5, 6 cold panel will generate more sound than the hot panel. The rate of sound energy emission, reflection,

Fig. 7 Variation of amplitude velocity under thermal load

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Fig. 8 Variation of sound power level under thermal load

Fig. 9 Variation of sound power under thermal load

transmission, or reception per unit of time is known as sound power, sometimes known as acoustic power. As per the definition, the integral of the product of the sound pressure and the component of the particle velocity in the direction perpendicular to a given surface is computed across that surface. The watt serves as the sound power SI unit (W). It has to do with how powerful a sound force is when it interacts with

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an aerial surface that houses a sound source. In contrast to sound pressure, sound power for a sound source is independent of both location and distance. In acoustics, sound pressure is a characteristic of the sound field at a specific location, whereas sound power refers to the overall amount of energy released by a sound source in all directions. The propagation of sound in a particular area is described as sound power, sound flux, or acoustic flux. At a temperature of 250 °C and a frequency of 636 Hz, the peak sound power is 30625 W. The generation of sound power is not significantly impacted by thermal loads throughout the whole frequency range, except for modal frequencies. At modal frequencies increase in the temperature increases the sound power generated from the surface of the panel. At modes 3, 4, 5, 6, the cold panel i.e., at − 50 °C panel is generating high sound power followed by panels at 350 and 50 °C. From the above analysis and comparison, it is concluded that there is high impact of thermal load at modal frequencies on the sound power, SPL, frequency response of GFRP curved panel.

3.4 Harmonic Acoustics Harmonic acoustics gives the results for the sound pressure level (SPL), Sound absorption coefficient (SAC). For this analysis, a curved panel was put inside an airtight enclosure, and radiation boundary conditions as well as port boundary conditions were provided in order to calculate the SPL and SAC. Amplitude velocity imported from the harmonic response analysis is given as the load. SPL at different frequencies is shown in Fig. 10. Fig. 10 Sound propagation in air medium of 250 °C panel at different frequencies

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Fig. 11 Variation of absorption coefficient with temperatures

Figure 10 shows the SPL in the section plane, it is observed that near to GFRP plate there is red zone which indicates the high SPL at a particular frequency and causes the damage to the ear and possibility to loss of hearing. Green zone is the more comfortable zone to hear followed by yellow zone. As the frequency increases, sound propagates to large area, eventually it becomes unsafe zone. Obviously near the panel high sound and as we go away from the panel less sound was observed. As the frequency increases, the entire enclosure shows the high sound indicated by red and yellow color at 1074 Hz. Materials’ sound-absorbing capacity is determined by their sound absorption coefficient (SAC). It is denoted by the symbol α and denotes the proportion of absorbed to incident energy. If α = 1, all the acoustic energy can be absorbed. With increase in temperature, SAC slightly decreases. It is understood that the slight reduction SAC was found as temperature increases as shown in Fig. 11. Even, those slight changes of SAC, was not observed at higher frequencies.

4 Conclusions The vibro-acoustic analysis of GFRP curved panel was carried out under non-uniform thermal load using ANSYS Software. The modelling of the composite curved panel was performed and thermal, static, modal, harmonic response and harmonic acoustic analysis were accomplished on the model. From the results of the analysis presented in the respective chapters, the conclusions are drawn from the following points.

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• The panel exhibits thermal strains and deformations when the body temperature rises or when a non-uniform thermal load is applied to it. Within the panel, hoop or circumferential stresses are produced. The rigidity of the panel decreases as the temperature rises. The thickness direction’s measured linear temperature distribution. • It has been noted that when temperature rises, the frequency of panel vibration reduces; this is a result of the structure’s loss of rigidity. Compressive stresses are produced, reducing the structure’s rigidity. • Except at or near the modal frequencies, the frequency response of the curve panel does not significantly alter. It is assumed that after 350 °C, larger amplitude occurred at 150 °C rather than 250 °C in the frequency range of 630–660 Hz. • The largest amplitude velocities in the frequency range of 930–1090 Hz were attained at − 50, 350, and 50 °C, followed by other temperatures. It demonstrates that hot panels vibrate at higher amplitudes between 630 and 660 Hz and cool panels vibrate at higher amplitudes between 930 and 1090 Hz. • Except at or around the modal frequencies, there is little difference in the SPLs produced by the curve panel. The greatest SPL is measured in the 630–660 Hz frequency band at 636 Hz and 250 °C, with a value of 164.84 dB. At 350 °C, 150 °C, 50 °C, − 55 °C, and 22 °C, respectively, 158.53 dB, 146.48 dB, 133.56 dB, 126.99 dB, and 115.5 dB were then heard. • To create the same SPL between 630 and 660 Hz, the heated panel vibrates at a lower frequency than the colder panel. • With a value of 30,625 W, the peak sound power is attained at 250 °C and 636 Hz. • An elevation in the thermal load resulted in a slight decline in the Sound Absorption Coefficient (SAC). • In harmonic acoustics, as sound propagates on panel more rapidly at higher frequencies. • It is observed that the slight reduction SAC was found as temperature increases. Even, those slight changes of SAC, was not observed at higher frequencies. • Several factors, including the polymer resin type, fiber content, orientation, and dimensions, which affect the thermal characteristics of GFRP plates. Among these factors, the fiber content predominantly determines the thermal conductivity of GFRP.

References 1. Sharma N, Mahapatra TR, Panda SK (2019) Vibroacoustic analysis of thermo-elastic laminated composite sandwich curved panel: a higher-order FEM–BEM approach. Int J Mech Mater Des 15(2):271–289 2. Chaupal P, Prakash R (2022) Damage identification in composite structure using machine learning techniques based on acoustic emission waveforms. Recent Adv Manuf Modell Optim Select Proc RAM 2021:149–158 3. Rath MK, Sahu SK (2012) Vibration of woven fiber laminated composite plates in hygrothermal environment. J Vib Control 18(13):1957–1970

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4. Kushwaha S, Bagha AK (2020) Application of composite materials for vibroacoustic–a review. Mater Today Proc 26:1567–1571 5. Chronopoulos D, Troclet B, Ichchou M, Lainé JP (2012) A unified approach for the broadband vibroacoustic response of composite shells. Compos B Eng 43(4):1837–1846 6. Sarigül AS, Karagözlü E (2014) Vibro-acoustic analysis of composite plates. J Phys Conf Series 490(1):012212 7. Jeyaraj P, Padmanabhan C, Ganesan N (2008) Vibration and acoustic response of an isotropic plate in a thermal environment. J Vib Acoust 130(5):051005 8. Baburaja K, Subbaiah KV, Arunkumar MP, Bhagat VS, Reddy R (2021) Vibration and acoustic characteristics of aluminium silicon carbide metal matrix composite under uniform and nonuniform thermal environment. SILICON 13(12):4715–4736 9. Li X, Yu K (2015) Vibration and acoustic responses of composite and sandwich panels under thermal environment. Compos Struct 131:1040–1049 10. Reddy RKK, George N, Mohan S, Bhagat V, Arunkumar MP (2022) Vibro-acoustic behavior of metallic foam doubly curved panels. Mater Today Proc 64(1):83–89 11. Li X, Yu K, Han J, Song H, Zhao R (2016) Buckling and vibro-acoustic response of the clamped composite laminated plate in thermal environment. Int J Mech Sci 119:370–382 12. Bhagat V, Jeyaraj P (2018) Experimental investigation on buckling strength of cylindrical panel: effect of non-uniform temperature field. Int J Non-Linear Mech 99:247–257 13. Madenci E, Özkılıç YO, Gemi L (2020) Buckling and free vibration analyses of pultruded GFRP laminated composites: experimental, numerical and analytical investigations. Compos Struct 254:112806 14. Arunkumar MP, Jagadeesh M, Pitchaimani J, Gangadharan KV, Babu ML (2016) Sound radiation and transmission loss characteristics of a honeycomb sandwich panel with composite facings: effect of inherent material damping. J Sound Vib 383:221–232 15. Patil HB, Pitchaimani J, Mailan Chinnapandi LB (2021) Buckling and free vibration of porous functionally graded metal ceramic beams under thermal and mechanical loading: a comparative study. J Inst Eng (India): Series C 102(5):1107–1117 16. Bhagat V, Jeyaraj P, Murigendrappa SM (2018) Buckling and free vibration behavior of a temperature dependent FG-CNTRC cylindrical panel under thermal load. Mater Today Proc 5(11):23682–23691 17. Li H, Ren X, Yu C, Xiong J, Wang X, Zhao J (2021) Investigation of vibro-acoustic characteristics of FRP plates with porous foam core. Int J Mech Sci 209:106697 18. Arunkumar MP, Pitchaimani J, Gangadharan KV, Leninbabu MC (2018) Vibro-acoustic response and sound transmission loss characteristics of truss core sandwich panel filled with foam. Aerosp Sci Technol 78:1–11 19. Jeyaraj P, Padmanabhan C, Ganesan N (2011) Vibro-acoustic behavior of a multilayered viscoelastic sandwich plate under a thermal environment. J Sandwich Struct Mater 13(5):509–537 20. Li H, Lv H, Sun H, Qin Z, Xiong J, Han Q, Liu J, Wang X, Wang X (2021) Nonlinear vibrations of fiber-reinforced composite cylindrical shells with bolt loosening boundary conditions. J Sound Vib 496:115935

Study the Mechanical Characteristics of NaOH & SLS Treated Cotton-Kenaf Fabric Reinforced Epoxy Composites Laminates A. Karthik , M. Bhuvaneswaran , and P. S. Sampath

Abstract In the present work, caustic soda (NaOH) and sodium lauryl sulphate (SLS) was used to surface-treat the plain weave cotton-kenaf with the following two primary objectives in mind: (1) to improve the strength of cotton-kenaf composites, and (2) to increase the fibre content in the composite. The cotton-kenaf composites were made with treated or untreated fibre concentrations of 25, 30, 35, and 40%wt by using compression moulding process. Composites were analysed for morphological and mechanical characteristics (impact, tension and flexural). The results indicated that cotton-kenaf fabric was more treated effectively with SLS than NaOH due to their different chemical compositions. When compared to untreated woven fabric composites (UTWFC), SLS treated woven fabric composites (TWFC) had better mechanical properties at higher (35%wt) fibre concentrations. This was attributed to stronger interfacial bonds between the resin and the fibre. Keywords Cotton/kenaf-woven fabric · Mechanical properties · Surface treatment

A. Karthik (B) Department of Mechatronics Engineering, Akshaya College of Engineering and Technology, Coimbatore, Tamil Nadu, India e-mail: [email protected] M. Bhuvaneswaran Department of Mechanical Engineering, K.S.R. College of Engineering, Tiruchengode, Tamil Nadu, India e-mail: [email protected] P. S. Sampath Department of Mechanical Engineering, K.S. Rangasamy College of Technology, Tiruchengode, Tamil Nadu, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_6

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1 Introduction The non-degradability of the fibres in these composite materials, while their superior mechanical qualities, results in environmental pollution. In the last ten years, the use of kenaf fibre as reinforcement has significantly increased. These other goods include furniture padding, decking, and extruded plastic fencing. Plant-based fibres with high specific strength and low density, such kenaf, hemp, and flax, are of applications with the most use in high strength and lightweight materials. For dashboards, headliners, package trays, seat backs, door panels and interior automobile components during the past ten years, European automotive companies and suppliers have adopted Natural Fibre Composites (NFC) with polymer matrices. Synthetic materials are now used less frequently in many engineering fields due to the growing demand for ecologically responsible products in the composites industry. Partially biodegradable and green composites are primarily classified depending on the kind of materials that make up each of them. The use of NFC manufacture has reportedly undergone a significant change worldwide [1]. Additionally, natural fibres are comparable to synthetic fibres, such as man-made fibers with several ecological factors and not mechanical characteristics. The strength of polymeric materials has been significantly increased by reinforcing natural fibres in a variety of ways, such as by giving them various chemical treatments and blending them with synthetic fibres. However, it was found that these treatments were required because the composites are weaker than other man-made fiber composites material; in comparison, weaving NFC in different fiber orientations improves the strength of composites materials and brings them up to par with them constructed with man-made fibers [2, 3]. Natural fibres can be weaved into fabric mats, continuously aligned, or randomly distributed in fiber-reinforced polymer composites [4]. Woven textiles are preferred because they offer more stability and conformability for complicated construction materials, making them more attractive as reinforcements. Weaving NFC into various textile forms is necessary to determine the ultimate properties of those fibres. By utilizing textile technologies with weaving patterns like knit and weave for a variety of natural fibres, an NFR composite with improved mechanical characteristics is developed [5, 6]. Through utilising three different weaving structures, Pothan et al. [7] examined woven sisal fibre composites with an emphasis on pressure applied, resin viscosity and weave pattern (plain, twill, and matt), as well as fibre surface change. The impact of spinning design and fibre wt% on the properties of composite materials were carefully investigated in this study. Eco-friendly jute fabric composites were created by Khan et al. [8] to study the woven structure affects physical properties. The warp direction of these composites was found to have more mechanical modulus and strength than the weft orientations. The mechanical properties of woven jute fabric composites were superior to those of non-woven jute fabric composites in both the warp and weft orientations. Sapuan et al. talked about the design and production of composites made from banana fabrics [9]. As being appropriate for use in the production of home telephone stands. Biodegradable resin composites reinforced with kenaf and bamboo fibres were examined by

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Shibata et al. [10]. They reported that despite fibre orientation, flexural modulus increases as fibre content increases. However, there was a significant variance in the bending modulus of elasticity between the cross-ply and longitudinally structures in FRP composites. The flexible characteristics and notch sensitivity of polyester hybrid composites supplemented with jute and jute-glass fibres were assessed by Ashmed et al. [11]. Coefficient de Poisson’s ratio decreases as the fiber content increases, they found that the modules of elasticity increase both in the warp and weft orientations [12, 13]. It is important to chemically treat the fibres to make them hydrophobic in order to produce composites with enhanced mechanical strength. For various studies to improve the properties of NFRCs, several chemical treatments have been used [14– 16]. By using the vacuum bagging technique, Jannah et al. [17] evaluated the effects of various volume% (5, 10, 15, and 20) of woven banana fabric composites with various chemical modifications. Water absorption, impact, and flexural characteristics of the composites were studied in relation to fibre content and fibre surface changes. Compared to untreated and NaOH-treated fibre composites, they discovered that acrylic acid treatment reduced the composites’ capacity to absorb water and improved their mechanical properties. Alkalization or acetylation of plant fibres, changing their surface topography and crystallographic structure, was examined by Mwaikambo et al. [18]. By treating kenaf fibre in a 6% (NaOH) solvent for 90 min, Atiqah et al. [19] utilized the mercerization process. In the hybrid composite reinforced with treated kenaf fibres, the highest impact, tensile, and bending strength were found. Natural fibres and the woven composites they create were the subject of Lai et al. [20]. Investigation into their physical, mechanical, and (SEM) analysis properties. Because kenaf fibres contain more cellulose than betel palm fibres, they have found that greater tensile characteristics. They also discovered through morphological investigations that treating the fibres with alkaline effectively cleans their surface and makes it rougher. Hybrid composites made of kenaf and banana fibres were used to study the effects of alkali and sodium lauryl sulphate treatment. For 30 min, fibres were treated with a 10% solvent of sodium hydroxide (NaOH) and a 10% solution of sodium lauryl sulphate (SLS). A constant 40% of fibre is used in the composite. Researchers examined the factor influencing morphological changes and mechanical qualities [21]. However, there has been very little research done on using cotton/kenaf fibre woven patterns in polymer composites. In terms of mechanical strength, researchers are also examining the effects of NaOH and SLS treatment on cotton/kenaf fibre.

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Fig. 1 Cotton/kenaf simple fabric

2 Materials and Method 2.1 Materials The woven form of natural fibres like light weight cotton and kenaf is utilized to fabricate the composite material that was used in this study, as illustrated in Fig. 1. The Anakaputhur Kenaf Weaver Association in Chennai, India provided the natural fibres. Epoxy resin grade LY556 and hardener grade HY951 have been used as the matrix material. The composites manufacturing process and mechanical testing were performed at the LMP R&D lab in Erode, Tamil Nadu, India. The natural cotton/ kenaf fabric used in this experiment is predicted by the rule of a mixture to be (25, 30, 35, and 40%) and the epoxy resin utilised will be (75, 70, 65, and 60%). The woven fabric’s simple weave pattern provides excellent fabric strength and high stiffness.

2.2 Chemical Treatment Fibers surfaces experienced two fundamental chemical modifications. Cotton/kenaf fibres were treated with 10% (NaOH) and (SLS) for ½ h, followed by a distilled water wash and drying. In this work, we tested a more recent chemical process that modifies the fiber’s surface utilising SLS.

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Fig. 2 Cotton/kenaf fabric reinforced epoxy composites

2.3 Composite Preparation The composite laminates for this study were fabricated using the compression moulding process, as shown in Fig. 2. To establish the various composites, the specimens were made for reinforcing at weights of 25%, 30%, 35%, and 40%, respectively. Initially, a form releaser was sprayed in the mould inner surfaces area. For the production of composite laminates, layers of woven cotton/kenaf fabric are layered on a flat mould. Each layer of cloth is applied, and then the epoxy resin is uniformly spread out and laid up by hand. After the hand layup, the top die is positioned on the laminated layers. The closed mould was then subjected to a pressure of 1500 PSI. The composite is then cured at 80 °C for one hour after the fabrics have been fully saturated with the matrix. The laminates were then taken out of the mould and sized for the appropriate specimens.

2.4 Specimen Preparation The dimensions of the prepared Untreated, NaOH-treated, and SLS-treated composite laminates are marked using a template made by ASTM standard for tensile testing D3039 (270 × 25 × 3 mm), ASTM standard for bending testing, D790 (127 × 13 x × 3 mm) ASTM standard D256 (67 × 13 × 3 mm) for impact testing, and ASTM standard E 834 (20 × 20). The specimen’s edge is smoothed using a filing and an abrasive paper to provide a smooth surface (Fig. 3).

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Fig. 3 a Impact, b bending and, c tensile samples of cotton/kenaf composite

3 Results and Discussion 3.1 Tensile Strengths The effect of wt% on the cotton/kenaf composites tensile properties is depicted in Fig. 4. Compared to the 25 wt% composites, the 35 wt% woven cotton/kenaf composites with SLS treatment had a higher tensile strength (66.95 MPa). The optimal fibre content for all composites, including untreated, NaOH-treated, and SLS-treated 35 wt% for cotton/kenaf composites. Because cotton/kenaf fibres have a relatively low aspect ratio and small surface area, this research found that the best tensile properties of cotton/kenaf composites are obtained at 35 wt% rather than 40 wt%. This is because these fibres require less matrix for effective wettability. The successful tangling of the fibres at a 35 wt% fibre concentration shows that the matrix effectively hydrated the fibres [22]. At this time, the composite was stiff and there was no slippage between the fibres because of the matrix’s firm hold on them. The efficiency of wetting and tangling between fibres also reduced with the increase in fibre content to 40 wt%, resulting in slipping between fibres and a reduction in tensile properties [23]. The ultimate tensile strength is defined as the highest stress that will exist under applied and varied loads in tension before breaking. The results show that the SLS-treated cotton/kenaf composite has the highest ultimate tensile strength of 66.95 MPa at 35 wt% to the NaOH and untreated cotton/kenaf composites. Based on the study of the tensile properties of untreated and NaOHtreated cotton/kenaf composites, the SLS composite shows better tensile properties [23].

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Fig. 4 Tensile strength of cotton/kneaf fabric reinforced composites

3.2 Flexural Strengths The flexural characteristics of cotton/kenaf composites are shown in Fig. 5. With a fibre content of 35 wt%, the cotton/kenaf composites’ optimum flexural characteristics were achieved. With these fibre densities, the load may be distributed and transmitted among the fibres, resulting in the maximum flexural strength. This is made possible by adequate and effective matrix wetting on the reinforced fibres [24]. Flexural properties start to decline at a fibre concentration of 40 wt% due to inadequate matrix wetting on the reinforced fibres. Insufficient wetting caused the reinforcement fibres to have poor matrix dispersion, which resulted in the development of weak spots at the interfacial areas and a decrease in strength [25]. In addition to the strength of the outer layers of cotton/kenaf composites, the interfacial interaction influences the flexural characteristics of composites. Poor fiber/matrix interfacial bonding, in accordance with Khalil et al. [26], is a factor in the weak flexural properties. The cotton/kenaf composite with SLS treatment has the maximum flexural properties, at 72.99 MPa, followed by the composite with alkali NaOH treatment, at 66.35 MPa, and the untreated composite at 47.44 MPa. As a result, the SLS-treated composite has 33% higher flexural properties than the untreated composite. The cotton/kenaf composite treated with SLS seems to have flexural properties that are also 16% higher than the composite treated with NaOH.

3.3 Impact Strengths The interlinear and interfacial adhesion of the epoxy resin and fibre has an impact on the impact property of composite laminates. Figure 6 illustrates the cotton/kenaf

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Fig. 5 Flexural strength of cotton/kneaf fabric reinforced composites

composites’ impact resistance. This indicates that variables other than the fibermatrix interface, structure, and geometry of composites [27], influence the impact strength of composites as the composites resistance to impacts relies on the kind of fibre treatment used to reinforce cotton/kenaf fibres. The layering pattern has no influence on the composite’s impact properties, according to Idicula et al. [24]. The impact strength of untreated cotton/kenaf composites is 18.07 kJ/m2 , but it’s 25.27 kJ/m2 for NaOH-treated composites and 27.80 kJ/ m2 for SLS-treated cotton/kenaf composites with 35 wt% content (Fig. 6). Impact strength is 33% higher in the SLS-treated cotton/kenaf composite than in the untreated composite and 10% higher in the NaOH-treated composite. Both sisal/banana and Fig. 6 Impact strength of cotton/kneaf fabric reinforced composites

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Table 1 Mechanical characteristics of various natural fibers composite Fiber/Matrix

Fiber Orientation wt%

Chemical Treatment

Tensile Strength (MPa)

Flexural Strength (MPa)

Impact (kJ/m2 )

Reference

Cotton- Kenaf/ 35wt% Epoxy

Untreated NaOH SLS

43.51 60.86 66.94

47.44 66.35 72.98

18.06 25.27 27.79

Present Work

Banana-kenaf/ Unsaturated polyester

40wt%

NaOH SLS

50 55

62 68

17.00 21.00

Thiruchitrambalam et al. [21]

Coir/Epoxy resin

30wt%

Untreated NaOH SLS

13.00 15.00 18.00

35.00 45.00 55.00

18.00 25.00 26.00

Karthikeyan et al. [28]

CottonBanana/Vinyl ester resin

30wt%

Untreated NaOH SLS

25.00 40.00 42.00

50.00 68.00 72.00

32.00 58.00 52.00

Umachitra et al. [22]

Banana-kenaf/ Unsaturated polyester

40wt%

Untreated NaOH SLS

90 100 110

120 130 150

22.50 25.00 27.00

Alavudeen et al. [25]

banana/kenaf composites that were 10% SLS-treated had enhanced results in terms of their mechanical characteristics [27]. Thus the obtained results are compared with the previous researchers and they are presented in Table 1.

3.4 Scanning Electron Microscopy SEM images show the morphological variations on the fiber’s surface as a result of the chemical treatment (Fig. 7a–c). The absence of fiber and the reduction of the adhesion area caused the strength reduction in 35 wt% fiber content untreated cotton/kenaf composites. Thus it is obvious that the tensile behaviour and stiffness of the natural fiber composites are firmly subjected to fiber addition. Up to a certain level the rigidity and modulus increased with expanding the fiber weight proportion. The increment in the fiber weight proportion has brought about a reduction in the tensile strength [28]. When the adhesion regions were decreased, the fibre is pulled out, voids form, and debonding happens. The tensile strength was improved in the composite due to the optimum fibre loading ratio [29]. Tensile-cracked specimens reinforced with NaOH-treated fibre of 35 wt% showed poor bonding. Surface contaminants on the fibre surface, which serve as a barrier between the fibre and the matrix, were the reason for the poor adherence. The voids that were produced during the tensile loading as a result of the fibre pullouts showed that there was poor adhesion between the fibre and matrix. As shown in Fig. 7a, the SEM image of the fibre-reinforced specimens after NaOH treatment revealed voids and poor adhesion between the fibre and matrix.The SLS treatment enhanced the

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Fig. 7 SEM pictures of a composite with untreated cotton/kenaf fibre, b composite with cotton/ kenaf fibre treated with NaOH, c composite cotton/kenaf fibre treated with SLS

adhesive properties. The SEM pictures of Fig. 7c the SLS treated specimen allowed for the identification of the enhancements to the specimen’s tensile characteristics and the significance of the 10% SLS treatment. The shearing off of the fibre has produced good fibre matrix adherence. By expanding the surface area of contact with SLS treatment, the bonding properties are enhanced [30]. The imaging of the rich matrix revealed improved resin flow and resin bonding with the fibre. As a result, the cotton/kenaf composites may be used for a variety of applications that need high strength and are lightweight [31]. The study’s future objectives include adding other fillers, such as carbon nanoparticles, to the composites. These key literature reviews [32–34] will serve as the foundation for the experimental research of the next scope study.

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4 Conclusions A composite material compared to untreated, NaOH and SLS treated cotton/kenaf epoxy composite an investigating the mechanical characteristics. The following conclusions are possible: • The cotton/kenaf composite, at a fibre loading of 35 wt%, has enhanced mechanical properties compared to other composite laminates. • The composite samples SEM images showed higher fibre-matrix interaction and surface adherence. • The impact, flexural and tensile strength of specimens made with fibre content of 35 wt% increased by 10%, 15%, and 12%, respectively, following NaOH treatment at 10% concentration. • When cotton/kenaf fibres are treated with the same concentrations of SLS and NaOH solutions, the mechanical properties of the SLS-treated fibre are better than the NaOH-treated fibre. • Thus, cotton/kenaf composites may be a preferable option for applications that require materials that are lightweight, very durable, and produced in a cost-efficient way. • Cotton/kenaf composites wear properties were tested utilizing various fibre contents and NaOH and SLS treatment. • Evaluation of cotton/kenaf composites dynamic mechanical and thermal properties. • Cotton/kenaf can be reinforced with biopolymers for applications using biodegradable composites.

References 1. John MJ, Thomas S (2008) Biofibres and biocomposites. Carbohydrate polymers 71(3):343– 364. https://doi.org/10.1016/j.carbpol.2007.05.040 2. Mylsamy B, Aruchamy K, Subramani SP, Palaniappan SK, Rangappa SM, Siengchin S (2023) State of the art of advanced fiber materials: future directions, opportunities, and challenges. Fiber Mater Des Fab Appl pp 9783110992892–97831109929014. https://doi.org/10.1515/978 3110992892-014 3. Sreenivas HT, Krishnamurthy N, Arpitha GR (2020) A comprehensive review on light weight kenaf fiber for automobiles. Int J Lightweight Mater Manuf 3(4): 328–337. https://doi.org/10. 1016/j.ijlmm.2020.05.003 4. Ahmed KS, Vijayarangan S (2007) Experimental characterization of woven jute-fabricreinforced isothalic polyester composites. J Appl Polym Sci 104(4):2650–2662. https://doi. org/10.1002/app.25652 5. Aruchamy K, Palaniappan SK, Lakshminarasimhan R, Mylsamy B, Dharmalingam SK, Ross NS, Pavayee Subramani S (2023). An experimental study on drilling behavior of silane-treated cotton/bamboo woven hybrid fiber reinforced epoxy polymer composites. Polym 15(14):3075. https://doi.org/10.3390/polym15143075

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24. Karthik A, Jeyakumar R, Sampath PS, Soundarararajan R (2022) Mechanical properties of twill weave of bamboo fabric epoxy composite materials (No. 2022-28-0532). SAE Tech Paper. https://doi.org/10.4271/2022-28-0532 25. Alavudeen A, Rajini N, Karthikeyan S, Thiruchitrambalam M, Venkateshwaren N (2015) Mechanical properties of banana/kenaf fiber-reinforced hybrid polyester composites: Effect of woven fabric and random orientation. Mater Des (1980–2015) 66:246–257 26. Bhuvaneshwaran M, Sampath PS, Balu S, Sagadevan S (2019) Physicochemical and mechanical properties of natural cellulosic fiber from Coccinia Indica and its epoxy composites. Polim 64(10): 656–664. https://doi.org/10.14314/polimery.2019.10.2 27. Akil H, Omar MF, Mazuki AM, Safiee SZAM, Ishak ZM, Bakar AA (2011) Kenaf fiber reinforced composites: A review. Mater Des 32(8–9):4107–4121. https://doi.org/10.1016/j. matdes.2011.04.008 28. Karthikeyan A, Balamurugan K, Kalpana A (2013) The new approach to improve the impact property of coconut fiber reinforced epoxy composites using sodium laulrylsulfate treatment. http://nopr.niscpr.res.in/handle/123456789/15888 29. Neisiany RE, Khorasani SN, Naeimirad M, Lee JKY, Ramakrishna S (2017) Improving mechanical properties of carbon/epoxy composite by incorporating functionalized electrospun polyacrylonitrile nanofibers. Macromol Mater Eng 302(5):1600551. https://doi.org/10.1002/ mame.201600551 30. Naeimirad M, Zadhoush A, Neisiany RE (2016) Fabrication and characterization of silicon carbide/epoxy nanocomposite using silicon carbide nanowhisker and nanoparticle reinforcements. J Compos Mater 50(4):435–446. https://doi.org/10.1177/002199831557637 31. Pothan LA, Oommen Z, Thomas S (2003) Dynamic mechanical analysis of banana fiber reinforced polyester composites. Composites Science and technology 63(2):283–293. https://doi. org/10.1016/S0266-3538(02)00254-3 32. Ku H, Wang H, Pattarachaiyakoop N, Trada M (2011) A review on the tensile properties of natural fiber reinforced polymer composites. Compos Part B Eng 42(4):856–873. https://doi. org/10.1016/j.compositesb.2011.01.010 33. Mylsamy B, Palaniappan SK, Subramani SP, Pal SK, Aruchamy K (2019) Impact of nanoclay on mechanical and structural properties of treated Coccinia indica fibre reinforced epoxy composites. J Mater Res Technol 8(6):6021–6028. https://doi.org/10.1016/j.jmrt.2019.09.076 34. Mylsamy B, Chinnasamy V, Palaniappan SK, Subramani SP, Gopalsamy C (2010) Effect of surface treatment on the tribological properties of Coccinia Indica cellulosic fiber reinforced polymer composites. J Mater Res Technol 9(6):16423–16434. https://doi.org/10.1016/j.jmrt. 2020.11.100

Green Synthesis of Silver/Iron(Ag/Fe) and Copper/Iron(Cu/Fe) Nanoparticles for Cytotoxic Investigation on Henrietta Lacks(HeLa) Cancer Cell R. Raja Nandhini , H. Joy Prabu , Ebenezer Thaninayagam , R. R. Gopi , I. Johnson , and Arockiasamy Felix Sahayaraj

Abstract Synthesized nano particles were used for drug delivery as well as therapeutic and energetic agents. It is associated with fewer side effects than radiation or chemotherapy. Silver, iron, and copper are the best agents for preventing inflammation in humans, and they exhibit better anticancer properties. The present work concentrates on the Silver/Iron (Ag/Fe) and Copper/Iron (Cu/Fe) nanoparticles using Annona muricata (Linn) plant extract in a green way. The nano particles were then characterized using XRD, FTIR, UV-Spectroscopy and FESEM with EDX. Ag/Fe and Cu/Fe nanoparticles were investigated in HeLa cervical cancer cells using the MTT assay. The cell death induced by Cu/Fe nanoparticles was significant at lower concentrations. As the concentration increased, cell death gradually increased. Thus, Cu/Fe exhibited superior anticancer properties. Keywords Anti-cancer · Cervical cancer · Drug delivery · Green synthesis · HeLa

1 Introduction Cancer is the riskiest disease that causes death and is characterized by the proliferation of abnormal cells. Radiotherapy, chemotherapy, and surgery are widely used in cancer treatment [1]. Although these methods are helpful in cancer treatment, they have severe side effects. Therefore, there is an immediate need for less toxic, inexpensive, and effective treatments, with fewer adverse effects. Nanomaterials range from 1 to 100 nm, comparable to large biomolecules, such as receptors and enzymes. R. Raja Nandhini · H. Joy Prabu (B) · E. Thaninayagam · R. R. Gopi · I. Johnson Department of Physics, St. Joseph’s College (Autonomous), Affiliated to Bharathidasan University, Tiruchirappalli 620002, India e-mail: [email protected] A. Felix Sahayaraj Department of Mechanical Engineering, KIT-Kalaignarkarunanidhi Institute of Technology, Tamil Nadu, Coimbatore 641402, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_7

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Nanoparticles exhibit distinctive interactions with biomolecules and could be used for the theragnosis of cancer. Bimetallic nanoparticles have attracted more attention than metallic nanoparticles have. The interactive effects of the two metal compounds show interesting new properties owing to their stability, selectivity, increased surface area, and reduced size. Mixing silver nitrate with plant extracts [2, 3] reduces side effects and produces AgNPs [4, 5]. Ag is a strong medical agent at the nanoscale level. Normally, cancer tissues have a larger level of copper that takes part in cellular processes to promote cancer development, such as angiogenesis. Organic compounds, such as plants, leaves [6], fruits, seeds, roots, and bark, which bind to copper, provide helpful tools for converting cancer-fighting agents from cancerencouraging agents. Iron plays an important role in cancer and metastasis owing to its great progress in cancer cell survival. Tumor cells have a higher demand for iron (anemia). Without affecting normal tissues, chelation therapy tends to target iron in cancer cells. Therefore, iron-chelating agents are promising candidates for cervical cancer treatment. Being eco-friendly, less toxic, inexpensive, and with fewer side effects provides better results than chemical methods. Chemical investigations of this Annona muricata (Linn) have revealed phytochemicals such as alkaloids, flavonoids, saponins, terpenoids, polysaccharides, and some mineral deposits such as potassium, calcium, copper, iron, sodium, and magnesium. The leaves of this sour soup plant contain compounds that fight cancer cells thousands of times better than those of chemotherapy. Hence, the present study aimed to synthesize Ag/Fe and Cu/ Fe nanoparticles via Annona muricata (Linn) plant extract. Conditions and properties of the prepared samples were evaluated. These were XRD, UV-visible spectroscopy, FTIR, SEM, and FESEM with EDX. The antitumor property of the synthesized Nanoparticles against HeLa cells [7, 8] was also studied. The IC50 values for both nanoparticles were calculated, as nanoparticles provide better properties for fighting cancer.

2 Materials and Methods 2.1 Materials The leaves of plant, Annona muricata (Linn) was collected from the Kolli hills (South India). The extract from this plant can be used as reducing and capping agent [9– 11]. The chemical compounds Silver nitrate (AgNO3 ), copper chloride (CuCl3 ), and ferric chloride (FeCl3 ) were purchased from Sigma-Aldrich, Germany.

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Fig. 1 Preparation of leaf extract

2.2 Preparations of Plant Extract The Kolli hills provided dried leaves with plant extract. To remove contaminants, they were extensively washed twice with demineralized water after being properly washed once with regular water. The leaves were carefully chopped into pieces and grounded with a mortar to obtain a homogenized extract. 90 ml of demineralized water and 10 g of leaves were added [12–14]. The mixture was steamed for 5 min at 90 °C. The Whitman filter paper sizes included 10–500 mm diameter circles and 460 mm × 570 mm shells. Finally, the plant extracts were purified. The extract was then stored at 4 °C (Fig. 1) [15–18].

2.3 Preparation of Ag/Fe Nanoparticles via plant Extract 0.5 M of silver nitrate and 0.5 M of ferric chloride were combined separately in 50 ml of distilled water to create Ag/Fe nanoparticles. Both solutions were blended concurrently in a stirrer for a few hours. Drop-by-drop, the plant extract was incorporated into the mixture [19–21]. Ag/Fe nanoparticle production was controlled by a yellowish to blackish-brown color change in the solution (Fig. 2). The precipitate was desiccated in an oven for an hour untill all the moisture is removed and centrifuged at a high speed of 12,000 rpm. Under UV-Vis analysis, Ag/Fe nanoparticle formation was seen [22, 23].

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Fig. 2 Preparation of Cu–Fe nanoparticles via plant extract

2.4 Preparation of Cu/Fe Nanoparticles via plant Extract 00.5 M of copper chloride and 0.5 M of ferric chloride were combined separately in 50 ml of distilled water to create Cu/Fe metallic nanoparticles. Both solutions were blended concurrently in a stirrer for a few hours. The plant extract was added dropwise to the mixture. Dark brown color changes in the fluid control the growth of the metallic Cu/Fe nanoparticles (Fig. 3). The precipitate was desiccated in an oven for an hour untill all the moisture is removed and centrifuged at high speed of 12,000 rpm. Under UV-Vis analysis, Cu/Fe nanoparticle formation was seen [24].

Fig. 3 Preparation of Ag-Fe nanoparticles via plant extract

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Fig. 4 X-ray diffraction of Cu–Fe and Ag–Fe

3 Materials and Methods 3.1 X-ray Diffraction The peaks for the synthesized Ag/Fe nanoparticles at 45.71, 66.93, and 76.17, corresponding to the (h k l) planes, were (1 1 1), (2 2 0), and (3 1 1), respectively, as shown in Fig. 4. The crystalline size of Ag/Fe Nanoparticles was 16.53 nm [25–27]. The peaks for the synthesized Cu/Fe nanoparticles at 35.01, 38.04, and 71.35 correspond to the (h k l) planes (3 1 1), (2 2 2), and (4 0 0), respectively, as referred in the (JCPDS file (77-0010)). The crystalline size of the Cu/Fe nanoparticles was 7.38 nm [28–30]. All the peak intensities were characteristic of face-centered cubic nanoparticle structures. The remaining peaks were due to the existence of bio-organic compounds in the sample. The crystalline size of Cu/Fe was better than that of Ag/Fe nanoparticles.

3.2 Vibrational Spectroscopic Analysis Using FTIR The FTIR analysis of Ag/Fe and Cu/Fe nanoparticles synthesized using plant extracts and their bands were found in the range from 350 to 4000 cm−1 , as shown in Fig. 5. The plant extract acted as a reducing agent for the production of metal oxide nanoparticles.

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Fig. 5 FTIR of Cu–Fe and Ag–Fe

3.2.1

FTIR for Ag/Fe

The extensive crest at 3407 cm−1 due to the company of polyphenols from A. muricata (Linn) plant extract [31–33]. The peaks present at 2933.42 and 1371 cm−1 indicate that stretching corresponds to the alkane group. The peak at 1115 cm−1 denotes the stretching amine group owing to the presence of phenolic compounds in the plant extract. The peak at 1627 cm−1 indicates the presence of a variable alkene group. The peak at 1371 cm−1 is attributed to the presence of the bending (C–H) alkane group. The peak absorbed at 666.84 cm−1 stretching amine group shows the presence of iron, and the peak observed at 463 cm−1 signifies the presence of silver.

3.2.2

FTIR for Cu/Fe

The broad peaks at 3587 cm−1 and 3497 cm−1 indicate strong (O–H) groups, respectively. The peak at 2946 cm−1 indicates the strong (C–H) alkane group. The absorption band at 1588 cm−1 directs the stretching (C=C) aromatic group because flavonoids and phenols act as reducing agents to form metallic nanoparticles. The peaks at 1397 and 1127 cm−1 denote stretching in alkyl halide groups. The peak at 601.31 cm−1 bending (C–H) alkene group indicates the occurrence of iron, and the peak near 512.89 cm−1 stretching (C–Br) alkyl halide group indicates copper. The above extra peak is due to the presence of biological molecules in the synthesized metal oxide nanoparticles [34–37].

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3.3 UV-Visible Spectroscopy The green syntheses of Ag/Fe and Cu/Fe nanoparticles were analyzed using UVvisible spectroscopy, as shown in Figs. 6 and 7. The visible changes in color in the chemical solution and plant extract indicated the development of nanoparticles. The color changes were due to plasmon resonance. The Ag/Fe metallic nanoparticles exhibited absorption peak at 408 nm in the region of the visible spectrum [38–40]. Cu/Fe exhibited absorbance band around approximately 213 nm in the UV region [41–44]. Another strong absorbance in the visible region is due to the existence of some biomolecules from the extract. Fig. 6 UV of Cu–Fe

Fig. 7 UV of Ag–Fe

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Fig. 8 SEM of a AgFe and b CuFe

3.4 Morphological Analysis The average size and morphology of samples were analyzed via SEM. Figure 8a, b show SEM images of both the Ag/Fe and Cu/Fe samples. From the micrographs, it can be seen that both samples are spherical and have a uniform particle distribution. The average particle sizes of Cu/Fe and Ag/Fe were 20–25 nm and 23–25 nm, respectively.

3.5 FESEM with EDAX The surface shape, average particle size, and material composition of the synthesized Cu/Fe and Ag/Fe nanoparticles were investigated using FESEM and EDX analysis. From Fig. 9, the average particle sizes of the Cu/Fe and Ag/Fe nanoparticles were established–to be 20–25 and 23–25 nm and both nanoparticles were spherical. The elemental composition of the nanoparticles of Ag/Fe and Cu/Fe was confirmed with the EDX spectrum. In Fig. 9 The sample was mainly composed of Cu, Fe, and C. The atomic radii of the elements are 22.77, 20.24, and 19.67. In Fig. 9, the compounds present in the particles are Ag, Fe, and C. The presence of the Ag peaks is shown

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in the Figure. Owing to its superior oxidizing agent, it has a greater tendency to be reduced. The atomic radii of the elements are 20.70, 52.58, and 3.87. The carbon content in both samples was mainly due to the presence of biomolecules in the plant extracts.

3.6 Investigation of Antitumor Property of Ag/Fe and Cu/Fe Nanoparticles in Contrast to the HeLa Cancer Cells The synthesized Ag/Fe and Cu/Fe Nanoparticles were assessed for their anti- proliferative activities in the HeLa cancer cells using an MTT assay [45–47]. It is the preliminary judgment for inhibition of tumor action i.e. to investigate the IC50 value (half Minimal inhibitory concentration) at a particular time. HeLa cancer cells [48– 50] were treated with various concentrations (20, 40, 60, 80, and 100 μg/ml) of the synthesized Ag/Fe and Cu/Fe Nanoparticles for 24 h. The concentration of Nanoparticles could significantly induce cytotoxicity in the cancer cells in a concentration based manner. The cell vitality results obtained by the MTT assay are shown in Fig. 10. Ag/Fe nanoparticles prevented the growth of HeLa cells. However, cell death occurs only at higher IC50 values. The percentage of cell death at a concentration of 100 μg/ml was 65.80% at 60 μg/ml after 24 h. These results reveal that it has a good inhibitory effect. For Cu/Fe nanoparticles, cell death at a concentration of 100 μg/ml was 47.79% at 50 μg/ml after 24 h. The cell death induced by Cu/Fe Nanoparticles was a significantly lower amount of IC50 than that induced by Ag/Fe NPs (Tables 1 and 2). With increasing concentration, cell death gradually increased. This investigation, concluded that Cu/Fe Nanoparticles have an excellent anti-cancer property [51–53], they could be used in the theragnosis of tumor and it shows good inhibition counter to HeLa cells. Results are compared with previous literatures to analyze the potential improvement and it’s proven to be better [54–58].

4 Conclusion The present work focuses on the green synthesis of Ag/Fe and Cu/Fe nanoparticles using an Annona muricata (Linn) leaf extract against the HeLa cell line using an MTT assay. As was observed in the SEM/FESEM and UV-Vis analysis/EDX the bio- synthesized Nanoparticles were Spherical and the particle size of Ag/Fe is 23.32 nm and Cu/Fe is 29.39 nm. The research study also discovered that the Cu/Fe nanoparticles showed better anti-cancer activities and good inhibition against HeLa cells [59, 60] compared to Ag/Fe nanoparticles. In this study we tried to incorporate the idea of targeted chelation therapy using Iron nanoparticles [61]. As we know, Tumor cells have high affinity towards Fe as it needs Iron to grow and metabolize. Iron is important for the improvement and

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Fig. 9 a EDAX of Cu–Fe. b EDAX of Ag–Fe

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Fig.10 a The cell viability by MTT assay of Ag–Fe. b The cell viability by MTT assay of Ag–Fe. c The cell viability by MTT assay of Cu–Fe. d The cell viability by MTT assay of Cu–Fe

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Fig.10 (continued)

Table 1 Cell viability AgFe S. No

Sample concentration (μg/ml)

Cell viability (%) (in triplicates)

Mean value (%)

1

Control

100

100

100

100

2

100 μg/ml

11.17

14.71

19.89

15.25

3

90 μg/ml

29.70

34.60

31.88

32.06

4

80 μg/ml

49.04

49.86

47.95

48.95

5

70 μg/ml

55.04

35.96

61.58

50.86

6

60 μg/ml

66.21

67.02

70.02

67.75

7

50 μg/ml

75.20

70.84

72.47

72.83

8

40 μg/ml

81.19

76.83

77.11

78.37

9

30 μg/ml

82.28

80.65

83.92

82.28

10

20 μg/ml

88.55

85.01

86.10

86.55

proliferation of tumor cells. In many cellular functions, such as DNA synthesis, energy metabolism, and cellular proliferation, iron, an essential nutrient, is crucial [62]. Heme, a vital component of hemoglobin that is responsible for carrying oxygen in the blood, is produced only when iron is present in the body. Heme is essential for tumor cells because they need a lot of oxygen and nutrients to develop and divide quickly. Numerous enzymes necessary for DNA synthesis, repair, and energy processing also need iron. Because of their high metabolic rates, tumor cells need a lot of energy to sustain their expansion and multiplication. As a result, they require lots of iron to keep these processes going. Tumor cells often overexpress transferrin receptors on their cell surface, which allows them to take up more iron from the

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Table 2 Cell viability CuFe S. No

Sample concentration (μg/ml)

Cell viability (%) (in triplicates)

Mean value (%)

1

Control

100

100

100

100

2

100 μg/ml

22.5

23.43

27.18

24.37

3

90 μg/ml

35.62

36.25

35.00

35.62

4

80 μg/ml

37.81

37.18

62.5

45.83

5

70 μg/ml

41.87

40.31

42.18

41.45

6

60 μg/ml

43.75

45.93

41.56

43.74

7

50 μg/ml

47.18

46.56

48.75

47.49

8

40 μg/ml

57.81

55.00

50.31

54.37

9

30 μg/ml

59.68

60.00

58.12

59.26

10

20 μg/ml

62.5

61.25

65.00

62.91

bloodstream. This high affinity for iron enables tumor cells to compete with other cells in the body for this essential nutrient, which further supports their growth and survival. This study will be further improved by the synthesis of synthetic RNA/DNA which can attach to the telomere produced by the telomerase enzyme of the malignant cell. The S-RNA functionalized bimetallic nanocomposite can be used in targeted drug delivery. This will help in the prevention of annihilation of normal cells whereas the malignant cancer cells can be destroyed. The product is in the beginning stages and can be mass produced after vigorous testing through clinical trials and will aid in furthering the knowledge about anti-carcinogenic nanomedicine. Nanomedicine is the future of healthcare industry and we believe this research will help in improving the standards. Therefore in a conclusion, it could be assumed that the bio-synthesized nanoparticles synthesis through plant extract is Non-toxic [12, 63, 64], inexpensive with lower side effects, and utilized in treatment for scaling up for the industrial purpose to widen the production of nanoparticles and doubtlessly would begin its commercial viability in medicine.

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LSPM-MAN (Manufacturing Technologies for Lightweight Polymeric Materials)

Effect of Manufacturing Techniques on Mechanical Properties of Natural Fibers Reinforced Composites for Lightweight Products—A Review M. Sasi Kumar , S. Sathish , M. Makeshkumar , S. Gokulkumar , and A. Naveenkumar

Abstract Technological changes in lifestyles, decreasing man-made resources, and growing global ecological issues have driven material advances throughout human history. This has prompted academics worldwide to seek more sustainable and adaptable solutions for the above concerns. The increasing use of green fibers in composite materials has helped maintain tree growth, which is important for mortality. Natural fiber composites can be fibrous or non-fibrous. They are derived from living things and inorganic substances alike. Cellulosic fibers are the most popular natural fibers due to their eco-friendliness and capacity to reduce global energy crises. Developing and utilising biocomposites to replace synthetic materials with eco-friendly ones is the main motivation. The natural fiber is used in several lightweight applications like pharmaceuticals, papermaking industries, health, biomedical, sports equipment, cosmetics, automotive, food packing aircraft, marine, railway, as well as in aerospace industries. The natural fiber composites polymer have studied by scholars, researchers, and engineers for years with a composition of sisal, jute, hemp, kenaf, luffa, sugarcane, coir, bamboo, etc. as reinforcement with polypropylene, epoxy, polylactic, as well as polyester, etc. as a matrix or resin. This paper shows the mechanical characteristics of composite matter based on natural fiber utilizing several manufacturing methods like hand layup technique, injection moulding method, compression moulding, extrusion, pultrusion, blow moulding, spray lamination, and rotational moulding, etc. Keywords Natural fiber reinforcement polymer · Resin · Mechanical performance · Manufacturing process M. Sasi Kumar (B) Department of Aeronautical Engineering, KIT-Kalaignarkarunanidhi Institute of Technology, Kannampalayam, Tamil Nadu, India e-mail: [email protected] S. Sathish · M. Makeshkumar · S. Gokulkumar · A. Naveenkumar Department of Mechanical Engineering, KPR Institute of Engineering and Technology, Arasur, Tamil Nadu, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_8

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1 Introduction Due to their numerous advantages over composites reinforced with conventional materials, natural composites polymer reinforced using bio fibers have recently attracted the concentration of academics as well as technicians [1]. In order to create composite materials with characteristics like rigidity, light weight, reusable, smoothness, affordability, nontoxic, environmentally friendly or recyclable, safe, and low cost, bio fibers are typically employed [1, 2]. The development of fiberreinforced polymers, among improved physical properties and environmental conditions, depends on the interface between thermoplastics and bio-fiber being improved. Bio-fibers, which are lignocellulosic materials found in nature, have a great potential for usage as thermoplastic reinforcement [3]. In the polymer matrices, reinforcements composed of natural reinforcement fiber obtained from renewable resources are becoming more prevalent. These products are eco-friendly due to their biodegradability and utilization of natural materials. The clarity of these fibers structural and mechanical features is a prerequisite for their efficacy. Environmental considerations, plant age, extraction processes, and geographic origin are only some of the many variables that might affect the final product’s characteristics. Fiber characterisation factor is based on these criteria [4]. Fiber wettability in the matrix phase improves strength. Chemically treating fibers creates wettability. Chemically treated composites have been studied by several researchers. Several types of chemical modification, including alkaline, silane, enzyme, benzoylation, and acetylation, have resulted in enhanced physical and mechanical qualities of natural fibers [5]. The most widespread chemical treatment for fibers is alkali treatment. It is most utilised in thermoplastic and thermosetting materials that incorporate reinforcement from natural fibers. Fibers treated with alkali become rougher, which enhances their mechanical interlocking. Tridax procumbens fiber that was treated with NaOH exhibited a similar type of improvement in physical and chemical characteristics. Chemical treatment enhanced the wettability of the fibers and increased the surface roughness. It was discovered that the removal of large quantities of cellulose and lignin had a detrimental effect on fiber characteristics when the NaOH concentration was increased [6]. Natural fibers such as coir, flax, sisal, husk, jute, banana, abaca, hemp, wood, grass, bamboo Corypha taliera, kenaf, and Cyperus compactus stems, are abundant in nature and can be used as reinforcement for manufacturing fiber composites material. As their low weight, extreme specific modulus, absence of toxicity, and ease of manufacture, these fibers are advantageous [4]. Natural fiber-based thermoplastic composites are manufactured by utilizing following techniques: injection techniques, filament techniques, hand layup techniques, spray techniques, compression techniques, and resin transfer techniques [7]. Natural fibers have been used in many industries, including home renovation, transportation, building, the arts, and recreation.

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Fig. 1 Manufacturing methods

2 Manufacturing Techniques Our concentration is on the elements influencing the mechanical properties of various bio-fiber-reinforced composite materials production processes. With composite materials, a variety of manufacturing processes are available, including hand layup techniques, compression techniques, injection techniques, filament techniques, spray techniques, and rotational techniques as shown in Fig. 1.

3 Hand Layup Method When producing composites, the most popular open moulding technique is the hand lay-up approach, which are vital in modern life. Gel-coated open mould followed by matrix pouring and fiber application. The cavity’s air bubbles are removed by revolving rollers. Composites cure at room temperature [8] (Fig. 2).

3.1 Materials Used for Hand Lay-up Method See Table 1.

3.2 Mechanical Properties of Hand Layup Method Mechanical performances has been examined for polyester resin and bamboo fiber composites. 160 mm of 40 wt% fiber was laid by hand. It offers improved mechanical characteristics for tensile modulus, strength, and flexural modulus up to 2.48 GPa, 3.70 GPa, and 128.5 MPa, respectively [9]. Polyester matrix and jowar fiber with 160 mm fiber length and 40% fiber weight were tested using hand layup. Tensile modulus raised by 2.75 GPa, tensile stiffness raised by 124 MPa, as well as flexural modulus raised by 7.87 GPa, flexural stiffness raised by 134 MPa have been reported [9]. The open mould or hand layup method was used to test sisal fiber and epoxy

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Fig. 2 Hand lay-up techniques

Table 1 Fiber and matrix used for hand layup

Fibers

Matrix

Sisal Jute Carbon Pulp Coir Luffa

Vinyl ester Polyimides Epoxy Phenolics Polyurethane Polyester

matrix with the length 10 mm of fiber as well as fiber weight up to 30%. During the experiment, several mechanical parameters including tensile modulus and strength of 0.187 GPa and 40.25 MPa, as well as flexural strength and modulus of 104.78 MPa, and 11.896 GPa were found, as well as impact toughness of 1.366 J/cm2 [10]. Analytical and experimental studies were conducted to investigate the mechanical characteristics of filled and unfilled jute fabrics-epoxy composites made with bio-fillers such as Azadirachta indica seed powder and discarded Camellia sinensis powder. Using hand layup procedures, composites filled with powder from Azadirachta indica seeds exhibited better mechanical characteristics and fewer voids than those filled with powder from discarded Camellia sinensis leaves [11]. Bagasse fiber reinforced the composite to evaluate mechanical characteristics, morphology, water absorption, and performance. Fiber Hand-laid composites have varied fiber weights. Fiber wt%

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enhances water absorption. SEM indicated that 5 wt% fiber and matrix bind better than 10 and 15 [12]. Figure 3 represents the hand layup approach, for the flexural strength, tensile strength, flexural modulus, and tensile modulus. Figure 4a, b represent the hand layup method to illustrate the tensile and flexural strengths of various fibres. It is found that the sawdust flour reinforced with polypropylene has high tensile stiffness up to 30 MPa as well as flexural stiffness up to 54 MPa when compared to other fibers for hand layup methods [13]. Table 2 presents several composites made by hand layup techniques.

Fig. 3 Mechanical properties versus composite designation

Fig. 4 Tensile and flexural strength by hand lay-up method for various composite materials. a Tensile stiffness versus hand layup method. b Flexural stiffness versus hand layup method

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Table 2 Composites made by hand lay-up techniques S. No

Method

Fiber/Resin

1

Hand lay-up Techniques

Basalt/Epoxy [14]

2

Dharbai fiber/Epoxy[15]

3

Mudar, snake grass fiber/Epoxy [16]

4

Cissus quadrangularis stem fiber/Epoxy [17]

5

Ipomoea staphylina plant fiber/Epoxy[18]

6

Caryota urens/Epoxy as matrix [19]

7

Areca fibers/Epoxy [20]

4 Compression Moulding Methods In the engineering sector, the usage of composite materials is growing, and certain moulding techniques are essential to this development. One of such is compression moulding, which is marketed as a suitable technique for complicated fiber glass reinforced polymers because of its quick cycle time and high volume/high pressure operation. The metal moulds, which are installed on a sizable hydraulic moulding press, are warmed to a temperature of between 2500 and 4000 F [8]. Other moving pieces in this process include the ejector pin, charge, moveable and fixed moulds, and others. Two components one permanent and the other movable will be used to build the structure. Next, using a mould with one portion fixed while a second part being carried out in which material is softly pressed, the matrix is set aside in the compression moulding technique (Fig. 5).

Fig. 5 Compression moulding techniques

Effect of Manufacturing Techniques on Mechanical Properties … Table 3 Fiber and matrix used for compression moulding

Fibers

Matrix

Tamarind fruit fiber Glass fiber Hybrid carbon fiber Banana fiber Nano clay Jute fiber

Polypropylene High density polyethylene Epoxy Low-density polyethylene

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4.1 Materials Used for Compression Moulding Method See Table 3.

4.2 Mechanical Performance of Compression Moulding Methods Compression moulding experiments were conducted using a polyester matrix and tamarind fruit fiber with a 100 mm fiber length and a 40% fiber weight. Mechanical characteristics like tensile strength and modulus of 77.4 MPa and 1.4 GPa, flexural strength and modulus of 88.5 MPa and 1.5 GPa, the strength of impact is 7.3 J/ cm2 , and hardness of 90 HRRW have been shown to be superior to those of another production procedure [21]. The Sansevieria cylindrica fiber, with a 30 mm length of fiber and 40% weight of fiber via compression moulding, was the subject of the experimental inquiry. Fine mechanical characteristics were discovered, including tensile strength and flexural strength raised by 84 MPa and 3 GPA, tensile modulus up to 75.75 MPa, and impact strength up to 9.5 J/cm2 [22]. Researchers looked at the mechanical characteristics of composite materials made using polypropylene resin and Musa paradisiac banana reinforcement. A length of fiber up to 70 mm and 20% weight of fiber were carried out in the compression moulding process. The observation revealed that it possesses excellent mechanical characteristics, including tensile stiffness as fine as modulus is 47 MPa and 2.6 GPa, impact stiffness is 2.656 J/ cm2 , hardness of 75 HRRW, and flexural stiffness of 73.24 MPa [23]. Figure 6 represents the flexural, tensile strength and modulus for several composites when using the compression moulding technique. The experiment on banana, jute fiber, and nano clay with polyester was conducted [24]. In this research, the compression moulding methods were employed to enhance mechanical characteristics of the natural fiber. After this research, they discovered improved results for impact strength and hardness of 22.12 kJ/m2 and 38.34 HRRW, but worse results for tensile strength as well as flexural strength raised by 36.9 and 112 MPa. Date seed powder was mixed with a vinyl ester matrix and put through a series of experiments to determine whether it could be used to acquire different mechanical properties using moulding techniques such as compression. It was then determined that the elastic

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Fig. 6 Mechanical properties versus composite designation

strength maximum is 23.7 MPa and the flexural strength maximum is 48.3 MPa [25]. The production of the vinyl ester matrix using the compression moulding process was done using both cooked eggshell and coir fiber combined with the matrix [26]. Tensile, flexural and impact strength results for this combined (hybrid) composite material are 24 MPa, 26 MPa, and 39.5 kJ/m2 , respectively. With the use of compression moulding, the hybrid composite material may be created [25] matrix vinyl ester and tamarind seed powder were used to create this composite material. The fine tensile strength is obtained up to 34 MPa, the flexural strength up to 121 MPa, the impact strength up to 14 kJ/m2 , and the hardness to be 42 HRRW. A new epoxy-based composite with fiber of pineapple/flax and filler as peanut oil cake was compression moulded and tested for wear, water absorption, and mechanical properties a function of Pineapple/flax fiber from 20 to 40 wt% and peanut oil cake from 1 to 3%. 20 weight percentage of Pineapple/flax fiber and 2 weight percentage of peanut oil cake composites had good flexural, tensile strength, and impact characteristics of 70.28 MPa, 37.89 MPa, and 96.99 J/m [27]. Figure 7a, b show both the tensile and flexural strengths of a range of composites made using compression moulding. The better tensile strength is found for date seed powder as fiber with vinyl ester as matrix and better flexural strength are found to be for tamarind seed powder as fiber and vinyl ester as matrix. Table 4 presents several composites made by compression moulding techniques.

5 Injection Moulding Methods The most popular method of producing net-shaped materials is injection moulding. The goods made from injection moulding have a inclusive range of uses in day-today life. An external heating source and a screw are used in the moulding process known as “injection moulding” to melt the material, which is then injected into a

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Fig. 7 Tensile and flexural strength by compression moulding method for various composite materials. a Tensile stiffness versus compression method. b Flexural stiffness versus compression method

Table 4 Composites made by compression moulding techniques S. No

Method

Fiber/Resin

1

Compression moulding method

Roselle, sisal, and banana/Epoxy [28]

2

Glass/Polypropylene [29]

3

Jute, banana, and sisal/Polymer based composites [30]

4

Sisal and flax as a fiber/Matrix as a polypropylene [31]

5

PLA as matrix material/Flax fibers [32]

6

Lygeum spartum L. fibers/Epoxy resin [33]

mould to create the desired product once the mould cools. High-precision composite components with complicated geometry may be created via injection moulding at incredibly cheap cost and in incredibly quick cycle times (Fig. 8).

5.1 Materials for Injection Moulding See Table 5.

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Fig. 8 Injection moulding techniques

Table 5 Fiber and matrix used for injection moulding

Fiber

Matrix

Nylon Flax Basalt

Polyoxymethylene HDPE Polycarbonate LPDE

5.2 Mechanical Properties of Injection Moulding This method was used to produce treated flax fiber and poly-lactic acid, where the fiber length is 6 mm and its weight percentage is 30. They discovered hardness up to 99 HRRW, tensile strength up to 23.6 MPa, and tensile modulus up to 1.1 MPa, impact stiffness and hardness up to 1.1 GPa, and 0.243 J/cm2 [34]. By the researchers the mechanical characteristics were investigated using composite material made of processed basalt fiber and poly-lactic acid [34]. We demonstrate the tensile strength of bio-fibers produced by injection moulding and compression moulding techniques applied to polypropylene matrices derived from various plant materials as shown in Fig. 9a. Figure 9b displays the strength of tensile for bio-fibers made from agave, sisal, and jute with polylactic matrix using compression moulding and injection moulding procedures. Figure 9c depicts the flexural strength of bio-fibers in a polypropylene matrix using injection moulding and compression moulding methods. Flexural strength for bio-fibers using a polylactic matrix produced by compression moulding and injection moulding procedures is depicted in Fig. 9d (Table 6).

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Fig. 9 Tensile strength as well as flexural strength of several composites fabricated by compression moulding techniques as well as injection moulding techniques Table 6 Composites made by injection moulding techniques S. No

Technique

Reinforcement/Matrix

1

Injection moulding techniques

Jute and sisal/Polypropylene [35]

2

Birch/HDPE [36]

3

Hemp and flax/Polypropylene [37]

4

Sisal/Polylactic acid [38]

5

Flax, jute, ramie, oil palm fibers/Polymers [39]

6

Luffa and coconut fiber/Polyester [40]

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6 Filament Moulding Methods A manufacturing technique called filament winding is particularly suited to open moulding automation, which uses a revolving mandrel as a mould. To create hollow, spherical, or prismatic pieces, filament winding is used. The carriage delivery eye travels horizontally in line with the axis of the revolving mandrel, holding up the fibers at the required sample or angle to the spinning axis while the mandrel rotates around the spindle. If the mandrel has been entirely covered with necessary layers, resin is then cured (Fig. 10).

6.1 Materials Used for Filament Winding Process See Table 7.

Fig. 10 Filament winding techniques

Table 7 Fiber and matrix used for filament moulding

Fiber

Matrix

Silk Kenaf Hemp Jute Cotton Sisal Coir

Polylactic acid Epoxy Polyester

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Table 8 Composites made by filament winding techniques S. No

Technique

Reinforcement/Matrix

1

Filament moulding techniques

Glass, carbon, aramid fibers/Epoxy composite [42]

2

Bamboo/Epoxy [43]

3

Kenaf/Unsaturated polyester [44]

4

Leaf/Phenol formaldehyde [45]

6.2 Mechanical Performance of Filament Moulding The experimental examination for flax and epoxy was conducted using the filament wounding method with a 52% fiber loading. It can be shown that mechanical properties like ultimate tensile stiffness, which is 191 MPa, and young’s modulus, which may reach 28 GPa, produce the best results [41]. Using the filament wounding process, flax fiber and epoxy matrix are used to make composite materials with a 48% fiber loading. They discovered that the young’s elastic modulus raised by 2 GPa as well as that the ultimate tensile hardness raised by 152 MPa [41]. Table 8 presents several composites made by filament winding techniques.

7 Spray Moulding Methods The open mould process (manual lay-up) methodology has evolved into the spray lay-up method. Spray-up, often referred to as chop, is a method for creating fiber glass products that involves releasing tiny glass strands using a pneumatic pump. It is distinct from the wet lay-up technique. The variety results from the way the resin and reinforcing elements are incorporated into the mould. Table 9 presents several composites made by spray moulding techniques (Fig. 11).

7.1 Materials Used for Spray Moulding See Table 10. Table 9 Fiber and matrix used for spray moulding

Fiber

Matrix

Hemp Kenaf Cotton Banana Silk Sisal

Phenolic Epoxy Polyester Vinyl ester

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Fig. 11 Spray up techniques

Table 10 Composites made by spray moulding techniques S. No

Technique

1

Spray moulding techniques

2 3

Reinforcement/Matrix Glass and carbon based-fiber/polymer [46] Jute, banana, ramie, kenaf and pineapple leaf fiber/Matrix composite materials [47] Jute and banana fibers/Polymer matrix composites [48]

8 Rotational Moulding Method Rotational moulding produces hollow pieces without weld lines. Rotational moulding’s key benefits are part design flexibility and the ability to make complicated forms in a variety of sizes. Moulds are cheap and don’t apply pressure, resulting in

Effect of Manufacturing Techniques on Mechanical Properties … Table 11 Fiber and matrix used for rotational moulding

Fiber

Matrix

Coir Flax Agave Sisal Palmyra Pineapple

Linear low-density polyethylene (LLDP) Green polyethylene (Green PE) Maleated polyethylene (MAPE)

113

stress-free parts. Material loaded, biaxial rotational speed, and mould thickness influence component thickness. Rotational moulding’s major disadvantages is extended processing time.

8.1 Materials Used for Rotational Moulding See Table 11.

8.2 Mechanical Performance of Rotational Moulding Linear Low-Density Polyethylene (LLDPE) powder was utilised as a foundation material and blended with varying weight percentages of Wood Dust fillers for the experiment. Mechanical characterisation and morphological studies showed that 10% WD fiber-added composites had acceptable strength [49]. Rotational moulding of HDPE and MDPE powders is examined. MDPE and HDPE were treated at three internal air temperatures and ASTM mechanical characteristics were determined. Internal air temperature increased tensile and impact strength. Hardness does not affect interior air temperature. MDPE has better impact strength and HDPE higher tensile strength. Using optical microscope, MDPE and HDPE powder shape and product microstructure were examined [50] (Table 12). Table 12 Composites made by rotational moulding techniques S. No

Method

1

Rotational method

Fiber/Resin Coir and agave/Polyethylene [51]

2

Agave, coir, and pine/Maleated polyethylene [52]

3

Banana fiber, Abaca fiber/Metallocene polyethylene [53]

4

Maple wood fibers/Maleated polyethylene [54]

5

Coir fiber/Plasma modified polyethylene [55]

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9 Conclusion Due to their favourable qualities, composite materials have become more popular in both industry and academia. These qualities cannot be obtained by the key component functioning independently. Researchers have been attempting to combine different necessary components up until recently in order to create composite materials, and several experiments have been taken out to observe their performance as well as phase changes. Researchers increased the proportion of fiber, the amount of the matrix, and a number of many other elements that work together to create a superior composite for improving the effectiveness of the composite material. Scientists have created a few better production approaches to reduce the delay time and difficulties of conventional techniques and achieve higher material efficiency. As a result it is found that the hand layup as well as the vacuum moulding technique are cost-effective for the manufacturing process whereas the injection moulding and the compression moulding technique showed better results for mechanical properties. To move forward it is investigated that the injection moulding technique showed fine results for mechanical properties as compared to the compression moulding technique. However, the reliability and durability of the structures can be obtained by using filament winding technique. Finally, it is revealed that all the techniques have their own advantages to use for different applications. Composite materials have gained popularity in both the industrial and academic spheres because they provide useful properties that cannot be obtained by any of the constituent parts functioning individually. For upcoming lightweight applications in significant industries like biomedical, automotive, chemical, aerospace, and sports, most of them were successful in improving material qualities.

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Characterization of Muntingia calabura Fiber as a Composite Reinforcement with Bleaching Variation Hastono Wijaya, Wirabbany Rukmana, Femiana Gapsari , Francisca G. U. Dewi, Putu Hadi Setyarini, Thesya M. Putri, and Clarissa Ratusima Arifi

Abstract This research investigated characterization of Muntingia calabura Fiber (MCF) as a composite reinforcement with bleaching treatment. MCF was treated with NaOH and varied NaClO concentrations with equal immersion times. This study characterized MCF using FTIR, XRD, and SEM–EDS. The changes in morphology of MCF increased the interaction between the matrix and the fiber in the composite. Alkali treatment is performed to improve composite fiber’s performance. However, the treatment makes the color of the fiber darker. Therefore, fiber bleaching is needed to ease the further process. Keywords Bleaching treatment · Characterization · Chemical · Morphology

1 Introduction Global warming which is happening so fast will cause many problems in the future. One thing that can be done is to use eco-friendly materials, such as composites. Composites are often used as a main structure of a component [1]. Composites are classified into two categories: natural fiber and synthetic fiber. The use of natural or synthetic fibers as an additional element in the polymer matrix makes it particularly suitable for many application [2]. The characteristics of fiber-reinforced composites depend on the characteristics of fiber and micro structure. The structural parameters are diameter, length, orientation, and volume of the fiber [2]. Currently, the expand of natural fiber composites as a substitute for synthetic fibers leads to the manufacture of environment friendly products to serve various applications in structure and manufacturing engineering [3, 4]. Although synthetic fiber has H. Wijaya · W. Rukmana · F. Gapsari (B) · F. G. U. Dewi · P. H. Setyarini · T. M. Putri · C. R. Arifi Mechanical Engineering Department, Faculty of Engineering, Brawijaya University, MT Haryono 167, Malang 65145, Indonesia e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_9

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superior mechanical properties compared to natural fiber, the risk posed by synthetic fiber waste is greater to the environment because it produces high CO2 emissions [2, 3]. Natural fiber has several benefits. It is light, abundant, cost-effective, renewable, easy to process, biodegradable, and has high strength and specific modulus. Composites is biodegradable and are harmless for engineering application [1–3]. Therefore, natural fiber is very potential as composite material reinforcement. However, it has several weaknesses. It is easy to adsorb water (hydrophilic) because it is a derivative of lignocellulose and has low melting point and interfacial adhesion [5–7]. The bark of the Muntingia calabura tree is soft, elastic, and easily dried. Based on the characteristics, the bark of the tree has a potential to be used as a reinforcing material for composites with a fiber composition consisting of hemicellulose, cellulose and lignin. The amount is around 65–70% of the dry weight of the plant containing hydroxyl which is important in water adsorption through hydrogen bonds. As a water absorber, holocellulose absorbs moisture and has hydrophilic properties [1, 8]. This weakens the interfacial bonds of the matrix and the fiber which may lead to unsuitable with the polymer matrix [9, 10]. The incompatibility reduces the composite mechanical properties. Therefore, the natural fiber surface is modified to alter the hydrophilic properties [8, 11–13]. There have not been any studies on NaOH treatment and variation of NaClO concentration on Muntingia calabura fiber (MCF). Therefore, chemical treatment on the fiber needs to be done to improve the composite functionality by improving the fiber and matrix compatibility [13, 14]. Various types of chemicals are used for natural fiber processing. Alkaline (NaOH) treatment is the most common procedure used on natural fibers. The treatment enhances the surface area of natural fibers by removing the lignin, wax, and oil that cover them. This leads to better interlocking of the fiber and the polymer matrix [15, 16]. Besides NaOH treatment, NaClO is also used in bleach. NaClO can delignify the lignocellulosic and change the color of the fiber so that it can be used for surface treatment of fiber for composites [13–15, 17]. Therefore, the concentration of NaClO for fiber were varied. The variation was applied to get the best concentration for color changes and the appropriate characterization so that it can be recommended in composite manufacture. The characterization of the MCF was analyzed using composition test, tensile strength test, SEM hardness test, FTIR, and XRD.

2 Material and Method 2.1 Fiber Sample Processing The process of fiber preparation was started by collecting the tree bark (Fig. 1a). The tree bark was prepared (Fig. 1b) and soaked in the water (Fig. 1c) for ± 10 days. It was done to separate the fiber from the tree bark. Then, the fiber was dried at room

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Fig. 1 The fiber release schematic from the bark of Muntingia calabura

temperature (24–30 °C) for one day (Fig. 1d). Once it got dry, the fiber was ready for chemical treatment (Fig. 1e).

2.2 Chemical Treatment NaOH Chemical Treatment Dry MCF was treated by immersing it in solution of NaOH (80 g) and water (1000 mL) at ambient temperature (24°–30 °C) for 2 h. Before the immersion, the solution was left for 10 min so that it got evenly dissolved and did not react again. After immersion (Fig. 2a), the fiber was dried at ambient temperature for one day (Fig. 2b) to remove the content of lignin, hemicellulose, and other impurities. Previous research shows that alkali treatment produced the best results in MCF with a concentration of 8% [17]. NaClO Chemical Treatment Dried MCF that had been previously treated with 8% NaOH was given NaClO treatment with concentration variation of 0.5–3.0% for 2 h at ambient temperature. Before the immersion, the solution was left for 10 min so that it became perfectly dissolved and did not react again. After that, the 2 h-NaClO-treated MCF with some variations (Fig. 2c) was dried at room temperature for one day (Fig. 2d). The treatment was performed to bleach the fiber surface and delignify the remnants of lignin, hemicellulose, and other impurities.

2.3 Composite Fabrication The composite dimensions were determined by the applicable standard for tensile testing. The standard used for the manufacturing was ASTM D638-03 standard [18]. The composite manufacture was meant to know the value of the tensile strength of the MCF composite that had been treated with NaOH and NaClO. The form of the fiber was made before the composite manufacturing to make the process easier.

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Fig. 2 a MCF after immersion in 8% NaOH, b MCF alkali treated in dry condition, c MCF-alkali treated in NaClO after immersion, d MCF alkali treated and bleached in dry condition

2.4 Tensile Test The test was performed using single fiber tensile test machine with capacity of 0–60 N. ASTM D3379-75[19] was used as the standard. The test was conducted by attaching the specimen with a predetermined standard to the chuck in the test equipment. Then, the tensile test was carried out with a torque of 0.5 N/cm. ASTM D638-03 was used as the composite tensile test standard. The specimen with predetermined standard was set firmly to the chuck in the test equipment. Tests were carried out with 3 repetitions.

2.5 Composition Test Van Soest analysis is a relevant system used to analyze feed ingredients for ruminants. The principle of the test is to classify feed substances into cell content and cell walls. The analysis includes the analysis of ADF, hemicellulose, cellulose and lignin.

2.6 FTIR (Fourier Transform Infrared) Test FTIR IRSpirit-T with Shimadzu brand and specification standard of ASTM E1252 was used in the test. It was performed to analyze the functional group of 8% NaOHNaClO variation concentration-treated MCF. The test was conducted with resolution

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of 4.0 cm−1 , spectrometer wavelength of 4000–450 cm−1 and scan speed up to 10/ min using KBr powder (1 mg) [9, 17].

2.7 XRD (X-ray Diffraction) Test Segal method was used to calculate the crystallinity index [20]. The test was carried out using XRD X’Pert3 Powder with PANanytical brand. Diffractometer was operated at 30 mA and 40 kV with target of 3 Cu monochromatic. The crystallinity index used Eq. 1 [20]. ICr =

I002 − Inon−Cr I002

(1)

I002 is the peak highest intensity value; Inon-Cr is the value of nanocrystalline diffraction intensity.

2.8 Roughness Test The roughness test used Mitutoyo Surface Roughness Portable Tester SJ-210 which was equipped with stylus detector. Average roughness (Ra), peak to trough average height (Rz), and maximum roughness were the three roughness parameters (Ry). The ISO 4287:1997 [19] standard was utilized to determine the fiber surface. Each panel was subjected to five surface roughness reading. The tester specification was determined at speed of 0.5 mm/s, pin diameter of 10 μm, and pin angle of 90°. The length of tracing line (Lt) was 12.5 mm and cut-off (λx) was 2.5 μm. The power of scanning measuring was 4 mN (0.4 gf). The measurement was made at 25 °C ± 2.

2.9 The Surface Morphology Test The test was performed using FESEM (Field Emission Scanning Electron Microscope) type with FEI—Quanta FEG 650 brand. The magnification was 1000 times with a potential acceleration of 3 kV electron beam. Two separate areas, namely the longitudinal and the cross-sectional area, were used to observe the surface morphology. Before tested, all samples were glued to stubs and were coated with gold using Quorum Q150R Plus sputter.

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Fig. 3 a Single fiber tensile strength, b composite tensile strength, c crystallinity index, and d surface roughness value (Ra)

3 Results and Discussion 3.1 Tensile Strength Figure 3a displays the MCF single fiber tensile strength with 8% NaOH and NaClO concentration variation. The highest tensile strength (2052.37 MPa) is in the fiber with 1.5% concentration. The lowest tensile strength (1387.12 MPa) is in the fiber with concentration of 3%. Figure 3b shows the diagram of stress and strain values of MCF-reinforced composite. The highest tensile strength (31.31 MPa) was found in composite with 1.5% NaClO treatment. The lowest tensile strength (10.97 MPa) was found in composite with 3% NaClO treatment.

3.2 Composition In Table 1, it is seen that hemicellulose and lignin tend to decrease with the increase in concentration. The cellulose content tends to increase to certain point and decreases thereafter.

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Table 1 MCF chemical composition Composition (%)

Concentration variation (%)

Hemicellulose

Cellulose

Lignin

NaClO 0.5

11.11

33.94

5.76

NaClO 1.0

10.55

35.57

5.52

NaClO 1.5

10.52

36.45

5.50

NaClO 2.0

8.51

33.46

5.18

NaClO 2.5

6.48

32.07

4.96

NaClO 3.0

5.68

30.17

4.05

2800

NaClO 3,0%

NaClO 2,5%

1029,72 1631,59

2920,88

NaClO 2,0%

1406,59

3345,89

Intensity (Counts)

Transmittance (%)

2400

1409,59

3347,32

1029,72

1631,59

2922,31

NaClO 1,5%

1407,67

3344,47

1635,49

2923,73

1021,17

1409,10

NaClO 1,0%

3344,47

1024,02 1604,49

2923,73

NaClO 0,5%

3338,76

1403,39

3338,76

4000

3500

3000

2500

1600 1200 800 400

1637,29

2925,16

2000

1406,24 1022,59

(a)

NaClO 3,0% NaClO 2,5% NaClO 2,0% NaClO 1,5% NaClO 1,0% NaClO 0,5%

1631,59

2919,46

2000

1500

Wavenumber (cm-1)

1024,02

1000

500

0

(b)

10

20

30

40

50

2 Theta (o)

Fig. 4 a FTIR, b XRD spectra analysis

3.3 Ftir The MCF FTIR spectra with 8% NaOH and NaClO variation is displayed in Fig. 4a. From the data, there are several peaks with changes in their functional groups: 3347.32–3338.76, 2925.16–2919.46, 1637.9–1604.49, 1409.59–1403.39, 1029.72– 1021.17 cm−1 . Based on the peaks, it is possible to identify the functional groups of MCF after being treated with 8% and NaClO concentration variation.

3.4 Crystallinity Index In Fig. 4b, the diffraction pattern shows the peak intensity. The low peak indicates the amorphous or non cellulose component of fiber. The 22.45° is the high angle that shows the fiber crystallinity. Significant differences are seen from the comparison spectrum that shows differences in the results of crystallinity and semi crystallinity content. Figure 3c shows that the highest crystallinity index (53.96%) was found in MCF-1.5% NaClO. The lowest crystallinity index (47.06%) is owned by MCF-3% NaClO.

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3.5 Roughness Test Figure 3d displays the results of roughness test of MCF surface with 8% NaOH and NaClO variation treatment. The data reveal that the highest roughness value (6.77 μm) is owned by MCF with 1.5% NaClO treatment. The lowest hardness (3.44 μm) is produced by MCF with 3% NaClO treatment.

3.6 The Surface Morphology Figure 5 informs the MCF surface morphology after NaClO treatment. Figure 5a shows that the surface still has impurities and some parts still shows an amorphous structure. Figure 5b shows that the surface of the fiber is getting more eroded than before, the rough surface is widening, and the color has changed to be lighter. Figure 5c shows that impurities are less than before, the rough surface reduces, and the color is lighter than before. In Fig. 5e, the impurities are less, the rough surface reduces, and the color is lighter. The same things are shown in Fig. 5f: the impurities and rough surface reduce and the color is lighter than before.

3.7 Discussion It can be seen that chemical treatment has given significant effects to the fiber structure [1, 20]. There was an increase caused by fiber delignification due to 8% NaOH treatment and NaClO further treatment. The result caused the fiber to erode and cause a change in color so that it increased to a certain extent and decreased thereafter. Other factors such as the agricultural parameters and tree age also greatly affect the tensile strength [21, 22] An increase in composite tensile strength was due to the surface and the composition (lignin and hemicellulose) delignification leading to the increased adhesion bond among the matrix and the fiber [23]. The decrease was due to the amount of concentration of chemical solution and the immersion time that were not in accordance with the optimum point of the fiber which resulted in damaged or worn surface causing the adhesion bond of the matrix and fiber to decrease [24, 25]. The result of fiber composition test indicated that the components such as hemicellulose, cellulose, lignin and others greatly determined the structure of morphology, mechanical and physical characteristics of MCF. The hemicellulose content tended to decrease. It is important for thermal resistance and water adsorption of fiber [26, 27]. Cellulose content tended to increase up to a certain concentration and decreased thereafter. Tensile characteristics and MCF density require cellulose content [27]. Lignin content tended to decrease. Lignin has a consequence on the fiber’s thermal resistance and tensile strength [28].

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Fig. 5 SEM morphology of MCF with 8% NaOH and NaClO variation, a 0.5%, b 1, c 1.5%, d 20%, e 2. 5%, and f 30%

From the fiber chemical composition test, it can be concluded that the water adsorption and thermal resistance decreased due to delignification of the lignin and hemicellulose by the chemical compound and impurities in the fiber. It would have a positive impact in the composite application, because the adhesion bond between the fiber and the matrix would be easier to form [29]. FTIR test was run to know whether there was a reduction in lignin after the treatment. FTIR test revealed that the Peak of 1637.9–1604.49 cm−1 shrank. This was related to the stretching of C=O in hemicellulose, C–O groups, C–H groups of aromatic rings, stretching of C–O in lignin, thus affecting the water absorption properties due to the decrease in hemicellulose and lignin groups in the fiber [14]. XRD analysis aimed to determine the content of the crystalline phase in the fiber and the presence of the amorphous phase in it. From the XRD analysis, it was found that the crystallinity index of MCF with 8% NaOH and 1.5% NaClO was the highest with a value of 53.96%. The crystallinity index revealed that the trend increased at a

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certain point and decreased afterward. NaOH treatment and further NaClO treatment were the treatments that most affected the delignification of lignin, hemicellulose, and impurities and the cellulose as well, although not significantly [24]. The roughness test revealed that the higher roughness value, the more it will affect the tensile test value [25]. The increase and decrease in the Ra value was caused by the treatment because lignin, hemicellulose, and other impurities were delignified which changed the surface morphology of the fiber. The result was the highest roughness level at concentration of 1.5% NaClO. The morphology of 8% MCF has rough and darker surface. This was due to the NaOH treatment on the surface which was able to increase the roughness morphology of the fiber and change the fiber color to be darker [21]. However, after NaClO treatment, the fiber roughness increased and the color became lighter along with the increase in the concentration. This is because NaClO was used in the immersion which delignified the remaining content of hemicellulose, lignin, and other impurities which could not be cleaned by NaOH [30].

4 Conclusion The characterization of the MCF with bleaching treatment was analyzed as composite reinforcement. MCF is potential to be natural reinforcement for composite. The highest crystallinity index (53.96%) was found in MCF-1.5% NaClO. 8% NaOH and 1.5% NaClO are recommended to improve the properties and to get better color. Optimal bleaching treatment supported alkali treatment to obtain good mechanical properties and attractive features. Further research is needed focusing on the age of the fiber and the use of chemical composition. Acknowledgements This research was funded by “Penelitian DIPA FT-UB”, grant number: 16/ UN10.F07/PN/2022, Fakultas Teknik, Brawijaya University.

References 1. Gapsari F, Purnowidodo A, Hidayatullah S, Suteja S (2021) Characterization of Timoho fiber as a reinforcement in green composite. J Mater Res Technol 13.https://doi.org/10.1016/j.jmrt. 2021.05.049 2. Sethuraman B, Subramani SP, Palaniappan SK et al (2020) Experimental investigation on dynamic mechanical and thermal characteristics of Coccinia Indica fiber reinforced polyester composites. J Eng Fiber Fabr 15.https://doi.org/10.1177/1558925020905831 3. Mylsamy B, Palaniappan SK, Pavayee Subramani S, et al (2019) Impact of nanoclay on mechanical and structural properties of treated Coccinia indica fibre reinforced epoxy composites. J Mater Res Technol 8.https://doi.org/10.1016/j.jmrt.2019.09.076 4. Fajrin J, Akmaluddin A, Gapsari F (2022) Utilization of kenaf fiber waste as reinforced polymer composites. Results Eng 13.https://doi.org/10.1016/j.rineng.2022.100380

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Bio-waste Composite Recycling Using 3d Printing: A Review Shashwath Patil

and T. Sathish

Abstract Using the waste management principle of Reduce-Reuse-Recycle, the circular economy concept can alleviate environmental issues. By-products and biowaste are frequently seen as significant resources. Extrusion-based rapid manufacturing is one of the advanced technologies that could potentially encourage their use as new materials. There has to be further research on the effects of primary (1°) and secondary (2°) recycling of PLA and its composite for biomedical applications, it was determined after analysing the present literature. In this study, an attempt was made to collect scattered information on work related to utilization of bio waste composites for recycling in filament production for fused deposition modelling. The use of bio-waste in the composite can also have environmental benefits by reducing waste and providing a sustainable solution. The review has been organized systematically to provide insight into the advancement of research work in this field. Keywords 3D printing · Bio-waste · Biomedical · Fused deposition modelling

1 Introduction Plastic waste management has been a key concern for developing nations such as India for many decades. Food waste, agricultural waste, industrial debris, biomedical waste, and various non-biodegradable materials all end up in landfills or incinerators as bio-waste [1]. Large quantities of plastic waste management have severe consequences, including pollution, biodiversity breakdowns, food chain contamination, energy waste, and economic loss [2]. The circular economy concept may address S. Patil (B) · T. Sathish Department of Mechanical Engineering, Saveetha School of Engineering, SIMATS, Chennai, Tamil Nadu 602105, India e-mail: [email protected] T. Sathish e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_10

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these environmental issues using the Reduce-Reuse-Recycle principle. Plastic recycling may be carried out using many methods to reuse the material. Polyesters and other polymers that degrade due to environmental factors can be recycled and used to create filaments for the additive manufacturing process. In general, three-dimensional printing is a manufacturing process that creates three-dimensional objects by layering or melting materials. Additive manufacturing (AM) or fast prototyping are other terms for 3D printing [3]. The cycle of product development for the additive manufacturing process is shown in Fig. 1. Fused Deposition Modeling (FDM) is the successfully used AM technology. FDM has indeed been selected by many investigators and industry in manufacturing owing to its easiness and adaptability [4] in comparison to other AM methods [5]. Parts with complicated geometries are quickly produced in FDM using numeric controlled with nozzles and the layer arranged one above one in the fabrication, with no clamps, jigs, or the fixtures essential as in conventional manufacturing procedures [6, 7]. FDM components are ideal for the conceptual modelling of the components, creation of functional prototypes, and end-use the manufacturing parts because of their excellent chemical as well as the mechanical qualities. Tight dimensional tolerances and complicated design elements previously unattainable with conventional procedures become feasible with FDM technology [8]. As a result, several biomedical, automotive, aerospace, and electronics sectors have adopted AM technology [9–11]. In the FDM technique, a constant filament consisting of a thermo-plastic polymer is utilized for the 3-dimensional printing of materials. A filament is extruded onto the substrate or above of earlier printed layers after being heated to a semi-liquid state at the nozzle. This method only works because of the thermoplastic of the polymer filament, which lets the filament material fuse while printing as well as hardening at

Fig. 1 The product development cycle of AM process

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room temperature after the fabrication of the component. The thickness of the layer, breadth, filament orientation and air gap (inside or across layers) are significant factors that influence the mechanical characteristics of fabricated products [12]. The growth of fiber reinforced fusions utilizing FDM has increased the characteristics of mechanical, printed products. Nevertheless, the primary problems arise with threedimensional printed composite components are void formation, void alignment, and matrix-fiber attachment. The 3D printing filaments are constructed with the properties such as bio-compatible and minimum of melting temperature medicinal polymers. These materials can also be utilized in FDM process to create scaffolds and other components that bind to human tissues [13]. Even though FDM materials come in a variety of grades, they all need low melting points and viscosities to flow out the nozzles and adhere to the previous layer under the low pressure employed in the extrusion mechanism. Figure 2 depicts the circular economy concept, which substitutes the traditional linear conception based on the “take-make-dispose” concept to respond to environmental and societal concerns. Recycling is widely known as a significant effective waste management strategy for recycling resources to make new products. Grinding, remelting, extrusion, decontamination, and purification are all techniques used to reuse polymer materials for 3-D printing. Globally, seven different types of plastics are now recycled, including ABS and polycarbonate: polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), low- and high-density polyethylene (LDPE, HDPE), and the “other” type (PC) [14, 15]. All of the aforementioned organisations have stated that they are being looked into for potential usage as 3D printing filaments. In this review work, an attempt has been made to collect scattered information on work related to the use of PLA for generating bio-composites by reinforcing some filler materials and the 3D printing of prototypes or products by employing the feedstock filaments extracted based on the composite.

Fig. 2 Close loop recycling based on additive manufacturing

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Fig. 3 3-D printing process using composites

Fig. 4 The PLA fabricated samples and resultant dental implant using 3-D printing

The synthesized PLA composite flakes are used to fabricate the 3D FDM filaments, the process of fabricating the 3D filament is shown in Fig. 3, in addition to this, the output Dental Implant using the filament is shown in Fig. 4. Analysed the cytokine profile of human monocytes on chitosan and PLA scaffolds created by 3-D printing. Discovering that material properties had the greatest impact on macrophages [16]. Extraction of solvent and particle leaching procedures to coat chitosan on to the PLA and then reported increased cell adhesion and proliferation of osteoblasts [17]. The potential of FDM by fabricating a PLA-based pharmaceutical delivery system in the case of controlled-release products. In two instances, nitrofurantoin filament made from PLA was successfully created and extruded with up to 30% drug content, with and without 5% hydroxyapatite, and in the form of discs [18]. Investigated loaded Poly lactic acid by gentamicin sulphate as well as methotrexate, resulting in the development of a novel group of biodegradable active 3D printing filament. These substances maintained their strong antibacterial and cytostatic properties throughout the production process, even with the heat required for the FDM printing [19]. Conducted cell cycle and apoptosis experiments on PLA and chitosan and investigated the cytocompatibility and the antibacterial characteristics of the resulting

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combination. Using the FFF 3D printing technique, evaluate the mechanical properties of newly designed chitosan-reinforced PLA scaffolds [20]. The prepared PLA composite supports are mechanically effective and are appropriate for medical use [21]. Studied the impact of 3-D printing variables on the mechanical characteristics of natural fibre reinforced FDM bio-composite, as well as the potential use of these factors to build self-bending devices with a quicker moisture-induced bending response. The findings reveal that the mechanical characteristics of Wood fibre reinforced bio composites FDM are highly influenced by printing orientation and width, with a low Young’s modulus than in compressed models due to increased porosity [22]. Investigate the formation of biocompatible composites for bone tissue use that are loaded with recycled swine bone powder, polylactic acid, and poly(-caprolactone). The results reveal that the synthesized composites have tensile strength and that the addition of chitosan gives antibacterial characteristics. Also proposed is the improvement of the synthesis process for electrospinning technique implementation in order to generate PCL-BP fusions reinforced using PLA-Chitosan micro-fibers [23]. The biocompatible feedstock filament, which was made in an FDM arrangement using biocompatible materials, i.e., pc and pp, and reinforced with HA elements. The process parameters were enhanced using the Taguchi L18 orthogonal array. Mechanical, metallurgical, and thermal characteristics have been illustrated in this study [24]. Evaluated a wide range of polymer matrix composites, such as PCL/HA, PCL/ DCB, PCL/TCP, and PCL/Bio-Oss. According to the findings, various mixes required varied process factors like extruder head speed, pressure, and temperature. Extruding the PCL/BO as well as PCL/DCB composites were observed to be more difficult than extruding the PCL/HAp as well as PCL/TCP composites [25]. Described that commercial-grade PLA was extruded into a filament and then used in 3-D printing. Then, the finished parts were disassembled and extruded to complete the 3D printing process. Mechanical, molecular, rheological, morphological, and thermal properties of samples from each cycle of repetition were investigated. The viscosity data show that PLA degrades rapidly as a result of numerous FDM 3D printing cycles, despite the fact that mechanical properties vary just slightly [26]. Investigated the distinctive necessity of fibre surface variation to attain maximum fiber-matrix attachment, traditional processing routes, the critical difficulties related to the NFRC’s manufacturing, and the usage of various AM techniques in processing polymer fusions. The difficulties and chances related to the additive manufacturing of NFRCs were critically examined [27]. Investigated PLA additives using bio filler hemp hurd, which is a filament evaluated through the FDM and the injection moulding techniques. The findings display that rise in the hemp hurd concentration enhances the irregularity and ridged form, as well as the flexural modulus, impact strength, and dimensional correctness. Mechanical analysis and the interaction between processing structures are important for the IM approach [28]. Studied the effects of various infill orientations on specific significant parameters of test specimens produced by fused layer modelling (FLM).

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Two specially created wood filaments were used to fabricate samples, and their fibre composition and infill orientation were examined. They were composed of a similar PLA polymer but had various wood fibre concentrations. It might be demonstrated that there is a direct relationship between the test specimens. There is no direct relationship, yet there is mutual dependence [29]. They investigated various technological techniques to decrease or remove them to attain superior characteristics in three-dimensional printed polymer and the composite using FDM. This article’s thermoplastic polymer is used as the matrix material to create filament with fibre reinforcement [30]. Conducted experimental testing to illustrate the characteristics of the materials and a bio-medical use of bio-plastic substances in order to evaluate their viability for FDM print. The outcomes in terms of strength, lightweight, and irregularities have been studied in detail. These materials’ interesting final characteristics make them viable for bio-medical applications, as shown by this research for the neck collar prototype described [31]. Utilized bio fibres as supplements and various resin systems as the initial building blocks for 3D printing techniques; all of these efforts provide solutions to some of the major problems with current 3D printing techniques, namely the restriction on the diversity of constituents and the subpar mechanical performance of 3D printed components. The study reveals prospective research lines that would be added to extend the usage of biofibers in 3D printing while maintaining sustainability [32]. Established the capability of fabricating chitosan enhanced PLA frameworks with FFF 3D print technique. The results showed that increasing infill density improved compressive strength while enhancing tensile strength. Moreover, flexural strength was deemed satisfactory, making these materials suitable for dynamic motions [33]. PLA could act as stress absorbers in 4D printing to fabricate components with complex shapes utilizing FDM. It is investigated while adjusting the operating parameters of the printing process based on experimental findings. PLA particles have acceptable shape memory characteristics, allowing quick recovery periods and more recovery rates. An activation temperature has been determined to be a process variable with the greatest influence on triggering the regeneration of the original form in a brief period [34]. Examined the properties of the PLA-polymer material and its shape memory behaviour, as well as the potential of PLA for 4-D printing and the fundamental idea behind the method for creating self-folding structures from PLA. Magnetic fields, temperature, and light, among other environmental stimuli, are all reacted to by the resulting materials [35]. Overviewed the ideas of the circular economy and how (bio)degradable polymers might contribute to it, in addition to recycling approaches such as employing waste as an excellent raw material for subsequent processing, recycling feedstock, composting, and anaerobic digestion [36]. By combining powdered waste walnut shells, waste powdered egg shells, and waste powdered white marble, three different types of PLA filaments were created. Findings indicate that white marble powder bio-composite and PLA have higher levels of hardness. Density is impacted by the inclusion of walnut shell powder in a PLA matrix. The composite made from powdered walnut shell and PLA has the

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highest tensile strength. Eggshell powder has increased the flexural strength [37]. Investigated the wood content affects the characteristics of 3D printed items. Four distinct filaments containing PBSA and varying quantities of Typha stem powder range from 0 to 15% by weight. The results revealed a rise in the density of the filaments and sections, as well as a rise in crystallization kinetics and a decline in the filament’s thermal firmness. The findings show that Typha stem might be utilized to successfully manufacture bio composite filaments for FDM applications [38]. Due to the characteristics of reused materials taking on the properties of fresh materials and energy being suggestively lower than chemical reusing, thermal reusing has been studied as an optimum appropriate for reusing CFs and GFs. The results demonstrate that the use of composite material in diverse sectors will only be sustainable if recycling and reusing composite are given equal consideration [39]. Investigated to find the qualities of PLA as well as the optimal processing parameters, including mechanical properties, characterization, and applications. The quality of a printed product is determined by the FDM processing variables. Because of its superior thermoplastic and biodegradability qualities, PLA polymer is employed in industrial applications such as medical, car, and electrical [40]. To analyze the elements made from multiple materials and focus on the biopolymer PLA used in 3D printing. It is noted that several modifications have been made to PLA’s properties, printing factors when integrated with other substances, filling, and surface formation for various sample geometries are all included [41] (Table 1).

1.1 Medical Applications Scaffolds and Composites Scaffolds and composites have a wide range of potential medical applications, especially when used in conjunction with 3D printing technology. Here are some ways that they could improve patient outcomes: • Tissue Engineering: Scaffolds made from bio-waste composite materials can be used to regenerate damaged tissues and organs in the body. By printing these scaffolds to match the specific shape and size of the damaged tissue, doctors can create a custom-fit implant that will integrate more easily into the body and promote faster healing. • Drug Delivery: Composites can be engineered to release drugs over time, making them ideal for drug delivery applications. By embedding drugs into a composite material, doctors can ensure that the drug is delivered directly to the target tissue or organ, improving the efficacy of the treatment and reducing side effects. • Orthopedics: Scaffolds and composites can be used to repair or replace damaged bone tissue. By printing a scaffold that mimics the structure of natural bone, doctors can promote bone growth and regeneration. • Dental Implants: Scaffolds and composites can also be used to create custom dental implants. By printing a scaffold that matches the shape and size of a missing

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Table 1 List of previous research on fabrication of FDM composite filaments for bio medical usage Author

Materials

Ceramics-polymer composition

Application/Uses

Venkatesh et al. [42]

PLA, HNT

3–5% HNT: PLA 95–97% PLA

Fabrication of FDM filament

Chen et al. [43]

PVA, b-TCP

80–95% PVA: 5–20% TCP

Bone scaffold

Calì et al. [31]

PLA, HEMP, WEED

15–25% HEMP, 10–15% WEED, 75–90% PLA

Neck collar prototype

Pu’ad et al. [44]

HAp, PCL, MMT

88–100% P-CL: 0–4% M-M-T

Fabrication of FDM filament

Wu et al. [45]

PLA, HA

5–15% PLA, 85–95% HA

Bone scaffolds

Nevado et al. [46]

PLA, BCPs

15% BCPs, 85% PLA

Bone scaffolds

Murugan et al. [15]

PLA, TCP

75–100% PLA: 0–25% TCP

Bone scaffold

Kim et al. [15]

PCL.HA

5–25% HA, 75–95% PCL

Bone scaffolds

Karimipour-Fard et al. [47]

PCL, nHA, CNW

97–100% PCL, 0–3% nHA, 0–3% CNW

Bone tissue scaffolds

Mocanu et al. [48]

PLA, HA

0–50% HA, 50–100% PLA

Fabrication of FDM filament

tooth, dentists can create a more natural-looking implant that is less likely to be rejected by the body. Overall, the use of scaffolds and composites in medical applications has the potential to significantly improve patient outcomes. By using bio-waste composite materials and 3D printing technology, doctors can create custom-fit implants that are better integrated into the body, more effective at delivering drugs, and promote faster healing.

2 Limitations and Challenges Associated with 3-D Printing Three-dimensional (3-D) printing, also known as additive manufacturing, is a rapidly growing technology that has gained attention in various fields, including the medical industry. However, there are still several limitations and challenges associated with 3-D printing that affect its scalability, cost, and regulatory approval for medical use. Scalability: One of the significant limitations of 3-D printing is scalability. While 3-D printing has the potential to create complex and customized medical devices and

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implants, it is still limited in terms of the size of the objects it can create. Large-scale printing is not yet feasible, and it is not yet possible to 3-D print an entire organ or tissue, which limits its potential applications. Cost: Another significant limitation of 3-D printing is its cost. While the cost of 3-D printing has decreased over the years, it is still more expensive than traditional manufacturing methods. The cost of 3-D printing materials, such as resins and filaments, is also relatively high, which increases the cost of the final product. Moreover, the cost of 3-D printing machines is also high, making it difficult for small medical practices and hospitals to invest in the technology. Obtaining regulatory approval for use in medicine is one of the major obstacles facing 3-D printing in the medical field. Strict legal requirements, such as those set down by the Food and Drug Administration (FDA) in the US, must be followed in the 3-D printing of medical devices and implants. The regulatory process can be timeconsuming and expensive, which might make it difficult for the medical industry to utilise 3-D printing technology. Furthermore, there are concerns regarding the safety and efficacy of 3-D printed medical devices and implants. There is a need for extensive testing and validation of 3-D printed medical products to ensure they meet safety and efficacy standards. In conclusion, while 3-D printing has the potential to revolutionize the medical industry, there are still several limitations and challenges associated with the technology that need to be addressed to achieve its full potential. These limitations include scalability, cost, and regulatory approval for medical use. Addressing these challenges will require ongoing research and development, collaboration between stakeholders, and regulatory agencies to ensure safe and effective use of 3-D printing in the medical industry.

3 Comparative Analysis Three-dimensional (3-D) printed scaffolds and composites are relatively new materials being explored for use in medical implants and devices. Compared to traditional materials, such as metals, ceramics, and polymers, 3-D printed scaffolds and composites have unique properties that may make them more suitable for certain applications. • Strength and Durability: One of the key advantages of traditional materials is their strength and durability. Metals, for example, are known for their high strength and resilience, making them ideal for load-bearing applications such as joint replacements. Similarly, ceramics are extremely hard and wear-resistant, making them ideal for dental implants and other applications where durability is important. While 3-D printed scaffolds and composites can be designed with high strength and durability, they may not yet match the properties of traditional materials in this regard.

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• Customization: One of the main advantages of 3-D printed scaffolds and composites is their ability to be customized to a specific patient’s needs. Traditional materials often require shaping or resizing to fit a particular patient’s anatomy, but 3-D printing can create implants that are precisely tailored to the patient’s anatomy. This customization can lead to better outcomes and faster healing times. • Biocompatibility: Another important factor in medical implants and devices is biocompatibility, or the ability of a material to interact with the body without causing harm. Traditional materials such as metals and ceramics can sometimes cause allergic reactions or other adverse effects. 3-D printed scaffolds and composites can be designed to be biocompatible, but the materials used in 3-D printing may need to undergo rigorous testing to ensure that they are safe for use in humans. • Degradation: Another consideration is the rate of degradation of the material. Traditional materials such as metals and ceramics may not degrade at all, while polymers may degrade too quickly. 3-D printed scaffolds and composites can be designed to degrade at a specific rate, which can be advantageous for certain applications such as bone regeneration. • Cost: Finally, cost is an important consideration when selecting materials for medical implants and devices. Traditional materials can be expensive, especially if they require shaping or resizing. 3-D printed scaffolds and composites can be more cost-effective, especially if they can be produced on a large scale. In summary, 3-D printed scaffolds and composites offer unique advantages over traditional materials in terms of customization, biocompatibility, and degradation rates. However, traditional materials still have advantages in terms of strength and durability, and may be more suitable for certain applications. The choice of material ultimately depends on the specific needs of the patient and the intended use of the implant or device.

4 Conclusion With recent advancements in additive manufacturing, it was simple to develop sophisticated prototypes or products for biomedical purposes. In this study, an attempt was made to collect scattered information on work related to the use of PLA for building bio-composites by reinforcing certain filler materials, as well as 3D printing prototypes or products using the feedstock filaments extracted from the composite. This paper reveals prospective study approaches and the areas for investigators working in related fields to enhance further the advanced technology and diversity of constituents that may be utilized in 3-D printing technology in a sustainable method. The key findings or insights after going through the available literature are, • Some of the researchers fabricated the PLA with biocompatible stable calcium phosphate compound material Bio-composite for biomedical applications.

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• The use of PLA alone as a material to identify the shape memory properties and also used in biomedical applications but little has been reported on the 4D capabilities of bio-composite. • 4D behavior of 3D printed components by FDM was observed but little has been conveyed about the 4D characterization of feedstock filaments. • Mechanical, Morphological, as well as Thermal Properties of 3D printed functional prototypes have been explored. • Fabrication of FDM Bio-composite feedstock filaments for various biomedical applications.

4.1 Limitations of the Study • The composite derived from bio-waste gives satisfactory results only up to two extrusion cycles and the mechanical properties degrade for tertiary cycling. • The majority of the scaffolds prepared by consuming the prepared filaments needs to be tested under SBF condition. • Types of bio-waste materials that can be used for 3D printing are limited. Some materials may not be suitable for 3D printing due to their properties, such as their viscosity or melting point.

4.2 Opportunities for Future Research Further studies may be conducted to get better real-life situations as under: • To miniaturize by varying the combination of infill patterns while performing 3D printing of the substrates to get implanted inside the body of a patient. • To perform the R-F characterization of the bio-sensor under the effect of SBF and obtain the output signal (lying in ISM band) on a Bluetooth device. • Real time monitoring of the growth of fractured bone of a patient by performing the in-vivo analysis of the bio-sensor.

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Preparation of Transparent Thin Film from Cellulose Extracted from Oil Palm Empty Fruit Bunch See Woan Qian , Nadia Adrus , and Jamarosliza Jamaluddin

Abstract Oil palm empty fruit bunch (OPEFB) is rich in cellulose, thus ideal for utilization as one major components for the productions of thin film. In this study, cellulose was extracted out from OPEFB to produce the thin film. The extracted cellulose was characterized using thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). And scanning electron microscopy (SEM). The FTIR spectral analysis has showed the removal of lignin and hemicellulose from the delignified cellulose at peak 1735 cm−1 and 1248 cm−1 respectively. TGA result shows the thermal degradation of extracted cellulose at 355 °C. The crystallinity index of native OPEFB fiber was estimated to be around 54% through XRD analysis. Furthermore, SEM has been utilized to investigate the surface morphology or physical properties of the OPEFB fibers. It shows a rigid strand’s surface which was not significantly different from the commercial cellulose. Transparent and flexible film was prepared by dissolving cellulose extracted from OPEFB in dimethylacetamide/lithium chloride (DMAc/LiCl) and regenerated through phase inversion. The film synthesis at cellulose concentration of 2 wt% showed a highest gel fraction 42.17% and low equilibrium swelling ratio of 3.32. The increasing of the concentration of cellulose cause the gel fraction to be higher but the equilibrium swelling ratio tends to decrease. Keywords Cellulose · OPEFB · Extraction · Transparent thin film

S. W. Qian · N. Adrus (B) · J. Jamaluddin Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_11

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1 Introduction In Malaysia, oil palm empty fruit bunch (OPEFB) is among the most plentiful lignocellulosic residues available, and it is a potential starting material for cellulose, as it is composed of 50% of lignocellulosic materials [1–4]. Cellulose consists of an amorphous structure and a significant crystalline region, formed by a linear polymer chain of anhydro-glucose monomer units connected by 1,4-linkages. Cellulose has a high degree of crystallinity, ranging from 55 to 85% [5, 6], which makes it a promising material for transparent thin films due to its high strength [7]. Pretreatment of lignocellulosic biomass of OPEFB is an important stage in the process of converting it into cellulose. Therefore, the application of hydrogen peroxide bleaching as a conventional reagent for the extraction and delignification of cellulose is extensively utilized. It has been reported that the pretreatment process for cellulose extraction from OPEFB involves ozonolysis followed by additional delignification with hydrogen peroxide [8, 9]. Among these pretreatments, hydrogen peroxide bleaching is one of the most promising since it effectively delignified the biomass. As an oxidizing agent, hydrogen peroxide can decolorize the fibers by eliminating lignin, hemicellulose, and surface impurities [10]. Cellulose offers a sustainable alternative to synthetic fibers as it is renewable, biodegradable, and have a lower environmental impact [11]. Moreover, cellulose’s exceptional characteristics, such as thermal insulation, low weight and high strength, make it a promising candidate for several applications like textiles, medical purposes, packaging, and substrate films [12]. The utilization of cellulose can further improve the mechanical properties and minimize the ecological footprint of these products [12, 13]. The continuous research on innovative techniques to extract, process, and modify cellulose has facilitated the enhancement of its properties, which has resulted in an increased scope of cellulose utilization for diverse applications. Thus, the dissolution of cellulose is a crucial stage in the transformation of cellulose into high-value products. In particular, the DMAc/LiCl solvent system is a commonly used polar solvent for cellulose dissolution [14]. Once cellulose is dissolved, the resulting solution can be used to create thin films through the phase inversion method. Numerous investigations have explored the impact of cellulose obtained from OPEFB on the characteristics of cellulose thin films [3, 15]. Moreover, studies have demonstrated that the resulting cellulose thin films possess desirable properties and can be used in conductive applications. The primary objective of this research was to isolate cellulose from OPEFB through the treatment of bleaching and investigate its chemical structure, crystallinity, thermal properties, and morphology. Subsequently, cellulose solutions with varying concentrations were prepared using DMAc/LiCl solvent and precipitated to form cellulose thin films by the method of phase inversion. The properties of these cellulose thin films, including the gel fraction and equilibrium swelling ratio, were also evaluated.

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2 Experimental 2.1 Materials In this study, microcrystalline cellulose powder (310,697) was purchased from Aldrich as a standard. The raw and ozonated OPEFB were kindly provided by CREG UTM. DMAc and LiCl were obtained from Nacalai Tesque, Japan, while ethanol was purchased from QREC (Asia). Hydrogen peroxide was purchased from Merck KGaA (Germany) and potassium hydroxide (KOH) was purchased from Sigma Aldrich. Prior to use, DMAc was stored in KOH for 3 days and LiCl was dried in a vacuum oven at 80 °C.

2.2 Extraction of Cellulose Ozonated OPEFB fibers were bleached with 30 wt/v% hydrogen peroxide, H2 O2 (solid to liquid ratio, 1:10) at 80 °C for 3 h aided by a magnetic stirrer. The bleaching process was repeated twice. The mixture underwent filtration and was rinsed with distilled water after a duration of three hours. The EFB was dried for 1 h in a 105 °C oven.

2.3 Preparation of Cellulose Solution A series of treated OPEFB with concentrations of 0.5, 1.0, 1.5, and 2.0% were weighed. The weighed cellulose were then added and stirred in 150 mL of distilled water, ethanol, and DMAc at room temperature to allow the cellulose to swell in each solvent for 24 h, with intermediate rinsing steps for each solvent. The cellulose were subsequently dried at room temperature under vacuum for 24 h. Subsequently, the dried celluloses were added to a flask containing dried DMAc and 6 g of dried LiCl and stirred at room temperature until the celluloses were dissolved. The dissolved celluloses were then centrifuged at 5000 rpm for 30 min at 25 °C to separate the insoluble portion.

2.4 Preparation of Cellulose Thin Film The cellulose thin films were prepared by precipitating the cellulose solutions with a concentration of 0.5–2.0 wt% through phase inversion. First, 10 g of the cellulose solution was transferred to a petri dish, which was then placed into a container with a sheet of tissue at the base. Next, 30 mL of ethanol was poured onto the tissue surface,

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Fig. 1 Schematic diagram for the preparation of cellulose thin film. The figure (petri dish) was partly generated using Servier medical art, provided by Servier, licensed under a creative commons attribution 3.0 unported license”

and the lid of the container was closed. The container was left undisturbed at room temperature for 24 h. To eliminate any residual traces, the obtained cellulose thin film was rinsed with distilled water. Figure 1 depicts a schematic diagram for the synthesis of cellulose thin film.

2.5 Fourier Transform Infrared Spectroscopy (FTIR) The functional groups of raw, ozonated, and bleached OPEFB were examined using FTIR spectroscopy with an IRTracer-100 Fourier Transform Infrared Spectrophotometer, Shimadzu (Japan). The samples were placed on the attenuated total reflection crystal surface and sealed. A total of 64 scans were performed on the samples with a resolution of 4 cm−1 with the spectra region of 400–4000 cm−1 for a duration of 2 min.

2.6 X-ray Diffraction Analysis (XRD) The crystallinity of the cellulose samples was determined using an X-ray diffractometer (Smart Lab, Rigaku, Japan) equipped with Cu KA radiation (λ = 1.5418) at 40 kV and 30 mA, in the range of 2θ = 5°–50°. The crystalline index (CrI %), which represents the degree of crystallinity, was calculated using Eq. 3 suggested by Segal et al. [16].

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CrI% =

I002 − Iam × 100 I002

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(1)

where I 002 and I am showed the peak intensities at 2θ values from highest intensity at 22° and 18° from minimum intensity that indicated the crystalline and amorphous parts of cellulose, respectively.

2.7 Thermo-Gravimetric Analysis (TGA) Thermogravimetric analysis was conducted to identify the weight loss and determine the thermal degradation of the bleached OPEFB. The analysis was performed by loading around 10 mg of samples into a TGA 4000 Perkin Elmer. The measurements were performed under a nitrogen flow of 20 mL/min and a heating rate of 10 °C/min, starting from room temperature to 500 °C.

2.8 Scanning Electron Microscopy (SEM) Prior to the scanning process, cellulose samples were prepared by freeze-drying using liquid nitrogen overnight. The morphologies of commercial MCC, raw, ozonated, and bleached EFB were observed using a scanning electron microscope model JEOL JSM-6390LV, after being sputtered with gold before SEM analysis [17].

2.9 Gel Fraction and Equilibrium Swelling Ratio For the determination of the gel fraction, the cellulose thin film samples were dried in an oven for 24 h at 50 °C until a constant weight (Md1 ) was obtained, followed by immersion of the hydrogels in distilled water for 24 h at room temperature. The films that had swollen were taken out from the distilled water, and the excess water adhering to the films was eliminated using tissue paper. The mass of the swollen films was recorded as Ms . Next, the swollen films were further dried for 24 h at 50 °C in an oven. The mass of the dried film samples was weighed and recorded. The gel fraction and equilibrium swelling ratio, Q, were calculated using Eqs. 2 and 3, respectively. Gel f raction(%) =

Md2 × 100% Md1

Equilibrium swelling ratio =

Ms Md2

(2) (3)

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where Ms is the mass of swollen film, Md1 is the initial mass of initial dried film and Md2 is the mass of second dried film.

3 Result and Discussion 3.1 FTIR Spectra The FTIR spectra of OPEFB and commercial MCC and OPEFB at various treatment stages are illustrated in Fig. 2. The spectra were obtained from 4000 cm−1 to 600 cm−1 to analyze the transformations in the chemical component of samples during the isolation of cellulose from OPEFB. The broad bands in the region of 3400 cm−1 in commercial MCC, raw, ozonated, and bleached OPEFB are attributed to the O–H stretching vibrations, while the peak frequencies at 2920 cm−1 correspond to C–H stretching vibrations in methyl and methylene groups. The FTIR spectra also display transmittance peaks at 1422 cm−1 , which are related to bending vibrations of C–H that are also present in most cellulose [18]. Moreover, significant peaks corresponding to the C=O acetyl group of hemicellulose ester or carbonyl ester of the p-coumaric monomeric lignin unit, and C–O–C of aryl–alkyl ether in lignin of commercial MCC and bleached EFB were not observed at 1735 cm−1 and 1230 cm−1 , respectively [18, 19]. Additionally,

Fig. 2 FTIR spectra of a raw OPEFB; b ozonated OPEFB; c bleached OPEFB and d commercial MCC

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significant peaks at 899 cm−1 (β-glycosidic bond bending) and 1051 cm−1 (C–O and C–H stretching vibrations) represent unique regions of all samples.

3.2 XRD XRD pattern of the treated OPEFB and commercial MCC is shown in Fig. 3. Treated OPEFB exhibited the typical diffraction pattern of polymorph type I, which can be identified at lattice planes at 101, 101, 002, and 040 with 2θ values of 15°, 18°, 22.6°, and 35°, respectively [2]. Based on Fig. 3, the peaks of treated OPEFB appeared at 2θ values of 15.68°, 22.26°, and 34.29°. The results demonstrated a similar diffraction pattern with commercial MCC, where the peaks were observed at 2θ values of 15.36°, 22.42°, and 34.51°. The minor peak intensity at 2θ values of 15.68° and 15.36° for treated OPEFB and commercial MCC, respectively, indicated the presence of amorphous components, specifically lignin, pectin, hemicellulose, and amorphous cellulose [20, 21]. The peak observed at around 22° in both treated OPEFB and commercial MCC corresponded to the lattice planes at 002 of cellulose I [22]. The calculated crystallinity index (CI) for the cellulose extracted from OPEFB was 54.38%, while the commercial MCC exhibited better CI at 67.03%. The CI of treated OPEFB in this study is relatively lower than fibers like cotton (68%), flax (72%), hemp (65%) and jute (71%) [23–25]. The possible reason for the lower crystallinity of the treated OPEFB could be its low purity. The disorganized structure

Fig. 3 XRD spectra of the treated OPEFB and commercial MCC

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of the cellulose may result in a more amorphous powder, leading to lower crystallinity than the commercial MCC [26].

3.3 TGA The thermograms and derivative thermogravimetric (DTG) curves of treated OPEFB and commercial MCC are shown in Figs. 4 and 5. TGA analysis of cellulose extracted from OPEFB showed two major degradation steps. The first degradation step occurred between 30 and 90 °C, which was attributable to moisture loss [27]. The second step occurs between 250 and 355 °C and is attributed to the decomposition of the hemicellulose, cellulose, and lignin components of OPEFB. During this stage, the glycosidic bonds in the cellulose component break, resulting in a high degradation rate of cellulose and a substantial weight loss of 75% in treated OPEFB [28]. Commercial MCC displayed a two-step degradation pattern in TGA analysis. The first step, 33–110 °C, was due to moisture loss, while the second step, 235–384 °C, was caused by cellulose degradation. The cellulose degradation led to a significant weight loss of 82%. The DTG analysis of OPEFB showed one peak, with the peak occurring at around 339 °C. The peak was attributed to the degradation of cellulose and lignin [29]. In comparison, the DTG analysis of commercial MCC showed only one peak, which occurred at around 347 °C and was attributed to the degradation of cellulose. The percentage of residue for the treated OPEFB is approximately 2.5%, which is similar to the results obtained from the findings of Noah that reported a residue percentage of 3.4% [30]. The results indicate that the bleaching treatment has effectively removed the lignin

Fig. 4 Thermal degradation of treated OPEFB and commercial MCC

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Fig. 5 DTG curve for treated OPEFB and commercial MCC

content, as evidenced by the reduced residue yield. This can be attributed to the fact that cellulose is more susceptible to thermal decomposition when lignin is absent, due to its increased thermal accessibility. Therefore, it is widely reported that a lower lignin content leads to a decrease in residue yield [31]. Aside from that, the low thermal stability of OPEFB could potentially be related to its SEM morphology. It has been shown to have a relatively porous and fibrous surface as indicated by the morphology in Fig. 6c. The porosity and fiber structure may contribute to its reduced thermal stability of OPEFB, as the internal structure of the material is more susceptible to degradation and breakdown when exposed to high temperatures [32].

3.4 SEM Figure 6 displays the microstructure and surface morphology of raw, ozonated, bleached OPEFB, and commercial MCC. It was found that the morphology of the fibres varies depending on the treatment process. The fiber bundles were split into individual fibers by ozonolysis and bleaching treatments, which resulted in a significant reduction in fibre diameter. The surfaces of the raw OPEFB appear uneven and knotted due to the lignin binder. The raw OPEFB consists of bundles of fibrils held together by cemented lignin and hemicellulose components. Conversely, ozonated OPEFB appears cracked compared to untreated fibers because the ozonolysis process cleaves the bonds between hemicellulose and lignin. The breakdown causes the opening of the fiber bundles and defibrillation [33]. In addition, the wax on the surface of ozonated OPEFB was reduced.

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Fig. 6 SEM micrographs at 500X magnification a raw OPEFB, b ozonated OPEFB, c bleached OPEFB, d commercial MCC

The bleached OPEFB fibers disintegrated into smaller particles and became more fibrous (Fig. 6c). Lignin and hemicellulose are the major non-cellulosic components of lignocellulosic materials like OPEFB and provide structural support to the fibers. The removal of these components has lead into the reduction in diameter of the OPEFB fibers after the bleaching process [32]. The surface morphology of the fibers was effectively modified by the bleaching treatment, resulting in a smoother texture compared to raw and ozonated OPEFB. As shown in Fig. 6, the surface structure of bleached OPEFB is similar to that of commercial MCC according to micrographic SEM readings.

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Fig. 7 Gel fraction and equilibrium swelling ratio of cellulose thin films at different cellulose concentrations

3.5 Gel Fraction and Equilibrium Swelling Ratio Gel fraction represents the portion of a cross-linked polymer that remains insoluble after removing the soluble portion with an appropriate solvent [34]. The equilibrium swelling ratio and gel fraction of the cellulose thin film composed of cellulose extracted from OPEFB are illustrated in Fig. 7. As depicted in Fig. 7, an increase in cellulose concentration leads to an increase in the gel fraction of the cellulose hydrogel. The cellulose thin film exhibits the lowest gel fraction of 39.21 and 40.48% for cellulose concentrations of 0.5 wt% and 1.0 wt%, respectively. On the other hand, the gel fraction gradually rises from 41.19% to 42.17% for cellulose concentrations of 1.5 wt% and 2.0 wt%, respectively. An increase in cellulose concentration leads to a reduction in solubility and a notable rise in the amount of hydrophilic groups. As a consequence, there is an increase in both intramolecular and intermolecular distances within the polymer matrix [35]. Another important finding is that the equilibrium swelling ratio of cellulose thin films decreases from 3.42 to 3.32 for cellulose concentrations ranging from 0.5 to 2.0 wt%. This finding is in agreement with Shen et al. ’s findings, where the swelling ratio gradually decreases with the rises in cellulose concentration, resulting in a decline in pore size and excellent absorbency at higher cellulose concentrations [7]. From the outcomes obtained, we can conclude that the maximum gel fraction and the minimum equilibrium swelling ratio were achieved at a cellulose concentration of 2.0 wt%.

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4 Conclusion Through the use of ozonolysis and bleaching treatments, the isolation of cellulose fibers from OPEFB was accomplished successfully in this study. The results indicated that bleaching treatment played an effective role in breaking down lignin linkage and solubilizing hemicellulose. The chemical structure of the treated OPEFB was found to be impacted by the bleaching treatment, as evidenced by FTIR analysis. Furthermore, the bleaching treatment demonstrated efficacy in removing both hemicellulose and lignin from the raw OPEFB. TGA results indicated that the isolated cellulose from OPEFB had a low thermal durability. According to XRD analysis, the extracted cellulose from OPEFB exhibited a crystallinity percentage of around 54%. The lower thermal durability and crystallinity were likely due to a less complex molecular structure arrangement. SEM image analysis revealed that bleaching treatment influenced the morphological structure of the treated OPEFB, which was more fibrous and similar to the micrograph of commercial MCC. The prepared cellulose thin films demonstrated a low swelling ratio and high gel fraction, which increased with the concentration of cellulose. Acknowledgements The authors would like to acknowledge the research grant UTMFR vot no. 20H84 and CRG vot no. 4B470 provided by University Teknologi Malaysia (UTM).

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Development and Characterization of Glycine Max Seed Powder Blended with Unidirectional Agave Fourcroydes Reinforced Epoxy Nanocomposite S. Gokulkumar , T. Kannan, N. Karthi , S. Sathish , L. Prabhu , M. Aravindh, and J. Alex

Abstract This research seeks to explore the mechanical and acoustical properties of Glycine max seed powder (32–45 nm) incorporated with the unidirectional Agave fourcroydes hybridized with an epoxy matrix. The varied weight proportions (0, 2.5, 5, 7.5, and 10% by weight) of Glycine max seed powder (GMSP) is mixed with unidirectional Agave fourcroydes, and laminates were manufactured using hand stacking and compression molding. The density and void content, tensile strength, flexural strength, and impact strength of the natural fiber reinforced composite (NFRCs) samples were assessed. The addition of 7.5 wt% GMSP enhanced the physicomechanical characteristics of the developed composite material. The developed NFRCs’ acoustic performance is evaluated. According to the results, the mixing of GMSP with unidirectional Agave fourcroydes enhanced the performance of the developed NFRCs with 7.5 wt% GMSP. In addition, it has a superior sound absorption capacity, which may have implications for acoustical applications in the automotive industries. Keywords Glycine max seed powder · Unidirectional Agave fourcroydes · Nano powder · Mechanical properties · Acoustical characterization

1 Introduction In recent years, scientists and researchers have focused on biomaterials for various industrial uses in order to create high-performance, lightweight manufactured materials produced from renewable biological resources and agricultural waste [1]. The aspect ratios and chemical compositions of these biomaterials can affect their processability, durability, and thermomechanical properties to satisfy the requisite strength and stiffness for certain applications [2]. However, these biomaterials have a variety S. Gokulkumar (B) · T. Kannan · N. Karthi · S. Sathish · L. Prabhu · M. Aravindh · J. Alex Department of Mechanical Engineering, KPR Institute of Engineering and Technology, Coimbatore 641 407, Tamil Nadu, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_12

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of drawbacks, such as poor biocompatibility, swelling qualities, and decreased impact strength, which leads to the propagation of cracks at the fiber-matrix interface. To address these limitations of biomaterials, a number of researchers have utilized hybridization of fibres over non-hybrid composites using synthetic or natural nanofillers [3]. Nanoparticles are currently regarded as a crucial (organic/inorganic) reinforcing filler ingredient for the development of hybrid eco-composites with enhanced mechanical, thermal and tribological properties and dynamic properties [4– 6]. Developing this type of new innovative hybrid eco composite, which is comprised of recycled bio fibres and agricultural residue fillers, serves as a waste-to-value addition to the hybrid eco composite for potential applications to reduce ecological and environmental harmful issues, such as greenhouse gas emissions and ocean pollution [7]. Moreover, the inclusion of multifunctional micro/nanofillers (organic/inorganic) with biomaterials can effectively improve mechanical properties by distributing functional fillers uniformly and generating strong hydrogen connections between them [8, 9]. Consequently, recycled fibres, agricultural residue fillers, and seeds are already emerging as suitable reinforcements to impart specific qualities with the goal of producing sustainable hybrid composites [10]. The purpose of bio-fillers is to reinforce the fiber-matrix interface in order to improve stress transmission, resulting in increased sustainability, durability, cost-effectiveness, and enhanced mechanical and physicochemical qualities [11]. Numerous research studies have also indicated that hybrid eco composites with bio fillers, such as Tamarindus indica seed powder [12], date palm powder [13], rice husk powder [14], peanut shell powder [15], walnut shell powder [16], fly ash, coconut shell powder [17], Polyalthia longifolia seed, orange peel powder, lemon peel powder, neem seed powder, thymus moroderi, pinewood [18] and black rice husk, betel nut husk [19], can now be used more. Through the synergistic action of multifunctional fillers, these promising qualities can be attained, leading in enhanced biocompatibility [20]. However, the use of inorganic fillers such as Al2 O3 , SiC, graphite, carbon nanotubes, and nanofibers renders hybrid composites nonbiodegradable. Therefore, the purpose of this study was to construct a partially eco-friendly composite made of Glycine max seed powder and unidirectional Agave fourcroydes, as well as to examine their mechanical and acoustical properties.

2 Materials and Methodology 2.1 Materials—Fiber and Matrix The study employed Agave fourcroydes with Glycine max seed powder to produce composites (GMSP). Glycine max, also known as soybean (family Leguminosae) native to East Asia. Due to its high fibre and protein content, it is the most important oil crop in the world and is consumed in a diverse range of ways [21]. Salt Spring Seeds, Canada supplies the global production of soybeans which is between 320

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Fig. 1 a Glycine max seed b glycine max seed powder

and 350 million tons. Henequen (Agave fourcroydes) is a species of Asparagaceae flowering plant indigenous to southern Mexico and Guatemala [22]. Anciently, Maya Indians cultivated and used this the plant for its fibre because it is an evergreen, succulent, perennial plant that produces wider stem [23]. Numerous Agave species have robust, sharp spines on the leaves and leaf tips. Henequen fibre is processed into twines and ropes for use in agriculture and maritime transportation. In addition, bags, hammocks, and shoe bottoms are manufactured with coarse henequen-fibre materials that are produced locally [21]. Both the Epoxy resin (LY 556) and the hardener (HY 951) were procured from Covai Seenu & Company in Coimbatore.

2.2 Extraction of Glycine Max Seed Powder (GMSP) The mature Glycine max seeds were subjected to manual removal of the outer layer, and the inner portion or cotyledon was sun-dried for a period of five days (Fig. 1a). Utilizing a Metso Outotec planetary ball mill, the seeds are then ball-milled. As illustrated in Fig. 1b, the ball-to-powder weight ratio is estimated to be 15:1 after 18 h, and the powder is analyzed with a particle size analyzer (Model: Mastersizer 3000) for the desired size range of 32–45 nm.

2.3 Fabrication of Agave fourcroydes/GMSP Composites In the production of GMSP/Agave fourcroydes composites, releasing agent, liquid resin (LY556 and HY951 mixture), and reinforcement layer (Agave fourcroydes) are placed to a mould by hand. The different weight proportions of GMSP (0, 2.5, 5, 7.5,

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Table 1 Samples composition and designation Matrix-fiber

Epoxy-unidirectional Agave fourcroydes—GMSP (60:40)

Sample ID

1

2

3

4

5

GMSP content (%)

0

2.5

5

7.5

10

Fig. 2 Fabrication of GMSP/Agave fourcroydes composite

and 10% by weight) as designated in Table 1 are manually mixed with the resin and well agitated with a mechanical stirrer (Model: 5-MLH Plu). A compact hand roller was used to inject reinforcement layers into other layers to create a composite laminate. This process was repeated until the desired thickness was achieved. The resulting laminate was then compressed using a hydraulically powered compression molding machine under a weight of 12.5 metric tons to create a homogeneous thickness as shown in Fig. 2. The final composite laminate has dimensions of 300 × 300 mm and a thickness of approximately 3.6 mm as represented in Fig. 3.

2.4 Mechanical and Physical Tests 2.4.1

Density and Void Content Test

Using alcohol as a medium, the density of the developed composites was measured using the Archimedes principle as per ASTM Standard D 792-91 [24]. For each and

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Fig. 3 GMSP/Agave fourcroydes composite

every composite composition, at least three samples were measured. Accounting for the discrepancy between the measured density and the theoretical density estimated using the rule of mixtures yields the void determination of the developed Agave fourcroydes/GMSP composites. Using Eq. (1), the density was theoretically determined, and Eq. (2) was used to compute the theoretical density. (Wair ) × ρupbuo ) ρexp = ( Wair − Wupbuo

(1)

where, Wair weight of fabricated sample placed in air Wupbuo weight of fabricated sample in upthrust buoyant ρbuo density of the upthrust buoyant.

ρthe = (

Wf + ρf

)

1 + (Wm + ρm ) + (Wfiller + ρfiller )

where, Wfiller , Wm , and Wf weight fraction of filler, matrix, and fiber ρfiller , ρm , and ρf density of filler, matrix, and fiber.

(2)

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The void content (Vc ) of the developed composite was theoretically calculated using Eq. (3). ) ( ρthe − ρexp Vc = ρthe

(3)

where ρthe and ρexp are the theoretical and experimental density, respectively. 2.4.2

Flexural and Tensile Test

Flexural strength is the most important test for determining a material’s fracture resistance and stiffness under various bending loads. It was performed at room temperature in accordance with ASTM D-790 using the universal tensile test (UTM) machine (Make: ZwickRoell Z100) with cross head speed of 2.3 mm/min and the gradual load was applied until sample gets fractured. Like, flexural test, tensile test also carried out with the same conditions as per the ASTM D-638.

2.4.3

Impact Test

The sample is fabricated with respect to ASTM D 256 standard, and testing is conducted using an Izod impact apparatus. The sample is placed in the specified holder and the pendulum is allowed to swing until it fractures or breaks. The energy required to fracture the material during the impact test is recorded and used to determine the impact strength of the material.

2.4.4

Sound Absorption Test

The acoustic performance (SAC and NRC) of the developed GMSP filled composite was evaluated as per ASTM 1050-12 and the two-microphone transfer function approach [25]. This technique is to determine the sound absorption coefficients (SACs) as shown in Eq. (4), in both the low- and mid-frequency ranges, a Brüel & Kjaer (with tubes of 29.5 and 99.5 mm) was utilized in this study as shown in Fig. 4. The noise reduction coefficients (NRCs) were finally determined with the arithmetic mean of the 1/3rd octave band frequencies (250, 500, 1000, and 2000 Hz) using the Eq. (5): S AC =

α125 + α250 + α500 + α1000 + α2000 + α4000 6

(4)

α250 + α500 + α1000 + α2000 4

(5)

N RC =

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Fig. 4 Impedance test tube method [26]

3 Results and Discussion 3.1 Analysis of Density and Void The mechanical performance of developed GMSP/Agave fourcroydes composites is governed by their fibre weight content, fibre and polymer type, fiber–matrix interaction, and, most importantly, the composite density, which is an indicator of the porosity content. This porosity will help in increasing the sound absorption capability of the developed composites. The theoretical and experimental density with its void percentage is listed in Table 2. The results indicate that the developed composites containing GMSP filler have higher theoretical and experimental densities compared to those without the filler. Moreover, an increase in GMSP filler content results in a decrease in densities, potentially due to the formation of air bubbles during blending, which leads to a gradual increase in void content [27]. The issue can be addressed by outfitting the vacuum bagging process with an autoclave that can apply heat, thereby minimizing the formation of air bubbles and reducing void content [28]. The integration of an

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Table 2 Theoretical and experimental density with void content Sample ID

Theoretical density (g/cc)

Experimental density (g/cc)

Void content (%)

1

1.045

1.028

1.627

2

1.126

1.107

1.687

3

1.239

1.211

2.260

4

1.257

1.234

1.830

5

1.186

1.158

2.361

autoclave with the vacuum bagging technique is a widely used industrial practice to manufacture thermoset composites that exhibit minimal void content.

3.2 Flexural Analysis Flexural strength is one of the ultimate and commonly measurable qualities of composite materials used in structural applications. Figure 5 depicts the influence of varied GMSP/Agave fourcroydes composite weight percentages on flexural strength measurements. At 7.5 wt%, the GMSP/Agave fourcroydes composite demonstrates a flexural strength of 107 MPa. The percentage increase in flexural strength between the composite without filler and the composite containing 7.5 wt% GMSP/Agave fourcroydes is 14.05%. This graph reveals that an increase in GMSP filler matrix interaction permits a greater transfer of stress from the matrix to the GMSP filler during external loading. Fig. 5 Flexural analysis of GMSP/Agave fourcroydes composite

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Fig. 6 Tensile analysis of GMSP/Agave fourcroydes composite

3.3 Tensile Analysis With the aid of digitalized UTM, the varied weight percentages of the GMSPreinforced Agave fourcroydes composites are tested, and the samples are allowed to fracture until it reaches the ultimate tensile stress. Figure 6 depicts the tensile strength of GMSP-reinforced Agave fourcroydes composites. When the filler percentage is increased from 0 to 10%, the strength increases from 63.4 to 73.1 MPa. Initially, the poor dispersion of GMSP with the matrix reduces the tensile strength, but at 7.5 wt%, the GMSP content accumulation in the produced composites raises the tensile strength. In this study, the ultimate tensile strength of the fabricated GMSP filled composites is 73.1 MPa for a 7.5 wt% of fillers due to proper distribution throughout the composite. Improving the stress transfer from the matrix to the GMSP filler during tensile loading is essential for achieving higher tensile strength, and this could be facilitated by the proposed modification.

3.4 Impact Analysis As the quantity of GMSP and Agave fourcroydes in the composite material increases, there is a corresponding increase in the impact strength of the composite. This suggests that the addition of GMSP and Agave fourcroydes to the composite can improve its impact resistance. Specifically, the composite with 7.5 wt% filler has a greater energy density and therefore higher impact strength of 31.3 kJ/m2 than the composite without GMSP filler as shown in Fig. 7. The composite with 0% GMSP filler enhances impact strength by 19.92%. It is seen that the addition of GMSP reinforced with Agave fourcroydes boosts the strength by 7.5 wt%, while the other weight percentages of GMSP fillers provide the lower impact values due to improper

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Fig. 7 Impact analysis of GMSP/Agave fourcroydes composite

dispersion. Due to this reason, the composite loses its ability to absorb impact energy. The sudden drop in impact strength is due to improper dispersion of the GMSP filler. When the GMSP particles are not well dispersed throughout the composite material, they can create weak points and areas of stress concentration that reduce the material’s ability to absorb impact energy [29]. This can result in a sudden drop in impact strength for sample 5 and an increase in the likelihood of fracture or failure. Therefore, it is important to control the dispersion of the GMSP filler to ensure that it is evenly distributed throughout the composite material, in order to maintain its impact resistance.

3.5 Sound Absorption Analysis On the basis of their microscopic structures, porous and tortuous materials can be categorized as fibrous, micro-cellular, nano-cellular or granular. Examples of fibrous porous materials are natural fibers, synthetic fibers, and foams. The sound absorption coefficient (SAC) measures how much sound a material blocks out of the sound that strikes it. The noise reduction coefficient (NRC) measures the effectiveness of a substance in absorbing sound. The NRC rating is determined by calculating the arithmetic mean of a material’s SACs at 250, 500, 1000, and 2000 Hz, and the value is then rounded to the closest 0.05. The NRC for the developed GMSP/ Agave fourcroydes composite is shown in Fig. 8, and it followed the increasing order as 5 > 4 > 3 > 2 > 1. From the graph, it is seen that the NRC seems to be higher for sample 5, which has a higher GMSP filler weight fraction. It is mostly due to the increase in porosity that results from the compression of fibrous material, which in turn increases the sound absorption properties [25, 26]. When compressed, the strands of material are brought closer together without any change in fibre size or deformation. A higher friction coefficient due to the dense fibre content will increase airflow resistance [30–32].

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Fig. 8 Sound absorption analysis of GMSP/Agave fourcroydes composite

Sound waves that enter a fibre have their amplitude diminished by the twists and turns they must navigate [33–35]. When a fiber is completely molded with epoxy, it becomes a solid material that does not allow sound waves to pass through it easily. However, if the fiber is part of a larger structure, such as a composite material, the sound waves can enter the fiber indirectly through the surrounding material. When a sound wave strikes a composite material, it can cause the material to vibrate. These vibrations can then be transmitted to the fibers within the material, including those that are molded with epoxy. Once the vibrations reach the fiber, they can propagate along the length of the fiber as a longitudinal wave. The epoxy material itself can also transmit some amount of sound energy, although it is not as efficient as transmitting sound as a material like metal or glass. This means that some amount of sound energy may be able to enter the fiber directly through the epoxy, although it will be significantly attenuated compared to the energy transmitted through the surrounding material. Consequently, the acoustic energy is converted into thermal energy. Therefore, the amount of sound energy that can enter a fiber that is completely molded with epoxy will depend on the specific properties of the composite material and the epoxy used, as well as the frequency and intensity of the sound wave.

4 Conclusion The study investigated the mechanical and sound absorption properties of a nanocomposite made from unidirectional Agave fourcroydes reinforced epoxy blended with Glycine max seed powder (GMSP). The findings reveal that,

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• The maximum density of the composite was found at 7.5 wt% GMSP suggests that this composition has a good balance of materials, resulting in optimal packing and minimal voids of 1.830%. The minimal void percentage is an important characteristic of composites as it indicates the amount of empty space within the material. A lesser void percentage can lead to improved mechanical properties and can also make the material more resistant to cracking and failure. • The addition of 7.5 wt% GMSP was found to enhance the composite’s tensile, flexural, and impact capabilities due to improved adhesion between the fibers and matrix. The addition of GMSP to the composite may have improved adhesion between the fibers and matrix by increasing the surface area of contact between the two materials. This increased contact area may have led to a stronger bond between the fibers and matrix, resulting in improved mechanical properties. • With regard to the Noise Reduction Coefficient (NRC), the composition with a larger weight fraction (10 wt%) and a porous structure performed better. Despite this, the composition containing 7.5 wt% (sample 4) exhibited superior NRC next to sample 5. This is due to factors such as the microstructure arrangement within the composite. GMSP nanoparticles, in particular, have been shown to have unique properties that make them suitable for use in structural applications. These properties include high strength, low void content, and good acoustical stability. The integration of GMSP nanoparticles into polymer nanocomposites can lead to improved mechanical properties such as increased stiffness, strength, and toughness. In addition to their mechanical properties, polymer nanocomposites containing GMSP nanoparticles can also exhibit improved acoustical properties. This makes them suitable for a wide range of applications such as aerospace, automotive, and construction industries. The future scope of this GMSP in polymer nanocomposites is to develop the sustainable materials as it reduces the dependence on non-renewable resources. Despite its numerous benefits, it has certain drawbacks, including limited availability, compatibility with polymers, and safety concerns during production.

References 1. Karthi N, Kumaresan K, Rajeshkumar G, Gokulkumar S, Sathish S (2021) Tribological and thermo-mechanical performance of chemically modified musa acuminata/corchorus capsularis reinforced hybrid composites. J Nat Fibers. https://doi.org/10.1080/15440478.2020.1870614 2. Sathish S, Kumaresan K, Prabhu L, Gokulkumar S, Dinesh S, Karthi N (2018) Experimental testing on mechanical properties of various natural fibers reinforced epoxy hybrid composites. Indian J Sci Technol 11:1–6. https://doi.org/10.17485/ijst/2018/v11i25/122231 3. Tarchoun AF, Trache D, Klapötke TM (2019) Microcrystalline cellulose from Posidonia oceanica brown algae: extraction and characterization. Int J Biol Macromol 138:837–845. https://doi.org/10.1016/J.IJBIOMAC.2019.07.176 4. Petersson L, Kvien I, Oksman K (2007) Structure and thermal properties of poly(lactic acid)/ cellulose whiskers nanocomposite materials. Compos Sci Technol 67:2535–2544. https://doi. org/10.1016/j.compscitech.2006.12.012

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Mechanical Properties and Abrasion Resistance of 3D Printed Lightweight CF-Reinforced PLA/ABS Composites Using Design of Experiments B. Suresha , Vikas Hanamasagar , Imran M. Jamadar , S. L. Arvind , and H. M. Somashekar

Abstract The present research work is to evaluate the three-body abrasive wear behaviour of composites of Polylactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) reinforced with Short Carbon Fibres (SCFs), fabricated by fused deposition modelling (FDM). Commercially available polymers for applications in 3D printing, PLA, PLA/SCFs and ABS/SCFs composites made by FDM were investigated. Dry sand abrasion tester having rubber wheel is used for implementing three-body abrasive wear experiments. Taguchi design of experiments is adopted for developing the experimental design and optimisation of parameters. Hardness, impact strength, specific wear rate (K s ) and worn surface morphologies of these samples were compared. The incorporation of SCFs raised the K s of thermoplastic composites. These outcomes could be explained by the SCFs significantly reducing final elongation at break, which is a crucial aspect of abrasive wear performance. Micro-cutting, plastic deformation and matrix pitting are the main wear processes in neat PLA/ABS. The wear mechanisms in case of SCFs reinforced composites are ploughing, micro-cutting, fragmentation of wear debris, and severe weakening of the fibre surface and delamination. When fiber reinforcement is added to any matrix, the wear behaviour of polymer-based composites will alter. In this study, SCFs reinforcement was used to improve the mechanical characteristics of PLA/ABS polymers. However, effects of SCFs on specific wear rate of PLA/ABS composites are not always positive. Keywords PLA/ABS composites · FDM · Mechanical properties · Three-body wear mechanisms B. Suresha (B) · V. Hanamasagar · I. M. Jamadar · S. L. Arvind Department of Mechanical Engineering, The National Institute of Engineering, Mysuru 570 008, India e-mail: [email protected] H. M. Somashekar Department of Mechanical Engineering, Dr. Ambedkar Institute of Engineering, Bengaluru 560056, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_13

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1 Introduction The tribological study of numerous components used in industrial applications has garnered interest for many years and is crucial in operation of the machineries. Tribology is interdisciplinary phenomenon including three crucial parameters namely wear, friction and lubrication [1]. Polymer composites have been used as an alternative material due to their self-lubricating property, higher wear resistance and ease of fabrication. Due to their capability to increase the mechanical and tribological behaviour, thermoplastics are utilized in many applications after suitable reinforcements addition. The majorly adopted fabrication processes for developing various thermoplastic components include thermoforming, extrusion, injection moulding and many more [2]. Additive manufacturing is been recently chosen as a method of fabrication due to its capability to produce multifaceted structures with higher precision and accuracy which is difficult to obtain by conventional methods [3]. Higher demands from industries resulted in development of different additive manufacturing technologies such as Fused Deposition Modelling (FDM), Stereolithography, Selective Laser Sintering (SLS), Selective Laser Melting (SLM) and so on [4]. In Fused deposition modelling, raw material which is in the form of filament is fed through rollers while being heated at nozzle in order to melt the filament. The filament is then layered on the build platform according to the necessary dimensions and this process repeats until desired part is obtained [5]. The thermoplastic-based composites of Polylactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) material are used extensively due to biodegradability, low melting, self-lubricating, and ease of fabrications. The mechanical properties of the materials are greatly influenced by printing parameters [5–9]. Dogru et al. [10], studied the effect of reinforcement of hemp natural fibers on the mechanical behaviour of PLA bio composites. The results showed an improvement in mechanical properties and aging causes in increment of impact strength of PLA material. Senthil and Manickam [11] attempted to Butt weld the 3D printed PLA sheets by friction stir welding, proving the material efficiency at elevated work conditions. Kumar and Roy [12] studied the result of glass fibers reinforcement on three-body abrasion wear behaviour of Nylon 6 thermoplastic under varying applied load against 320 grit size abrasive paper. The specific wear rate reduced significantly at 30% reinforcement. Plastic deformation and formation of groves were seen as the main wear mechanism. The strengthening due to carbon fibers and graphite fillers reduced the wear resistance of thermoplastic composites fabricated by injection moulding technique [13, 14]. The wear characteristics were correlated with mechanical properties following the Lancaster model [14–16]. Taguchi design of experiments (DOE) has been used as effective statistical tool for optimisation of tribological parameters. Hemant et al., adopted Taguchi DOE approach for optimisation of parameters of SCFs reinforced

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Table 1 Physical and mechanical properties of thermoplastic composites Parameters

PLA

CF-PLA

ABS

CF-ABS

Density (g.cm−3 )

1.21–1.43

1.29–1.5

1.035–1.096

1.075–1.100

Melting point (°C)

195–215

215–225

235–255

240–260

60–65

60–70

105–110

110–115

Glass transition (°C)

polyester composites. The abrasive wear performance of the composites has a significant influence on the ultimate elongation at break in comparison to hardness and ultimate tensile strength of the materials [16]. Micro cutting, deep ploughing, and fracture of carbon fibers as the wear mechanisms of carbon fiber reinforced Polyamide/ Polytetrafluoroethylene blends [17]. Impact of SCFs on the mechanical properties of various thermoplastic composites fabricated by conventional methods such as Injection moulding, hot pressing and many more have been studied by many researchers, but a limited work on tribological behaviour of short carbon fiber reinforced thermoplastic composites has been obtained. In the present work, the study of effect of SCFs on the three-body abrasive wear of PLA and ABS thermoplastic composites which are fabricated using 3D printing by FDM is presented.

2 Materials and Methods 2.1 Materials The thermoplastic materials namely ABS and PLA which is in the filament form bearing 1.75 mm diameter were procured from eSUN 3D, Karnataka, India. The SCF reinforced ABA and PLA composites were fabricated by twin screw extruder technique. To get better bonding at the interface between the fiber and matrix, 20% carbon fiber reinforcement ought to be optimum. Inclusion of reinforcement greater than 20% induces brittleness in the filament and is unfavorable for fabrication of specimens. The physical and mechanical properties of the thermoplastic composites as obtained by the suppliers are outlined in Table 1.

2.2 Fabrication of Test Specimens Figure 1 exhibits the process for of test specimen’s fabrication of PLA, ABS, CF-PLA and CF-ABS composites using 3D printing by FDM technique. The initial stage involves development of CAD model of necessary dimensions and is stored in the STL format. These models are then exported to the Ultimaker Cura slicing software for slicing the STL model and preparation of G-codes. The

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Fig. 1 Process for fabrication of specimens by FDM technique

parameter of printing considered for fabrication of specimens are tabulated in Table 2. These developed G-codes are then used as input to the creality-ender 3 pro FDM printer. The composite material in the form of filament is delivered to the heating unit through rollers. The filament is then heated to a required temperature in the nozzle, and it is moved following the G-codes provided, allowing the material to deposit on the developed platform. The process is recurring continuously till the required specimen is achieved. Table 2 Printing parameters for fabrication of specimens by FDM technique Material

PLA

CF-PLA

ABS

CF-ABS

Parameters Nozzle temp. (°C)

205

210

245

255

Bed temp. (°C)

60

60

100

110

Layer thickness (mm)

0.12

0.12

0.2

0.2

Infill density (%)

100

100

100

100

Printing speed (mm/sec)

70

70

80

60

Orientation direction

[90, 90]

[90, 90]

[90, 90]

[90, 90]

Build orientation

Vertical

Vertical

Vertical

Vertical

Infill pattern

Lines

Lines

Lines

Lines

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3 Experimentation 3.1 Three-Body Wear Test Dry sand rubber wheel abrasion test rig as shown in Fig. 2 is used for performing the three-body wear tests following ASTM G-65 standards [18]. The specimen having length 75 mm, width 25 mm and thickness of 5 mm was used for conduction of experiments. The specimen surfaces were cleaned by means of acetone to take away the excess material and dust. The pilot experiments were carried out based on the previous literatures as mentioned in Sect. 1. The initial trials were performed at the lower and higher values of tribo-parameters considered; the test specimens had a destructive wear on the surfaces. The tribo-parameter values were reduced and the final values were achieved in accordance with the low-medium–high trend. The final testing parameter considered for the experimentation are as tabulated in Table 3. The correlation of the wear data with mechanical characteristics of the composites is performed and correlation coefficient is determined by using Eq. (1).

Fig. 2 Dry sand abrasion test rig

Table 3 Tribo-parameters taken into consideration for three-body wear tests Sl. No

Control factors

Designation

Levels 1

2

3

1

Material

A

PLA

CF-PLA

CF-ABS

2

Applied load (N)

B

10

20

30

3

Particle size (µm)

C

225

325

425

4

Distance (m)

D

750

1000

1250

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(∑ ) (∑ )(∑ ) n xy − x y r = /( (∑ ) (∑ )2 )( (∑ ) (∑ )2 ) n x2 − n× y2 − x y

(1)

where, r represents coefficient of correlation, n represents number of experiments or observations, x represents mechanical property and y represent wear volume of the composites.

3.2 Design of Experiments For minimizing the quantum of experiments and optimization of tribo-parameters, design of experiments (DOE) approach was used for studying three-body wear behaviour of developed composites. In the present work, DOE approach was implemented for this purpose and L27 orthogonal array was considered for experimental design. A statistical Analysis of Variance test (ANOVA) was conducted aimed at identification of tribo-parameters that are statistically significant. Later, based on Taguchi and ANOVA, the optimum combination of tribo-parameters for three-body wear was predicted with agreeable level of accuracy.

4 Results and Discussion The tribological three-body wear tests were executed to determine effect of SCFs on the abrasive wear of the PLA and ABS composites.

4.1 Effect of SCF on Specific Wear Rate Three-body wear tests were performed on PLA, CF-PLA and CF-ABS thermoplastic composites by applying Taguchi DOE approach and considering silica sand as abrasive particles. The experiment design was developed using L27 orthogonal array as shown in Table 4. The lower the K s , higher is the estimated S/N ratio and it was noted that the optimum value for K s obtained was 2.4780 × 10–12 m3 /N m under 10 N applied load, distance 1250 m and for sand particle size of 325 µm. Figure 3 represents the images of the worn surfaces of SCFs reinforced PLA and ABS composites respectively. The effect of tribo-parameters on K s value and S/N ratio are as shown in Figs. 4 and 5 respectively. It can be noted that the K s value of CF-ABS and CF-PLA increased for CF-ABS and CF-PLA composites by 13 and 5.5 × 10–12 m3 /N m as compared to PLA composite. With increment in applied load from 10 to 30 N, the K s value

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Table 4 L27 orthogonal array for three-body wear test Distance

Expt. K S (× 10–12 m3 /N m)

Sl No

Material

Load (N)

Particle size (µm)

1

PLA

10

225

750

4.2662

2

PLA

10

325

1000

4.1121

3

PLA

10

425

1250

1.7514

4

PLA

20

225

750

4.7214

5

PLA

20

325

1000

2.9417

6

PLA

20

425

1250

1.5012

7

PLA

30

225

750

5.1217

8

PLA

30

325

1000

2.9517

9

PLA

30

425

1250

1.5814

10

CF-PLA

10

225

1250

6.6502

11

CF-PLA

10

325

750

10.4717

12

CF-PLA

10

425

1000

7.5147

13

CF-PLA

20

225

1250

5.1214

14

CF-PLA

20

325

750

11.0214

15

CF-PLA

20

425

1000

6.5124

16

CF-PLA

30

225

1250

4.9474

17

CF-PLA

30

325

750

11.5147

18

CF-PLA

30

425

1000

6.2131

19

CF-ABS

10

225

1000

12.8364

20

CF-ABS

10

325

1250

10.9455

21

CF-ABS

10

425

750

15.1200

22

CF-ABS

20

225

1000

14.9971

23

CF-ABS

20

325

1250

10.7541

24

CF-ABS

20

425

750

17.7474

25

CF-ABS

30

225

1000

15.5140

26

CF-ABS

30

325

1250

13.154

27

CF-ABS

30

425

750

18.514

Fig. 3 Test specimens before and after test of a PLA b CF-PLA and c CF-ABS composites

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increased marginally from 7.6 to 8.5 × 10–12 m3 /N m with rise in load from 10 to 30 N. The rise in applied load, leads to the increment in stress developed at the interface between the rotating rubber wheel disc and test specimen surface and due to which sand particles gain higher energy, causing more wear loss on the specimen surface. The K s value initially increased with increase in particle size from 225 to 325 µm from 7.7 to 8.2 × 10–12 m3 /N m and then decreased up to 8 × 10–12 m3 /N m for 425 µm sand particle size. Increase in the sand mesh size, indicates finer particle sizes of abrading particles, therefore cause lower wear loss. The increase in abrading distance caused reduction in wear rate of specimens. The wear loss increases drastically at the initial stage whereas, after formation of wear track on the surface of test specimen, the abrading particles get more space for movement and begins to slide through the

Fig. 4 Effect of tribo parameters on mean K s

Fig. 5 Main effective plots of S/N ratios

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Table 5 Response table for S/N ratios Level

Material

Applied load (N)

Particle size (µm)

Distance (m)

1

− 9.300

− 16.741

− 17.145

− 19.629

2

− 17.401

− 16.314

− 17.480

− 16.691

3

− 23.025

− 16.667

− 15.107

− 13.412

Delta

13.725

0.427

2.373

6.217

Rank

1

4

3

2

wear track, reducing wear loss. The obtained trends are in well agreement with the research works [16, 17, 19]. Table 5 represents the response of S/N ratios for individual tribo parameter. It is seen that material composition has a greatest influence on the K s value. The next effect on K s value is of abrasive particle size, abrading distance and applied load in decreasing order. Therefore, indicating the significant role of material composition in three-body abrasion wear.

4.2 ANOVA Analysis and Effect of Tribo Parameters Table 6 shows ANOVA for S/N ratios of tested composites. R-sq had a correlation of 98.63%, whereas R-sq (adj) had a correlation of 98.03% showing good predictability of model. It is apparent from the ANOVA that, the material composition has the greatest contribution of 79% on specific wear rate of developed composites followed by abrading distance (16.06%), abrasive particle size (2.7%) and applied load (0.08%). Regression analysis provides a relation between the K s value and the tribo parameters considered for experimentation within the range specified and is as shown in Eq. (2). ( ) K s ×10−12 m3 /N m = 5.57 − 5.591 × material + 0.0325 × load (N) + 0.00127 × particle size (µm) − 0.00935 × distance (m) (2) Table 6 ANOVA data for S/N ratios Source

DOF

Seq SS

Adj SS

F-value

P-value

Contribution (%)

Material

2

856.93

856.9

340.80

0.000

79.02

Load

2

0.96

0.956

0.38

0.689

0.08

Particle size

2

29.70

29.70

11.81

0.001

2.7

Distance

2

174.13

174.3

69.25

0.00

16.06

Residual error

18

22.63

22.63

–

–

–

Total

26

1084.3

–

–

–

100

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Table 7 Confirmation experiments for three-body abrasion wear Sl. no

Material

Applied load (N)

Particle size (µm)

Distance (m)

Predicted K s (× 10–12 m3 /N-m)

Expt. K s (× 10–12 m3 /N-m)

Error (%)

1

PLA

10

425

1250

4.0136

4.212

4.94

The coefficient of load applied and particle size in Eq. 2 are positive, indicates that specific wear rate escalates with rise in these tribo parameters. The negative coefficient of abrading distance shows decreases in specific wear rate with rise in abrading distance.

4.3 Confirmation Experiment Table 7 denotes the forecasted and experimented results found for optimal wear conditions for minimum K s for PLA, CF-PLA and CF-ABS thermoplastic composites. The K s value found by confirmation testing is nearer to the experimental K s obtained via Taguchi model. PLA composite showed minimum K s among all the composites studies. Confirmation tests were performed on the predicted factors of neat PLA, 1250 m, 425 µm silica sand particle size, and 10 N for validating the predicted optimum RSM control factor. Table 7 presents the findings of the tests, predicted values and the error in the response characteristics. There is a strong agreement between the experimental findings as well as the predicted values with a minimum reported error of 4.94%.

4.4 Relationship of Wear Data with Mechanical Properties The primary reason for addition of reinforcements is to improve their tribological and mechanical properties of the composites. The three-body wear results showed reinforcement of SCFs into PLA and ABS composites reduced the resistance to wear of composites. Similar results were observed by previous literature work [19]. Therefore, Ratner-Lancaster model efficiently correlates the wear data with the mechanical properties of composites [10]. The mechanical behaviour of neat and reinforced PLA specimens was tested by following ASTM standards [20, 21]. There was considerable reduction in the mechanical strength of CF-PLA specimens in comparison to neat PLA specimens. The reduction is mainly due to weak interlayer bonding within the carbon fibers and the PLA matrix. The sudden cooling of 3D printed sample from higher melting temperature to atmospheric temperature causes weaker interlayer bonding. Relationship of mechanical properties of thermoplastic composites

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Table 8 Correlation coefficients for three-body abrasion wear Material

PLA

Mechanical characteristics

Correlation coefficient

Hardness (Shore D) (H)

Elongation at break (e) (%)

Tensile strength (S) (MPa)

(e)−1

(He)−1

(Se)−1

84.5

10.24

70.29

0.002521

0.00636

0.15541

CF-PLA

80.7

10.01

27.23

0.002807

0.01689

0.47600

CF-ABS

73.3

10.42

23.77

0.041680

0.02030

0.79630

considered with the wear data were correlated by Pearson’s regression coefficient and is as tabulated in Table 8. It can be noted that, the correlation coefficient for PLA composite has the least value in terms of (He)−1 , (e)−1 and (Se)−1 in comparison to CF-PLA and CF-ABS composites. Therefore, the lesser correlation of wear characteristics with mechanical characteristics indicates improved wear resistance of the material. The CF-PLA and CF-ABS composites showed lower wear resistance due to reduction in mechanical strength [13, 14].

4.5 Worn Surface Morphology Figure 6 show the worn surface morphologies of PLA obtained by SEM under applied load of 20 N, 1250 m abrading distance and abrading particle size of 425 µm. With reference to Fig. 6a, the parallel grooves can be clearly observed and are formed due to wear by sliding of abrasive particles on the surface. The sand particles were seen on the worn surface due to high pressure causing penetration. No plastic deformation on the surface of test specimen was found and higher wear resistance was observed due to strong interlayer bonding between the layers, hence proving the efficiency of FDM process.

Fig. 6 Worn surface features of PLA composites at different magnification a X 250, b X 1000

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Figure 7 shows worn out surface of the CF-PLA composite under applied load of 20 N, 425 µm abrasive particle size and abrading distance of 1000 m. With reference to Fig. 7a, the formation of deep long grooves along wear track was observed due to weak resistance of short carbon fibers against abrading particles. The damage of short carbon fibers and matrix were clearly observed due to weak bonding between them. Smaller voids were observed on the surface left over by worn out short carbon fibers during wear, showing higher specific wear rates. The micro cracks were observed due to fracture and fatigue load applied by abrading particles. Figure 8 showed the SEM images of CF-ABS under applied load of 20 N, 425 µm abrading particles at abrading distance of 750 m. The severe destruction of matrix and carbon fibers along with larger wear track were observed and are the main characteristics of the microscope images as observed in Fig. 8. The deep furrows observed indicate micro cutting of carbon fibers and plastic deformation. Micro cracks are formed on the worn surface because of surface fatigue caused due to repetitive abrasion by sand particles. The carbon fibers were deboned easily by the abrasive particles because of weak bonding at the interface of matrix-reinforcement showing very high specific wear rates.

Fig. 7 Worn surface features of CF-PLA composites at different magnification a X 250, b X 1000

Fig. 8 Worn surface features of CF-ABS composites at different magnification a X 250, b X 1000

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5 Applications PLA and ABS polymer based thermoplastic composites can be possibly used for applications in bearing due to their high resistance to wear, self-lubricating properties and light weight. Prototypes of sleeve bearings were fabricated to express the flexibility and ease of fabrication of composites by FDM technique. Figure 9 shows the sleeve bearings used in motor pumps for low load conditions and Fig. 10 shows the sleeve bearings with bottom support provided for high load conditions. Carbon fiber reinforced thermoplastic showed excellent printing ability with minimum visible pores and possesses high strength.

Fig. 9 Sleeve bearings under low load conditions

Fig. 10 Sleeve bearings with bottom support for high load conditions

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6 Conclusions The test specimens of PLA, ABS, CF-PLA, and CF-ABS composites were successfully fabricated using 3D printing by FDM. The following conclusions are drawn according to the wear results obtained by experimentation. • The three-body wear tests data exhibited that addition of SCFs decreases the wear resistance by 60% and 78% of PLA and ABS composites when compared to neat PLA composite. The reinforcement of short carbon fibers showed detrimental influence on wear resistance of the composites. • ANOVA results indicated material composition has the major influence on specific wear rate followed by Abrading distance, particle size and load applied. • The optimum parameters were obtained for PLA composites at 10 N applied load under 1250 m abrading distance exposed to 425 µm silica sand particle size. • The correlation coefficients developed between the wear data and the mechanical properties of the composites provided the decremental nature by reinforcement of short carbon fibers into neat PLA and ABS composites. • The SEM micrographs revealed the destructive wear on the worn surface of CFABS composites. The weak bonding between the carbon fibers and PLA matrix caused the fibers to slip off from the matrix by the action of abrasive particles.

References 1. Aravind D, Senthilkumar K, Thitnun U, Senthil MK, Rajini N, Chandrashekar M, Ganeshan C (2021) Desirability of tribo-performance of natural based thermoset and thermoplastic composites: a concise review. Appl Sci Eng Prog 14:606–613 2. Biron M (2018) Thermoplastics and thermoplastic composites. William Andrew, Elsevier 3. Mueller B, (2012) Additive manufacturing technologies–Rapid prototyping to direct digital manufacturing. Assembly Autom 4. Gibson I, Rosen DW, Stucker B, Khorasani M, Rosen D, Stucker B, Khorasani M (2021) Additive manufacturing technologies, vol 17. Springer, Cham, Switzerland 5. Penumakala PK, Santo J, Thomas (2020) A critical review on the fused deposition modeling of thermoplastic polymer composites. Compos Part B Eng 201:108336 6. Tymrak BM, Kreiger M, Pearce JM (2014) Mechanical properties of components fabricated with open-source 3-D printers under realistic environmental conditions. Mater Des 58:242–246 7. Shishavan SM, Azdast T, Ahmadi SR (2014) Investigation of the effect of nanoclay and processing parameters on the tensile strength and hardness of injection molded acrylonitrile butadiene styrene–organoclay nanocomposites. Mater Des 58:527–534 8. Lopes BJ, d’Almeida JRM (2019) Initial development and characterization of carbon fiber reinforced ABS for future additive manufacturing applications. Mater Today Proc 8:719–730 9. Wang K, Li S, Rao Y, Wu Y, Peng Y, Yao S, Ahzi S (2019) Flexure behaviors of ABS-based composites containing carbon and Kevlar fibers by material extrusion 3D printing. Polymers 11(11):1878 10. Dogru A, Ayberk S, Ozgur SM (2021) Effect of aging and infill pattern on mechanical properties of hemp reinforced PLA composite produced by fused filament fabrication (FFF). Appl Sci Eng Prog 14:651–660

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11. Senthil SM, Manickam BK (2022) Effect of tool rotational speed and tranverse speed on friction stir welding of 3D-printed ploylatic acid material. Appl Sci Eng Prog 15:5403 12. Kumar S, Roy BS (2020) Tribological properties of acrylonitrile butadiene styrene in self– mated contacts and against steel disc. Mater Today Proc 26:2388–2394 13. Urs MD, Suresha B, Hemanth G, Kulkarni G, Charan MS (2021) Influence of graphene nanoplatelets on tribological properties of short carbon fibre reinforced PA-66/TCE composites. Mater Today Proc 43:1640–1646 14. Hemanth G, Suresha B, Hemanth R (2019) The effect of hexagonal boron nitride on wear resistance under two and three-body abrasion modes of polyetherketone composites. Surf Topogr Metrol Prop 7(4):045019 15. Rajashekaraiah H, Mohan S, Pallathadka PK, Bhimappa S (2014) Dynamic mechanical analysis and three-body abrasive wear behaviour of thermoplastic copolyester elastomer composites. Adv Tribol. https://doi.org/10.1155/2014/210187 16. Harsha AP (2011) An investigation on low stress abrasive wear characteristics of highperformance engineering thermoplastic polymers. Wear 271(5–6):942–951 17. El-Tayeb NSM (2008) Abrasive wear performance of untreated SCF reinforced polymer composite. J Mater Process Technol 206(1–3):305–314 18. ASTM E (2021) Standard test method for measuring abrasion using the dry sand/rubber wheel apparatus. ASTM G65-21 19. Nirmala U, Yousif BF, Rilling D, Brevern PV (2010) Effect of betel nut fibres treatment and contact conditions on adhesive wear and frictional performance of polyester composites. Wear 1354–1370 20. ASTM E (2017) Standard test method for rubber property-durometer hardness. ASTM D 2240-15 21. ASTM E (2015) Standard test method for tensile properties of plastics. ASTM D 638-14

Tribological Characterization of Two Different Elastic Polymers Produced via FDM Enes Aslan

and Gül¸sah Akincio˘glu

Abstract In this study, two commercial flexible polymers which have different components inside were used to manufacture cylindrical scaffolds for experiments via fused deposition modelling. One of the purposes of this study is to show that scaffolds can be produced using flexible filaments with FDM machine. The second one is to contribute to literature about the tribological properties of the polymeric scaffolds. Additive manufacturing has been widely used in many areas to manufacture prototypes, toys, even real products. Polymers are main materials used in the additive manufacturing systems to obtain light weight products. Samples for the experimental work has been produced via FDM system successfully as a cylindrical shape. Wear and friction properties of the flexible polymers were investigated using pin-on-disc test device. Diameter and hardness of the samples were measured. Effects of load variations and material differences on the tribological characteristic of samples was observed. Even these two polymers have the similar base material, due to small component differences between these filaments, significant differences were observed on hardness and coefficient of friction (COF) values. Similar graph profile was obtained from the pin-on-disk device, but small variations were observed on COF values when using the same material under different load values. However, there were significant differences between COF of two material under the same load. Similar situation can be said for hardness values. The cylindrical shape scaffolds were produced successfully from the flexible polymers using FDM system. And so tribological properties of the samples produced via FDM were observed. As far as we know that there is a lack of tribological studies of flexible polymer in the literature. We believe that this study can provide some useful knowledge to the literature. Keywords Flexible polymer · FDM · Tribology E. Aslan (B) Department of Mechatronics Engineering, Engineering Faculty, Düzce University, Düzce 81620, Türkiye e-mail: [email protected] G. Akincio˘glu Department of Machine and Metal Technologies, Düzce University, Düzce 81850, Türkiye © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_14

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1 Introduction Additive manufacturing or 3D printing, which is a method in which various products are manufactured layer by layer from the bottom up, has been used a lot in recent years. With the 3D printing method, the product is printed in very wide areas. Various products are manufactured with this method in fields such as health, engineering and food sectors [1]. The reasons for choosing 3D printing technology; material wastage, complex parts can be produced, and design flexibility [2]. There are too many parameters in the additive manufacturing process. To these; In addition to the layer thickness, which affects the measurement accuracy of the manufactured parts, the filament temperature, filling density, filling pattern and bed temperature can be cited as examples. However, the most influential factors are infill density, printing speed and layer thickness [3]. Researchers have generally worked on these parameters. Thermoplastic polyurethanes (TPU) are a class of melt-processable polyurethanes and can be processed by various manufacturing methods. For example; extrusion injection, compression moulding, coating as solution or blowing etc. [4]. Thermoplastic polyurethane (TPU) is one of the materials frequently used in production with 3D printing. The reasons for their preference are that they are flexible and elastic. They are also resistant to abrasion, impact and weather conditions. TPUs are versatile materials [5]. Shin et al. produced biobased TPU for 3D printing filament in their work. They examined the mechanical properties of the material they produced. The results showed that the bio-based TPU samples can present the similar properties with commercial petroleum-based materials mechanically and thermally [6]. Candal et al. investigated the adequacy of nanocomposite (TPU/CTN), developed by mixing TPU produced from renewable resources and carbon nanotubes (CNT), for additive manufacturing. For this purpose, thermal and rheological properties were examined in terms of printing suitability. They observed the entanglement density and crystallization process by conducting experiments. They concluded that both samples were sufficient for the 3D printing method. However, there are some differences, the viscosity is higher for TPU/CNT (especially at low shear rates), but this value is located within the viscosity range of other thermoplastics used for EAM [7]. Additive manufacturing has many advantages as well as some disadvantages. Sometimes it is difficult to ensure the measurement accuracy of the parts. The aim of the research conducted by Garg et al., examining this problem, is to enhance the dimensional accuracy of FFF Thermoplastic Polyurethane (TPU) parts by optimizing printing speed, infill density and thickness of the layer. The results showed that the thickness of the layer is the most significant specification in creating dimensional accuracy. This is followed by printing speed and filling density [8]. Patton et al. worked on ink selection for additive manufacturing, investigated the features of freestanding films of a TPU polymer and an Ag-CB (Ag–carbon black) TPU PNC. The suitability of these materials for AM was investigated in lightly loaded, low-strain compression contact. TPU presented a long-time retardation and huge viscoelastic

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reaction. Enough time was required to relax of polymer chain and measurable adherence. They observed that a sufficiently large contact field is needed to ensure a longer lasting stable polymer arrangement in contact, which provides higher adherence, better and reliable performance [9]. One of the areas where 3D printing is used is health. Nadnif et al. The primary cause of low back pain is known that might be as lumbar intervertebral disc (IVD) degeneration, for treatment of this problem, they produced 3D printed parts that match the anatomical characteristic of IVD. Monolithic total disc replacement (MTDR) samples were produced with TPU 87A and TPU 95A materials. The MTDR design includes two configurations, anatomy-based (ABC) configurations and full cage (FLC). The produced parts were evaluated for their physical, mechanical and cytotoxic properties. The results of geometric assessment present tolerable production results, and the two materials show slight degradation rates and well wettability. Mechanical investigation exhibits that ABC-MTDR has more similar mechanical characteristics to an IVD than FLC-MTDR [10]. Wang et al. In this study, samples of different materials containing polylactic acid (PLA) and thermoplastic polyurethane (TPU) were prepared with fused deposition modelling (FDM) 3D printing technology [11]. The tensile strengths of the samples were examined and proposed a model validated by experimental data to predict and evaluate the tensile strength of 3D-printed PLA/TPU. They also observed the fracture topography and surface morphology of PLA/TPU samples by scanning electron microscopy. As a result; PLA played a main role in the tensile strength of PLA/TPU. The proposed model to predict and evaluate the tensile strength of 3D-printed PLA/TPU has been validated with experimental data. Gumus et al. The researchers investigated the effect of printing temperature in the range of 170– 250 °C on the mechanical and physical properties of TPU samples. The mechanical properties of the samples were analysed by tensile tests. A sample prepared by compression moulding (CM) at 230 °C was used to explain the effect of the manufacturing method. Among the samples containing CM, the highest tensile strength and elongation at break were 37.6 MPa and 922%, respectively, and were determined in the sample printed at 230 °C [12]. The textile industry is one of the areas where 3D printing method is used. Kasar et al. this study sought a 3D printable material which presents a minimal friction on the skin. So, thermoplastic polyurethane (TPU) and polyamide (TPA) which are known as low friction 3D printable materials, were chosen. Tribological tests were performed against a water-sensitive skin model. Slip tests were performed in dry and wet conditions on the Rtech-Tribometer. To measure frictional interactions against 3D-printed polymers during sliding, the skin model was wrapped on a 6.35 mm diameter steel ball. Due to the 3D printed patterns, the COF (coefficient of friction) fluctuated in the dry condition. It suggested that the printing pattern should be taken into account when designing 3D printed fabrics/accessories to achieve the desired comfort [13]. Steinmetz and Ehrmann also applied 3D printing in the textile field. In the study, they compared pure and printed textile fabrics. They studied the effect of elastic 3D printed patterns on the tribological properties of the textile surface. Therefore, thermoplastic polyurethane (TPU) has been 3D printed in different patterns

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on various textile fabrics. The nozzle diameter used is 0.4 mm. In order to avoid different temperatures on the surfaces of textile fabrics of different thicknesses, the print bed temperature was kept at room temperature. Extruder temperature is set to 230 °C. These reviews show that 3D printed TPU pattern combinations can affect textile fabrics in terms of mechanical properties or protect the surface from undesirable effects due to abrasion. However, in any case, optimizing the z-distance is a necessary prerequisite to achieve adequate adhesion between both materials [14]. Verbelen et al. extensively studied the machinability of four different TPUs in laser sintering. The parameters studied include shrinkage and curing behaviour, rheology of the melt, and powder flow. Analysis of four different TPU powders revealed that TPU materials have very specific and versatile properties that could make them successful materials for laser sintering. These properties include well-flowing powders, low melt viscosities and low shrinkage after curing [15]. Complex, hollow composite geometries can be produced with the Bladder Supported Composite Manufacturing (BACM) technique. However, the cost and manufacturing time are high in traditional bladder manufacturing methods. For this reason, additively produced bladders are offered as an alternative solution to traditional bladders. Kim et al., they produced balloons additively using the Fused Deposition Modelling (FDM) technique with thermoplastic Polyurethane (TPU). Ultimately, 3D-printed TPU bladder has been successfully used for consolidation and hardening of carbon fibre cylinders using the BACM process. It has been observed that pressure bladders can provide significant cost savings in prototyping special composite parts. The void content was measured in order to assessed the consolidation of composite samples manufactured by BACM technique with four different internal pressures. The void content of samples produced using 3D printed bladders at different amounts of air pressure is lower than 1% [16]. In the work of Sharma et al.; produced samples using thermoplastic polyurethane (TPU), acrylonitrile styrene acrylate (ASA) and multi-material (TPU + ASA) polymers by additive manufacturing method. They analysed the wear behaviour of these parts in important process parameters such as molten deposition modelling, filling density, velocity and made the optimization of the experimental results with the GAANN method. They also validated the optimized results with experimental results. As a result of the wear tests, the extrusion temperature and the filling density significantly affected the wear value. For multi-material (material density 1.14 g/cm3 ), the lowest wear rate achieved according to the hybrid GA-ANN model is 0.3880 mm3 /m. Scanning angle is 45 °C, fill density is 40%, extrusion temperature is 240 °C, speed is 46,667 mm/s, and wall thickness is 0.8 mm, and these values have been experimentally verified [17]. In their study, Jayswal and Adanur mixed PLA with varying weights of TPU to gain composite filaments with ideal flexibility and strength that can be suitable for 3D printing. The amounts of TPU polymer in the blend are 10%, 20%, 30% and 40% of the total weight of the composition, respectively. The filaments are 1.56–1.86 mm in diameter. They studied the properties of filaments. Dynamic mechanical analyses of 3D printed samples produced with composite filaments were made. The tensile strength and modulus of the filaments decreased with increasing TPU content in the composite. The amount of elongation at break increased. The

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investigation also presented partial miscibility of the polymer components in the mixture of the composite filaments [18]. Lin et al. in their work; investigated how to optimize the manufacturing process to improve mechanical performance in a 3D printing using soft filament feedstock. They proposed an easy method to check the printing specifications using certain TPU filaments of differentiate hardness. They measured the tensile strength and tear resistance of printed samples to evaluate the optimization printing (OP) approach. Based on the OP approach, the tensile and tear strength was significantly improved over the samples obtained by injection moulding, with rates ranging from ~ 95 to ~ 126.8% [19]. According to the literature, additive manufacturing or 3D printing method has been the subject of a wide variety of studies in very wide areas. In this study, the friction properties of two different polyurethane thermoplastic elastomers materials were compared. The friction tests of the samples were made with a pin on disc test device. Friction wear, hardness and dimensional sensitivity of two different types of elastomers were evaluated.

2 Material and Methods Thermoplastic polyurethane (TPU) based filaments were used in this study. TPU is a flexible and elastic polymer that has a glass transition temperature below room temperature and a melting temperature of around 140 °C. Two kinds of TPU polymers were purchased from the local manufacturer (Sava Filament) in Turkey. The commercial name of TPU-based polymers used in this study is TPU92 and CARBOV60. Both polymers have black color and 1.75 mm diameter, and their print temperature is above 210 °C. Some physical properties of the materials based on the information provided by the manufacturer are: for TPU 92, hardness 92 Shore A (~ 40 Shore D), tensile elongation 810% and specific gravity 1.22 g/cm3 and for CARBOV60, hardness 55 Shore D, tensile elongation 520% and specific gravity 1.23 g/cm3 . Filament based additive manufacturing system was used to produce test specimens for this research study. The print temperature was 220 °C for TPU92 and 230 °C for CARBOV60 material. The specimen was printed as a cylindrical shape (diameter: 10 mm and height: 20 mm), in a rectilinear pattern with a 100% infill ratio with a 0.2 mm layer height. The nozzle diameter and printing speed were 0.4 mm and 80 mm/s, respectively. Three similar specimens were produced from each material, and all measurements were repeated three times at least. In Fig. 1, test samples produced with TPU92 and CARBOV60 filaments are given. Hardness, diameter, coefficient of friction (COF), weight losses, and temperature variations were determined using different measurement devices in this study. A Shore D device was used to find out the hardness values of the samples immediately after production. The calibration of the device was made with a standard gauge before the measurement. The diameters of the specimens were measured with a digital micrometer.

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Fig. 1 Test samples TPU92, CARBOV60 designed model and printing pattern

Coefficient of friction (COF) values were investigated by performing a pin-on-disc device. The device was calibrated before the experimental study based on the manufacturer manual (Turkyus). Wear and friction characteristics of TPU and CARBOV60 specimens were observed under three different loads (6 N, 12 N and 18 N). The experiment was performed based on the friction between the polymer pin surface and the AISI D2 disc surface at the room temperature during 20 min. The device was set up as a revolution of 200 rpm and 40 mm track diameter. The surface of the disc and specimens was elaborately cleaned prior to tests in order to avoid effects of any debris. The weight of the specimens was weighed with a precision balance before and after the pin-on-disc procedure to investigated the weight losses. The temperature of the pin surface contacted with the disc was monitored with a thermal camera (Flir, USA) at the end of the friction test prior to cool down. A digital microscope (Dino Lite, AM7915MZT) was used to obtain the digital images of the samples prior and subsequent to experiment.

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3 Results and Conclusion In this part, the hardness, diameter deviation and tribological properties of the samples produced with TPU92 and CARBOV60 filaments were evaluated.

3.1 Hardness and Diameter The hardness and diameter of the samples produced at 100% fill rate using TPU92 and CARBOV60 filaments were evaluated. The hardness and diameter dimensions of the samples are given in Fig. 2. It was understood that the hardness of CARBOV60 samples was higher. The hardness of CARBOV60 samples is 43.45% higher than TPU92 samples. The results obtained are proportional to the filament harnesses. The hard structure of the CARBOV60 filaments also ensured that the produced samples were tougher. TPU92 and CARBOV60 samples were desired to be produced with a diameter of 10 mm. However, deviations are observed in the diameter values measured after production. These deviation values differ according to the pattern, mass ratio and polymer type used. Because the plastic shrinkage shares of polymer-based filaments are different. Shrinkage is defined as the shrinkage of the plastic raw material during shrinkage, solidification or cooling. During cooling, some polymers shrink more, some less. The least deviation from the obtained diameter values was determined in CARBOV60 samples (2.2%).

Fig. 2 a Samples hardness value and b Diameter values of samples and deviation values from the designed dimensions

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3.2 Coefficient of Friction and Weight Losses The average friction coefficients of the samples produced with different filaments were determined (Fig. 3). Friction wear tests were performed at different loads (6 N, 12 N and 18 N). The friction coefficients of TPU92 and CARBOV60 samples differed. In all tests, the friction coefficient of CARBOV60 specimens is lower than TPU92 specimens. In addition, it is seen in the friction graphs that the coefficients of friction fluctuate momentarily differently. The friction coefficient of CARBOV60 samples fluctuated less. The difference in the results obtained is due to the different properties of the filaments. Softer and more elastic TPU92 filaments were effective in these results. These electrical samples adhered to the disc, causing the vibration and friction force to increase. This resulted in a higher coefficient of friction. The highest coefficient of friction was found in TPU92 samples and 18 N load. The lowest coefficient of friction was found in CARBOV60 samples at 6N load. In addition, in friction tests, it was observed that the shape stabilization of TPU92 samples deteriorated due to their elastic structure. This result shows that TPU92 specimens do not perform well under load. After the friction tests, the weight losses of the samples were measured. Weight losses of the samples are given in Fig. 4. It is seen that the weight losses increase as the test loads increase. As the load increases, the surface area of the polymer materials in contact with the disc surface increases. Increasing the surface area caused more wear of the specimens due to increased friction. When the samples were evaluated according to the filament types, the least weight loss was obtained in the CARBOV60 samples. The weight loss in CARBOV60 samples under 6 N load

Fig. 3 Coefficient friction spectrum of a TPU92 and b CARBOV60 specimens under different loads, and comparisons of TPU92 and CARBOV60 samples under c 6 N d 12 N e18 N load, and f average COF values of all samples

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Fig. 4 Weight losses of the samples after the pin-on-disc experiment under the different loads (per thousand)

decreased by 73.27% compared to TPU92 sample. This shows that the filament type has a significant effect on weight loss.

3.3 Worn Surface In friction tests, the worn surfaces differ according to the test parameters and filament types. The abrasions on the contact surfaces of the samples after the friction wear tests are given in Fig. 5. It has been understood that the deformations of the worn surfaces are different according to the test loads. It is seen that the wear on the surfaces increases with the increase of test loads. These results are similar to the weight loss results. Weight loss increased with increasing test loads. The increased contact surface area with the increase of test loads affected the results. When TPU92 and CARBOV60 samples are evaluated, it is seen that their abrasions differ. The properties of the filaments affected the condition of the wearing surfaces. It was understood that more surface areas were in contact with TPU92 samples. This can be attributed to the low hardness value of TPU92 samples. The more elastic structure of TPU92 samples created a disadvantage in the wear tests. This is clearly seen in the tests of TPU92 samples under 18 N load (Fig. 5). These elastic specimens subjected to high load were deformed circularly. The geometric shape of the samples is distorted.

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Fig. 5 Digital images of samples before the test and after the pin-on-disc under different load conditions

3.4 Thermal Images and Temperature Variations The temperatures of the samples were measured using a thermal camera immediately after the friction test. Thus, the temperatures formed in the samples in friction tests were evaluated. Temperatures occurring in friction tests can give us information about the friction phenomenon. The temperatures formed in the samples after friction tests at different loads are given in Fig. 6. As the test loads increased, the temperature formed in the samples increased. This situation can be attributed to the increase in the contact area and the increasing friction forces with the increase in the pressure applied to the samples with the increase of the loads. There are similarities between the temperatures occurring in the samples and the wear rates. This shows that the obtained results support each other. According to the results in Fig. 6a, less temperature was formed in the CARBOV60 samples. In the tests at the highest load, 18 N, the temperatures formed in the CARBOV60 samples are 3.56% less than the samples in TPU92.

4 Conclusions The results obtained in the wear tests performed under 6, 12 and 18 N loads with TPU92 and CARBOV60 samples produced at 100% fill rate are given below. • Hardness of CARBOV60 samples is higher than TPU 92 samples. Filament properties affected the result obtained. • Diameter deviation values of the samples produced at 100% fill rate were obtained lower in CARBOV60 samples.

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Fig. 6 a Thermal images and b Temperatures on top surfaces of TPU92 and CARBOV60 samples under different friction loads

• Average friction coefficient values were measured lower in CARBOV60 samples than in TPU92 samples. As the test loads increased, the coefficient of friction also increased. The highest coefficient of friction was found at 18 N test load. • After the friction tests, it was understood that the measured temperatures were different. The highest test temperature was measured on TPU92 samples. It has been determined that as the test loads increase, the temperature formed in the samples also increases. • It has been understood that the wear behaviour of CARBOV60 samples is better than TPU92 samples. In future studies, the wear behaviour of these samples in different patterns and infill ratios can be examined. Costs can be reduced by reducing the filling ratio without losing its tribological properties.

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References 1. Shahrubudin N, Lee TC, Ramlan RJPM (2019) An overview on 3D printing technology: technological, materials, and applications. Procedia Manuf 35:1286–1296 2. Saran OS et al (2022) 3D printing of composite materials: a short review 3. Aslani K-E et al (2020) On the application of grey Taguchi method for benchmarking the dimensional accuracy of the PLA fused filament fabrication process. SN Appl Sci 2(6):1–11 4. Yao Y et al (2021) A short review on self-healing thermoplastic polyurethanes. Macromol Chem Phys 222(8):2100002 5. Ahirwar D et al (2022) A short review on polyurethane polymer composite 6. Shin EJ et al (2022) Synthesis and fabrication of biobased thermoplastic polyurethane filament for FDM 3D printing. J Appl Polym Sci 139(40):e52959 7. Candal MV et al (2021) Study of the interlayer adhesion and warping during material extrusionbased additive manufacturing of a carbon nanotube/biobased thermoplastic polyurethane nanocomposite. Polymer 224:123734 8. Garg N, Rastogi V, Kumar PJMTP (2022) Process parameter optimization on the dimensional accuracy of additive manufacture thermoplastic polyurethane (TPU) using RSM 9. Patton ST et al (2016) Characterization of thermoplastic polyurethane (TPU) and Ag-carbon black TPU nanocomposite for potential application in additive manufacturing. Polymers 9(1):6 10. Nadhif MH et al (2022) Anatomically and biomechanically relevant monolithic total disc replacement made of 3D-printed thermoplastic polyurethane. Polymers 14(19):4160 11. Wang F et al (2022) Tensile properties of 3D printed structures of polylactide with thermoplastic polyurethane. Polymers 29(8):1–14 12. Gumus OY et al (2022) Effect of printing temperature on mechanical and viscoelastic properties of ultra-flexible thermoplastic polyurethane in material extrusion additive manufacturing. J Mater Eng Perform 31(5):3679–3687 13. Kasar AK et al (2022) Tribological interactions of 3D printed polyurethane and polyamide with water-responsive skin model. Friction 10(1):159–166 14. Ehrmann A, Steinmetz PJCiD, AoT Products (2021) Influence of elastic 3D printed polymers on the mechanical properties and tribology of textile fabrics. Commun Dev Assembling Text Prod 2(2):115–122 15. Verbelen L et al (2017) Analysis of the material properties involved in laser sintering of thermoplastic polyurethane. Addit Manuf 15:12–19 16. Kim G et al (2019) 3D printed thermoplastic polyurethane bladder for manufacturing of fiber reinforced composites. Addit Manuf 29:100809 17. Sharma A et al (2022) Investigation of wear rate of FDM printed TPU, ASA and multi-material parts using heuristic GANN tool 18. Jayswal A, Adanur SJJoTCM (2021) Characterization of polylactic acid/thermoplastic polyurethane composite filaments manufactured for additive manufacturing with fused deposition modeling, p 08927057211062561. 19. Lin X et al (2021) Desktop printing of 3D thermoplastic polyurethane parts with enhanced mechanical performance using filaments with varying stiffness. Addit Manuf 47:102267

Effect of Mixing Parameters on the Friction Performance of Non-asbestos Organic Based Automotive Brake Friction Composites G. Sathyamoorthy , R. Vijay , and D. Lenin Singaravelu

Abstract This study aims to determine the effect of mixing parameters (Timing Variation) on the tribological performance of NAO-HCV Brake Liner automotive applications. In this study, the brake liners were created by varying the Timing (3, 6, 9 min) for the fibre in the mixing parameters while keeping the other ingredients constant. The brake liners were developed as per the industrial procedure. The brake liner’s mechanical, physical, and chemical properties were evaluated using industry standards. The Chase test was used to examine the tribological properties. The worn surface analysis was done using the scanning electron microscope. The testing findings reveal that fibre-based brake linings with a mixing duration of 3 min feature an excellent physical, chemical, and mechanical properties, as well as steady friction and a lower wear rate, owing to their superior mixing capability. This research discusses the influence of mixing parameters (Timing Variation) on HCV Brake Liners for boosting tribological performance via the proper mixing sequence and its implementation. Keywords Brake liners · Mixing parameters—Timings · Friction · Wear characteristics

1 Introduction Materials used for brake friction are matrix composites based on polymers. These composites comprise fillers, binders, friction modifiers, and reinforcements. Via dry friction, these friction materials are often used as sacrificial materials to transform kinetic energy into mechanical energy [1]. As a result, the most important and technically demanding requirement of brake friction material is to offer low wear with a high and steady coefficient of friction with low wear regardless of temperature, G. Sathyamoorthy · R. Vijay · D. Lenin Singaravelu (B) Department of Production Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620015, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_15

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environmental friendliness, squeal, low noise fade, and speed change. The composition contains an amalgamation of 10–15 components to accomplish such properties [2]. The binder holds all of the elements together. Reinforcements provide strength to brake friction materials. Fillers are utilized to fill space, reduce product costs, clean the mating surfaces, and sustain the build-up of friction films [1]. Friction modifiers provide lubrication for mating surfaces and aid in the performance of braking systems. The friction pair’s tribological properties primarily govern the braking system’s performance. Asbestos-based brake friction materials work better and cost less, making them popular in the automobile industry. It has excellent friction efficiency, thermal stability, and reinforcing ability. Due to its dangers, asbestos was banned by the Environmental Protection Agency in 1989 [3]. Lung Cancer, Mesothelioma, Water & Air Pollution, Pneumoconiosis, Respiratory Problems, and Sediment & Soil Pollution are the harmful effects of asbestos. Because it may harm aquatic life, the use of copper in friction materials is being phased out, and by the year 2025, it may be forbidden in industrialized nations [4]. Replacing it is challenging due to Cu’s multi-functional performance in friction materials. Creating suitable alternatives for Cu is a significant worldwide scientific effort. The formulation, the choice of ingredients, and the setting of production conditions influence the requirements for brake friction materials [5]. Only a few research have examined the friction material manufacturing processes. Ertan and Yavuz [6] examined the impacts of manufacturing factors on friction material’s tribological behavior to attain optimum manufacturing parameters and, as a result, increase their performance. Using image analysis, Makni et al. [7] studied ingredient repartition generated by combining organic friction composite materials. The effect of the kinds and relative quantities of raw material elements on the characteristics and performances of friction materials has also been extensively researched. Studies on manufacturing’s hot molding and post-curing processes influence friction material characteristics and performance. However, the effect of mixing process is not studied well. Brake liners start with mixing, and the sequence of components—mixing time, speed, loading capacity influence this process [8]. Each parameter affects the mixture’s microstructure and characteristics. Thus, the mixing stage should be explored thoroughly. This research investigates the effect of mixing time (variation 3, 6, and 9 min) for NAO HCV Brake Liner friction material’s physical, chemical, and mechanical characteristics and tribological behavior.

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2 Materials and Methods 2.1 Materials and Formulation of the Brake Friction Composites Braking friction composites were created as standard brake liners to suit automobiles on Indian roads, with 15 parental ingredients [9], as shown in Table 1, and labeled as NAO1, NAO2, and NAO3. Table 2 describes the mixing conditions; Table 3 shows the time duration of the manufacturing process, and Fig. 1 depicts the production operations for generating the brake liners.

2.2 Characterizations of the Brake Liner To calculate the density, digital density equipment based on the Archimedes principle was used. A steel ball indenter with a 3.125 mm diameter and a weight of 1500 N was used to determine the material’s hardness [2]. Testing was done on several composites to determine the percentage of uncured resin generated using Soxhlet equipment. In a hot air oven, a sample measuring 10 × 10 × 4 mm was exposed to a temperature of 200 ± 3 °C for about 40 min to conduct a heat swell test. The thickness variance was measured. The water swell test was conducted by submerging a 50 × 25 mm sample in water for 30 min [10]. Differences in thickness were observed before and after examinations. An ignition loss (LOI) was calculated using a 5–10 g sample kept in silica crust for 2 h at 800 °C in a muffle furnace. The weight disparity was noted. The study that was done according to International Standard IS2742-Part-3 is the one that was discussed before. In addition to that, the shear strength was investigated and computed. The JIS-D-4418 technique was used to provide an accurate reading of the porosity. The details on the procedure and the sample size may be found in Vijay et al. [11]. Three different samples were examined for each test, and the findings of each test were reported consistently. According to the industry’s standards, the highest amount of error could be tolerated was 5%. Following IS2742-Part-4, friction testing equipment manufactured by Chase was used to evaluate the tribological performance of a sample that measured 25 × 25 mm and was moved over a cast iron drum 280 mm in diameter. Before a specimen test, the drum was polished using 320-grit abrasive paper. The burnish cycle lasted 20 min at 308 rpm under a 440 N load. The protocol included a 660 N load and 411 rpm speed wear cycle, a baseline test, two fade cycles, and two recovery cycles. Vijay et al. [11] performed, fade, heat, recovery, normal characteristics, and the % of the fade, recovery, and wear rate, respectively. To investigate the worn surface characteristics of the sample, an electron scanning microscope (SEM) equipped with a Tescan VEGA 3LMU was used in the Czech Republic.

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Table 1 The effect of mixing parameters Timing Variation 3, 6, 9 min for NAO HCV Brake Liner automotive application S. No

1

Raw material

% by weight NAO -1

NAO-2

NAO-3

Card details

Mixing sequence timing

Reinforcement fibers Aramid pulp

12

12

12

Card 1

3 min NAO1

Card 2 15

15

15

10 min constant for all the card 2 ingredients [12]

33

33

33

4.0

4.0

4.0

36

36

36

Card 3

Cutter OFF–Shovel ON (3 min)

2

Hydrated lime

3

Cellulose pulp

4

Chopped glass fibre 6 mm reduced texture

5

Alkyl benzene modified phenolic resin

6

Nitrile rubber powder

7

Crum rubber

8

Artificial graphite—99% pure

9

Metal lubricants—Iron sulphide

10

Calcium Oxide

11

Tin powder

Binders

6 min NAO2

9 min NAO3

Lubricants

Inert and In Organic fillers 12

Synthetic barytes—99.0% pure

13

Furfuraldehyde modified cashew particles

14

Kaolin clay

15

Exfoliated vermiculite

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Table 2 Mixer condition—constant 3000 rpm cutter speed and 140 rpm shovel speed S. No

Properties

Unit

Card-1: 3 min fiber opening time

Card-1: 6 min fiber opening time

Card-1: 9 min fiber opening time

Other material Other material Other material 10 min 10 min 10 min 01

Particle size Particle size: 100 gms.sample/ 15 min. Sieve Analysis—Ro-tap + 36 BSS

%

6.0

10.50

15.60

− 36 + 60 BSS

%

24.50

32.50

34.50

− 60 + 100 BSS

%

60.0

37.50

17.40

− 100 (Pan)

%

9.50

19.50

32.50

100.00

100.00

100.00

0.320

0.450

0.675

400

320

260

4000

4800

5200

Total 02

Bulk density 1000 ml (1000 ml measuring Cylinder)

Gram/cc

03

Wet volume: 60 g/ Ml 1000 ml water and tumbling/after 30 min measurement

04

Surface area of mix

05

Moisture/Hot air % (1.5 oven method—110 Max) C two hours

0.64

0.82

1.02

06

Volatiles: 160 C Hot air oven—2 h

2.6

2.90

3.2

Cm2 /gm

% (3.5% max)

3 Results and Discussions 3.1 Analysis of Brake Liners in Terms of Physical, Mechanical, and Chemical Qualities The composite’s mechanical, chemical, and physical features are shown in Table 4. The density of every composite friction sample ranged between 2.20 and 2.30 g per cubic centimeter. Because of the highly dense particles formed due to more mixing, the density value of composite NAO1 is more significant than the density values of NAO2 and NAO3, respectively [13]. Because of the less mixing time duration, it has more pores, and NAO1 has a lower hardness level than other composites.

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Table 3 Time duration of the manufacturing process VEHICLE 16 HP, 16–40 Tons vehicle application—Bus/Trucks NAO1 NAO2 NAO3

S. No 1

2

Preform Preform weight

1200 g

Pressure

1 ton/inch2

Cycle time

30 s

Curing Temperature °C

155–160

Cycle time

3

At breathing

(20 + 4) * 9 = 216 s

At final curing time

504 s

Post Curing Process Ambient to 150 °C Raise

30 min

At 150 other material 10 min C

3h

Raise from 150 °C to 180 °C

1h

At 180 °C

2h

Manufacturing Procedure

Different Ingredients

Mixing

Pre forming

Curing

Post curing

Finished Brake Liner

Fig. 1 Manufacturing process of brake liners

The hardness value rises with decreasing porosity value; NAO3 has similar behavior comparable to this one. The findings from the literature of Sathyamoorthy et al. [14] are consistent with this behavior. In addition, it is necessary to be aware that a lower wear rate is often connected with a higher hardness material [15]. NAO1 followed the same pattern; it demonstrated a high resistance to wear, which resulted in a lower rate of wear overall [16]. The extraction of acetone displays the percentage of uncured resin still present after the curing process. Because the liner’s bigger pores can absorb more heat, leading to a more rapid healing process. If insufficient pores exist, the curing process will not work well, leading to a more incredible amount of uncured resin—Vijay et al. [10]. The deterioration of LOI in NAO1 resulted from a

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Table 4 Developed friction composites—results S. No

Properties

Unit

NAO1

NAO2

NAO3

1

Density

g/cc

2.23

2.27

2.28

2

Hardness

HRL

77

86

95

3

Acetone extraction

%

1.31

2.20

2.93

4

Heat swell

mm

0.14

0.2

0.26

5

Water swell

mm

0.02

0.06

0.09

6

Cross breaking strength

kg/cm2

270

300

380 (High brittle failure)

7

Porosity

%

6

5

2

8

Loss of ignition

%

27

28

29

proper mixing time duration than in other composites. The mixing duration of fibres in NAO1 is less than the other composites and was the cause of the decrease in heat and water swell in NAO1. Cross breaking strength of NAO3 composites is much higher than that of different types. This is because the increased duration of mixing leads to more breaking failures [10].

3.2 Fade and Recovery Characteristics Figures 2 and 3 show the results of the fade-recovery tests. Liners have a higher µnormal than µhot, indicating a quicker recovery rate at the expense of increased vulnerability to heat diffusion and the consequent degradation of sub-optimally stable components. The reduced frictional undulation (Δµ) in the composite NAO1 is due to the correct mixing of reinforcements over a proper mixing period (3 min) [14]. Due to their high temperature and abrasion resistance, abrasive and lubricant particles have shown substantial promise for application in brake friction materials. The NAO3 demonstrates a lower µP (performances) than the other samples, indicating that the lengthy mixing duration would not maintain the good mechanical interlocking of fibres when bound to other components under changing operating circumstances [17]. Fade refers to the decrease in braking efficiency when frictional heat is applied. Friction and wear rely heavily on this phenomenon. The pyrolysis of materials (primarily phenolic resin) and the breakdown of tribo film are the root causes of fading [16]. Suitable abrasives to remove the pyrolysis layer is crucial when using solid lubricants in friction materials. The optimum mixing period of NAO1 composites enhances fading and helps reduce the pyrolysis layer created by solid lubricants. µ is more in NAO2 than in NAO3 and less than in NAO1. Mixing for 6 min of fibres induces a fast breakdown of polymer ingredients, enabling fracture propagation on matrix surfaces containing fewer stable components. In addition, the 9 min mixing duration of fibres in NAO3 serves as a third body, ploughing the friction surface and

208

Fig. 2 Frictional properties of chase tested brake friction composites

Fig. 3 Chase-tested composites—fade and recovery results

G. Sathyamoorthy et al.

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preventing contact by disintegrating the produced tribofilm. Due to the ploughing action of the reinforcements and the production of a friction film and reformation process, it recovers when the temperature decreases. For healthy brake friction materials, recovery has to be higher than fade [18]. The material’s porosity plays an essential function in the higher recovery rate. According to industry standards, higher porosity in friction materials (about 10%) enhances heat dissipation at the braking contact [11]. This, in turn, results in excellent degradation management of polymeric parts, as shown in NAO1 composites. On the other hand, the higher ploughing action decreases recovery when using NAO2 composites, even when the porosity is increased. The rise in NAO1 is due to an increase in the actual contact area between the surfaces. The real contact area will be more significant if it is more noticeable. This happens when the components that make up the brake friction are cooled during the recovery process. This causes the tribo layer produced at the friction contact to become stiff and clogged with debris. The brake’s friction material recovery performance may characterize the performance of debris particle progress. Because the debris particle collection increases the contact area between a worn composite surface and a brake drum, the force required to stop the vehicle also rises [16]. The formation of main plateaus between worn surfaces and the backward transfer of the least stable components, as demonstrated in NAO1, increases the actual contact area utilized. Fade and recovery rate is the most critical factors in determining the friction performance of brake friction materials. Improved performance is always feasible with minimum fading and rapid recovery [19]. The recovery of composites made with NAO1 was much greater than that of other composites. With correct mixing (3 min), time enhances NAO1’s fade resistance and recovery rate. Furthermore, it reduces the degradation kinetics of the interfacial friction film/friction layer, increasing hard wear debris at the braking contact, which serves as a third body to improve recovery performance [20]. Organic friction composite materials degrade at high temperatures, releasing gas that may get trapped between friction surfaces and act as a force in opposition to the applied load. The reduction in fade cycles at high temperatures suggests thermal degradation, softening, and rapid combustion of phenolic resin, which weakens the matrix-reinforcement bond. Thermal decomposition of components and consequent deterioration of a contact region at the friction interface affect fade performance. The percentage of fading resistance follows the trend NAO3 > NAO2 > NAO1 (lower is preferable); nonetheless, the recovery rate follows the pattern NAO1 > NAO2 > NAO3 (higher, the better).

3.3 Wear Characteristics of the Composites Wear is a complicated phenomenon in friction materials [21]. Abrasion & adhesion are the primary wear processes for friction composites. The development of the film decreases the contact area between the mating surfaces, increasing the wear resistance of friction composites. Composite surfaces that are more rigid decrease

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Fig. 4 Chase-tested composites—wear loss

thickness and weight (lower wear). The wear rate in the Chase test is represented as a percentage of weight and thickness [22]. Figure 4 depicts the fading and recovery wear characteristics of numerous friction composites. Because of the improved wear resistance of the NAO1 composite during fading, appropriate mixing of all the constituents forms a more effective lubricant film (thin tribo-layer) at higher temperatures. Because of the compact’s increased tribo surface area, direct contact of composites with the counterface minimizes wear rate. Additionally, a greater hardness rating is often associated with a slower wear rate. The temperature change of phenolic resin, fibres, and organic fillers determines the wear of brake friction materials [23]. The fiber-matrix interface is debonding, creating matrix separation and a weaker surface layer. As a result of increased fiber-matrix bonding, the composite NAO1 gains strength, hardness, and wear resistance.

3.4 Worn Surface Characterization Primary plateaus created by adhering fibres prevent microscopic wear particles from crossing the contact. Polymers, aramid, and other tiny wear particles stick together during braking, generating secondary plateaus. Primary plateaus with excellent loadbearing capability enhance friction, but secondary plateaus decline [11]. Therefore, more main plateaus and fewer secondary plateaus are advised. The hardness

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decreases surface scarring. The third body is abrased by hard particles in the NAO1 composite’s SEM picture in Fig. 5a. Combining fibres with other ingredients due to proper mixing (3 min duration) provides an ironing mechanism [24]. More main contact plateaus and fewer back transfer patches result after 3 min appropriate mixing, eliminating the pyrolysis layers. Figure 5b shows 6 min mixing ploughs more than the mating surface—creating more surface pits. This action boosts the interface temperature, causing material pull-outs, thermal overloading, and plateau debonding [2]. Figure 5c shows that 9 min of mixing generated additional wear scars with pits and cracks [25].

Fig. 5 SEM pictograph of a NAO1; b NAO2; c NAO3—chase-tested composites

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4 Conclusions The brake linings were generated by altering the Timing (3, 6, and 9 min) for the fibre in the mixing conditions while keeping the other components constant. and evaluated to satisfy industrial standards. The following are the test results: • NAO3 brake liners had greater specific gravity, hardness, and shear strength, whereas NAO1-based brake liners had superior ignition loss, acetone extraction, and porosity. • Reduced frictional fluctuations were seen using NAO1-based brake liners during the Chase test, resulting in enhanced fade and recovery performance. Due to the adequate mixing length of fibres, friction composites based on NAO1 exhibited acceptable recovery behavior. NAO1 brake liners had the best wear resistance, followed by NAO2-based brake liners. • Differential contact patches and NAO1-dependent surface undulations were important in regulating the composites’ tribological performance, as demonstrated by scanning electron microscope of worn surfaces. Thus, the NAO1 brake lining was the most effective for stopping Heavy Commercial vehicles.

References 1. Chan D, Stachowiak GW (2004) Review of automotive brake friction materials. Proc Inst Mech Eng Part D J Autom Eng 218:953–966 2. Sathyamoorthy G, Vijay R, Lenin Singaravelu D (2022) Brake friction composite materials: a review on classifications and influences of friction materials in braking performance with characterizations. Proc Inst Mech Eng Part J J Eng Tribol 236:1674–1706 3. Mahale V, Bijwe J, Sinha S (2019) Efforts towards green friction materials. Tribol Int 136:196– 206 4. Aranganathan N, Bijwe J (2015) Special grade of graphite in NAO friction materials for possible replacement of copper. Wear 330–331:515–523 5. Sudhan Raj J, Christy TV, Darius Gnanaraj S, Sugozu B (2020) Influence of calcium sulfate whiskers on the tribological characteristics of automotive brake friction materials. Eng Sci Technol Int J 23:445–451 6. Ertan R, Yavuz N (2010) An experimental study on the effects of manufacturing parameters on the tribological properties of brake lining materials. Wear 268:1524–1532 7. Makni F, Kchaou M, Cristol AL et al (2017) A new method of mixing quality assessment for friction material constituents toward better mechanical properties. Powder Metall Metal Ceram 56:1–13 8. Basha NA, Rathinavel T, Sridharan H (2023) Activated carbon from coconut shell: synthesis and its commercial applications—a recent review. Appl Sci Eng Prog 16(2):6152 9. Sasanam S, Thumthanaruk B, Rungsardthong V et al (2023) Physicochemical and pasting properties of rice flour, banana flour, and job’s tears flour: flour blends and application in gluten-free cookies. Appl Sci Eng Prog 16(2):5992 10. Vijay R, Manoharan S, Lenin Singaravelu D (2020) Influence of natural barytes purity levels on the tribological characteristics of non-asbestos brake pads. Ind Lubr Tribol 72:349–358

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11. Vijay R, Lenin Singaravelu D, Filip P (2020) Influence of molybdenum disulfide particle size on friction and wear characteristics of non-asbestos-based copper-free brake friction composites. Surf Rev Lett 27 12. Erunkulu I, Malumbela G, Oladijo OP (2023) Geopolymer synthesis and alkaline activation technique of fly ash and slag source material: a review. Appl Sci Eng Prog 16(4):6600 13. Sugozu I, Mutlu I, Sugozu KB (2016) The effect of colemanite on the friction performance of automotive brake friction materials. Ind Lubr Tribol 68:92–98 14. Sathyamoorthy G, Vijay R, Lenin Singaravelu D (2022) Tribological characterizations of biopolymer based ecofriendly copper-free brake friction composites. Ind Lubr Tribol 74:588–596 15. Wongchalerm B, Arunchai T, Khamkenbong T et al (2023) Simulation and experimental studies on sustainable process optimization of CO2 adsorption using Zeolite 5A Pellet. Appl Sci Eng Prog 16(2):5861 16. Sathyamoorthy G, Vijay R, Lenin Singaravelu D (2022) Synergistic performance of expanded graphite—mica amalgamation based non-asbestos copper-free brake friction composites. Surf Topogr Metrol Prop 10:015019 17. Mahale V, Bijwe J (2020) Role of thermal conductivity in controlling the tribo-performance of non-asbestos organic brake-pads. J Compos Mater 54:4145–4155 18. Vineeth Kumar V, Senthil Kumaran S, Dhanalakshmi S (2020) A case study focusing on investigating the tribological performance of Cu–Sn sintered brake pad of off-high road vehicles. J Compos Mater 54:4299–4310 19. Mahale V, Bijwe J, Sinha S (2019) A step towards replacing copper in brake-pads by using stainless steel swarf. Wear 424–425:133–142 20. Joo BS, Gweon J, Park J et al (2021) The effect of the mechanical property and size of the surface contacts of the brake lining on friction instability. Tribol Int 153:106583 21. Kim SS, Hwang HJ, Shin MW, Jang H (2011) Friction and vibration of automotive brake pads containing different abrasive particles. Wear 271:1194–1202 22. Lee PW, Filip P (2013) Friction and wear of Cu-free and Sb-free environmental friendly automotive brake materials. Wear 302:1404–1413 23. Akıncıo˘glu G, Uygur ˙I, Akıncıo˘glu S, Öktem H (2021) Friction-wear performance in environmentally friendly brake composites: a comparison of two different test methods. Polym Compos 42:4461–4477 24. Dhandapani A, Krishnasamy S, Nagarajan R et al (2023) Study on the inter-laminar shear strength and contact angle of glass fiber/ABS and glass fiber/carbon fiber/ABS hybrid composites. Appl Sci Eng Prog 16(3):6732 25. Mahale V, Bijwe J (2020) Exploration of plasma treated stainless steel swarf to reduce the wear of copper-free brake-pads. Tribol Int 144:106111

Increasing the Lifetime of Mill Rolls by Applying Polymer Materials on Their Bodies S. I. Platov , D. V. Terentyev , E. Yu. Zvyagina , L. F. Kerimova , M. A. Levantsevich , A. Ya. Grigoriev , and V. L. Basiniuk

Abstract A key reason for breakdowns of backup rolls of hot and cold rolling mills is abrasive wear of their bodies. To increase the lifetime of the rolls, it is suggested to apply a wear-resistant single-layer coating from polymer antifriction materials (for example, fluoropolymer) or a double-layer coating (for example, copper–polymer) on the ground bodies. The coatings are applied by cladding with a flexible tool (a rotary wire brush). The surface layer of rolls is hardened, forming the required surface roughness, reducing an alignment period during their operation. The technical effect lies in the decrease in the friction coefficient to boundary friction (f = 0.01–0.05) and hardening of a surface layer of rolls. The authors developed a roll treatment method introduced on hot rolling mill 2500 at PJSC Magnitogorsk Iron and Steel Works. A brief description of the method is as follows: having ground backup rolls and achieved the required shape, an operator installs a wire brush instead of a grinding wheel on a roll grinding machine. A bar feeding device is installed on the shell. A single-layer coating (fluoropolymer grade F4K20) is applied in two passes of the tool (the rotary wire brush) along the surface of a rotating roll. The roll is removed from the machine after the treatment, assembled according to the operating procedure and installed into a stand. Then, after seven days of the operation, the roll is removed from the stand, and the surface wear is measured along the radius. The analysis of the industrial experiments showed that the wear rate of the rolls treated with rotary wire brushes and covered with a fluoropolymer coating was by 1.7–1.9 times lower than the wear rate of the rolls operating with no cladding. This method contributed to increasing a period between changes of backup rolls in finishing stands by twice, reducing a downtime period, increasing rolling mill performance, and reducing the roll consumption. S. I. Platov · D. V. Terentyev · E. Yu. Zvyagina · L. F. Kerimova (B) Nosov Magnitogorsk State Technical University, Magnitogorsk, Russia e-mail: [email protected] M. A. Levantsevich · V. L. Basiniuk Academy of Sciences of Belarus, Minsk, Belarus A. Ya. Grigoriev V.A. Belyi Metal-Polymer Research Institute of the National Academy of Sciences of Belarus, Gomel, Belarus © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_16

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Keywords Polymer · Mill · Hot and cold rolling

1 Methods Used in the Study For the study, a method of applying shock-friction coatings was chosen, which is implemented using rapidly rotating metal brushes, allows applying anti-friction, wear-resistant, restoring, anticorrosive, workable, extreme pressure coatings made of various metals, as well as polymers, for example, fluoroplast, formed on the surface of products in the form of a solid film 0.5–200 microns thick. The applied layer thickness depends on a tool shape, state of a material to be applied, treatment modes and other factors. This method contributes to applying multi-layer steel-polymer coatings. A group of scientists from Russia and Belarus is involved in studies of this method [1–5].

2 Materials Used for Research Tribology tests were carried out on samples of medium-carbon steel coated and treated with an impact-friction method (using equipment of Mikheev Institute of Metal Physics, the Ural branch of the Russian Academy of Sciences).1 The structure of a thin (1–15 μm) surface layer of carbon steel, coated with fluoropolymer-4 by an impact-friction method, was studied using a transmission electron microscopy technique on JEM-200CX electron microscope at an accelerating voltage of 160 kV. Workpieces of foils, about 0.3 mm in thickness, were cut with a spark discharge method from the surface of a coated part (roller). Workpieces of foils were mechanically ground on the one (internal) part, using abrasive papers of various grits and underwent single-side, electrochemical thinning in a chloroacetic electrolyte spray at 50 V, until making a hole on the foil surface. A fluoropolymer coating was not removed from the surface of the foil workpiece and the coating discontinuity was only near the hole, resulting from the electrochemical polishing of steel. The said procedure helped study a microstructure of the steel roller at close proximity to the coating. When studying an original structure of steel, foil workpieces cut at ~0.5 mm from the roller surface, were mechanically ground and then electropolished on both sides. Figure 1a, b shows a microstructure of steel at a distance of about 0.5 μm from the roller surface. It can be observed that this structure is lenticular low-tempered α-martensite with finely dispersed plates of ε-carbide (Fig. 1b). The microdiffraction images, corresponding to this structure, show reflections of martensite, iron carbide and residual austenite (type (200)γ, Fig. 1a). Microhardness of steel is 6200 MPa. 1

The tribology tests were performed by I.L. Yakovleva, L.G. Korshunov.

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Martensite with a lenticular morphology, residual austenite considerably present in steel, and high microhardness show that carbon content in steel is 0.4–0.5% (wt) or higher. In this case, steel did not undergo considerable plastic deformation, as evidenced by unbroken martensite plates; there was no expansion in the azimuthal direction in reflections of martensite, and metastable residual austenite without martensite γ–α-transformation. Figure 2a, b shows a microstructure of a surface layer of steel close to the coating, namely at a distance of 1–5 μm from the surface. It is shown that as a result of local severe plastic deformation of the roller surface, when applying the coating, the layer under study contains an ultra-disperse structure of martensite, characterized by a microdiffraction image of almost uniform Debye rings (Fig. 2a). The dark field images in areas of the rings (110) α show that a size of α-martensite crystal grains is 0.1–0.5 μm, and there is a considerable disorientation between the crystal grains (Fig. 2b). There are no reflections of residual austenite, suggesting the transformation of metastable austenite to martensite as a result of severe plastic deformation of the layer under analysis. Microhardness of this structure is 8000 MPa.

Fig. 1 An original structure of steel: a is a microdiffraction image of a part of the structure; b is a bright field image in the reflection (×30,000). The reflection of residual austenite of type (200) is represented by the arrow

Fig. 2 The structure of steel at 1–5 μm from the surface: a is a microdiffraction image from an area of the structure; b is a dark field image in the (110)α reflection (×73,000)

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Fig. 3 The structure of steel at ~5–10 μm from the surface: a is a microdiffraction image from an area of the structure; b is a dark field image in the reflection (×73,000)

When the distance from the surface increases to 5–10 μm (Fig. 3a, b), the sizes of martensite crystal grains (fragments) increases to 0.5–1.0 μm, and their disorientation decreases as shown in the dark field image in the (110)α reflection (Fig. 3b). The type of the diffraction image (Fig. 3a) shows the martensite texture: (111)α planes of various crystal grains are positioned in parallel to the plane of foil (the roller surface). The results indicate a lower rate of severe plastic deformation of steel, when the distance from the surface of mechanical impact increases. A structural state of state at a depth of 10–15 μm from the surface is given in Fig. 4a, b. The diffraction image (Fig. 4a) indicates the texture maintained in martensite and considerable residual austenite in steel (the (200)γ reflection is found). The latter is obviously characteristic of a lower rate plastic deformation, advancing at a longer distance from the surface of mechanical impact. The structure of steel approaches the original one with a further increase in a distance from the surface. Wear tests were carried out with sliding friction of the flat specimen—plate at a reciprocating motion of the specimen. The tribology tests of a polymer coating applied by friction surface cladding show that the friction coefficient is within a range of 0.1 ÷ 0.3, and the wear rate of coated parts is by 1.5 ÷ 1.6 lower as compared with uncoated ones.

Fig. 4 The structure of steel at ~10–15 from the surface: a is a microdiffraction image from an area of the structure; b is a dark field image in the (110)α reflection (×73,000)

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The studies performed suggest that a polymer coating applied on backup rolls of hot rolling mills prolongs their lifetime. A key reason for breakdowns of backup rolls of hot and cold rolling mills at PJSC MMK is abrasive wear of their bodies. This is mainly attributed to the following: – a ground surface of rolls in areas of contact between backup and work rolls has a rather high friction coefficient (f = 0.1…0.25), resulting in a considerable wear rate during an alignment period and a shorter lifetime, – a ground surface of rolls experiences residual tensile stresses, entailing microcracks during rolling, a source of spalls and delamination of a solid wear-resistant layer, differing in higher hardness and limited plasticity. To increase the lifetime of the rolls, it is suggested to apply a wear-resistant singlelayer coating from polymer antifriction materials (for example, fluoropolymer) or a double-layer coating (for example, copper–polymer) on the ground bodies. The coatings are applied by cladding with a flexible tool (a rotary wire brush). The surface layer of rolls is hardened, forming the required surface roughness, reducing an alignment period during their operation. The technical effect lies in the decrease in the friction coefficient to boundary friction (f = 0.01–0.05) and hardening of a surface layer of rolls. The authors developed a roll treatment method introduced on hot rolling mill 2500 at PJSC MMK. The use of this method contributed to a longer period between changes of backup rolls in finishing stands (by twice), lower downtime, higher performance of the rolling mill, and a lower consumption of rolls. The principle of the method is as follows: backup rolls are ground to achieve the required roll forming, then a grinding wheel on a roll grinding machine is replaced with a wire brush. A bar feeding device is installed on the shell. A single-layer coating (fluoropolymer of F4K20 grade) is applied in two passes of the tool (the rotary wire brush) along the surface of a rotating roll (Fig. 5). Diameter of backup rolls used on the mill (Dr) is 1520–1480 mm, roll body length (Lb) is 2400 mm, roll material is steel grade 75KhMF. Treatment parameters are set as following: roll rotational speed (n1) is 15 rpm; brush rotational speed (n2) is 600–700 rpm; interference fit (drawing together axes of the brush and roll after their contact) is 2–3 mm; axial feed speed of the wire brush is 0.4 m/min; brush diameter (Dbr) is 750–800 mm. Figure 6 is given for reference of the backup roll in the group of finishing stands, whose surface was partially treated with a wire brush and coated with fluoropolymer. The roll is removed from the machine after the treatment, assembled according to the operating procedure and installed into the stand. Then, after seven days of the operation, the roll is removed from the stand, and the surface wear is measured along the radius. Figure 7 shows a change in the profile of the rolls that have stood in the cage for seven days, which indicates an increase in service life and a decrease in wear of the rolls subjected to cladding.

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3

4 Dr

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n1 N

D

Fig. 5 Roll treatment method: 1 is a mill roll; 2 is a rotary wire brush; 3 is a coating on a roll body; 4 is a bar of a coating material

Fig. 6 A backup roll with treated (on the left) and non-treated surfaces

3 Discussion and Recommendations During the experiment, microroughness and hardness of the roll surface were measured after grinding, after applying a coating and after removing the rolls from the stand. The analysis of the experiments shows that the wear rate of the rolls treated

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Fig. 7 Changes in the roll profile from the length of the roll barrel with and without coating

with rotary wire brushes and covered with a fluoropolymer coating is by 1.7–1.9 times lower than the wear rate of the rolls operating with no cladding (Fig. 8). During the research, a change in the structure of steel and its microhardness was revealed, depending on the distance to the roller surface. It is determined that when removed at distances of 0.5 microns, 5 microns and 10 microns, at first the steel material does not undergo noticeable plastic deformation, then intense plastic deformation is observed, with an increase in the microhardness of the surface by 1.29 times, followed by a decrease in intense plastic deformation. It is established that the use of this method allows to increase the inter-rolling period of the support rolls [6] of the finishing group of the stands of the 2500 hot rolling mill of PJSC MMK by 2 times, reduce downtime, increase the productivity

Fig. 8 Wear rate of backup rolls in stands 10 and 11 depending on the treatment method

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of the rolling mill and reduce the consumption of rolls. The results obtained can be used in solving problems of hardening the surfaces of bearing assemblies.

References 1. Platov SI, Dema RR, Latypov OR, Belevskii LS, Levantsevich MA, Zotov AV, Pilipchuk EV, Urtsev NV (2020) Study of metal coatings deposited by rotating wire tool. Steel Transl 50(12):911–915 2. Basinyk VL, Vityaz PA, Levancevich MA, Grigorovich KV, Platov SI, Terentyev DV, Kharchenko MV, Dema RR, Rubanik VV (2021) Effect of the processing method on the microtopography of rough layers and on oil absorption by friction surfaces. J Friction Wear 42(4):246–255 3. Belevskii LS, Efimova YuYu, Dema RR, Platov SI, Grigorovich KV, Vityaz PA, Basinyuk VL, Levantsevich MA, Devyaterikova NA (2021) Testing coatings, applied by friction surface cladding, on a coupling machine. Heavy Eng 7–8:39–44 4. Grigorovich KV, Platov SI, Dema RR, Vityaz PA, Basinyuk VL, Levantsevich MA, Latypov OR (2021) Shaping the set microroughness of wire rod, using a flexible wire tool, before drawing. In: Promising materials and technologies, Minsk, 446–448 (2021, August 23–27). Belarusian State Institute of Standardization and Certification 5. Rubanik VV, Grigorovich KV, Platov SI, Dema RR, Vityaz PA, Basinyuk VL, Levantsevich MA (2022) Currently relevant issues of strength. Cladding with a flexible tool. Information and Computing Center of the Ministry of Finance, Minsk, p 540 6. Urtsev VN, Platov SI, Antsupov VP, Kadoshnikov VI, Terentev DV, Khabibulin DM, Anikeev SN (2004) Mill roll treatment method: RU Patent for invention No. 2224822. Inventions. Utility Models Bull 7

Impregnation of Wood Derived Scaffolds with Cellulose Acetate Winfried A. Barth , Arndt Weiske, and Steffen Fischer

Abstract The investigation of engineered wood products seems to be an essential column to reach sustainable development goals. For this reason, shortcomings of natural wood need to be exceeded by the means of chemical and physical modification. The presented approach contains the preparation and characterization of cellulose acetate composites with high cellulose content and hierarchical structure. In order to get mesoporous scaffolds, a delignification process of native beech wood veneers is realized with acetic acid and hydrogen peroxide. Thereby porosity is increased from 54 to 72%. It was found, that the intensity of the delignification is responsible for increasing porosity and shifting average pore diameter. Subsequent vacuum impregnation of the scaffolds with cellulose acetate (CA) is performed resulting in maximal WPG of 52.7%. In this way, the delignified wood structure, can be reinforced by polymer impregnation. Not only tensile strength is increased from 47 to 85 MPa but the water contact angle also increases from 30 to 51° indicating that the polymer contributes to enhanced hydrophobicity. Nevertheless, the anisotropic structure of wood is an obstacle for homogeneous impregnation. Wood is a lightweight sustainable material, such as the polymer cellulose acetate, which can be derived from wood as well. The combination of both yields in appealing properties but also challenging processing. Keywords Delignification · Impregnation · Chemical wood modification · Cellulose acetate · Fagus sylvatica L

1 Introduction The synthesis of bio-based polymeric materials which are bio degradable is of high interest and receives even more attention because of disadvantages of conventional fossil based polymers. Recent problems require a transition to new high performance W. A. Barth (B) · A. Weiske · S. Fischer Technical University Dresden, Pienner Str. 19, 01737 Tharandt, Germany e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_17

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structural materials as substitutes for energy intensive or scarce resources. Especially in the building sector is an urgent need for alternative raw materials [11]. To address this issue renewable resources like wood and annual plants have been taken into account as broadly available feedstock for industry. Most efficiently in this case is the utilization of trunks for veneer production. Furthermore, the slicing of the bulk wood facilitates a chemical modification because of better accessibility to the inner structure. The objective of modifications is to improve mechanical strength [9], dimensional stability, fire retardancy [14] or to enhance the material with additional properties like transparency [10]. As this is currently a hot research topic, many investigations are undertaken to observe best parameters for delignification and suitable polymers for impregnation. A common way to produce translucent wood is to use sodium chlorite for delignification and Poly(methyl methacrylate) [5] or epoxy resin [1] for impregnation in single or multilayer [19] structures mostly of low density wood species like Balsa (Ochroma pyramidale) [18] or basswood (Tilia spp.) [17]. This work relates to a similar approach for the preparation of bio composites but it copes with nontoxic substances and high cellulose fraction by using beech wood (Fagus sylvatica L.) veneer and a catalyzed acetic acid treatment for selective removal of lignin out of the cell wall to obtain mesoporous scaffolds. The objective of this work is the development of sustainable lightweight materials with high mechanical strength with the challenge, that tissues should be composed of bio based and bio degradable materials to minimize environmental harm. Therefore, the prepared composites are the combination of chemically treated wood and cellulose derivatives.

2 Materials and Methods 2.1 Materials and Chemicals Slice cut beech wood veneer with 0.9 mm in thickness was used with a dry matter content of 92.8%. The oven-dried density was around 650 kg/m3 . Acetone (≥ 99%), glacial acetic acid (≥ 99%), hydrogen peroxide (50%), were purchased from Roth, Germany and used as received. Cellulose acetate and polyethylene glycole 400 (380– 420 g/mol) were purchased from Sigma Aldrich (Fluka).

2.2 Manufacturing of Beech/polymer Composites Beech wood veneers were delignified according the previously described method [2] and were cut to dimensions of 200 × 110 cm2 and wrapped in metal meshes. The specimens were immersed in an aqueous delignification solution containing acetic acid (70 wt%), hydrogen peroxide (5 wt%) and a catalyst. The treatment was left to proceed at 70 °C under stirring. The reaction time was 3 h for partial delignification

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Fig. 1 Schematic representation of the process steps

(samples called DB_3h) and 5 h for total delignification (DB_5h). After the reaction, the delignified samples were rinsed with deionized water and kept in water over night. The obtained scaffolds were transferred to a vacuum dryer and kept there at 40 mbar and 40 °C for 24 h. Impregnation solution was mixed from 5 g cellulose acetate powder (40% acetyl content) in 100 ml acetone and 1 g polyethylene glycole 400. The mixture was poured over the dry sample in an underpressure vessel and low vacuum was applied, immediately. After 25 min the vessel was ventilated and the process repeated once more. The infiltrated specimens were sandwiched between glass plates and dried at 50 °C for 24 h. Cellulose acetate impregnated samples from partially delignified beech were called DB_3h_CA and from totally delignified beech DB_5h_CA, respectively. A schematic representation of the process steps is given in Fig. 1.

2.3 Characterization Lignin determination in native wood and delignified wood samples was performed according to Klason method. In the course of this, 15 ml of 72 vol% sulfuric acid was added to 0.5 g test sample in a beaker. The content was stirred frequently with a glass rod during 2 h dispersion time. Subsequently, 560 ml deionized water was added and the mixture was refluxed for 4 h. The residue was washed and filtered in a G4 glass sand core funnel. After 24 h drying at 103 °C the acid-insoluble lignin was weighed out. Weight percent gain (WPG in %) is calculated by dividing the difference in bulk density of impregnated (ρ i ) and unimpregnated (ρ 0 ) substrate by the bulk density of

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unimpregnated substrate. WPG =

ρi − ρ0 ∗ 100 ρ0

(1)

Tensile tests were carried out with universal testing machine “Inspekt table 10 kN” (Hegewald und Peschke, Germany). Samples were cut to dimensions of 90 × 5 mm2 and conditioned at 20 °C and 65% rH before testing. The tests were carried out in fibre direction with clamping length of 30 mm and 30 mm of span. Measurements started at pretension 5 N, operated at strain rate of 2 mm/min and were detected by video extensometer. To compare the hydrophobicity of the samples, water contact angle test was done with DSA100, Krüss, Germany. The static contact angle was measured by dropping 1.3 µl of water onto the surface of the sample (dosing speed of 5.0 µl/min). Photos were taken every 0.5 s for 5 s. The picture at 1.5 s was used for contact angle measurement. FT-Raman spectra were obtained with Bruker MultiRAM spectrometer in the wavenumber range of 400–4000 cm−1 at a resolution of 4 cm−1 . The laser power was 100 mW with laser wavelength 1064 nm. Each sample was measured fife times with 100 scans, defocused. The spectra were averaged and vector normalized by software Opus 7.0. Fluorescence microscopy was conducted with Lab.A1 AXIO (Carl Zeiss AG, Germany) equipped with Canon EOS 200D at stimulation of 365 nm light source. SEM images were taken with FEI Quanta TM 650 FEG operating at acceleration voltage 2 kV for delignified wood and 5 kV for impregnated in low vacuum mode. Samples were cut with a razor blade and observed without coating. Mercury intrusion porosimetry (MIP) was performed with Porotec Pascal 140 and Porotec Pascal 240 (Hofheim am Taunus, Germany). The principle is based on floating a porous structure with a non-wetting liquid by pressure. Calculation basis is the Washburn equation. pr = 2γ cos(ʘ)

(2)

In the equation the applied pressure (p) multiplied with the pore radius (r) equals two times the surface tension of mercury (γ ) multiplied with the cosine of the contact angle of mercury (Θ). Mercury is an incompressible liquid with assumed contact angle about 141.3° and 472 * 10–3 N/m surface tension. So pore radius is indirectly proportional to applied pressure. Three pieces of each sample with the dimensions 10 × 25 × 0.9 mm3 were weight in a dilatometer. The pore volume was determined by the amount of mercury intruded at specific pressure.

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3 Results and Discussion 3.1 Preparation of Wood Derived Scaffolds The preparation of composites based on wood derived scaffolds includes two major steps. The first step is the delignification process, which can be executed in many different ways. The preferred method in this work is based on the acetosolv process and utilizes only nontoxic chemicals, which is advantageous compared to standard sodium chlorite delignification. Acetic acid is used as main component and forms with hydrogen peroxide peracetic acid. This leads to selective removal of lignin, caused by radical cleavage of aromatic structures, degradation and dissolution, eventually [6]. The largest share of lignin is located in the S2 layer of the wood cell wall. But the concentration of the targeted macro molecule is in the middle lamella and the cell corners the highest [4]. Hence, these areas are affected the most by the delignification treatment (Fig. 2b). Nevertheless, hierarchical wood structure can be preserved in the peracetic acid delignification despite very low lignin contents [12]. By comparison of the cross sections of native beech wood (Fig. 2a) with delignified beech wood (Fig. 2b), a degradation of the middle lamella and adjacent primary walls (compound middle lamella) can be observed. Additionally, voids appear in cell corner areas. As it is to be seen in FT-Raman spectra (Fig. 2d) the peak at wavenumber 1603 cm−1 that is assigned to the symmetric aryl ring stretching vibrations is decreasing strongly after three hours of delignification time. After 5 h of treatment the peak has almost disappeared, suggesting that the lignin has been dislodged. In addition to this, acetic acid with concentration of 70 wt% leads to a moderate extend of derivatization. The formation of acetyl groups, implied by the peak at wavenumber 1740 cm−1 can be seen in Fig. 2d as well.

3.2 Preparation and Characterization of Cellulose Acetate Composite The second step of composite preparation is the impregnation with a polymer. In this study, cellulose acetate with degree of substitution 2.5 was chosen, because of good mechanical properties at low density (1.3 g/cm3 ). Furthermore, the refractive index of the biopolymer (RI = 1.48–1.51) is a good matching to cellulose scaffolds, what provides the possibility of making translucent wood in the next step. Unlike other chemicals that were used to impregnate wood, cellulose acetate needs to be dissolved to penetrate into the scaffold. It’s a matter of fact, which leads to some problems while processing. Firstly, it is not possible to apply vacuum in the infiltration chamber. Because of the high vapor pressure of acetone (30.6 kPa at 25 °C) the solution immediately starts to boil which also causes foam when vacuum is applied. However, vacuum is essential to get rid of the included air in the porous samples and the pore system cannot be flooded by the impregnation medium. Secondly, because

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a)

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Fig. 2 a SEM image of native beech wood fibre in cross section. b SEM image of delignified beech wood fibre with degraded middle lamella and voids in cell corners. c SEM image of delignified and cellulose acetate impregnated beech wood veneer at 500 × mag. d FT-Raman spectra of native, partially delignified and total delignified beech wood veneer. e FT-Raman spectra of delignified beech wood before and after impregnation with cellulose acetate

of the low dry matter content of the cellulose acetate solution (5.9 wt%), the bigger voids in early wood are not filled completely after evaporation of the acetone (shown in Fig. 3d). On the other hand, lumen in late wood areas are impregnated properly. By comparison of the relative intensities of the FT-Raman spectra, information about chemical composition of the composites can be deduced. But impregnated cellulose acetate is hardly to distinguish from the wood derived scaffold, as structuring material, itself. As a derivative of cellulose, it returns almost the same signals as completely delignified wood in FT-Raman spectroscopy. That’s why the spectra in Fig. 2e are very similar to each other. The major difference after the impregnation is the increased peak around wavenumber 1740 cm−1 which is attributed to C=O stretching vibrations in acetate groups. The microscopic structure reveals the disadvantage of solvent-based impregnation systems and shows significant differences between late and early wood. The heterogeneous filled wood structure can also be seen in light and fluorescence microscopy (shown in Fig. 3c, d). By the means of mercury intrusion porosimetry the pore size distribution was measured. Regarding to Plötze and Niemz [13], there are four pore size classes of beech wood. Two macropore classes with pore radii 2–58 µm and 0.5–2 µm were found, one mesopore class 80–500 nm and micropores 3.6–80 nm. It was found, that

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c Fig. 3 a Porosity of native and delignified wood (5 h). Cumulative pore volume and histogram of relative pore volume as a function of pore diameter of native and delignified beech wood veneer. b Porosity of delignified (5 h) and delignified + impregnated beech wood veneer. Cumulative pore volume and histogram of relative pore volume as a function of pore diameter of delignified and delignified + impregnated beech wood veneer. c Fluorescence microscopic image of sample DB_ 3h_CA. d Light microscopy image of delignified and CA impregnated beech wood veneer

delignification process leads to mesoporous structured scaffolds with high specific volume (Fig. 3a) but in comparison to Grönquist et al. [7] measured pore radii were not below 2 nm. After the impregnation process the cumulated specific volume is almost as high as in native wood (Fig. 3b). The decrease of porosity (Table 1) in impregnated samples is attributed to cellulose acetate filled pores. The polymer can either occupy the overall lumina or block channels within the wooden structure [3]. Impregnation step shifted the pore size distribution slightly which indicates that mostly pores with diameters between 0.1 and 1 µm were filled by the polymer. Mechanical properties, such as tensile strength and modulus of elasticity (MOE) are presented in Fig. 4a, b and show the impact of the treatments. After 3 h of delignification (DB_3h) a part of the lignin is removed and self-densification while drying is likely. This effect depends mostly on the drying conditions [16]. If the overall structure gets more compact, higher tensile strength than natural wood is achieved. In contrast to this, longer delignification times lead to enormously reduced tensile strength and minor decrease of MOE (Fig. 4b). An explanation for this is the acid hydrolysis of the carbohydrates, which are responsible for tensile strength. The impregnation step doesn’t improve values of partially delignified wood but has large impact on totally delignified samples. MOE is enhanced

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and tensile strength is approximately doubled. Table 1 shows material properties before and after different treatments of the originally substrate. The determination of water contact angle shows that at Klason lignin content of 0.4 wt% the droplet is soaked in the material immediately because of hydrophilic character of the holocellulose scaffold. This behavior is changed through impregnation, leading to improved but nevertheless low water contact angles of 51.1° for DB_5h_CA. Besides, a characteristic value for lightweight materials is the breaking length, which takes into account that the density is changed throughout the process steps. Native beech wood veneer was measured with a breaking length of 12.4 km which is firstly increased and then decreased during the lignin removal. The samples DB_5h are reinforced by cellulose acetate and reveal breaking length of 12.4 km as well. The highest values are achieved by the partially delignified wood veneers (19.6 km). By comparison of the wood CA composite with other composites and polymers (Fig. 5) it can be claimed, that fiber reinforcement results in improved mechanical Table 1 Klason lignin before and after delignification process, water contact angle at 23 °C and 50% rH, breaking length at 20 °C and 65% rH of native, delignified and impregnated veneers, bulk density and porosity of samples (mean (sd)) Specimen

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Bulk density (g/cm3 )

Porosity (%)

Native

21.6

65.0 (15)

12.4

0.72

53.68

Delignified 3 h

6.4

69.9 (7.7)

19.6

0.67

58.10

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0.4

< 30

10.4

0.46

71.82

Delignified 3 h CA impra

68.5 (13.1)

16.2

0.72

53.11

Delignified 5 h CA imprb

51.1 (5.3)

12.4

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55.04

WPG = 6.6%, b WPG = 52.7%

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Fig. 4 a tensile strength of native beech veneer in comparison to delignified and delignified + cellulose acetate impregnated beech veneer. b Modulus of elasticity (MOE) of native beech veneer in comparison to delignified and delignified + cellulose acetate impregnated beech veneer

Impregnation of Wood Derived Scaffolds with Cellulose Acetate Fig. 5 Comparison of polymers and composites regarding tensile strength and Young’s modulus

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properties. Tensile strength and Young’s modulus of the manufactured material is higher than in most traditional plastics or commercial wood polymer composites (WPC). Unlike in this case where wood structure is preserved, the advantageous effect is also given when disintegrated fibers are used. Regarding to Hoque et al. [8] natural fiber based composites show great opportunities not only for structural applications but also in the fields of biosensors and medical devices. Moreover, 4D printed biopolymeric scaffolds in tissue engineering [15] have huge potential in biomedical therapeutic approaches. In this concern synergies of wood derived scaffolds with biocompatible functionalization are likely.

4 Conclusions The investigation of a composite based on wood derived scaffolds showed that: • totally delignified and fragile tissues can be reinforced by impregnation with cellulose acetate. • SEM and MIP showed the highly porous structures (porosity 71.8%) with low lignin content (0.4 wt%) in samples that were treated 5 h in an acetosolvdelignification solution at 70 °C. • Examination with FT-Raman spectroscopy showed disappearing aromatic stretching vibrations after lignin removal. • The impregnated samples revealed heterogeneous character with a density gradient.

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Because of the irregular impregnation, macroscopic properties scatter a lot, due to high variance. Obviously, the overall benefit of this approach is not optimized, yet. Hence, Cellulose acetate as refractive index matching polymer could be adjusted for the preparation of translucent wood. Therefore, the factors should be investigated that influence scattering in the material. Densification could be an approach to overcome the light scattering in lumen and intercellular cavities in the composite structure. Moreover, other cellulose derivatives should be taken into consideration for impregnation, e.g. cellulose acetate butyrate to enhance mechanical strength. In total, the impregnation of delignified natural material is a versatile method in producing functionalized materials. Wood derived bio composites perform with lightweight properties, sustainable resources and tunable characteristics. Therefore, they are appropriate substrates to face bioeconomy and in development of innovative products. Acknowledgements This research is funded by Federal Ministry for Economic Affairs and Climate Action, Germany.

References 1. Ansari F, Sjöstedt A, Larsson PT et al (2015) Hierarchical wood cellulose fiber/epoxy biocomposites—materials design of fiber porosity and nanostructure. Compos A Appl Sci Manuf 74:60–68. https://doi.org/10.1016/j.compositesa.2015.03.024 2. Barth WA, Dietrich T, Freese M et al (2022) Acetosolv-delignification and IPA-acetylation of beech wood veneer. In: Németh R, Bak M, Hansmann C et al (eds) 10th Hardwood conference proceedings. University of Sopron Press 3. Ding W-D, Koubaa A, Chaala A et al (2008) Relationship between wood porosity, wood density and methyl methacrylate impregnation rate. Wood Mat Sci Eng 3:62–70. https://doi. org/10.1080/17480270802607947 4. Fengel D, Wegener G (1989) Wood. Chemistry ultrastructure reactions. de Gruyter, Berlin 5. Gao J, Wang X, Tong J et al (2022) Large size translucent wood fiber reinforced PMMA porous composites with excellent thermal, acoustic and energy absorption properties. Compos Commun 30:101059. https://doi.org/10.1016/j.coco.2022.101059 6. Gierer J (1982) The chemistry of delignification. A general concept, 1437-434X, vol 36, pp 43–51. https://doi.org/10.1515/hfsg.1982.36.1.43 7. Grönquist P, Frey M, Keplinger T et al (2019) Mesoporosity of delignified wood investigated by water vapor sorption. ACS Omega 4:12425–12431. https://doi.org/10.1021/acsomega.9b0 0862 8. Hoque ME, Rayhan AM, Shaily SI (2021) Natural fiber-based green composites: processing, properties and biomedical applications. j.asep. https://doi.org/10.14416/j.asep.2021.09.005 9. Jungstedt E, Montanari C, Östlund S et al (2020) Mechanical properties of transparent high strength biocomposites from delignified wood veneer. Compos A Appl Sci Manuf 133:105853. https://doi.org/10.1016/j.compositesa.2020.105853 10. Li Y, Fu Q, Yu S et al (2016) Optically transparent wood from a nanoporous cellulosic template: combining functional and structural performance. Biomacromol 17:1358–1364. https://doi.org/ 10.1021/acs.biomac.6b00145 11. Montanari C, Ogawa Y, Olsén P et al (2021) High performance, fully bio-based, and optically transparent wood biocomposites. Adv Sci 2100559. https://doi.org/10.1002/advs.202100559 12. Park K-C, Kim B, Park H et al (2022) Characterization of a translucent material produced from Paulownia tomentosa using peracetic acid delignification and resin infiltration. Polymers (Basel) 14:4380. https://doi.org/10.3390/polym14204380

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13. Plötze M, Niemz P (2011) Porosity and pore size distribution of different wood types as determined by mercury intrusion porosimetry. Eur J Wood Prod 69:649–657. https://doi.org/ 10.1007/s00107-010-0504-0 14. Samanta P, Samanta A, Montanari C et al (2022) Fire-retardant and transparent wood biocomposite based on commercial thermoset. Compos Part A Appl Sci Manuf 106863. https://doi. org/10.1016/j.compositesa.2022.106863 15. Thanigachalam M, Chinnappan BA, Raghavan P (2023) Applications and future aspects of 4D printed biopolymeric scaffold materials in tissue engineering: a systematic literature review. j.asep. https://doi.org/10.14416/j.asep.2023.01.007 16. Vitas S, Segmehl JS, Burgert I et al (2019) Porosity and pore size distribution of native and delignified beech wood determined by mercury intrusion porosimetry. Materials (Basel) 12:416. https://doi.org/10.3390/ma12030416 17. Wachter I, Štefko T, Rolinec M (2019) Optimization of two-step alkali process of lignin removal from basswood. Res Papers Fac Mater Sci Technol Slovak Univ Technol 27:153–161. https:// doi.org/10.2478/rput-2019-0016 18. Yin X, Zhang Y, Xu Y (2022) Luminescent transparent wood from Balsa wood (Ochroma pyramidale) loaded by graphite carbon nitride for implication of photoelectric device 19. Zhu S, Kumar Biswas S, Qiu Z et al (2022) Transparent wood-based functional materials via a top-down approach. Prog Mater Sci 101025. https://doi.org/10.1016/j.pmatsci.2022.101025

Development of Cassava Starch-Based Biodegradable Plastic with PCC for Industrial Application Emekwisia C. Chukwudubem , Osita M. Chinazor , Ibeh T. Chukwuka , and Ezekwesili C. Chinecherem

Abstract Biodegradable plastics are often made from various natural polymers reinforced with minerals and helps in solving the problem of environmental pollution caused by the conventional synthetic plastics. This work examined the development of cassava starch biodegradable plastic, reinforced with Precipitated Calcium Carbonate (PCC). The method used for making the bio-plastic is the melt intercalation method. The cassava starch was mixed thoroughly with distilled water, PCC and glycerol in a charcoal stove to prepare a bio-plastic composite. Investigation on the properties of the composite were conducted in relation to the %weight of PCC from 0.4 to 1.0%. The optimum tensile Strength (21.88 MPa), yield strength (14.87 N/m2 ), and thickness (1.20 mm) were obtained at 0.4% PCC, while the %elongation was obtained at 0.8% PCC. The biodegradability test was also examined using the Soil Burial Test (SBT) at 14-day intervals, and the optimum percentage weight loss (19.78%) was obtained on the 56th day with 0.4% PCC. The control sample (unreinforced bio-plastic) was also examined at 0.0% PCC, which showed higher values of mechanical properties with faster degradable nature. This composite was applied in the production of bio-plastic tablespoon, which can easily degrade and aids in solving the problem of environmental pollution caused by plastics. Keywords PCC · SBT · Bio-plastic

1 Introduction The menace of plastic scraps has become very prevalent in our society with an increasing challenge every day which cannot be over-emphasized, coupled with her unimpressive accelerated poverty rate that has posed a serious threat [1]. The waste E. C. Chukwudubem · O. M. Chinazor (B) · I. T. Chukwuka · E. C. Chinecherem Department of Metallurgical and Materials Engineering, Nnamdi Azikiwe University, Awka 420007, Anambra State, Nigeria E. C. Chukwudubem e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_18

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from plastics can be efficiently managed through the production of biodegradable plastics, which are plastics that can degrade by the attack of living organisms, usually microbes, into the water, carbon dioxide, etc. [2]. These bio-plastics have several potential benefits in various industries including packaging industries among many others, and mostly in food. The essence of packaging is to be a physical protector between the outside environment and the food so that it could avoid contamination and reduce oxidation [3]. So far, the packaging used commonly is from synthetic plastic because it is lightweight, flexible, strong, and not easily broken [4]. But unfortunately, the use of such packaging causes several environmental problems, such as soil and water pollution, and also with the heating up of the plastic packaging, it could produce harmful residues on food and can interfere with health [5]. This led to the emergence of the development of degradable packaging (bio-plastic), which is destroyed by the action of microorganisms after being disposed into the environment, therefore reducing pollution. These bio-plastic packaging is also responsible for providing protection against product quality and has the potential to extend the shelf life [6]. They are gotten from natural or synthetic polymers. These are polymeric materials sourced either from biological (renewable) resources or petroleum (nonrenewable) resources [7]. One of the major ingredients used for making bio-plastics is starch [8]. Starch from cassava is a type of carbohydrate, known as glycan, which is often gotten by extraction. When this starch is modified, it becomes an example of biodegradable plastic and this is widely available in Nigeria making it the most preferred choice for bio-plastic manufacturing. However, it has some inferior properties. The fragility of cassava bio-plastic can be conquered by the addition of plasticizers such as glycerol. This therefore increases its flexibility but reduces the strength [9, 10]. Thus, to increase the strength, a filler material is added when making the bio-plastic, which also increases the stiffness and reduces the solubility to water [11]. The filler/ reinforcement material, mostly Calcium Carbonate is added to increase the rigidity and strength of the bio-plastic. It has no odor nor taste, decomposes in the soil and also has the capacity to absorb moisture from the air [12]. The properties of bio-plastics is strongly influenced by the type of source of starch, its content, and additional materials like plasticizers and fillers. One of the most widely used plasticizer is Glycerol. This is due to its best interaction ability when compared to other plasticizers, even after its combination with starch. Sorbitol, being another plasticizer in bio-plastic production depends often on the starch’s properties. Thus, the need to add certain fillers that will help to improve the mechanical quality of the resulting bio-plastic [8]. The combination of these two and more materials, which individually have different properties but result in better properties when combined are known as Composites. They include Ceramics matrix composite, metallic matrix composite, and polymer matrix composite which are of two types; fiber reinforced composites and particle-reinforced polymer composites [13]. Bio-plastic composite is a type of particle-reinforced polymer composite, which is fast growing in recent times to become an alternative to the existing conventional plastic, especially in packaging applications.

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Yunus and Fauzan [14] examined the properties of bio-plastic cassava films. It therefore reported that the tensile strength of the material had a significant improvement with an increase in the addition of ZnO, however, elongation at break of the composites was reduced. This proved that bio-plastic reinforced with either Calcium carbonate or Zinc oxide has almost the same behavior at the varying of the filler to the fixed weight percent of the starch used. Nuriyah et al. [15] obtained the maximal value of cassava starch bio-plastics when reinforced with calcium carbonate using glycerol as plasticizer. The blending and cast printing methods were used to prepare the bio-plastics. Calcium carbonate was added in variations of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0%. At 0.4% calcium carbonate, the tensile strength showed the best result (22.88 ± 1.46 MPa). However, the addition of 0.5% to 1.0% decreased the strength. The elongation value was best obtained at 0.8% calcium carbonate (27.57 ± 0.14%). This study is focused at the design of a cassava starch based biodegradable plastic (plastic tablespoon), reinforced with Precipitated Calcium Carbonate (PCC). The cassava starch served as the matrix, the PCC served as the reinforcement, with the glycerol as the plasticizer. The mechanical (the tensile strength, yield strength, elongation tests), physical (thickness) and the biodegradability tests were carried out. These properties gave an understanding of the biodegradation properties of the produced plastic [16]. This study helped to consolidate the work done by [15], which also strengthened the efforts made in the managing of plastic waste. It will optimally find essence in this current trend through the growing of a new generation of eco-friendly products and materials that can take the place of the synthetic ones.

2 Materials and Methods Materials used include 15 kg Aluminum scrap, Sand, Cement, Cassava starch, Glycerol, Precipitated Calcium Carbonate (PCC), Water, and Food colorant; and the equipment includes Crucible Furnace, Shovel, Brush, Trowel, Rammer, Riddle, Draw spikes, Clamps, Charcoal stove (heat source), Non-stick pot, Spatula, Thermometer, Beaker, Aluminum Mold, and digital weighing balance.

2.1 Materials Sourcing Cassava starch used for the research was gotten from cassava tubers harvested from a local farm at Isiagu town in Awka South Local government of Anambra State. The cassava tubers having stayed for about nine months in the soil were first uprooted from the soil and washed with water. The outer part was peeled off and the tubers were washed again with water before allowing them to sun dry for about eight days. The speedy drying of the tubers was mainly possible because of the harmattan season. After drying the tubers, they were taken to a grinding mill and ground to a fine mesh.

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One liter of glycerol, two kilograms (2 kg) of Calcium carbonate, and food colorant were purchased from an approved pharmaceutical company located at Ogbo-ogwu, Head bridge Onitsha. Aluminum scrap, being one of the most abundant metal after silicon, which is also manufactured for marketing purposes was easily obtained from aluminum cans (especially canned drinks) sourced from different food restaurants and eateries within the Awka metropolis. The collected aluminum cans were properly washed with water and dried before being melted in a furnace at about 660 °C at Metallurgical Training Institute, Onitsha.

2.2 Preparation of Cassava Starch Starch processing was done using a physical extraction process. In general, it is divided into three sections: Raw material cleaning, Starch extraction, and refining, and Dehydration and drying. Firstly, the impurities attached to raw cassava tubers were removed. The two steps mainly adopted here are—dry cleaning and wet washing. In dry cleaning, the harvested cassava tubers were taken into a dry sieve, where the impurities such as sand, weeds, stones, etc. attached to them were removed. After which the cleaned cassava was transferred to a deep basin for washing. Other attached debris like soil, etc. on cassava was thoroughly washed away under the action of paddle stirring and counter-current washing principle (this is known as wet washing). After the cleaning section, the cassava starch was extracted and separated from non-starch impurities to get pure starch. To extract the starch, the cassava tubers were cut into smaller pieces and crushed into pulp to release starch using a Rasper. It is the most advanced crushing machine at present, it can fully break the cassava cells to ensure the release of starch to the most extent. With Rasper, a more than 94% breaking rate is achievable. After crushing, the cassava mash was obtained, which contains starch and other impurities like fibers, protein, fats, etc. To get purified starch, those impurities were removed one by one. The separation process was done using the centrifugal and fine fiber sieve, which removed the fibers. Afterward, the disc separator and hydro cyclone unit are furnished to remove protein and other impurities. The purified starch with high quality was then obtained. This starch was dried and the edible starch was gotten. Besides, all parts that came in contact with the material are made of food-grade stainless steel.

2.3 Preparation of Metal Mold Molds made of sand are relatively cheap. In addition, a fitting adhesive known as bentonite was mixed with sand. The mixture was dampened slightly with water to develop the plasticity and strength of the clay, which also made it suitable for molding. In this process, the pattern (plastic tablespoon) was fixed into the sand to form a mold cavity. The pattern and the sand were incorporated into a gating system.

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The pattern was removed from the sand mold and the mold cavity was filled with a molten metal cast. The cast was allowed to cool for 25 min. The sand mold was then broken, and the cast was removed.

2.4 Preparation of Bio-plastic The preparation of bio-plastic was done using the melt intercalation method. The bio-plastic was prepared with the use of 25 g cassava starch, poured into a nonstick metal pot, and mixed with 250 ml of distilled water. Five different quantities of PCC ranging from 0.0 g to 1.0 g were mixed with glycerol (between 15.8 g and 16.6 g) and poured into the mixture. One sample contained 0.0 g PCC to be used as control. These materials were stirred together in the pot using a spatula to achieve a thoroughly mixed composite. It was continuously stirred until most of the lumps were removed. At this point, the color of the mixture became milky white and was relatively watery. The pot was mounted on the charcoal stove and set to a medium to low temperature (~95 °C). As the mixture heats, the stirring continued until it came to a gentle boil. On continuous heating, it became more translucent and began to thicken. The total heating time was around 10–15 min. At this stage, a food colorant of 1–2 drops was added to the mixture using a teaspoon and stirred again. Then it was removed from the heat source as it became blue and thick. The blue color achieved was as a result of the blue food colorant added. If the mixture is allowed to overheat, lumps may begin to form again. The blue heated mixture was poured into the mold and shaken to ensure an even spread of the material within the interstices of the mold, while some mixtures were poured in a piece of metal sheet to obtain the samples for the property test. The plastic was allowed to dry in a cool dry place for at least 48 h and the pattern (plastic tablespoon) was formed (see Fig. 6). The finishing process was engaged, after which the bioplastics were cut and the property test conducted. The process is shown on the flow chart (see Fig. 7). Figure 1, 2, 3, 4 and 5 showed the images of the prepared composite samples at various composition of PCC.

Fig. 1 1.0 wt% PCC

Fig. 2 0.8 wt% PCC

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Fig. 3 0.6 wt% PCC

Fig. 4 0.4 wt% PCC

Fig. 5 0.0 wt% PCC (control sample)

Fig. 6 Image of the pattern (plastic tablespoon) at 0.4 wt% PCC, at which point the optimum tensile strength was achieved

2.5 Tensile Strength Test The material samples were placed in the Universal Testing Machine (Model: M50025CT) and were tested according to ASTM D638-22. This standard is used to measure plastics tensile properties, which includes the tensile strength, yield strength and elongation. The samples were placed between the two “grips” on the UTM, which clamped the material. The material was cut into 1 × 6.0 cm and the 5 mm/min crossspeed was used [17]. Weight was applied to the material gripped at one end while the other end is fixed. The weight (or the load or force) was constantly increased while at the same time measuring the change in the length of the sample. The test result is a graph of load (force) versus displacement [18].

Development of Cassava Starch-Based Biodegradable Plastic with PCC … Mixing of cassava starch and distilled water. (A)

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Mixing of PCC + Glycerol (B)

Mixing of (A) and (B)

Stirring

Heating

Addition of Colorant

Removal from heat Pour on the piece of metal

Pour into the tablespoon metal Allow to cool

Finishing

Cut the Bio-plastic for property test

Fig. 7 A flow chart for bio-plastic sample preparation

2.6 Thickness Test Bio-plastic thickness is measured using a digital screw micrometer inside a brand with an accuracy of 0.001 mm. Thickness was measured at five (5) different points, namely one in the middle and at the four corners of the sample, and the average was determined using Eq. (1) [16]. Average thickness =

Point 1 + Point 2 + Point 3 + Point 4 + Point 5 (1) 5

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2.7 Elongation Test Percent elongation is the percentage of increment in length of a bio-plastic film. It was determined from the initial length when withdrawing until the film broke. The same tool used to measure tensile strength was also used to measure elongation. The lengthening of the bio-plastic, which was measured in percentage, was measured during the tensile strength test. At this point, the sample was given a pulling force that brought an increase in the distance between molecules, resulting to an increase in length of the sample. The amount of elongation value was calculated using Eq. (2). %E =

ΔL × 100 Lo

(2)

where %E = Extension break (%); Δ L = Sample’s change in length (mm); Lo = Sample’s Initial length (mm) [18].

2.8 Yield Strength Test Yield Strength of material is often used to determine the allowable load of a mechanical component at maximum point, which represents the upper limit to forces that can be applied without producing permanent deformation. This was measured with the aid of the same tool used to measure tensile strength. It measures the force as a function of the strain being applied to the plastic sample [18].

2.9 Biodegradability Test The biodegradability test was conducted using the SBT (Soil Burial Test) method in line with ASTM D5526 [19]. The sample was buried in the soil for 56 days according to ASTM standards. The weight loss was observed at every 14-day interval until it reached the last day (the 56th day). The initial (W1 ) was taken before the test, while the final weight (W2 ) was gotten on the last day. This occurred in aerobic conditions with the help of bacteria and fungi on the ground. The test showed how long it takes for biodegradable plastics to degrade using the soil burial test method by calculating the sample loss of weight. This was obtained using Eq. (3) [17]. Initial Weight at beginning (W1) −Final Weight after 14 days interval (W2) × 100 %Weight Loss = Initial Weight (W1)

(3)

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3 Results and Discussions 3.1 Mechanical and Physical Properties The result of the mechanical and physical properties of the bio-plastic were determined. It can be seen that the bio-plastic at different weights of PCC showed different results. Five samples were tested. One sample contained 0% PCC to be used as control. The other variables of the PCC that was used are 0.4, 0.6, 0.8, and 1% as stated in Table 1. Observations were made on the tensile strength of the bio-plastic composite as shown in Fig. 8. The strength continued to reduce as the weight percent of PCC increased. The optimum strength (21.88 MPa) was observed at 0.4% PCC. Comparing this with the control sample (0% PCC) which gave 25 MPa. The result showed that the control sample obtained a higher tensile strength. This means that as the PCC increased, the tensile strength of the bio-plastic decreased. This is due to the hygroscopic properties of the PCC. Thus, the more the PCC, the weaker the tensile strength of the bio-plastic. The lowest strength (13.20 MPa) of the bio-plastic was obtained at 1.0% PCC. which also reported that the tensile strength of bio-plastic with calcium carbonate is going to drop with the addition of more calcium carbonate. This is due to the amorphous structure of bio-plastic. Such amorphous molecular structure contains many branches, which are not structured closely, the gap then creates weak bonds between molecules. This weak bond in bio-plastic makes the force needed to draw the plastic apart in a relatively low measure. This is in line with the work of [15]. The thickness of the composite was also observed. This showed a decrease in the thickness with a continuous increase in the percentage weight of PCC. Thus, the optimum thickness (1.20 mm) was observed at 0.4% PCC. The yield strength was also observed. This is the material property and the stress which corresponds to the yield point, wherein the material begins to plastically deform. It showed that the yield strength of the composite, like in the thickness test, continued to decrease with a continuous increase in the percentage weight of PCC, while the optimum yield strength was observed at 0.4% PCC at 14.87 N/m2 . When compared with the unreinforced, the results of the thickness and yield strength showed that the control Table 1 Property tests at various weight of PCC S/N %PCC weight

Glycerol weight (g)

Tensile strength (MPa)

Thickness (mm)

Yield strength (N/m2 )

Elongation test (%)

1

0.0

16.6

25.00

1.41

17.09

13.30

2

0.4

16.4

21.88

1.20

14.87

17.25

3

0.6

16.2

19.56

0.95

13.30

23.00

4

0.8

16.0

15.21

0.89

10.34

27.55

5

1.0

15.8

13.20

0.75

8.97

25.00

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Thickness (mm)

Yield strength(N/m2)

Elongation Test (%)

30

Property

25 20 15 10 5 0 0

0.4

0.6

0.8

1

%Weight of PCC Fig. 8 Graph of the property tests of the bio-plastic at various %weight of PCC

sample obtained a higher property. This decrease in the properties might also be due to the hygroscopic nature of the PCC and the possible fragile property of the cassava starch as noted in the work of [14]. The Elongation of the bio-plastic is measured as the difference that occurred between the final sample length after being tested and the initial sample length. This elongation is affected by the process of gelatinization, coupled with the amount of PCC added, and the glycerol. An increase in length between 0.4% and 0.8% PCC addition occurred in the bio-plastic sample, however, a decrease was observed when the amount of PCC was at 1.0%. The optimum elongation value (27.55%) was obtained at 0.8% PCC, in line with the work of [15], and 16 g glycerol content. Addition of this plasticizer reduces the brittle nature and increases the flexibility of the polymer film. This is done by the breaking of the hydrogen bonds existing adjacently between the molecules of the polymer. Also, increase in PCC resulted to decreased elongation. Most filler materials cause a reduction in the distance of the intermolecular bond, which brought about separation in the molecules of the plasticizer outside the polymer phase. The decrease in the bond distance was due to the increasing number of hydrogen bonds formed between the molecules with amylopectin and amylose This then makes the bio-plastic to become more rigid and less elastic [8].

3.2 Biodegradability (%Weight Loss) Test The result of the biodegradability test was examined. Five sample tests were conducted. One sample is unreinforced, which contained 0% PCC, and was used

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as the control sample. The other samples contained PCC of 0.4%, 0.6%, 0.8%, and 1% respectively as shown below (Table 2 and Fig. 9). The biodegradability result showed how long it took for the bio-plastic to degrade using the soil burial test method by calculating the sample weight loss over a period of 56 days. The initial weight of the biodegradable plastic was taken before the testing commenced and compared with the final weight. After the test, observation showed that the bio-plastic had decomposed in the soil. This means as the burial time increases, the weight loss of the bio-plastic also increases, that is, the higher the degradation of the bio-plastic. The number of weight loss kept increasing at every 14-day interval until it reached 19.78% on the 56th day. However, the unreinforced (0% PCC) showed faster degradation than the reinforced samples. The magnitude of this mass reduction was because the bio-plastic composition was a natural material that is easily affected by moisture, temperature, oxygen, and micro-organisms living in the soil. Thus, the addition of PCC reduces the degradation rate of bio-plastic, especially when compared to the bio-plastic of cassava without PCC. Also, higher rate of the glycerol concentration increases the degradation rate of the bio-plastic. This is as a result of the property of the glycerol which is hydrophilic in water. In addition, the hydroxyl group in cassava starch absorbs the water in the soil to initiate a reaction known as hydrolysis, which decomposes the bio-plastic into smaller particles [20]. The environmental factors such as temperature, humidity and presence of the Table 2 Biodegradability tests at various weights of PCC S/N

%PCC weight

Glycerol (g)

Initial weight, W1 (mg)

Final weight, W2 (mg)

% Loss of weight (or Biodegradility)

1

0.0

16.6

47.4

35.7

24.68

2

0.4

16.4

45.5

36.5

19.78

3

0.6

16.2

43.9

37.4

14.81

4

0.8

16.0

42.3

38.3

9.46

5

1.0

15.8

40.7

39.2

3.69

Biodegradability Test

30 25 20 15 10 5 0 0

0.4

0.6

0.8

1

%Weight of PCC

Fig. 9 Graph of the Biodegradability test of the bio-plastic at various %weight of PCC

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microorganism also contributes to the degradation in the soil. These microorganism breaks the hydroxyl, carbonyl and ester in the cassava starch [21]. Moreover, glycerol can also absorb water easily as water is the medium for most bacteria in the soil. Thus, as the glycerol increases, the amount of water penetrating through the structure of the bio-plastic also increases. This makes the bio-plastics easy to degrade. But the addition of PCC could decrease the rate of the degradation, since it possesses a hydrophobic property that can repel the absorption of water. Therefore, by adding the PCC as a filler, the degradation rate of bio-plastic will slow down compared to the bio-plastic of cassava starch without filler [20].

4 Conclusion This research was done to develop cassava starch-based biodegradable plastic using PCC as reinforcement and glycerol as the plasticizer. After testing the mechanical properties of the plastic, the best property was used to develop a plastic tablespoon. From this research, the following conclusions were drawn; 1. The addition of PCC caused a continuous decrease in the properties of the bioplastic composite, which could be due to the hygroscopic nature of PCC and the possible brittleness of cassava starch. When compared with the control sample (0% PCC), the result showed a higher property, possibly due to the absence of the filler materials. However, the elongation property was exceptional, which could be due to the increase in glycerol content. 2. The biodegradability test showed how long it takes for biodegradable plastics to decompose using the soil burial test, however, the addition of PCC decreased the rate of degradation. This, therefore showed that as the PCC increases, the thermal stability of the composite also improves. However, the unreinforced bio-plastic (0% PCC) showed faster degradation than the reinforced samples. 3. This work provides an understanding of the behavior of cassava starch, PCC, and glycerol in composite films and their characteristics, with the additional benefit of generating opportunities to produce novel bio-composites, at possibly lower costs than the conventional synthetic plastics. 4. Cassava-starch composite produced with PCC and glycerol can be applied in the production of disposable plastic food utensils, which degrades after usage and helps to reduce the challenge of plastic waste. 5. This study will help to strengthen the efforts made in the managing of plastic waste and adds to the growth of a new generation of eco-friendly plastic materials. Acknowledgements The Researchers would like to express their sincere appreciation to the Department of Metallurgical and Materials Engineering, Nnamdi Azikiwe University Awka— Nigeria, and the Nigerian Metallurgical Institute Onitsha. Author Contributions This work was written through the contributions of all authors. All authors contributed equally and have given approval to the final version of the manuscript.

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Conflict of Interest The authors declared no conflicts of interest.

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Identifying the Effect of Stacking Sequence on Water Absorption, Mechanical and Fracture Properties of Flax/Glass Hybrid Composites Yashwant Munde , Avinash Shinde , Prashant Anerao , and I. Siva

Abstract With the increasing development and growth of today’s technology, the requirement for material is also expanding gradually, and this challenging need will not be met by using polymers, ceramics, and metal alloys. Natural fiber-reinforced composites entice technologists, and researchers because of their environmentally friendly and degradable properties. NFRC limited their application to interior parts because of their hydrophilic nature. Therefore, these days hybrid composite materials with natural/synthetic fiber reinforcement are in demand to rise wide spectrum of engineering applications. This paper intends to investigate the physio-mechanical characteristics of epoxy composites reinforced with woven flax/glass fiber. These composites with dedicated and hybrid stacking of fiber are fabricated through the compression molding technique. The tests are performed on these composites as per ASTM standards to evaluate their properties as composite density, water absorption, tensile, bending, Izod impact, and fracture toughness. Also, the morphology of ruptured tensile samples is examined through fractography images obtained by Scanning Electron Microscopy (SEM). The density of Flax/Glass hybrid composites is observed in a range of 1.26–1.31 gcc. In the Water Absorption (WA) test, dedicated Flax composites showed the highest maximum WA of 9.86% and the lowest of 1.51% for Glass/Epoxy composites. Comparisons between dedicated Flax composites and hybrid composites have revealed an enhancement in the tensile, impact, flexural, and fracture characteristics. The fiber breaking, delamination, and fiber pull-out were witnessed through SEM images of ruptured tensile test samples. The hybridization of Flax has facilitated the achievement of improved static mechanical and fracture Y. Munde (B) · A. Shinde Department of Mechanical Engineering, MKSSS’s Cummins College of Engineering for Women, Pune 411052, India e-mail: [email protected] P. Anerao Department, of Mechanical Engineering, BRACT’s Vishwakarma Institute of Information Technology, Pune 411048, India I. Siva Department of Civil Engineering, Rajas Institute of Technology, Nagercoil, Tamil Nadu 629001, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_19

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properties and diminished WA when compared to the dedicated Flax composite. This indicates that the developed hybrid composites could be more appropriate as semi-structural components in automotive applications. Keywords Woven flax fiber · Woven glass fiber · Hybrid bio-composites · Water absorption · Static mechanical · Fracture toughness

1 Introduction In today’s era, we are facing environmental issues due to man-made material product’s life cycle and not degrading over years after disposal. So instead of using these products, technology has moved towards using another material for these products so that effects on the environment can be avoided. Most industries like construction, furniture, automotive, aerospace, and packaging are researching new materials and processes [1]. Composite materials which are heterogeneous and are made up of combining two or more materials embedded in the matrix have superior static mechanical characteristics, a high strength-to-weight ratio, and minimum thermal expansion. Thermoplastic or thermosetting plastics have been used as resin mixed up with respective hardeners in synthetic fiber composites. Synthetic fiber which is mostly utilized in aerospace and automobile interior structure need an abundant quantity of energy during its manufacturing cycle, is non-recyclable, and has a high cost of the material. Jagadeesh et al. [2] reviewed the implementation of E-Glass, Carbon, and Graphite fiber reinforced epoxy composites in different parts of the railway sector. Graphite-reinforced so instead of using synthetic fiber-based composites, we are moving towards natural fiber based composites incorporating jute, sisal, flax, cotton, bamboo, banana, etc. [1]. Deeraj et al. [3] reviewed damping properties of cellulose fiber reinforced composites investigated through DMA. This insighted about extensive range of temperature and frequency of NFRC under dynamic loading. Vinod et al. [4] reviewed newly discovered cellulose based natural fiber and their composites in terms of physio-mechanical and thermal characteristics for a lightweight application. It took review of Perotis indica, Acacia Caesis, Senna auriculata, Nendran Banana Peduncle etc. plant-based fibers discovered during year 2018–2022. Natural fibers having better mechanical characteristics with environmental advantages are used as reinforcement material in composites as they are biodegradable and renewable. One of the studies with sisal and coconut shows that the composites with outer glass fiber layers are in tensile and bending performance while the one with natural fiber on the outer layer had better impact performance. The damping ratio found from experimental results was also better than synthetic fiber-based composites under identical conditions [5]. In contrast to ancient metals such as metals, compounds may be enhanced by the expected performance by attaching strands to functional matrics and placing them in an orderly fashion. The utilization of fibers extracted from natural resources in composite materials has attracted notable consideration from researchers. Compared to glass fibers, Hemp, sisal, and flax natural fiber

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reveal low density, minimal price, and prominent specific mechanical properties. Recyclability is easy and will be useful for the life cycle [6]. Among all natural fibers, flax is most often used as reinforcement in short fibers or plain-woven cloth form. Natural fibers are hydrophilic hence they show lower compatibility with hydrophobic polymers and they also have poor moisture resistance, lower impact resistance, and lower strength and modulus than synthetic fiber composites [7]. Hence the research leads to using multiple fibers with different properties in a one polymer matrix making up the disadvantages of natural plant based fiber and taking advantage of these in which single fiber can’t achieve those properties and that is called hybridization [8]. Unidirectional composites which are based on layup methods are Inter layer hybrids, Intralayer Hybrids, and sandwich hybrids [9]. Among the composite materials composed of natural and synthetic fibers, there are composed of flax and glass fibers, where their composition, type of matrix, shape, production techniques, and test parameters can vary. A few experimental experiments have been performed to better know all the behaviors of these objects depending on the context of each boundary. Flax fiber is the strongest fiber in plant fibers, 2–3 times stronger than cotton fiber, thus it’s additional proof against wear and abrasion. The glass fibers area unit is widely used among affordable composite materials with low chemical compound prices, they are doing not decompose but offering with rational tensile and heat resistance with chemical stability [10]. In order to look into the consequences of hybridization, Zhang assessed the mechanical characteristics of a flax based hybrid composite. The strength and failure strain remained affected by the stacking sequence, but not the tensile modulus [11]. Glass and flax fibres embedded in polyester resin underwent a hybridization process. These laminates’ tensile, impact resistance, flexural, and water absorption capacity, were examined [12]. Kumar et al. studied the mechanical and morphological analysis of glass/flax-reinforced vinyl ester composites with varied lay-up sequence [6]. Sathishkumar et al. [13] fabricated coconut shell, graphite, silica tri filled hybrid epoxy composites using injection moulding and evaluated wear and friction behaviour. It shown that the higher content of graphite lead to enhance wear resistance of hybrid composites. Vinod et al. [14] studied influence of layer pattern of jute/hemp bio-epoxy composites on physical and mechanical properties. H/J/H stacking pattern outperformed for tensile and flexural but weaker in shear properties. Santulli et al. manufactured epoxy composites by hybridization of jute, basalt with E-glass and investigated the influence of layup pattern on tensile and bending performance [15]. Cerbu et al. examine the causes of temperature (20, 50, 70 °C) on the tensile properties of jute/flax/glass fiber based hybrid composites. Microscopic analysis were done to identify the reasons for the lowering of tensile performance [16]. Ramesh et al. manufactured flax/glass fiber-based hybrid bio-composites with 0° and 90° orientations to evaluate static mechanical characteristics and SEM analysis to exhibit interfacial attributes [7]. Selver et al. found that using glass, flax, and jute combinations and changing the stacking sequence like GG, JJ, FF, GJ, JG, GF, FG, how does layup effects mechanical performance of these [17]. Literature review clearly depicts the maximum of the studies and look at has been done on the unidirectional natural fiber for their mechanical, physical, and dynamic

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properties. The flax fiber with some different natural fibers and polymers has been observed to provide gratifying consequences. With most of the applications being majorly in automotive or sports, epoxy-based composites are preferred. Also most of the work in hybrid composites dedicated with Jute/Glass, Hemp/Glass, Coconut/ Glass compared to Flax/Glass. The present work focused to develop dedicated and hybrid composite of woven fiber of glass and flax with epoxy and identify the finest stacking sequence for the enhanced physical, mechanical, and fracture toughness properties.

2 Materials and Methods Raw materials used are flax fiber with woven cross-ply [0°/90°], glass fabric [0°/90°], and epoxy resin. The flax fiber of 300 GSM and density of 1.45 gm/cc is bought from Vrushika Composites Pvt. Ltd Chennai. It has several benefits, including a superior strength-to-weight ratio, quick accessibility, biodegradability, and renewability, making it an excellent alternative to synthetic fibres. A bidirectional glass fabric of 360 GSM and a density of 2.56 gm/cc was purchased from Shreepad Enterprises, Pune. A polymer matrix as LY556 epoxy and hardener HY 951, supplied by Herenba Instruments, Chennai. The release agent Axel F-57LNC helps with the easy removal of thermoset composites, as the epoxy sets well after curing on a smooth surface.

2.1 Composite Constituents and Manufacture The Rule of Mixture (RoM) is utilized to find out the density and mass of reinforced fiber and the quantity of resin required. Six different compositions of composite are produced by hand lay-up and compression moulding. Each laminate contains four sheets of fiber. The mold volume is 250 × 250 × 3 mm3 , and the fiber mats which were procured were cut down to the size of a mold 250 × 250 mm2 . The mold was covered with a release agent for easy removal of composite. The reinforcement is stacked with a 20% volume fraction in all compositions. After the layering process mold was placed in a compression molding with a pressure of 100 kPa for 24 h. The developed bio-composite cut to the required sample sizes utilizing a water jet machining setup. The specimens prepared were designated as shown in Table 1 as per the layers stacking sequence with the glass layer represented as G and the flax layer represented as F. Table 1 depicts compositions formed and specifications of the constituents.

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Table 1 Composition and specifications of the constituents of the composites Compositions

S1

S2

S3

S4

S5

S6

Layup sequence of fiber

FFFF

FGGF

GFFG

GFGF

GGFF

GGGG

Glass fibre volume fraction (%)

–

0.1

0.1

0.1

0.1

0.2

Volume fraction of flax (%)

0.2

0.1

0.1

0.1

0.1

–

Volume fraction of epoxy (%)

0.8

0.8

0.8

0.8

0.8

0.8

The density of composite (gm/cc)

1.25

1.361

1.361

1.361

1.361

1.472

Weight of glass fiber (gm)

–

48.37

47.94

50.04

49.56

96.00

Weight of flax fiber (gm)

53.90

26.95

27.18

27.11

28.30

–

Weight of epoxy resin (gm)

180.5

179.68

179.8

177.85

177.14

180.00

Weight fraction of glass (%)

–

0.188

0.188

0.188

0.188

0.35

Weight fraction of flax (%)

0.23

0.1066

0.1066

0.1066

0.1066

–

Weight fraction of epoxy (%)

0.77

0.71

0.71

0.71

0.71

0.65

Thickness (mm)

3.47

3.26

3.02

3.18

2.86

2.56

2.2 Physical Characteristics Density Measurement: Density measurements assess the concentration and purity of the sample and provide information about its composition. Here, ASTM D792 is used to measure the density of composites in which the mass of the specimen is determined in water and air utilizing analytical weighing balance and density calculated by Archimedeans’ principal. Water Absorption Test: The water absorption performance of the flax/glass composite was assessed as per ASTM D570. This experiment is used to establish the relative rate of absorption of water by composites. The specimen is first dehydrated in hot air oven for about 24 h at 50 °C and weighed. After that specimen is placed in distilled water, weight measurement was taken at the interval of 24 h. The weight of specimens before and after water absorption was calculated using a precise analytical weighing balance of accuracy 0.1 mg. The % of WA was estimated using Eq. (1) W A(%) =

W2 − W1 × 100 W1

(1)

where W1 and W2 are weight of the sample before and after water absorption respectively.

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2.3 Mechanical Characterization Tensile, three-point bending, and fracture toughness tests were performed utilizing a ball screw driven type UTM (Make: Kalpak Instruments and Controls, Pune) of 10 kN load cell capacity and an Impact test using an Izod impact test machine (International Equipments, Mumbai) of 25 J capacity. For each composition, the three samples were used to verify the repeatability, and the average of these sample values was reported. Tensile Test: The tensile test was performed on all six combinations of stacking sequence as per ASTM 3039, on a Universal Testing Machine. Three specimens of each combination of size 250 × 25 × 3 mm3 , with a span and grip length of 170 mm and 40 mm respectively, were tested at 5 mm/min crosshead speed. Flexural Test: The three-point flexural test was performed on all six combinations of stacking sequence according to ASTM D790. Three samples of each combination of size 127 × 12.7 × 3 mm, were tested with a crosshead speed of 1.52 mm/min. A span length of 54 mm was employed to support specimen in three point flexural test. Fracture Toughness Test: These test methods include loading a single-edge-notch bending (SENB) specimen according to ASTM D5045. The specimen size width is double of breadth and the length is 4.4 times of width. So, the specimen size for the fracture test is 52.8 × 12 × 3 mm and notch of 0.5 times of width using a hacksaw. Impact Test: The intent of the impact test is to ascertain how much energy is absorbed by an object during a break. A specimen of 63.5 × 12.7 × 3 mm was used to perform the Izod impact test, which was conducted utilizing an Izod Impact tester according to ASTM D256. The ‘V’ notch on the specimen was as per the standards described in ASTM of impact testing. Three specimen per composition were used for experimentation to report average value.

2.4 Scanning Electron Microscopy Using a scanning electron microscope, the morphological pictures of the flax/glass hybrid composites were examined. SEM pictures were obtained using specimens that had ruptured during a tensile test. It is used to examine how flax and glass fibres disperse across the epoxy matrix.

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1.6

Density (gm/cc)

1.4 1.2 1 0.8 0.6 0.4 0.2 0 FFFF

FGGF

GFFG GFGF Composition

GGFF

GGGG

Fig. 1 Density of dedicated flax/epoxy, glass/epoxy, and hybrid composites

3 Results and Discussion 3.1 Density Glass/epoxy composites possess the highest density of 1.42 gm/cc while flax/epoxy has the lowest density of 1.21 gm/cc. Hybrid composites like FGGF, GFFG, GFGF, and GGFF have a density of 1.26, 1.32, 1.31 and 1.27 gm/cc respectively. The density of developed hybrid composites is fewer than that of glass and lies in between dedicated flax and dedicated glass composites. The low density of hybrid composites will help to design composite structures with minimal weight.

3.2 Water Absorption Water abortion samples were cut and weighed at ambient temperature before immerse in distilled water. The weight of samples after water immersion is measured every 24 h of time duration till it saturates. The saturation is defined as the sample was unable to absorb large amounts of water, when the absorption did not exceed the previous level by 1% or when the absorption weight was less than 0.005gm. Figure 2 displays the variation of the WA of dedicated and hybrid Flax/Glass epoxy composites with an absorption time. As immersion time increases water absorption increases and at a certain point it reaches its saturation level beyond which this curve remains constant. Saturation time is different for a different specimen as it is least for GGGG specimen compared to FFFF and hybrid composites. FFFF composites exhibited the highest water absorption as flax fiber is hydrophilic. The saturation time for these specimens is 12.96^0.5 h. The higher water absorption rate of FFFF

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Water Absorbtion (%)

10

GFFG 8

GFGF GGFF

6

GGGG

4 2 0 0.000

4.899

6.928

8.485

9.798

10.954 12.000 12.961

Time 0.5 (hr)

Fig. 2 Variation of % WA of Flax/Glass epoxy composite with an absorption time

composition is due to greater capillary effects and it could have also been possible due to micro-cracks present inside specimens. In hybrid composites if the number of layers of flax fiber is the same, the WA rate should be the same but as the sequence changes water absorption rate also changes. These changes in the rate of WA in hybrid composites are caused by the presence of the flax layer at the outer layer or inner layer. This indicates the layup sequence of flax in hybrid composites impacted WA characteristics. The kinetics of moisture absorption is defined by diffusion kinetics Eq. (2) shown below.   Mt = log(k) + nlog(t) log Mm

(2)

where, Mt and Mm are WA at time t and at saturation respectively, k, n: Constants The letter “k” stands for the structural properties of the polymer network as well as the interaction between the sample and water. Furthermore, n denotes the kind of fluid transport mechanism. In order to calculate n and k for   flax/glass–epoxy composites, Fig. 3 displays the curve fitting of variation of log MMmt with respect to log (t). It has been defined by linear regression analysis and is shown in Table 2. From Table 2, we observed that estimates of n are close to 0.5 and hence it follows Fickian’s behaviour.

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0.0100 0.0000 0.0000

2.0000

4.0000

log ( Mt/Mm)

-0.0100

y = 0.0369x - 0.0895 R² = 0.8488

S1 S2

y = 0.0326x - 0.083 R² = 0.87

S3

y = 0.0047x - 0.0115 R² = 0.2275

-0.0400 S4 -0.0500

8.0000

y = 0.0031x - 0.021 R² = 0.8681

-0.0200 -0.0300

6.0000

y = 0.0559x - 0.1436 R² = 0.9465 y = 0.0135x - 0.0352 R² = 0.9382

S5 S6

-0.0600

log (time0.5)

Fig. 3 Curve fitting for WA of Flax/Glass epoxy composites

Table 2 WA constants for Flax/Glass epoxy composites Composition

Slope (m)

W∞ (%)

Wt (%)

Constant ‘n’

S1

0.0559

9.866

1.604

0.410

S2

0.0369

8.552

1.389

0.425

S3

0.0031

3.993

1.576

0.447

S4

0.0135

12.586

1.756

0.449

S5

0.0326

7.362

1.618

0.436

S6

0.0047

1.062

1.820

0.459

3.3 Mechanical Properties Tensile Properties: Fig. 4 shows the tensile strength of FFFF, FGGF, GFFG, GFGF, GGFF, and GGGG composites. The lowest tensile strength is observed for dedicated Flax/Epoxy composites i.e. FFFF and an rise in glass fiber improves in tensile strength but less than dedicated Glass/Epoxy composites. In hybrid composites, GFFG composition shows higher strength as it has glass at the skin layer position [18], where glass fiber can withstand higher strain than flax fiber. When both outermost layers are of flax fiber (FGGF) it shows TS of 71.133 MPa and it is improved by 9% as one of outer layer is of glass fiber (GFGF/GGFF). The further rise in TS is observed and it reached to 79.86 MPa for composition GFFG in which both outermost layers are of glass fiber. GFGF and GGFF composition shown TS of 77.67 and 77.52 MPa, indicates altering sequence of second and third layer does not much contribute to affect the tensile strength.

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180 Tensile Strength (MPa)

16000

Tensile Modulus (MPa)

140

14000

120

12000

100

10000

80

8000

60

6000

40

4000

20

2000

Tensile Modulus (MPa)

Tensile Strength (MPa)

160

0

0 FFFF

FGGF

GFFG

GFGF

GGFF

GGGG

Composition

Fig. 4 Tensile strength and modulus of dedicated and hybrid composites

The tensile modulus for FFFF, FGGF, GFFG, GFGF, GGFF, and GGGG is also illustrated in Fig. 4. A tensile modulus of 12.467 GPa is superior for GFFG when glass layers are on the outer side. From these results GFFG sequence promising in terms of tensile modulus in comparison with other compositions of hybrid [11]. In hybrid, influence of layup sequence on tensile modulus has shown similar trend as that observed for tensile strength. FGGF < GGFF < GFGF < GFFG is the order for increasing tensile property of hybrid composites. Flexural Properties: The Flexural Strength (FS) of dedicated and hybrid composites are depicted in Fig. 5. In comparison to glass/epoxy, flax/epoxy has a lower flexural strength. It is examined that flexural strength increases when glass fiber is interlaced in flax/epoxy to form hybrid composites. GFFG composites showed the highest FS of 94.21 MPa in comparison with all hybrid composites. It contains glass fiber layers at the bottom and top surface which help to contribute to higher resistance in bending [6]. The distance of glass textiles from the neutral axis affects a hybrid composite’s FS. So FGGF has shown the lowest flexural strength of 74.06 MPa amongst all hybrid composites [12]. Position of both outermost layers of flax fiber (FGGF) shows FS of 74.06 MPa and as one of outer layer is of glass fiber (GFGF/ GGFF) it improved by 10.8%. When both outermost layers are of glass fiber, FS has been further increased and reached to maximum of 94.21 MPa (GFFG). Also, altering sequence of second and third layer has slight influence on flexural properties. Figure 5 depicts the flexural modulus of dedicated and hybrid composites. Lowest FM of 2067.26 MPa for FFFF composites whereas GGGG has shown the highest of 6871.26 MPa. Amongst hybrid composites, GFFG composition showed a maximum FM of 4550.83 MPa. It is observed that when composites have glass fiber at the outer ply they performed outstandingly. In hybrid composites, effect of layup sequence on flexural modulus is in analogous as that noticed for flexural strength.

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200

10000 Flexural Strength (MPa)

9000

Flexural Modulus (MPa)

160

8000

140

7000

120

6000

100

5000

80

4000

60

3000

40

2000

20

1000

0

Flexural Modulus (MPa)

Flexural Strength (MPa)

180

0 FFFF

FGGF

GFFG GFGF Composition

GGFF

GGGG

Fig. 5 Flexural strength and flexural modulus of Flax/Glass epoxy composites

Impact Strength: Figure 6 indicates the impact strength for composite with a variation of a type of fiber and its layup. The impact strengths for dedicated FFFF and GGGG composites are 37.2 and 828.33 J/m respectively. The impact strength for hybrid composite ranges within the pure glass and pure flax composite. GFFG composite shows the highest strength of 506.6 J/m among all hybrid composites as it has glass layers on the outer sides. The consequences imply that the composites in which glass fibers on either side of the outer have superior impact strength (GFGF and GGFF) and further improvement observed when both outmost layers are of glass fiber (GFFG). The energy absorption of glass fabric is much more excessive compared to flax, the aid of such glass on each aspect supplies supplementary strength to the specimen on the way to resist impact [19]. Fracture Toughness: Single Edge Notched Beam (SENB) specimen with predetermined crack tested under three-point bending to get maximum load bearing capacity of composites. The based-on peak load and notched width of specimens, the stress intensity factor is calculated as depicted in Fig. 7. The fracture toughness characteristics are represented by the computed stress intensity factor. Figure 7 shows the fracture toughness of dedicated composites FFFF and GGGG as 0.45 and 1.66 (MPam0.5 ) respectively. Glass fabric has a regular knit structure and hence in pure glass/ epoxy bridging has not been found and shown higher fracture toughness whereas flax/epoxy composites bridging occurred on the internal surface. Comparing hybrid composites to flax/epoxy composites, they exhibit better fracture toughness qualities. GFFG composite shows high fracture toughness of 0.84 (Mpa-m0.5 ) as it has glass layers on both sides which resit more to separate.

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Impact Strength (J/m)

900 800 700 600 500 400 300 200 100 0 FFFF

FGGF

GFFG

GFGF

GGFF

GGGG

GGFF

GGGG

Composition Fig. 6 Impact strength of Flax/Glass epoxy composites

Stress Intensity Factor

2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 FFFF

FGGF

GFFG

GFGF

Composition Fig. 7 Stress intensity factor of Flax/Glass epoxy composites

3.4 Fractography Analysis Through SEM Figure 8 depicts morphological SEM images of tensile fracture specimens of dedicated and hybrid composites. The failure mode for tensile specimens is predominantly fiber breakage that to flax fiber. In Fig. 8a for FFFF composites, there is poor interfacial bonding is observed which is due to the lower surface adhesion of flax with epoxy and the polar nature of flax fiber. There is a fiber pullout of flax fiber which depicts typical brittle failure [15]. There is a rupture of all specimens into two parts so surface cracks are also observed. For FFFF composite failure fiber,

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pull-out is dominant as less energy is needed for pull-out of fiber [19]. The FGGF fractured specimen morphology is depicted in Fig. 8b. In FGGF, flax sheets are on outer layers and the core is glass. The interaction among the glass fibre and the matrix is finest than the interaction between the flax fibre and the matrix, and resin peeling morphology can be seen on a cross-section of glass fibre. As flax fiber has good toughness, it’s on the outer side so there will be a decrement in the peeling of glass fiber from the epoxy matrix [20]. Cracks are also observed in the middle of the interface and inside flax bundles. There are voids present that indicate fiber pullout due to another part that has been separated at the time of the tensile test. For GFFG composition, glass layers are on the outer side, and the core is filled with flax fiber. In Fig. 8c, fiber breaking along with matrix dislocation is witnessed. As there is a plain surface area has been seen and glass fibers have been broken while flax fibers have been bent. GFFG has demonstrated superior mechanical qualities in comparison to an arrangement like FGGF [19]. Resin peeling morphology has been seen because glass and matrix bonding is better than flax and matrix bonding. For GFGF composition, as glass and flax fabric are arranged alternatively thus strength is decreased in this sequence as fibers are dispersed. In Fig. 8d, we can see that voids are present in a larger number comparatively other specimen. Voids are present because of fiber pull-out due to the separation of another part at the time of the tensile test [20]. For GGFF composition in Fig. 8e, lots of glass fiber has been torn from fabric and this is in between glass and flax fabric [20]. Both glass and flax are on the outer sides, hence there is a plane surface observed which tends to crack and delamination is there. For GGGG composition as all fibers are glass, Fig. 8f shows so clean surface with delaminated fiber with almost no fiber bridging [20]. Delamination and fiber breaking is the predominant mode of failure in this case. The fracture may be visible due to the increased strength taken by the fiber before the fracture as there is additional shear strength which can transfer pressure from the matrix to the fiber and as a result there is maximum mechanical properties [19].

4 Conclusions This research investigated the flax/glass–epoxy composite’s density, water absorption, static mechanical, and fracture toughness properties along with morphological analysis. In comparison to a NFRC, the hybridization of the composite has assisted in enhancing its physio-mechanical properties. • Dedicated FFFF composite shown lowest density and GGGG as highest one whereas hybrid composites density is in between of them. • Hybridization resulted to drop in water absorption of dedicated flax composites. The water absorption rate slightly influenced by stacking sequence and demonstrated Fickian’s behaviour of absorption.

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Fig. 8 SEM images of fractured tensile test specimens of flax/glass epoxy composites a FFFF b FGGF c GFFG d GFGF e GGFF f GGGG

• For tensile strength, almost all hybridized composites have twice than dedicated flax/epoxy composite. Among all hybrid compositions, GFFG has the maximum tensile strength (79.86 MPa) as there was a glass fiber at the skin. • GFFG has the highest flexural and impact strength of 94.21 MPa and 506.6 J/m respectively which are considerably superior than Flax/Epoxy composites. • GFFG composite depicted elevated fracture toughness of 0.84 MPa-m0.5 which is almost twice that of dedicated flax composites. • SEM analysis observed fiber orientation, fiber bonding, fiber dispersion, and surface morphology of tensile ruptured specimens. • The current hybrid composites extend semi-structural potential in the automotive, athletics, and medical industries.

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References 1. Saba N, Jawaid M, Alothman OY, Paridah MT, Hassan A (2016) Recent advances in epoxy resin, natural fiber-reinforced epoxy composites and their applications. J Reinf Plast Compos 35:447–470 2. Jagadeesh P, Puttegowda M, Rangappa SM, Siengchin S (2022) Role of polymer composites in railway sector: an overview. Appl Sci Eng Prog 15 3. Deeraj BDS, Joseph K, Jayan JS, Saritha A (2021) Dynamic mechanical performance of natural fiber reinforced composites: a brief review. Appl Sci Eng Prog 14:614–623 4. Vinod A, Sanjay MR, Siengchin S (2023) Recently explored natural cellulosic plant fibers 2018–2022: a potential raw material resource for lightweight composites. Ind Crops Prod 192:116099 5. Narayana VL, Rao LB, Devireddy SBR (2020) Effect of fiber percentage and stacking sequence on mechanical performance of unidirectional hemp and palmyra reinforced hybrid composites. Rev des Compos des Mater Av 30:153–160 6. Naga Kumar C, Prabhakar MN, Song JI (2019) Effect of interface in hybrid reinforcement of flax/glass on mechanical properties of vinyl ester composites. Polym Test 73:404–411 7. Ramesh M, Sudharsan P (2018) Experimental investigation of mechanical and morphological properties of flax-glass fiber reinforced hybrid composite using finite element analysis. SILICON 10:747–757 8. Arbelaiz A, Fernández B, Cantero G, Llano-Ponte R, Valea A, Mondragon I (2005) Mechanical properties of flax fibre/polypropylene composites. Influence of fibre/matrix modification and glass fibre hybridization. Compos Part A Appl Sci Manuf 36:1637–1644 9. Kureemun U, Ravandi M, Tran LQN, Teo WS, Tay TE, Lee HP (2018) Effects of hybridization and hybrid fibre dispersion on the mechanical properties of woven flax-carbon epoxy at low carbon fibre volume fractions. Compos Part B Eng 134:28–38 10. Kiran MD, Govindaraju HK, Jayaraju T (2018) Evaluation of mechanical properties of glass fiber reinforced epoxy polymer composites with alumina, titanium dioxide and silicon carbide. In: Materials today: proceedings. Elsevier Ltd, pp 22355–22361 11. Zhang Y, Li Y, Ma H, Yu T (2013) Tensile and interfacial properties of unidirectional flax/glass fiber reinforced hybrid composites. Compos Sci Technol 88:172–177 12. Meenakshi CM, Krishnamoorthy A (2018) Preparation and mechanical characterization of flax and glass fiber reinforced polyester hybrid composite laminate by hand lay-up method. In: Materials today: proceedings. Elsevier Ltd, pp 26934–26940 13. Sathishkumar TP, Navaneethakrishnan P, Maheskumar P (2021) Thermal stability and tribological behaviors of tri-fillers reinforced epoxy hybrid composites. Appl Sci Eng Prog 14:727–737 14. Vinod A, Tengsuthiwat J, Gowda Y, Vijay R, Sanjay MR, Siengchin S, Dhakal HN (2022) Jute/Hemp bio-epoxy hybrid bio-composites: influence of stacking sequence on adhesion of fiber-matrix. Int J Adhes Adhes 113:103050 15. Santulli C (2016) Effect of stacking sequence on the tensile and flexural properties of glass fibre epoxy composites hybridized with basalt, flax or jute fibres. Mater Sci Eng with Adv Res 1:19–25 16. Cerbu C, Wang H, Botis MF, Huang Z, Plescan C (2020) Temperature effects on the mechanical properties of hybrid composites reinforced with vegetable and glass fibers. Mech Mater 149:103538 17. Selver E, Ucar N, Gulmez T (2018) Effect of stacking sequence on tensile, flexural and thermomechanical properties of hybrid flax/glass and jute/glass thermoset composites. J Ind Text 48:494–520 18. Cihan M, Sobey AJ, Blake JIR (2019) Mechanical and dynamic performance of woven flax/ E-glass hybrid composites. Compos Sci Technol 172:36–42

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19. Abd El-baky MA, Attia MA, Abdelhaleem MM, Hassan MA (2020) Mechanical characterization of hybrid composites based on flax, basalt and glass fibers. J Compos Mater 54:4185–4205 20. Wang H, Yang L, Wu H (2021) Study on mechanical and thermomechanical properties of flax/ glass fiber hybrid-reinforced epoxy composites. Polym Compos 42:714–723

LSPM-DES (Design Optimization of Lightweight Polymeric Materials)

Rheological Properties of Polyacrylamide and Modified Polyacrylamide Under Specific Heating Effect and pH Effect Between Fann Viscometer and Marsh Funnel Jin Kwei Koh , Chin Wei Lai , Mohd Rafie Johan , Sin Seng Gan , and Wei Wei Chua

Abstract This study is to determine the comparison of rheological properties between bare polyacrylamide (PAM) and modified PAM using two different measurement tools, which are Fann viscometer, and Marsh Funnel. Further, the specific heating and pH were applied in the rheological measurement to study the heat resistance and chemical stability of drilling fluid. The rheological data from Fann viscometer was simulated in accordance with American Petroleum Institute (API), which is correlated with the Bingham Plastic concept. Additionally, the plastic viscosity (PV), apparent viscosity (AV), and yield point (YP) were studied. However, Marsh viscosity was obtained from Marsh Funnel, which is simpler, and an alternative to viscosity measurement. The heating effect for each rheological measurement was conducted from ambient conditions to 80 °C, while the pH effect for each rheological measurement was conducted from ambient, 9 to 10. Throughout the rheological analysis using a Fann viscometer, AV and PV of bare PAM declined when heating was at 60 °C, then incline after heating at 80 °C, while YP of bare PAM has an inverted trend from AV and PV. Additionally, modified PAM had a similar trend in AV, but fluctuated in PV and YP. The marsh parameters of bare PAM are observed to decrease over the increasing of the temperature, while the modified PAM are insignificantly decreased. For the pH effect, the marsh viscosity of bare PAM was decreased over the pH, while the marsh viscosity of modified PAM was increased. Hence, Fann viscometer is sensitive to rheological measurements. J. K. Koh (B) · C. W. Lai (B) · M. R. Johan Nanotechnology and Catalysis Centre (NANOCAT), Institute for Advanced Studies (IAS), Universiti Malaya, Level 3, Block A, 50603 Kuala Lumpur, Malaysia e-mail: [email protected] C. W. Lai e-mail: [email protected] S. S. Gan · W. W. Chua Synergy Lite Sdn Bhd, No. 31, Jalan PP11/4, Alam Perdana Industrial Park, 47130 Puchong, Selangor, Malaysia © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_20

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Keywords Fann viscometer · Marsh Funnel · Polyacrylamide · Heating · pH

1 Introduction A critical component in the drilling design is drilling fluid [1]. As the drilling fluid can be applied to the offshore, mining, and excavation industries, the constituent of drilling fluid are concerned in the engineering and development regarding the drilling aspect. Hence, the rheological profile of drilling fluid is the crucial factor to oversee the drilling performance. The constituent selection in drilling fluid is also a critical factor affecting the rheological profile of drilling. Various viscosifier is important in rheological control that is employed in foundation drilling. The most common viscosifier in foundation drilling is bentonite and polyacrylamide (PAM). PAM has emerged in foundation drilling over 30 years but there are presently no agreed-upon baseline standards for evaluating PAM for construction usage. Further, the rheological behaviours of polymer-based drilling fluid depend on the fundamental polymer properties, it is unlikely that bentonite has a technical datasheet provided by suppliers. Hence, PAM usage in construction are not standardised in the technical datasheet and this may have risk in construction foundation design, such as unstable pile issue leading to soft toe issue. Although PAM has insufficient published information in geotechnical engineering, PAM still can be a potential additive in such fields as PAM is biodegradable and more inexpensive than bentonite [2–5]. Besides, PAM has weaknesses in heat resistance and chemical stability as reported by several researchers. Especially, the heat resistance and chemical stability of polymer are the usual issues that always garner attention in drilling fluid technology as the high temperature and extremely acidic conditions cause the poor rheological performance of drilling in operation. Further, the flocculation of PAM occurs easily when the drilling operation is at a high temperature. Similarly, the high pH can cause the polymer to coagulate, which can form the flocs in drilling fluid. In short, these phenomenon is caused by the changes in intermolecular charge with its configuration in PAM. Several researchers enhanced the rheological profile of drilling fluid using additives, such as nanomaterials, functionalised materials, and others. Because these materials have unique properties, which can promote better thermal stability. For instance, Haruna et al. [6] improved the rheological properties of polymer-based drilling fluid using graphene oxide that can promote high thermal stability in the drilling operation. Further, Perween et al. [7] also utilised bismuth ferrite to boost the rheological performance of water-based drilling fluid. For pH, the drilling fluid is recommended controlling in the range of 9 to 10 because an acidic environment can cause damage to the equipment and the overall cost of drilling operations [8]. In this study, silica (SiO2 ) was investigated in the modification of PAM, which is in the agreement with Koh et al. [9] to oversee the heating effect towards PAM-based drilling fluid, while soda ash was used in pH adjustment.

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In order to oversee the rheological performance of PAM, two models were applied in the measurement of viscosity, which is a Fann viscometer and a Marsh Funnel measurement. Fann viscometer is known as a rotational type viscometer in which the fluid is contained between coaxial cylinders. This model is designed with rotor-bobtorsion spring combinations. This geometry design is proposed by Couette in the 1890s and has emerged commonly in the drilling field to determine the rheological behaviour of drilling fluid, such as plastic viscosity, apparent viscosity, and yield point values directly from the dial reading at 300 and 600 rpm. The temperature used in this viscometer can be conformed according to API Recommended Practice 13-2B [10, 11]. In 1931, Hallan N. Marsh implemented a rapid and simpler measurement for the viscosity of a fluid, known as Marsh Funnel. This model is also able to provide the relative changes in the rheological behaviour of drilling fluid, which can trigger the drilling engineer making corrective action immediately on the site. Hence, this model is popular and commonly applied in the construction site. The viscosity was obtained from the proportion of the fluid speed when it flows via the outlet tube as shear rate to the fluid weight as a force leading to the flow of drilling fluid as shear stress. It is normally derived as the time in seconds needed for a fluid volume in 1-quart equivalent to 946 ml to pass through the outlet of Marsh Funnel to the mud cup [10, 12, 13]. Both measurement techniques were utilised to determine the rheological properties of bare PAM and modified PAM under specific heating effects and pH effects. This study also compares the data collection between both measurements to investigate the discrepancy of Marsh Funnel with Fann viscometer measurement.

2 Methodology 2.1 Material Preparation The drilling fluid involved in the rheological testing were bare PAM and modified PAM. 1000 ppm PAM-based drilling fluid was prepared as bare PAM, which was supplied by Synergy Lite Sdn Bhd. However, modified PAM was formulated with 1000 ppm PAM, 0.5 wt% SiO2 (Sigma Aldrich), and 0.2 wt% SDS (Merck). All the drilling fluid samples were mixed at a specific speed with ambient conditions (25– 30 °C, pH: 5.5–6) using a Joanlab overhead stirrer. The formulation used in drilling fluid samples was followed in agreement with Koh et al. [9]. Further, the drilling fluid samples were further treated with 2 different conditions before proceeding with rheological testing, which are heating and pH adjustments. For heating conditions, each sample was heated using a Joanlab hotplate stirrer at a few specific temperatures (40, 60, and 80 °C). For pH adjustment, each sample was adjusted at specific pH (9, 10).

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2.2 Fann Viscosity Measurement After material preparation, the data collection from Fann viscosity measurement was conducted using a 6-speed rotational viscometer. Refer to Table 1, the drilling fluid samples with ambient conditions (25–30 °C, pH: 5.5–6), with heating effect (40, 60, 80 °C), and with pH adjustment (pH: 9, 10) underwent the rheological testing accordingly with at least three samples testing for each condition. Firstly, the steel cup was filled with 350 ml of drilling fluid sample. That cup was lifted after adjusting the knob to ensure the bob and rotor were contacted with the drilling fluid sample, as shown in Fig. 1. Then, the rheological testing was simulated using the equations below according to American Petroleum Institute, which is in agreement with Koh et al. [9]. Plastic viscosity, P V = ϕ600 − ϕ300

(1)

Apparent viscosity, AV = 0.5ϕ600

(2)

Yield point, Y P = 2(2ϕ300 − ϕ600)/2

(3)

where ϕ600 and ϕ300 are the dial reading in mPa.s at 600 and 300 rpm, respectively. Table 1 Parameters of fann viscosity measurement

Parameters

Conditions

Temperature, °C

Ambient, 40, 60, 80

pH

Ambient, 9, 10

Volume of drilling fluid, ml

350

Fig. 1 Setup of 6-speed rotational viscometer. The condition of a steel cup a before adjustment of knob and b after adjustment of a knob

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2.3 Marsh Funnel Measurement The rheological data was also further obtained in Marsh Funnel measurement. Refer to Table 2, the drilling fluid samples with ambient conditions (25–30 °C, pH: 5.5–6), with heating effect (40, 60, 80 °C), and with pH adjustment (pH: 9, 10) underwent the rheological testing accordingly with at least three samples testing for each condition. A 1500 ml drilling fluid sample was prepared before proceeding with Marsh Funnel measurement, as shown in Fig. 2a. Besides, a 200 ml drilling fluid sample was filled in a balance cup and weighed by the mud balance testing tool set shown in Fig. 2b. The measurement of viscosity was obtained when the level bubble was ensured at the centre of the sight glass after the balance is level as shown in Fig. 2c. Table 2 Parameters of Marsh Funnel measurement

Parameters

Conditions

Temperature, °C

Ambient, 40, 60, 80

pH

Ambient, 9, 10

Volume of drilling fluid, ml

1500

Fig. 2 a Marsh Funnel set b Mud balance set c level bubble location in mud balance

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The data were simulated according to the equation proposed by Pit [1, 14]. μ = ρ(t − 25)

(4)

where μ = effective viscosity in centipoise (captured from Marsh Funnel testing) ρ = density in g/cm3 (captured from mud balance testing) t = quart funnel time in seconds.

3 Result 3.1 Rheological Analysis with Heating Effect Figure 3a shows the rheological behaviours between bare PAM and modified PAM under heating effect with the use of Fann Viscometer Measurement, which was reported in previous studies in agreement with Koh et al. [9]. Compared to bare PAM, modified PAM has lower PV and AV from ambient and heating at 40 °C. After further heating at 60–80 °C, the plastic viscosity and apparent viscosity of modified PAM were higher than bare PAM. However, YP of the modified PAM had a lower trend than the bare PAM. From this situation, modified PAM was not ideal as bare PAM that had lower PV and high YP. Usually, the drilling fluid is favourable in low PV with high YP because this kind of rheological behaviour is conducive to cutting efficiency in drilling operations [15]. Further, Fig. 3b shows the rheological behaviours between bare PAM and modified PAM under heating effect with the use of Marsh Funnel method. The effective viscosity of bare PAM also obviously decreased over the increasing of the temperature, while the modified PAM insignificantly decreased. Meanwhile, the bare PAM had a higher viscosity than the modified PAM over the increasing temperature. In short, the viscosity in Marsh Funnel showed decreasing trend while Fann viscometer measurement decreased from ambient conditions to 80 °C but increased further after heating at 80 °C.

3.2 Rheological Analysis with pH Effect Figure 4a shows the rheological behaviours of bare PAM and modified PAM under the pH effect with the use of Fann Viscometer measurement in a previous study that is in agreement Koh et al. [9]. Compared to bare PAM which had a decreasing trend in PV and AV with an increase of YP from ambient condition to pH 10, modified PAM showed an increase of PV with a decrease of AV and YP after pH was adjusted

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Rheological properties

(a) 15 10 5 0 Bare polymer

Modified polymer

PV, mPa.s ambient

heating after 40 °C

Bare polymer

Modified polymer

AV, mPa.s Heating after 60 °C

Bare polymer

Modified polymer

YP, Pa Heating after 80 °C

(b)

Effective viscosity, mPa.s

140 120 100 80 60 40 20 0 Ambient

40 60 Temperature, °C Bare Polymer Modified Polymer

80

Fig. 3 a Fann viscometer measurement data that are adapted with Koh et al. [9], and b Marsh Funnel measurement data under heating effect

from ambient conditions to 9. Additionally, PV and AV decreased with the increase of YP in modified PAM fluid that adjusted further at pH 10. Most drilling application is favourable to pH 9 to 10 because the drilling performance can be enhanced with the cost reduction within this range of pH [8]. This study showed that bare PAM and modified PAM had lower PV and higher YP at pH 10 than those fluids tested at pH 9. However, the bare PAM was decreased from ambient to pH 10, while the modified polymer was increased, as depicted in Fig. 4b. In short, both viscosity measurements showed a decreasing trend in bare PAM but the modified PAM has a different trend that reflecting in the data collection between Fann viscometer and Marsh Funnel measurements.

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Rheological properties

(a) 16 14 12 10 8 6 4 2 0 Bare PAM

Modified PAM

Bare PAM

PV, mPa.s

Modified PAM

Bare PAM

AV, mPa.s Ambient

pH 9

Modified PAM

YP, Pa

pH 10

(b) Effective viscosity, mPas

140 120 100 80 60 40 20 0 Ambient

Bare Polymer

9 pH

10

Modified Polymer

Fig. 4 a Fann viscometer measurement data that are adapted from Koh et al. [9], and b Marsh Funnel measurement data under heating effect

3.3 Discussion Fann viscometer measurement showed various data than Marsh Funnel measurements as it can investigate PV, AV, and YP. Although it can study various parameters, it has time consumption in the data collection. Throughout the data analysis between both measurement tools, there is a discrepancy between the effective viscosity from Marsh Funnel measurement and the rheological properties (PV, AV, and YP) from Fann Viscometer due to the different equations applied in the rheological calculation. Besides, the heating effect caused the fluctuation in the rheological properties

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of fluid samples using Fann viscometer measurements. Usually, the polymer can be degraded when a higher temperature is applied causing a lower PV in the rheological behaviours of drilling fluid. In this measurement, the PV of bare PAM and modified PAM increased after heating further at 60 °C and 80 °C, respectively, which is an unusual phenomenon. It was suspected that the large floc formation when the higher temperature was applied in the drilling sample was in agreement with Koh et al. [9]. Referring to Marsh Funnel measurement in heating effect, the marsh effective viscosity showed decreasing trend in bare PAM and modified PAM. The rheological properties of drilling fluid can be affected by flocculation, followed by aggregation during heating, which is undesired in drilling fluid operations. All these situations are indistinct because the flocculant role in PAM is not in agreement with whether conducive to the rheological performance of the drilling fluid [16, 17]. Drilling fluid is usually maintained at pH 9–10, as reported by several researchers [8, 16, 18]. A high pH can cause a high gelation effect, while low pH can cause damage to drilling equipment, as well as filtration loss in drilling performance [19, 20]. Hence, the drilling study was performed at a pH range of 9–10. Fann viscometer measurement showed fluctuations with the effect of pH in bare PAM and modified PAM. However, Marsh Funnel measurement showed that bare PAM had a decreasing trend in effective viscosity, while the modified PAM had a slightly increasing trend in effective viscosity. The reason for rheology changes in drilling fluid is the intermolecular charge with its configuration of drilling fluid changed after pH was adjusted from ambient to high pH. For PAM, its viscosity is reduced, as a result of its dispersive behaviour that has been restricted by the addition of pH. Meanwhile, modified PAM has slightly increased in viscosity due to the unique structure of functionalised SiO2 playing the rheological properties of drilling fluid [8, 21]. Compared to Marsh Funnel measurement, Fann viscosity measurement allocates a longer time in the rheological testing, which probably contributes to the unusual result of viscosity measurement using Fann Viscometer after further heating at higher temperatures or during pH adjustment. This is a limitation on the set-up of equipment in terms of heating.

4 Conclusion The fundamental of Fann viscometer and Marsh Funnel measurements have been introduced in this study. The application of both measurements have been applied to the bare PAM and modified PAM fluid to investigate the effects of heating and pH. The discrepancy in data collection between both measurements has been discussed. The summarised findings are shown below: (a) The rheology of drilling fluid is interrelated with the flocculation and aggregation of PAM during heating. (b) The configuration and intermolecular charges of PAM can be altered by further addition of pH in drilling operations.

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(c) There is a discrepancy in the rheological investigation between Fann Viscometer and Marsh Funnel measurements at specific heating and pH. In the future, there are requirements for advanced tools to enhance the heating and pH effect in Fann viscometer set-up to ensure in-place control of temperature or pH.

References 1. Gowida A, Elkatatny S, Abdelgawad K, Gajbhiye R (2020) Newly developed correlations to predict the fluid using neural networks. Sensors 20(2787):1–18 2. Jefferis SA, Lam C (2022) Fundamental properties of polyacrylamide-based polymers for bored piling and diaphragm walling fundamental properties of polyacrylamide-based polymers for bored piling and diaphragm walling. In: Rahman MM, Jaksa M (eds) Proceedings of the 20th international conference on soil mechanics and geotechnical engineering, ICSMGE 2022. Australian Geomechanics Society, Sydney, Australia, pp 3815–3820 3. Jefferis SA, Ouyang Y, Wiltcher P, Suckling T, Lam C (2017) The on-site management of polymer support fluids for the construction of drilled shafts and diaphragm walls. In: Gazzarrini P, Richards Bruce DA, Byle MJ, Mohtar CSE, Johnsen LF (eds) Grouting 2017: jet grouting, diaphragm walls, and deep mixing. American Society of Civil Engineers, USA, pp 523–532 4. Ejezie JO, Jefferis SA, Lam C, Sedighi M, Ahmad SM (2021) Permeation behaviour of PHPA polymer fluids in sand. Geotechnique 71(7):561–570 5. Lam C, Jefferis SA, Suckling TP (2018) Treatment of bentonite fluid for excavation into Chalk. Proc Inst Civ Eng Geotech Eng 171(6):518–529. ICE Publishing, UK 6. Haruna MA, Pervaiz S, Hu Z, Nourafkan E, Wen D (2019) Improved rheology and hightemperature stability of hydrolyzed polyacrylamide using graphene oxide nanosheet. J Appl Polym Sci 136(22):47582 7. Perween S, Thakur NK, Beg M, Sharma S, Ranjan A (2019) Enhancing the properties of water based drilling fluid using bismuth ferrite nanoparticles. Colloids Surf, A 561:165–177 8. Gamal H, Elkatatny S, Basfar S, Al-Majed A (2019) Effect of pH on rheological and filtration properties of water-based drilling fluid based on bentonite. Sustainability 11(23):6714 9. Koh JK, Lai CW, Johan MR, Rangappa SM, Siengchin S (2022) A comparative study of pH and temperature on rheological behaviour between Polyacrylamide (PAM) and its modified PAM. In: 2022 Research, invention, and innovation congress (RI2 C 2022), E3S Web Conference, 355, pp 02005, EDP Science, France 10. Vidaur M, Carlos J (2018) Experimental study of automated characterization of non-Newtonian fluids. University of Stavanger, Norway. http://hdl.handle.net/11250/2569905. Last accessed 28 Feb 2023 11. Jain R, Mahto V, Sharma VP (2015) Evaluation of polyacrylamide-grafted-polyethylene glycol/ silica nanocomposite as potential additive in water based drilling mud for reactive shale formation. J Nat Gas Sci Eng 26:526–537 12. Almahdawi FHM, Al-Yaseri AZ, Jasim N (2014) Apparent viscosity direct from marsh funnel test. Iraqi J Chem Petrol Eng 15(1):51–57 13. Sedaghat A, Omar A, Damrah S (2016) Mathematical modelling of the flow rate in a marsh funnel. J Energy Technol Res 9:1–12 14. Al-Khdheeawi EA, Mahdi DS (2019) Apparent viscosity prediction of water-based muds using empirical correlation and an artificial neural network. Energies 12(16):1–10 15. Wang J, Chen M, Li X, Yin X, Zheng W (2022) Effect of synthetic quadripolymer on rheological and filtration properties of bentonite-free drilling fluid at high temperature. Crystals 12(2):257

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16. Fokuo M, Aggrey WN, Rockson NAD, Sokama-Neuyam YA, Boakye P, Amenuvor G, Sarkodie K, Pinto E, Karimaie H (2021) Tannin-based deflocculants in high temperature high pressure wells: a comprehensive review. Adv Chem Eng Sci 11(4):263–289 17. Tehrani A, Gerrard D, Young S, Fernandez J (2009) Environmentally friendly water-based fluid for HPHT drilling. In: 2009 SPE international symposium on oilfield chemistry, vol 2. SPE International, Texas, USA, pp 1079–1086 18. Mao H, Wang W, Ma Y, Huang Y (2020) Synthesis, characterization and properties of an anionic polymer for water-based drilling fluid as an anti-high temperature and anti-salt contamination fluid loss control additive. Polym Bull 78(5):2483–2503 19. Gu X, Sang H, Pu C, Zhang L, Zhao Q (2015) Effect of pH on gelling performance and stability of HPAM/Cr3+ weak gel. In: Proceedings of the 2015 international forum on energy, environment science and materials. Atlantis Press, Paris, pp 401–404 20. Alaskari MKG, Teymoori RN (2007) Effects of salinity, pH and temperature on CMC polymer and XC polymer performance. Int J Eng 20(3):283–290 21. Saleh TA, Rana A, Arfaj MK, Ibrahim MA (2022) Hydrophobic polymer-modified nanosilica as effective shale inhibitor for water-based drilling mud. J Petrol Sci Eng 209:109868

The Effect of Overlap Length on Adhesive Bonded Composite Joint Using Digital Image Correlation Avinash Thirunavukarasu

and Rahul Singh Sikarwar

Abstract In this paper, the effect of varying the overlap length of the adhesivebonded single-lap composite joint has been studied using Digital Image Correlation (DIC). The study of surface strain and stress distribution with time steps helps to predict the behaviour of joints under the change in load magnitude. The samples of single lap adhesive bonded joints were prepared using unidirectional glass fiber reinforced polymer composite at 0° orientation as an adherend. The surface pretreatment was done to remove dust particles and make the surface rough for good bonding strength. The structural adhesive 3m-DP8805ns was used to bond the varying overlap lengths of 10, 25, and 40 mm. Speckle patterns were formed on the surface of the samples. DIC was used to visualize the displacement and surface strain of the joint. The joint failure observed in all overlap lengths was cohesive failure. The maximum load was carried by the overlap length of 40 mm. The significant increase is because of uniform stress distribution, visualized using the DIC, and surface strains on the adherend help to predict future damage in the future for using the backface strain technique. The present work helps to understand the effect of varying overlap lengths of adhesive-bonded composite joints prepared using adhesive on strength, strain, and stress distribution. Therefore, the study concludes that strain would reduce and load-carrying capacity would rise in proportion to an increase in the bonded area. The failure load significantly increases from 25 mm, and carries higher strain. Hence the 25 mm is selected as optimal overlap length. Keywords Adhesive · Overlap length · Single-lap joint · Composite · Digital image correlation

A. Thirunavukarasu · R. S. Sikarwar (B) School of Mechanical Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu 632014, India e-mail: [email protected] A. Thirunavukarasu e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_21

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1 Introduction Fiber-reinforced polymer (FRP) composites have several advantages such as high stiffness to weight and strength to weight ratios, improved fatigue, and resistance to corrosion, all of which provide significant economic and functional benefits, tend to range from strength increase and reduced weight to durability. Engineers involved in structural design become interested in them due to various advantages. Composite joints are used to connect several composite parts that are bonded together with adhesives or mechanical fasteners. A joint’s principal purpose is to transfer weights from one member to another. A joint is the weakest part of any construction, and it is where the majority of breakdowns occur. When compared to other materials such as metals and ceramics, joining composite materials poses a unique difficulty in terms of achieving joint performance and functionality that is comparable to the parent material. The continuity and integrity of the fibers in composites are challenging to maintain throughout the joint. Adhesively bonded joints play a crucial role to attain a uniform distribution of load and keeping away problems that lead to stress concentrations such as bolts or rivet joints. Adhesives have the potential to eliminate the stress concentration caused by mechanical fasteners while maintaining surface integrity. Compared to other conventional joints the single lap adhesive joint offers many advantages such as simple design, cost-efficient, high strength, and saving time. It is a permanent joint that does not allow the dismantling of assembled components without rupturing them. Shaikh et al. [1] and Jeevi et al. [2] concentrated on the factors such as joint design, the thickness of adhesive, and surface treatment, that affect the loading capacity of the single-lap adhesive joint, which had been investigated at different bond areas which have different strengths. The study’s key findings are that it clarifies the joining of two plates using an adhesive joint and examines failure analysis using FEA and experimental testing. It shows the importance of maintaining the thickness of the adhesive and a more uniform stress distribution was observed. Budhe et al. [3] and Banea and da Silva [4] reviewed the parameters such as joint configuration, bond line thickness, and thickness of the adhesive, length of bonded region, material selection, surface pretreatment and modes of failures that affect the bonding regions. Lup˘as¸ and Dupir [5] varied the thickness and overlap lengths of adhesives. GFRP is used as adherends and bonded using structural adhesive. As a result, the overlap of 100 mm and adhesive thickness of 1 mm carried a maximum load. Bocciarelli et al. [6] proposed two failure criteria one is stress-based, and another one is fracture mechanics-based criteria. The shear and peel stress were validated by the analytical and numerical models. Analytical prediction gave a close range with FEM results and experimental results. Fawcett et al. [7] enhanced the tolerance of damage at the joint, maximum load, and displacement till the failure of a tensile test by using the penetrative reinforcement technology. Aluminum (2024-T3) and GFRP are used as substrate and the adhesive used was Loctite Frekote (770-NC). Concluded that, despite the presence of penetrative reinforcement, the adhesive had the worst static and fatigue performance. This suggested to obtain the optimal joint performance

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with this sort of penetrative reinforcement, adhesive bonding was required. Lee et al. [8] carried an experimental investigation of supported single lap joint and double strap joint using GFRP as adherend and three different adhesives (TYPE A, B, and C) the results concluded that the joint strength was nearly unaffected by the type of adhesive, the thickness of the adhesive layer was decreased and increased with overlap length. The adhesive thickness of 0.2 mm has high joint strength than the thickness above 0.5 mm and the overlap length of 100 mm carries more load than the other overlap length. Sun et al. [9] investigated the strength of unidirectional carbon/epoxy prepreg bonded utilizing LJM 200 film with seven overlaps and five adherend widths. When adherends overlap 20 mm, matrix cracking and delamination occur within. Instead of increasing overlap length, increasing width helps enhance load-carrying capacity linearly, and delamination takes up a major portion of the failure region. Longer overlaps minimize coherent failure areas. Campilho et al. [10] examined the parameters of cohesive for a triangular cohesive-zone model (CZM) used to simulate how an adhesive thin layer might act in bonded joints. Single-lap geometry was selected with eight different overlap lengths. Unidirectional carbon/epoxy prepreg bonded using Araldite 2015. Numerical modeling anticipated and confirmed the maximum load-carrying capacity when the overlap length grew to 80 mm. Luci et al. [11] used aluminium Al-99.5 as adherend and Loctite 7061 as adhesive to fabricate the single lap joint, by varying the overlap length at five different lengths, to obtain the optimum length and to predict the strength of the adhesive joint by using numerical modeling. As a result, 40 mm was the optimal overlap length achieved. The results are successfully validated with the help of numerical modeling. Seong et al. [12] used carbon composite and aluminium as adherend to investigate the bonding failure of SLJs by varying the parameters such as overlap length and bonding pressure. It was successfully reported as Slight increase in the failure load at the joint of an overlap length larger than 30 mm. The delamination was improved by increasing the bonding pressure on the joint region strength is improved. Anyfantis [13], Reddy et al. [14], Ribeiro et al. [15] worked hybrid joints on predicting the strength of the bonded region by varying the length of the bonded regions. Kumar et al. [16] worked on an analytical and experimental investigation to predict the failure of the joint. The single-lap joint was formed by using uni-directional Carbon Prepreg CP105ns as adherend and Araldite AV138M and Hardener HV 998 as adhesive. As a result, the peel strain and shear strain were measured using DIC and the failure load which was predicted by the theoretical model had been higher than the experimental failure loads. Schieler and Beier [17] investigated the factors that affect the thickness of the flim and the welding temperature. Mohabeddine et al. [18] compared the ductile and brittle adhesive and studided the uniform distribution of both adhesive and concluded as ductile showed more uniform distribution than brittle. Liewald and Marx [19] used institute for metal forming technology for bonding the carbon textile and sheet metal. Verma [20] reviewed the polymer with graphene (functional graded), concluded with the advantages of using the functional graded material, which helps to improve the strength of the bonded regions. Öz and Öztürk [21] induced the carbon fillers in epoxy in three different weight proportions to improve the strength of the joints and

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the tests were monitored using DIC. As a result 1 wt% carried higher load, SEM as well as DIC reveals that as long as the epoxy ductility is increased the toughness and load carrying also increases. The major objective of this research is to investigate how the distribution of strain occurs in the single lap adhesively bonded composite joints of GFRP and GFRP which are prepared using the structural adhesive 3M DP8805NS, behaves under the variation of overlap length. The specimens were tested by varying the overlap length of the adhesive of the specimens. The tensile test images are captured at various steps of the tensile test, strains along the loading direction and the displacement that developed in the overlap regions were visualized with the help of DIC.

2 Experimental Setup 2.1 Materials and Manufacturing Uni-directional Glass Fiber Reinforcement Polymer (GFRP) was contemplated as adherends of the adhesively bonded single lap joints (ABSLJ). A laminate was fabricated at 0° orientation in the dimensions 250 mm × 250 mm × 2.5 mm. For laminate fabrication, epoxy (LY 556) and hardener (HY 998) were used as matrix. The GFRP laminates were cut into the adherends of dimension 101.6 mm × 25.4 mm × 2.5 mm, Fig. 1. The surface pretreatment is done to remove all the contaminants from the surfaces, to have good bonding between the adherend and the adhesive. Physical pretreatment had been followed for surface preparation as per the ASTM D2093 acetone is used for cleaning the surface of the bonding areas of the adherends and let it clean for 10 min so that the liquid solvents get evaporated. Sanding has been done by emery sheet and cleaned with a dry cloth to remove unwanted particles from the sanding and bonded the joints as soon as the surface treatment is done. Then the adhesive is applied over the 3 different over-lap lengths as 10, 25, and 40 mm, Fig. 1. The adhesive used is 3m DP8805ns adhesive. It is important to maintain the adhesive layer thickness throughout the overlap length. As illustrated in Fig. 2 the fixture is used to achieve the adhesive thickness of 0.2 mm, by applying the pressure evenly at the overlap length of the specimen. Furthermore, a 24-h room-temperature cure was performed on the bonded specimen. Alignment tabs had been tailored at the edge of the samples which helps to neglect the misalignments of the gripping and bending caused because of eccentric force, Fig. 1.

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Fig. 1 Geometric dimension of single lap joint Fig. 2 Fixture used to prepare the single lap adhesive joints

2.2 Universal Testing Machine (UTM) and Digital Image Correlation (DIC) The Universal Testing Machine is used for tensile testing. The strain rate was 1 mm/ min till the joint attains its maximum load. The load vs displacement values are extracted, which helps to find the maximum load carried by the joint. The DANTEC DYNAMIC digital image correlation is used for the experimental setup, Fig. 3. The setup contains 2 cameras (MASTER and SLAVE) of 12 megapixels each. The camera helps to capture the images and transfer the image to Data Acquisition System (DAQ) box, which helps to convert the images into signals and transfer them to the commercial DIC software called ISTRA 4D. The fundamental need is to have a fine speckle pattern, which can be either black background white dots or white background black the dots, it should be very fine and distributed randomly as shown in Fig. 4, to obtain an accurate result. The images are visualized properly on the screen as shown in Fig. 5. The DIC records the visualized images of each step and those images are saved and used for calibration. The visualized images are calibrated using a calibration board after recording the test. The software helps us to visualize the strains, displacements, every step of the tensile load images. The saved

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images are calibrated and results are extracted from visualization settings and they are exported as images or videos or data. Fig. 3 Experimental DIC and UTM

Fig. 4 A fine speckle pattern over the surface of the single lap specimen

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Fig. 5 Visualized UTM image captured by DIC during tensile testing

3 Results and Discussion 3.1 Load Versus Displacement of Different Overlap Length Specimens were manufactured by varying the bonded region into three different overlap lengths were examined to determine the effect of overlap length on the strength of single lap adhesive bonded joints. From Fig. 6 as length of bonded region increases, the joint strength also increases. The high load was carried by 40 mm overlap of the bonded region, this is because of uniform stress distribution. The experimental data were used to plot the graph and maximum load before breaking was identified after load vs displacement graph. This had been done for all three various overlaps lengths. The maximum joint strength of the material has been reached out, and failed cohesively, which makes sure that fabrication of samples was made successfully. From Fig. 6 it can see that the maximum load carried by the overlap length of 10 mm was 1471.5 N, for 25 mm was 6660 N and the joint of 40 mm was 13,680 N. From the mean maximum load, we can say that 40 mm has a high load-carrying capacity. Figure 7 shows that as the overlap length increases the strain decreases. And the 25 mm overlap length carries high strain value than the other two overlap lengths. To make sure the percentage variation has been calculated in Table 1 to find the optimum overlap length. It shows that increasing the bonded region by more than 25 mm is not that much effective. The resistance of an adhesive to pressures applied perpendicular to the bonded surfaces is known as its lap shear strength. Adhesive bonded joints are often engineered such that the adhesive is only exposed to in-plane stresses, resulting in shear stress within the adhesive. Shear strength is measured using the maximum load by width of the joint and cross section region of the bonded region. The adhesive shear strength by varying the overlap length has been calculated and values are shown in Table 2. Increasing the overlap length increases the shear strength. The maximum

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Fig. 6 Load versus displacement of the three different over-laps

Fig. 7 Stress–strain of different overlap length

Table 1 Table captions should be placed above the tables

S. No.

Specimen label

% Load increase

1

10–25 mm

77.9

2

25–40 mm

51.3

shear strength was obtained by the overlap length of 40 mm. Shear strength measurements are helpful, but the way joints fail tells us just as much about their quality. Cohesive failure was seen at the joint, however, increasing the bonded region, the failure mode of the bonded area shifted to adherend failure from the cohesive failure. The non-linear connection between overlap length and load directly results from the failure in adherend.

The Effect of Overlap Length on Adhesive Bonded Composite Joint … Table 2 Shear strength of the adhesive by varying the overlap length

287

S. No.

Overlap length (mm)

1

10

Shear strength (MPa) 5.79

2

25

10.488

3

40

13.46

3.2 Measurement of Directional Strain Using DIC The images which had been extracted from DIC helped us to visualize the uniform stress distribution as well as the strain–displacement along the overlap length. The strain–displacement cure has been extracted from DIC, Fig. 8. It can be observed as the overlap length increases, the strain reduces. The overlap length of 25 mm carries a higher strain value than the other two overlap lengths. The 25 mm can be selected as the optimum value for bonding region. Figure 9 shows the visual images of the uniform stress distribution of the optimized bonded region 25 mm. This helps to understand the uniform distribution of stress that acts along the loading direction. Fig. 8 Strain–displacement of various bonded region

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Fig. 9 Displacement at overlap length 25 mm along a total displacement, b x-direction, c ydirection and d z-direction

4 Conclusion The behavior of single-lap adhesively bonded joint with a variation of three different overlap lengths under tensile load has been studied experimentally and the full field technique is used to visualize the images during tensile testing and strains are evaluated from the captured using the commercial software while the joints under tensile load. The tensile strains results are successfully validated using the strain results of the DIC, which helps to find the optimum bonded region length. • The maximum load carried was observed in the joint of 40 mm, they have the high strength. Carries higher shear strength than the other overlap lengths. • As overlap length increases the strain decreases and therefore the 25 mm is optimal overlap length which can be used for bonded region in future works. • When we increase the overlap length the load-carrying percentage is decreasing. • Therefore, increasing overlap length by more than 25 mm is not that effective. • If you keep on increasing the overlap length then the load carrying is not increasing proportionally. • The image captured by DIC is used to evaluate the directional strains, which it helps to visualize the strain acting along the longitudinal direction.

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Future work surface strains on the adherend help to predict the damage in the future for using the backface strain technique.

References 1. Shaikh S, Anekar N, Kanase P, Patil A, Tarate S. Single lap adhesive joint (SLAJ): a study. IJCET INPRESSO 7(July):2277–4106 2. Jeevi G, Nayak SK, Abdul Kader M (2019) Review on adhesive joints and their application in hybrid composite structures. J Adhes Sci Technol 33(14):1497–1520. https://doi.org/10.1080/ 01694243.2018.1543528 3. Budhe S, Banea MD, de Barros S, da Silva LFM (2017) An updated review of adhesively bonded joints in composite materials. Int J Adhes Adhes 72:30–42. https://doi.org/10.1016/j. ijadhadh.2016.10.010 4. Banea MD, da Silva LFM (2009) Adhesively bonded joints in composite materials: an overview. Proc Inst Mech Eng Part L: J Mater: Des Appl 223(1):1–18. https://doi.org/10.1243/146442 07JMDA219 5. Lup˘as¸ V, Dupir I (2016) Behaviour of composite-to-composite interface for adhesively bonded joints experimental set-up 62:14 6. Bocciarelli M, Colombi P, Fava G, Poggi C (2009) Prediction of debonding strength of tensile steel/CFRP joints using fracture mechanics and stress based criteria. Eng Fract Mech 76(2):299–313. https://doi.org/10.1016/j.engfracmech.2008.10.005 7. Fawcett A, Chen X, Huang X, Li C (2019) Failure analysis of adhesively bonded GFRP/ aluminum matrix single composite lap joint with cold worked penetrative reinforcements. Compos B Eng 161:96–106. https://doi.org/10.1016/j.compositesb.2018.10.051 8. Lee HK, Pyo SH, Kim BR (2009) On joint strengths, peel stresses and failure modes in adhesively bonded double-strap and supported single-lap GFRP joints. Compos Struct 87(1):44–54. https://doi.org/10.1016/j.compstruct.2007.12.005 9. Sun L, Li C, Tie Y, Hou Y, Duan Y (2019) Experimental and numerical investigations of adhesively bonded CFRP single-lap joints subjected to tensile loads. Int J Adhes Adhes 95:102402. https://doi.org/10.1016/j.ijadhadh.2019.102402 10. Campilho RDSG, Banea MD, Neto JABP, da Silva LFM (2012) Modelling of single-lap joints using cohesive zone models: effect of the cohesive parameters on the output of the simulations. J Adhes 88(4–6):513–533. https://doi.org/10.1080/00218464.2012.660834 11. Luci M, Stoi A, Kopa J (2006) Investigation of aluminum single lap adhesively bonded joints 12. Seong M-S, Kim T-H, Nguyen K-H, Kweon J-H, Choi J-H (2008) A parametric study on the failure of bonded single-lap joints of carbon composite and aluminum. Compos Struct 86(1–3):135–145. https://doi.org/10.1016/j.compstruct.2008.03.026 13. Anyfantis KN (2012) Finite element predictions of composite-to-metal bonded joints with ductile adhesive materials. Compos Struct 94(8):2632–2639. https://doi.org/10.1016/j.compst ruct.2012.03.002 14. Reddy NS, Jinaga UK, Charuku BR, Penumakala PK, Prasad AVSS (2019) Failure analysis of AA8011-pultruded GFRP adhesively bonded similar and dissimilar joints. Int J Adhes Adhes 90:97–105. https://doi.org/10.1016/j.ijadhadh.2019.02.004 15. Ribeiro TEA, Campilho RDSG, da Silva LFM, Goglio L (2016) Damage analysis of composite– aluminium adhesively-bonded single-lap joints. Compos Struct 136:25–33. https://doi.org/10. 1016/j.compstruct.2015.09.054 16. Kumar RV, Bhat M, Murthy C (2013) Experimental analysis of composite single-lap joints using digital image correlation and comparison with theoretical models. J Reinf Plast Compos 32(23):1858–1876. https://doi.org/10.1177/0731684413500859 17. Schieler O, Beier U (2015) Induction welding of hybrid thermoplastic-thermoset composite parts. KMUTNB: IJAST:27–36. https://doi.org/10.14416/j.ijast.2015.10.005

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18. Mohabeddine A, Malik G, Correia J, Fantuzzi N, De Jesus A, Castro JM, Calçada R, Berto F (2022) Comparison between brittle and ductile adhesives in CFRP/steel joints. Procedia Struct Integrity 37:1043–1048. https://doi.org/10.1016/j.prostr.2022.02.043 19. Liewald M, Marx L (2016) Further development on joining of metal and fibre components using semi-solid forming technology. KMUTNB: IJAST:1–8. https://doi.org/10.14416/j.ijast. 2016.01.003 20. Verma A (2022) A perspective on the potential material candidate for railway sector applications: PVA based functionalized graphene reinforced composite. JASEP. https://doi.org/10. 14416/j.asep.2022.03.009 21. Öz Ö, Öztürk FH (2022) Effect of carbon filler–modified epoxy adhesive on failure behavior of bonded single-lap joint: an experimental study combined with digital image correlation method. Weld World 66(10):2143–2156. https://doi.org/10.1007/s40194-022-01347-9

Experimental Investigations on the Effect of Carbon Nanotubes and Nanoclay Additives on Thermo-Kinetics and Mechanical Characteristics of Acrylonitrile Butadiene Styrene (ABS) S. L. Aravind , H. P. Bharath , B. Suresha , B. Harshavardhan , Imran M. Jamadar , P. K. Samal , and A. Anand

Abstract Thermoplastic materials are gaining precedence in a practical world because of their high rigidity, lightweight, and corrosion resistant characteristics. These qualities, thermoplastics can be used in a variety of applications. The current study examines the effects of Multiwall Carbon Nanotubes (MWCNT) and Nanoclay additives on the thermo-kinetics and mechanical characteristics of ABS. The effect of these additives on thermal characteristics of ABS is evaluated using simultaneous TGA and DSC tests in nitrogen atmosphere at three heating rates. The kinetics are evaluated using Flynn Wall Ozawa and Kissinger models. The experimental findings showed that the addition of MWCNT and Nanoclay enhanced the activation energy by 72.85% with Flynn Wall Ozawa and 65.23% with Kissinger models, therefore resulted in improved thermal stability of blended mixture. The effect of additives on mechanical characteristics of ABS is examined by subjecting the samples for hardness and impact tests. The outcome showed that the inclusion of MWCNT and Nanoclay has increased the hardness number from 67.2 to 70.4 and decreased the impact strength from 8.335 to 4.985 kJ/m2 . Keywords ABS · Carbon nanotubes · Nanoclay · Thermokinetics · Mechanical characteristics

S. L. Aravind (B) · H. P. Bharath · B. Suresha · B. Harshavardhan · I. M. Jamadar · P. K. Samal · A. Anand Department of Mechanical Engineering, The National Institute of Engineering, Mysuru, Karnataka 570008, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_22

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1 Introduction Polymers gaining importance because of their high rigidity, low weight, and corrosion resistant qualities. Polymers are classified in to thermoplastics and thermosets. The advantages of thermoplastics over thermosets are their capacity to be reused, ease of manufacture, and environmental friendliness. Thermoplastics can be employed in a variety of applications. Acrylonitrile Butadiene Styrene (ABS) is a polymer which belongs to class of thermoplastics. ABS has good impact strength and corrosion resistance properties, however, it has low durability in high temperature application. Additives are utilized to refine the thermo-mechanical characteristics of the material. The Multiwall carbon nanotubes (MWCNT) addition to the ABS and its blends has improved the thermal stability [1, 2]. The inclusion of carbon nanofiber improved the mechanical behaviour of ABS [3] and addition of 5 wt% nanoclay had maximum enhancement in the mechanical properties [4]. Carbon nanotubes composites have received much interest from researchers and industry as a result of their remarkable mechanical, electrical, and thermal characteristics. The higher aspect ratio leads to better mechanical, thermal and electronic applications [5]. Nanoclay is a low cost nano-filler which is widely available. The high aspect ratio of nanoclay makes it an efficientfiller and reinforcing agent [6]. Thermal degradation of a material is a crucial topic to study the behaviour of the material in dynamic heating [7]. Thermal behaviour is studied using TGA and DSC. The thermogram of TGA indicates the degradation onset and offset temperature and mass loss percentage of the material. DSC thermogram depicts the phase transition of the material. Jogi [1] added MWCNT to the PA6/ABS blend and subjected the samples to DSC and TGA analysis in presence of nitrogen. The addition of MWCNT shifted the temperature by 4.5 °C to right. Amir Rostami et al., [2] subjected the PC/ABS with MWCNT to the TGA analysis. The degradation temperature increased in presence of MWCNT. Narayan Debnathet al., investigated effect on thermal and mechanical characteristics with the addition of carbon black and nanoclay to the ABS/Polyaniline and ABS/Polypyrrole blends. They noticed an enhancement of 65.83% in tensile strength for wt% 91/3/3/3 and slight improvement of glass transition temperature [6]. Mu-Hoe Yang investigated the thermal degradation of ABS under various gas atmospheres like oxygen, air and nitrogen. The kinetics were examined and obtained activation energy of 133.8 kJ/mol, 143.9 kJ/mol, 178.6 kJ/mol under oxygen, air and nitrogen respectively [8]. Bano et al. [9] studied the kinetic parameters of ABS-PC blends at different heating rates and evaluated the kinetic parameters. The activation energy of value 51.4 kJ/mol, 105.75 kJ/mol and 145.65 kJ/mol were obtained using Kissinger, Flynn wall and Friedman respectively. Ujfalusi et al. [10] studied the kinetics of ABS using TGA and DSC. They noticed that Tg of ABS is 103.89 °C and decomposition peak temperature is 423.03 °C. Lopes et al. [11] examined the impact of carbon fiber on mechanical and thermal characteristics of ABS. ABS was reinforced with carbon fiber with 5 wt% to examine its effect on thermal and mechanical characteristics of ABS. The decomposition peak increase from 469.98

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to 476.17 °C with addition of carbon fiber and increment of 38% in tensile strength is noticed. The kinetic parameters are examined using different models. Vacha and Bor˚uvka [12] examined the effect of carbon nano-tubes on mechanical characteristics of ABS and noticed the enhancement in tensile strength by 15.2% and hardness increased from 71.84 to 74.28 and impact strength decreased by 78.06%. Mamaghani Shishavan et al. [13] evaluated the effect of MWCNT and nanoclay on hardness of ABS where increasing the wt% of nanoclay and MWCNT increased the hardness of ABS. Khun et al. [14] examined the effect of graphene on mechanical and tribology characteristics of epoxy composites. Inclusion of graphene increased the stiffness and hardness but decreased the friction and wear. Deeraj et al. [15] made a brief review on the thermal transition and damping properties of natural fiber reinforced composites material with influencing factors. Sathishkumar et al. [16] studied the thermal strength and wear characteristics of tri-fillers reinforced hybrid composites using injection moulding techniques. This paper aims; (i) To investigate and interpret the thermal behaviour of pure ABS under dynamic heating. (ii) To investigate the influence of MWCNT and nanoclay additives on thermo-kinetics of ABS for dynamic heating with heating rates 7.5, 10 and 12.5 °C min−1 in nitrogen atmosphere. (iii) To evaluate the kinetic parameters using Flynn Wall Ozawa and Kissinger models and compare the results of pure ABS and MWCNT ABS nanoclay blend. (iv) To investigate the impact that MWCNT and nanoclay have on the ABS’s hardness.

2 Experimentation 2.1 Materials Pellets of pure ABS (Augment 3Di India Ltd), nano-particle additives MWCNT and Nanoclay (Adnano Technologies Private Limited, India) of 5 wt% each is blended using magnetic stirrer for duration of 25 min with acetone as a solvent. Then the mixture is fed in to the Hot Press with temperature of 200 °C and pressure of 30 bar for duration of 30 min to get the desired shaped of the sample in a die. Then the sample is cured at room temperature for 48 h. Now the samples of desired shapes are tested for thermal behaviour and mechanical stability.

2.2 Method The thermal behaviour of pure ABS and the blend is studied using simultaneous TGA–DSC (Netzsch Jupiter STA449-F3 DSC-TG). The sample of mass < 10 mg powder of each pure and blended ABS on aluminium crucible is studied at heating rates 7.5, 10 and 12.5 °C min−1 spanning a temperature range of 30–600 °C in

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nitrogen atmosphere. The hardness of the pure and blended samples are investigated using Shore D hardness tester with ASTM 2240 and the impact strength is investigated using Impact Izod tester with ASTM D256 respectively.

3 Kinetics of Thermal Degradation The TGA thermogram depicts the degradation onset, maximum degradation temperature and mass loss%. The DSC kinetics exhibits the phase transition temperature. In this study the kinetic parameters are assessed utilising the Ozawa and Kissinger model equations [17]. The activation energy is computed using the slope obtained from the Ozawa and Kissinger plots. Flynn Wall Ozawa model Ea =

R d(log β) ( ) 0.457 d T1

(1)

Kissinger model ( ) β d ln 2 T Ea ( ) = R d T1

(2)

The pre exponential factor is evaluated using the equation A=

−Ea β Eae( RT ) RT 2

(3)

where β = heating rate, R = Universal gas constant, Ea = Activation energy and T = Degradation peak temperature.

4 Results and Discussion The thermal behavior of pure ABS is studied under nitrogen atmosphere at different heating rates. Then the obtained outcomes are contrasted with the findings of ABS/ MWCNT/nanoclay blend.

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4.1 Thermal Analysis of Pure ABS The TGA analysis curve shows the mass loss%, degradation onset and maximum degradation temperature. Figures 1, 2 and 3 are the thermogram of pure ABS at different heating rates. The degradation transpired in a single stage for pure ABS. The onset temperature is at 379.82, 390.71 and 393.26 °C at respective residual mass of 5.02, 6.12 and 4.22% noticed. DSC thermogram displays the phase transition temperature. The first endothermic peak represents the glass transition phase of ABS where the styrene-acrylonitrile copolymer (SAN) changes from the state of glass to rubber. The crystallization

Fig. 1 Thermogram of pure ABS at 7.5 °C/min heating rate

Fig. 2 Thermogram of pure ABS at 10 °C/min heating rate

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Fig. 3 Thermogram of pure ABS at 12.5 °C/min heating rate

temperature of ABS is represented by the following exothermic peak. It is the phase when the amorphous nature of ABS changes to the crystallinity. ABS do not show the true melting point due to its amorphous nature [18]. The deterioration peak temperature of ABS is the succeeding endothermic peak. The degradation peak temperature is 412.4 °C, 418.79 °C and 421.17 °C at 7.5 °C min−1 , 10 °C min−1 and 12.5 °C min−1 respectively. The thermal behaviour of the pure ABS is corroborated with the findings of Ujfalusi et al. [10].

4.2 Thermal Analysis of ABS/MWCNT/Nanoclay Blend The TGA analysis curve shows the mass loss %, degradation onset and offset temperature. Figures 4, 5 and 6 are the thermogram of ABS/MWCNT/nanoclay blend at heating rate 7.5 °C min−1 , 10 °C min−1 and 12.5 °C min−1 respectively. The blend showed two stage degradation at 7.5 and 10 °C min−1 heating rate. The onset temperature is at 396.7, 405.21 and 408.83 °C without residual mass. DSC thermogram shows the phase transition temperature. Glass transition phase can be identified by the first endothermic peak of ABS where the styrene-acrylonitrile copolymer (SAN) changes from the state of glass to rubber. Addition of MWCNT to ABS elevates the glass transition temperature because carbon hinders the segmental motion at the interface and also affects the mobility in polymer chain. Thus, the glass transition phase of ABS elevated [10, 18]. The crystallization temperature of ABS is represented by the following exothermic

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Fig. 4 Thermogram of ABS/MWCNT/nanoclay blend at 7.5 °C/min heating rate

Fig. 5 Thermogram of ABS/MWCNT/nanoclay blend at 10 °C/min heating rate

peak. It is the phase when the amorphous nature of ABS changes to the crystallinity. ABS do not show the true melting point due to its amorphous nature [18]. The successive endothermic peak is the degradation peak temperature of ABS. The degradation peak temperature is 421.6, 423.2 and 427.3 °C at different heating rates (Tables 1 and 2). The thermal characteristics of ABS have been enhanced by the inclusion of MWCNT and nanoclay, which has led to a shift in the Tg temperature, degradation onset and peak temperature. Pure ABS has residual mass whereas the residual

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Fig. 6 Thermogram of ABS/MWCNT/nanoclay blend at 12.5 °C/min heating rate

Table 1 Thermal data of pure ABS using TGA and DSC Heating rate ºC min−1

Glass transition temperature ºC

Crystallization temperature ºC

Onset temperature ºC

Peak temperature ºC

Residual mass %

7.5

102.19

215.6

379.82

412.4

5.02

10

102.61

221.8

390.71

418.79

6.12

12.5

102.26

223.9

393.26

421.17

4.22

Table 2 Thermal data of ABS/MWCNT/Nanoclay blend using TGA and DSC Heating rate ºC min−1

Glass transition temperature ºC

Crystallization temperature ºC

Onset temperature ºC

Peak temperature ºC

Residual mass %

7.5

104.01

150.7

396.7

421.6

NIL

10

105.52

205.28

405.21

423.2

NIL

12.5

106.17

230.29

408.83

427.3

NIL

mass of the blended mixture is nil due to presence of carbon and the material had degraded completely.

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5 Kinetic Analysis The pure ABS and the blended samples are subjected to the TGA and DSC to study the behavior to the dynamic heating and to determine the kinetic parameters. The values listed in Table 3 are used to plot the Kissinger and Ozawa plot for pure ABS. To evaluate the kinetics, the graph of log(β) versus 1000/T and ln(β/T2) versus 1000/T is plotted as indicated in Fig. 7. The activation energy is calculated using Eq. (1) and (2) for Ozawa and Kissinger respectively. The activation energy of pure ABS was found to be 73.67 kJ/mol using Ozawa and 69.36 kJ/mol by using Kissinger model. The activation energy of the pure ABS corroborated with the findings of Dul et al. [19]. The kinetic parameters are tabulated in Table 4. Also, the ABS/MWCNT/ Nanoclay blend subjected to TGA and DSC and evaluated the kinetic parameters. The ABS/MWCNT/Nanoclay blend Kissinger and Ozawa plot is created using the information listed in Table 5. To evaluate the kinetics, the log(β) versus 1000/T and ln(β/T2) versus 1000/T graph is plotted as shown in Fig. 8. The pre exponential factor is computed using the Eq. (3). The activation energy is calculated using Eqs. (1) and Table 3 Thermal data of pure ABS for Kissinger and Ozawa plots Heating rate ºC min−1

Peak temperature (T) ºC

1000/T

Kissinger ln(β/T2)

Ozawa log(β) 0.875

7.5

412.4

2.42

− 10.02

10

418.79

2.38

− 9.77

1

12.5

421.17

2.37

− 9.56

1.096

Fig. 7 Kissinger and Ozawa plot for pure ABS

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Table 4 Kinetic parameters of pure ABS using Ozawa and Kissinger method Method Ozawa Kissinger

Ea (KJ/mol)

A (s−1 )

Liner correlation coefficient (R2 )

73.67

4.97 ×

10–4

0.93

69.36

4.69 ×

10–4

0.91

(2) for Ozawa and Kissinger respectively. The activation energy of ABS/MWCNT/ Nanoclay blend was found to be 127.34 kJ/mol using Ozawa and 114.61 kJ/mol by using Kissinger model. The kinetic parameters are listed in Table 6. It is clear from the kinetic parameters listed in Tables 4 and 6 that adding MWCNT and nanoclay to ABS increases the activation energy of ABS. The activation energy increased from 73.67 to 127.34 kJ/mol by Ozawa model and from 69.36 to 114.61 kJ/ Table 5 Thermal data of ABS/MWCNT/nanoclay blend for Kissinger and Ozawa plots Heating rate ºC min−1

Peak temperature (T) ºC

1000/T

Kissinger ln(β/T2 )

Ozawa log(β)

7.5

421.6

2.37

− 10.01

0.875

10

423.2

2.36

− 9.79

1

12.5

427.3

2.34

− 9.58

1.096

Fig. 8 Kissinger and Ozawa plot for ABS/MWCNT/nanoclay blend

Table 6 Kinetic parameters of ABS/MWCNT/Nanoclay blend using Ozawa and Kissinger Ea (KJ/mol)

A (s−1 )

Liner correlation coefficient (R2 )

Ozawa

127.34

8.21 ×

10–4

0.93

Kissinger

114.61

7.42 × 10–4

0.95

Method

Experimental Investigations on the Effect of Carbon Nanotubes … Table 7 Hardness of pure ABS and ABS/MWCNT/ nanoclay composite

301

Sl. No.

Material

Shore D Hardness

1

ABS

67.2

2

ABS/MWCNT/Nanoclay

70.4

mol by Kissinger model. The data indicate that combining MWCNT and nanoclay enhances thermal stability.

6 Mechanical Characteristics 6.1 Effect of MWCNT and nanoclay on hardness of ABS The hardness of both pure ABS and ABS/MWCNT/Nanoclay blend is determined using shore D hardness. The hardness of the samples are tabulated in table 7. The outcomes demonstrated that adding MWCNT and Nanoclay boosted the ABS’s hardness because those additives make the samples surfaces more durable. The hardness of ABS/MWCNT/Nanoclay blend corroborated with the findings of Vacha and Mamaghani et al. [12, 13].

6.2 Effect of MWCNT and nanoclay on impact strength of ABS The samples of pure ABS and ABS/MWCNT/Nanoclay blend are subjected to the impact tester to check the effect of additives on the impact strength of the ABS. The results are tabulated in the Table 8. The obtained results are averaged for two samples. The findings demonstrate that the ABS’s influence has been lessened by the use of additives 8.335–4.985 kJ/m2 . Due to the increasing hardness of MWCNT and Nanoclay, the impact strength reduced and also the increased brittleness was due to the increment in the hardness of the sample. The marginal increase in the hardness leads to large increment in brittleness. So the impact strength of the blend is lesser than the pure ABS. The impact strength of ABS/MWCNT/Nanoclay blend corroborated with the findings of Vacha and Bor˚uvka [12]. Table 8 Impact test results of pure ABS and ABS/ MWCNT/nanoclay composite

Sample

Impact strength KJ/m2

ABS

8.335

ABS/MWCNT/nanoclay

4.985

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7 Conclusion The thermal behaviour of the pure ABS and ABS/MWCNT/Nanoclay blend is studied using simultaneous TGA and DSC. The behaviour is investigated in order to confirm the thermal stability of pure ABS and the blend in a nitrogen environment. • According to the TGA results, the addition of additives caused a 15 °C increase in the degaradation onset temperature and a complete absence of residue at the completion of decomposition. • The DSC data reveal that the inclusion of carbon causes an increase in the glass transition temperature of the blend.To comprehend how a material degrades, TGA and DSC are both essential and critical approaches. To comprehend the degradation process, the kinetic parameters activation energy and pre exponential factor are also assessed. • The onset temperature was earlier in the pure ABS than compared to blended ABS. The activation energy of pure ABS was found 73.67 kJ/mol using Ozawa and 69.36 kJ/mol using Kissinger modeland activation energy of ABS/MWCNT/ Nanoclay blend was found 127.34 kJ/mol using Ozawa and 114.61 kJ/mol using Kissinger model. The above results show that the addtion of MWCNT and nanoclay to ABS have enhanced the thermokineticproperties of ABS. • The effect of additives on the mechanical properties of ABS is examined by subjecting samples to hardness and impact tests. • The hardness number of ABS increased from 67.2 to 70.4 and impact strength decreased from 8.335 to 4.985 kJ/m2 with the inclusion of MWCNT and nanoclay. Acknowledgements The authors are grateful to the Center for Research and Development, The National Institute of Engineering, Mysuru for continuous encouragementand support to this work.

References 1. Jogi BF (2022) Influence of multiwall carbon nanotubes and styrene acrylic acid on morphology and thermal properties relationship of 80/20 PA6/ABS blends. Plastics, Rubber and Compos:1– 15 2. Rostami A, Masoomi M, Fayazi MJ, Vahdati M (2015) Role of multiwalled carbon nanotubes (MWCNTs) on rheological, thermal and electrical properties of PC/ABS blend. RSC Adv 5(41):32880–32890 3. Bilkar D, Keshavamurthy R, Tambrallimath V (2021) Influence of carbon nanofiber reinforcement on mechanical properties of polymer composites developed by FDM. Mater Today: Proc 46:4559–4562 4. Shishavan SM, Azdast T, Ahmadi SR (2014) Investigation of the effect of nanoclay and processing parameters on the tensile strength and hardness of injection molded acrylonitrile butadiene styrene–organoclay nanocomposites. Mater Des 58:527–534 5. Kumar S, Rath T, Mahaling RN, Das CK (2007) Processing and characterization of carbon nanofiber/syndiotactic polystyrene composites in the absence and presence of liquid crystalline polymer. Compos A Appl Sci Manuf 38(5):1304–1317

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6. Debnath N, Panwar V, Bag S, Saha M, Pal K (2015) Effect of carbon black and nanoclay on mechanical and thermal properties of ABS–PANI/ABS–PPy blends. J Appl Polym Sci 132(38) 7. Balart R, Garcia-Sanoguera D, Quiles-Carrillo L, Montanes N, Torres-Giner S (2019) Kinetic analysis of the thermal degradation of recycled acrylonitrile-butadiene-styrene by non-isothermal thermogravimetry. Polymers 11(2):281 8. Yang MH (2000) The thermal degradation of acrylonitrile-butadiene-styrene terpolymer under various gas conditions. Polym Testing 19(1):105–110 9. Bano S, Ramzan N, Iqbal T, Mahmood H, Saeed F (2020) Study of thermal degradation behavior and kinetics of ABS/PC blend. Pol J Chem Technol 22(3) 10. Ujfalusi Z, Pentek A, Told R, Schiffer A, Nyitrai M, Maroti P (2020) Detailed thermal characterization of acrylonitrile butadiene styrene and polylactic acid based carbon composites used in additive manufacturing. Polymers 12(12):2960 11. Lopes BJ, d’Almeida JRM (2019) Initial development and characterization of carbon fiber reinforced ABS for future additive manufacturing applications. Mater Today: Proc 8:719–730 12. Vacha J, Bor˚uvka M (2015) Mechanical properties of acrylonitrile butadiene styrene thermoplastic polymer matrix with carbon nanotubes. NANOCON 13. Mamaghani Shishavan S, Azdast T, Mohammadi Aghdam K, Hasanzadeh R, Moradian M, Daryadel M (2018) Effect of different nanoparticles and friction stir process parameters on surface hardness and morphology of acrylonitrile butadiene styrene. Int J Eng 31(7):1117–1122 14. Khun NW, Zhang H, Lim LH, Yang J (2015) Mechanical and tribological properties of graphene modified epoxy composites. KMUTNB Int J Appl Sci Technol 8(2):101–109 15. Deeraj BDS, Joseph K, Jayan JS, Saritha A (2021) Dynamic mechanical performance of natural fiber reinforced composites: a brief review. Appl Sci Eng Progr 14(4):614–623 16. Sathishkumar TP, Navaneethakrishnan P, Maheskumar P (2021) Thermal stability and tribological behaviors of tri-fillers reinforced epoxy hybrid composites. Appl Sci Eng Progr 14(4):727–737 17. Aravind SL, Sivapirakasam SP, Balasubramanian KR, Surianarayanan M (2020) Thermokinetic studies on azodicarbonamide/potassium periodate airbag gas generants. Process Saf Environ Prot 144:15–22 18. Billah KMM, Lorenzana FA, Martinez NL, Wicker RB, Espalin D (2020) Thermomechanical characterization of short carbon fiber and short glass fiber-reinforced ABS used in large format additive manufacturing. Addit Manuf 35:101299 19. Dul S, Pegoretti A, Fambri L (2018) Effects of the nanofillers on physical properties of acrylonitrile-butadiene-styrene nanocomposites: comparison of graphene nanoplatelets and multiwall carbon nanotubes. Nanomaterials 8(9):674

Molecular Energies of Lightweight Al, Cu and Alloys: Evaluation and Insights Aditya Kataria, Akarsh Verma, Sachin Sharma, Sanjay Mavinkere Rangappa, and Suchart Siengchin

Abstract Aluminium (Al) and copper (Cu) have been utilized widely by humans to produce high quality alloys since a long time. They also possess exceptional physical and mechanical properties that make them scientifically and industrially invaluable. All these properties are attributed to multiple energies inside the Al–Cu lattice and domain. This mini review aims at understanding some of these properties, namely cohesive energy and grain boundary energy, how it originates, methods for its detection and comparison, and its influence on Al, Cu and their alloys. These energies have been successfully calculated via experimental techniques, and compared with theoretical values and found to be accurate. Ultimately, we reviewed how these methods of investigation have varied overtime. Keywords Grain boundary energy · Cohesive energy · Copper · Aluminium · Aluminium–Copper alloys

A. Kataria · A. Verma (B) · S. Sharma Department of Mechanical Engineering, University of Petroleum and Energy Studies, Dehradun 248007, India e-mail: [email protected] A. Verma Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan S. Mavinkere Rangappa · S. Siengchin Department of Materials and Production Engineering, The Sirindhorn International Thai-German School of Engineering, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand 10800 © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_23

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1 Introduction 1.1 Cohesive Energy When atoms inside a metal are structured to form a crystalline state, these atoms acquire an energy. This energy is termed as cohesive energy. High cohesive energies indicate tight links between the bonded atoms and materials with such high cohesive energies exhibit considerable mechanical strength, like insulators. The cohesive energies of metals having sp-bond electrons are exceptionally low. The crystals are only barely kept together by this form of metallic connection. Simple metals, such as sodium, have poor mechanical properties as single crystals. The crystals are mechanically similar to warm butter when they are at room temperature. Because these crystals are readily deformed, more caution is required while handling them. Metals come in a variety of topologies, but are majorly present in three configurations: hexagonal closed packing (hcp), face centred cubic (fcc) or body centred cubic (bcc). It must also be logical then to think that each topology has a different cohesive energy. Theoretical calculations, surprisingly present a different picture. The cohesive energy of any arbitrarily chosen metal turns out to be nearly the same in every potential crystal arrangement; hence, it can be said of crystal configurations that they turn out to be irrelevant when metals have their electrons bound in the sp-shells. Transition metals, which are metals with empty d-shells on their atoms, have a different sort of metallic bonding. Electrons tend to make a stronger bond to the d-shell when their bonding is compared to a sp-shell. This is due to the d-shell with the electron interacting with a d-shell on the neighbouring atoms to form a covalent bond. D-orbital bonding does not take place in a tetrahedral structure, but rather in a different direction. The bonds formed by d-orbitals in metals are not filled with electrons. The only notable exception to this case is the eight electrons present in a semiconductor’s tetrahedral bonds. The d-electrons show a similar ability in transition metals where they have the ability to form substantially stronger covalent bonds which is not possible in sp-electrons in basic metals. Transition metals have a much greater cohesive energy than other metals. Titanium, iron, and tungsten, for example, are exceedingly strong mechanically. The close-packed crystal structures of transition metals play a vital role in their behaviour [1]. Gaudoin et al. in [2] described the formula that describes the cohesive energy in terms of the bulk modulus and the volume of the unit cell. The said formula is mentioned in Eq. 1. B=V

∂2 E ∂V 2

(1)

The cohesive energy is calculated by first finding the value of the energy of the unit cell in its equilibrium state, which is at zero pressure. Then the energy of a single atom is found. The difference between these two values is called cohesive energy.

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1.2 Grain Boundary (GB) Energy Bulatov et al. in [3], electrical and thermal conductivity, hydrogen embrittlement, stress corrosion cracking, thermal coarsening, corrosion resistance, impurity segregation, and mechanical strength and ductility are all affected by grain boundaries (GBs) in crystalline materials [4]. The influence of the respective border to the physical attribute can mostly be determined by its surplus energy per unit area, that is determined by the boundary geometry or crystallography. Five macroscopic degrees of freedom (DOFs) establish the geometric character of a boundary, allowing for numerous different depictions, the most notable of which is in terms of grain misorientation (three DOFs) + boundary plane tilt (two additional DOFs) [5–7]. The GB energy, notably in face-centred cubic (fcc) metals, is anisotropic and can change dramatically with misorientation and inclination mutually [8–10]. The GB energy anisotropy has not been extensively measured, despite its acknowledged relevance and a great amount of experimental and hypothetical work on this particular issue. A notion of the GB energy dependency on plane inclination, which is tough to quantify empirically, is particularly missing. With rare exceptions, existing models of GB network evolution ignore GB energy anisotropy entirely or simply justification for the misorientation dependency of the GB energy, reflecting this lack of knowledge. Boundaries of the same grain misorientation could have significantly varying energies dependent on the GB plane orientation [9, 10]. Furthermore, except for nanocrystals, where the grains can spin, the capillary force that drives border motion is defined by changes in GB energy with plane tilt rather than misorientation. Both experimental measurements and atomistic computations demonstrate some common and persistent tendencies in GB energy fluctuations across materials of a certain crystallographic class (fcc, bcc, etc.), implying that lattice geometry is important in determining GB energy anisotropy. The tight correlations reported amongst the GB energy and the interplanar spacing linking lattices parallel to the boundary, as well as the size of the planar unit cell area, are particularly notable [11–14]. In a nutshell, this mini review will help to understand the properties namely cohesive energy and grain boundary energy, how it originated, methods for its detection and comparison, and its influence on Al, Cu and their alloys.

2 Aluminium 2.1 Cohesive Energy Aluminium is the 13th element on the atomic table with an atomic weight of 26.981. It crystallizes as a fcc lattice with a coordination number of 12. The crystal is retained from 4 K up to its boiling point. Gaudoin et al. [2] used two regular approaches for initial mathematical computations of solids’ cohesive energy, bulk modulus and

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lattice constant. First technique is DFT is usually inside the local density approximation (LDA), and second technique is multiple variations of Monte Carlo (MC). In DMC, DFT Kohn–Sham orbitals are frequently utilised. Still only a few metal MC investigations have been reported so far [15, 16]. It has been claimed that MC approaches may be insufficient for metals because of the computational complexity of working with huge simulation cells, that can be believed are required to model the partly filled bands of a metal properly. However, it was discovered that VMC is as exact for aluminium as for several common non-metallic compounds. The energy of a system with frozen point-like nuclei is calculated using electronic structure calculations. However, like electrons, nuclei are mechanical objects present in the quantum state. The properties of such minute mechanics on nuclei are often minor, nonetheless, they must be approximated when precise findings are desired. Such computations have recently been carried out using the quasi-harmonic approach, which requires the assessment of the complete phonon spectrum [17, 18]. This is a difficult undertaking that is currently impossible to do in a Monte Carlo context because effective sizes of Monte Carlo systems can only be increased to a limited unit cells using present day processors. The wavelengths of the phonons that may be investigated are limited by the system size. To determine the phonon contribution, another way is to utilise the Debye temperature (D). The corrected experimental values may then be calculated, which are directly equivalent to normal electronic assembly computations. The full-core atomic DFT calculation was carried out using a programme built by Fuchs et al. [19] inside the local spin density approximation (LSDA) [20] and involved relativistic properties inside a scalar-relativistic approximation [19, 21]. Boeckstedte et al. [22] provided a code that was used to do these LDA computations, using 20 Ryds of the value for the cut-off of the plane-wave and the LDA constraints of Perdew and Zunger [23]. A 10 × 10 × 10 fcc superlattice was represented by the grid. The results are associated to experimental data, which has been adjusted to exclude the effects of zero-point motion and finite temperature [24]. The existence of a Fermi surface, as well as the difficulty to accurately describe it in MC simulations with smaller simulation boxes, does not rule out the use of traditional MC methods in metals research. This could surprise you at first. It’s crucial to note, though, that applying the approach to MC results in a DFT-based finite-size improvement that compensates for variance in DFT total energy as density of DFT kpoint sampling mesh grows. This section discusses the one-body contributions to the MC finite-size mistake. The MC approach clearly addresses many-body correlation energy in physical space by proving exchange–correlation hole. Exchange–correlation energy is expected to converge quickly when size of simulation box is increased since hole is relatively short-ranged. As a result, the finite-size inaccuracy for many bodies is small. False interactions between the exchange–correlation hole’s regularly repeated copies generate the highest remaining finite-size error. This error may be dealt with using only the MPC interaction. Due to the numerical character of MC computations, there is the normal constraint. The arithmetic character of MC approach makes precise MC calculations of bulk moduli problematic considering energy derivatives like bulk modulus are particularly vulnerable to error in data. This

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restriction is in place for both metallic and insulating systems. Unlike much earlier research, we find that LDA yields a remarkably precise value for Al’s bulk modulus. The inclusion of finite-temperature and zero-point motion effects contributed to the precision of our conclusion. These factors suggest that the estimated bulk modulus for aluminium should be around 7% larger than the observed value, elucidating other authors’ seeming over valuating of the bulk modulus [25, 26].

2.2 GB Energy Saylor et al. discovered significant anisotropy in spreading of grain boundary planes at fixed lattice misorientations in 2004 [27, 28], and that same low index surfaces that govern the source of internal grain surfaces also dominate the distribution of equilibrium crystal shapes alongside crystal growth habits [29–31]. Additionally, an inversely proportional link has been found amongst the energy at a given grain border and the concentration of this energy in the supply [28]. A specimen on which the experimentation was done was cut from an aluminium alloy 1050 sheet. This sheet had been cold rolled for the purpose of reducing its thickness to 80% of its original value. To divide the orientation maps into grains with a continuous orientation, areas with similar orientations were widened until the tiniest grain had at least 8 adjoining data points, and then average orientation of each grain was considered and assigned to all points within adjoining area [32]. A previously described stereological technique [31] is used to derive GB feature distribution from these data. In the current study, grain boundary traces were retrieved from orientation maps using a method developed by Wright and Larsen [33]. Previous experiments, both computational and experimental in nature, have made It safe to assume that grain boundaries with high populations will similarly have low energies [28]. The key characteristics of the determined energy are replicated in detected populace: population upsurges at trivial misorientation angles like λ (60°/[111], [111]), and at the [311] 180° twist, which is also λ (50°/[110], [113]). Finally, while they are ∑3 and ∑11 lattice misorientations, it is not distinguishing property which sets these orientations apart from other boundaries. Equivalent lattice misorientations occur inside the same set of symmetric tilt borders, but they have no energy or population differences. The boundary that aids the development of the plane distinguishes small energy configuration from superior energy configurations alongside the identical lattice misorientation in this example. Grain boundary populations have a substantial link amongst surface energy anisotropy, which has been established in previous studies [29–31]. Low-energy grain boundaries along with low-index planes correlate to distribution local maxima. In ceramics like MgO, SrTiO3 , TiO2 , and MgAl2 O4 [29, 34], where surface energy anisotropy is considered to be substantial (less than one tenth), the connection is fairly striking. In these instances, asymmetric borders by means of one of 2 grains ended by a low index face are preferred above more symmetric barriers with lower energy predicted due to atomic coincidence in the grain boundary plane.

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The most common planes in a Fe–Si alloy with a body-centered cubic structure were {110} planes, but tendency was fainter than in additional anisotropic ceramic systems [35]. The (111) surface has the least amount of energy, (110) has the greatest, and (100) is halfway, according to studies of microscopic holes in aluminium [36]. The overall anisotropy, on the other hand, is just 5%. The fact that the populations of (111) twists, (100) twists, and (100)||(111) formations are each greater than twist boundaries formed up of former surfaces shows that these grain boundaries are made up of planes or surfaces with lesser energy. The grain boundary energy must be equal to the total of the energies necessary for the generation of the neighbouring surfaces, less the energy freed as 2 surfaces are linked and atoms present from nearby crystals materialize bonds and lessen to lower energy formations. The binding energy refers to the later contribution. The binding energy increases with the average interplanar separation of the two surfaces next to the border, according to theoretical estimations [37, 38]. For case of ∑11 misorientation, λ(n|50/[110]), peak is at [113] position. This boundary may alternatively be represented as a 180° twist around the [311] axis, with all 180° twists with indices [w11] having reasonably large concentrations. Because low energy is not anticipated based on the assumed binding energy anisotropy, it could be conjectured that a distinct coincidence relationship within boundary plane could improve binding energy more than projected based on the spacing between the planes, which could lead to a decrease in energy. Wolf [13] used atomistic simulations to study the relationship between cleavage energy, GB energy, and boundary crystallography. He observed that energy of high-angle GBs formed by chance is inversely proportional to configuration of terminating plane at boundary. He also established that cleavage energy is inversely proportional to GB energy, and that grain boundary energy balances cleavage energy for common borders. Also, only boundaries based on {113} and {111} planes have remarkably low energies; whether a Lennard–Jones potential or an inter-atomic potential adapted to characteristics of gold was used in the computation, the findings were substantially the same. It is not feasible to relate the detected population to the energy of such boundaries since Wolf [13] did not analyse borders with {100}||{111}. Overall, grain boundary energy couls not be aided by atomistic simulations to show a substantial relationship with average surface energy, which is consistent with the boundary population data. In economically pure aluminium, GB character distribution is relatively isotropic. Grain boundaries, on the other hand, have a definite propensity to dismiss on low index planes with equally fewer surface energies and higher value of spacing between planes. While grain borders ending by {111} planes have the largest populations, certain grain boundaries terminated by higher index planes, such as {113}, also have larger concentrations than would be predicted in an arbitrary distribution.

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3 Copper 3.1 Cohesive Energy Parrot et al. in [39], examined that numerous computations of the band structure of crystalline copper were done [40–48]. Various features, like the density of states and Fermi surface, have been examined. The Xα technique [49], which is developed from Slater’s statistical approximation exchange potential and guides to easy equations inside the autonomous particle model, has been believed to yield relatively accurate findings for a system’s ground state properties. The whole energy of solids may thus be calculated by combining the Xα exchange with the A.P.W. approach for calculating electron states. Numerous computations on alkali metals confirm said viewpoint along with demonstrating, when given a good adoption of the exchange constraint α, errors of less than 10% may be expected, at least for the heavier alkali metals [50, 51]. An extremely precise A.P.W.-Xα software was deployed that was able to calculate 7 varying values of the lattice constant for the the electron density of f.c.c, copper. The foundation was thought to be made up of 18 electrons, however it was shown to be up to the 3p 6 shells. Atomic-like wave functions were used to describe new potential at each iteration. For the unbound atom, a self-consistent technique was used to compute the maximum value of the lattice parameter. The theorem 3PV = Et + Ec is met in this model, and the pressure P was derived using it. Here V is unit cell volume, Et is total energy and Ec is kinetic energy per cell respectively. At the normal, adjusting the constant to produce a zeropressure using Xα as a semi-empirical technique is required and for that purpose the lattice constant value is set as aex = 6.83087 a.u.. Interpolating the values found at yielding α = 1 and with α = 2/3, the pressure at α = 0.7936 was found. The variance of total energy amongst the two latest reiterations was less than 1 × 10–3 Ryd at every value, whereas non-variational kinetic energy fluctuations turned out to be 5 × 10–3 Ryd. The pressure has an average uncertainty of roughly 10 kbar because of this. The energy fluctuations of E t and E c as well as the pressure P, are all function of the lattice parameter ‘a’. Because of linear determination of α, P = 0 is only roughly met for a = aex . ao = 6.57 a.u. is determined to be the equilibrium parameter. The cohesive energy, which is compared to the investigational result [52]: 0.259 Ryd. turns out to be 0.250 Ryd, indicating an extremely well agreement. The compressibility − V[(∂P/∂V](a=ao) was also computed, and the tile value of 1470 kbar produced matches the investigational value of 1390 kbar rather well. Hence, the X α approach is a handy and practical way for computing the bulk characteristics of a system.

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3.2 GB Energy Mclean, in [53], emphasized that dislocation theory had models that reasonably offered low-angle tilt and twist borders, the assembly of large-angle grain boundaries remained a source of controversy. Brandon et al. [5] expanded Hargreaves and Hills’ [54] coincidence-lattice model, which imparts specific features for borders amongst crystals that have been oriented to coincide a percentage of each crystal’s lattice sites. Even little deviations from the coincidence orientation impair the degree of coherency linked with such kind of boundaries. Other authors [55] have suggested that even if the crystals do not appear to have a coincidence-based connection in the boundary plane, it may be accomplished. According to Brandon [56] and Bollmann [57], border coincidence might be achieved among crystals that differ little from a coincidence misorientation (by 10°) by superposition of a regular array of dislocations, or steps, on tiny coincidence-lattice boundary. It’s more straightforward to consider two aspects of grain-boundary energy anisotropy. To begin with, altering the border orientation between crystals with fixed misorientation produces an effect comparable to surface energy anisotropy. Grain boundaries are more sensitive to fluctuations in grain-boundary energy caused by crystal misorientation. Highly pure copper wire with a diameter of 0.13 mm was strengthened in dry hydrogen for 2 h at 1030 °C. Electron microscopy was used to investigate the grain-boundary groove profiles, with a specimen container proficient of spinning the sample in the electron beam around the wire axis. Standard Laue X-ray back-reflection methods were used to determine grain-boundary orientations. A KDF9 computer developed in Algol was used to analyse the data. Similar sheet material was made and annealed under almost identical circumstances. Interference microscopy was used to evaluate the groove profiles, and a twin-trace approach was used to identify the crystal orientations. Only one high-angle grain boundary was discovered to split crystals with a high coincidence misorientation, out of twenty that were extensively investigated utilising wire specimens. σ/γ_100 = 0.32 ± 0.01 revealed no substantial fluctuation in grain-boundary energy at non-coincidence borders. However, one grain-boundary energy was shown to be significantly lower when separating crystals that were misoriented by a 50º 30' (±1º) spin along a [110] axis: σ/γ_100 = 0.26 ± 0.01. The incoherent twin-boundary energy does not vary much with boundary inclination: σ/γ_100 = 0.21 ± 0.01. This indicates that σT plot has a circular cross-section normal to the twinning plane’s axis. The border energy between twinned crystals (i.e. [110] 70º 30' rotation) is, on the other hand, around three-tenths lower than ordinary high-angle boundary energies. There is minimal variance in high-angle grain-boundary energy under the experimental settings given. Boundaries separating crystals with high coincidence (∑ = 3 and ∑ = 11)*, on the other hand, have substantially less energy. Since ∑ = 3 and ∑ = 11 borders have around 33 and 9% coherencies respectively, one may anticipate grain-boundary energy drops to be comparable in size. Experiments show reductions of 33 and 20%, respectively. The misorientation of neighbouring crystals was not under any control. As a result, no information on the high-coincidence ∑ = 5, 7, and 9 borders is

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provided as they did not happen inherently in the specimens studied. The observations of incoherent twin-boundary energy imply that at great temperatures, fixed crystal misorientation has minimal reliance on boundary inclination. Except for the ∑ = 3 and ∑ = 11 borders, where the anisotropy of grain-boundary energy is fewer than 10%, our results show that the σT plot is typically spherical with a pronounced cusp at the coherent twin-boundary orientation. This is far lower than the expected anisotropy. The calculations, however, do not take into account either configurational or vibrational entropy, therefore they solely pertain to 0 K. The depth of a certain grain-boundary cusp can be determined by estimating the dislocation array’s energy and entropy. According to Ishida and McLean [58], the Burgers vectors of dislocations associated with such arrays are fewer than those of lattice dislocations.

4 Aluminium Copper Alloys Due to the superior combination of mechanical, physical, and tribological qualities of them over base alloys, aluminium and aluminium alloys are acquiring significant industrial importance. Seizure and wear resistance, high specific strength, increased high-temperature strength, regulated thermal expansion coefficient, stiffness and improved damping capacity are among these qualities [59]. The inclusion of copper as principal alloying element (usually in the range of 3–6 wt%), with or without magnesium as an alloying ingredient (usually in range of 0–2%), permits solidification of the material via precipitation hardening, which results in extremely strong alloys. In addition, the wear and tear qualities of this series are excellent. Copper is prone to pitting, intergranular corrosion, and stress corrosion because it likes to precipitate along grain boundaries [60]. The strength of alloy can be increased by precipitation hardening up to 12 wt% copper, the presence of Mg is optional; hardening is attained by the precipitation of Al2 Cu or Al2 CuMg intermetallic phases during ageing, which results in strengths just next to highest strength 7xxx series alloys [61]. After altering proportions, the copper in the alloy, it was discovered that as the percentage of copper in the alloy grows, the ultimate strength, hardness, and fatigue of the alloy increases as well. The alloy with 11% copper has the highest ultimate strength (114.28 MPa) [62]. In 2009, Dolgopolov et al. [63] examined the grain boundary diffusion (GBD) of copper in aluminium in the temperature range of 300–400 °C. The research was carried out using a scanning electron microscope with an electron probe X-ray microanalysis attachment. The Fisher criterion was used to calculate the triple product sδDgb (s is used to define the segregation coefficient which is GB width, and δDgb is GBD coefficient). EPMA [64] and AES [65, 66] methods, as well as the development of the phases [67, 68], were used by the authors of [64–67] to explore the GBD in thin films. The GBD was examined for bicrystals. The angle in the vertex of the diffusion wedge was found in by depositing a copper layer of only a few angstroms, the layers of Mg + Cu were employed as the source of copper, and the GB was examined at higher temperatures (> 0.7 Tm Al) using EPMA. Copper was deposited via evaporation in all of the works. All of the

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Fig. 1 Schematic of molecular dynamics simulation simulation box/set up (Adapted from the Ref. [74])

evidence points to an activation energy of around 90 kJ/mol, which is slightly lower than our findings. The EPMA technique was used to explore coppers grain boundary diffusion in aluminium in the temperature range of 300–400 °C. For the values of triple product obtained by measuring the concentration and angles at vertex of this intensity profile was determined using an optical microscope. sδDgb was 5.1 × 10– 11 × exp[102000/(RT)] m3 /s in the first example and 1.4 × 10–11 × exp[– 94,000/ (RT)] m3 /s in second, respectively. A review of the data in the literature revealed that the activation energies in all works are similar, ranging from 77 to 102 kJ/mol. Hu et al. in [69], reported the cohesive energy to be AlCu (B1) 3.69 eV. Further readings are suggested by the authors in molecular dynamics (whose working methodology is discussed by Kumar et al. [70] and an example of the simulation box is shown in Fig. 1 [71] and characterization of composites materials field [72–104].

5 Conclusion GBs are the defects/faults that possess an excessive amount of free energy per unit area. In this mini review, the authors have reported the various experimental techniques that have been acquired to evaluate the GB and cohesive energy for Al, Cu and their alloys. Although, the material along the grain border is preferentially deleted during most thermal and chemical etching techniques but still the GB energy is prevalent. On the other hand, on comparing with gas state, cohesive energy is the energy acquired by organising atoms in a crystalline structure. Both these energies play a major role in how a metallic alloy is made. The authors still believe that there are enough research gaps in the computational field (especially molecular dynamics simulations) regarding the calculation of these energies. In particular, developing better interatomic potentials would be a challenging task for the atomistic-scale simulations scientists.

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Acknowledgements Corresponding author would like to appreciate the financial support from SEED Grant of University of Petroleum and Energy Studies, India.

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Impact of Different Parameters on Adhesively Bonded Composite Joint on Shear Strength—A Review Vinayak S. Hiremath , D. Mallikarjuna Reddy , Rajashekara Reddy Mutra , and Gopalan Venkatachalam

Abstract Composite materials, the new revolution in the aviation, automotive, and marine industries, are taking over from conventional materials because of their excellent strength-to-weight ratio. Over the past few decades, adhesive joints have become increasingly popular and have grown in popularity as a result of the rising requirement for lightweight materials, as well as their superior mechanical specificity and design adaptability. The current article reports a detailed review of recent developments in composite joints and the primary factors that influence the joints, like bonding technique, adherend surface preparation, geometrical factors, environmental effects, etc., as well as the impact of Nano-fillers like multi-wall carbon nanotubes (MWCNT) and graphene Nano-particles (GNP) on composite joints to enhance the shear strength and tensile load. By inventing different materials, procedures, and models over the past few years, many issues have been fixed. Nevertheless, there is always a chance to assess and determine the ideal set of factors that would boost the effectiveness of composite adhesive joints. The impact of fibreglass pin introduction on the shear parameters of composites made using various procedures, such as co-curing, cobonding, and secondary bonding processes, as well as the impact of metallic and carbon fibre pin introduction on composite joint strength and fatigue resistance. Lastly, remarks are made addressing the most significant unresolved issues in this field, along with suggestions for further research.

V. S. Hiremath · D. Mallikarjuna Reddy (B) · R. R. Mutra · G. Venkatachalam School of Mechanical Engineering, Vellore Institute of Technology, Vellore, Tamilnadu 632014, India e-mail: [email protected] V. S. Hiremath e-mail: [email protected] R. R. Mutra e-mail: [email protected] G. Venkatachalam e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_24

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Keywords Bonding parameters · Adhesive joints · Nano-fillers · Analytical model · Mechanical properties · Environmental effect

1 Introduction The usage of adhesive bonding has risen recently across all industries, because it is better in many ways, including its high strength and low weight, flexibility in design, and damage liberality over traditional method. In reality, adhesive bonding has found use in many of industries, including those in the construction, sports, maritime, oil, electronics, automotive and aviation sectors. In all of the afore mentioned industries adhesively bonded connections are being used more often for the composite repair of damaged components. Many studies have demonstrated that due to their intrinsic qualities, polymer-based composites are quickly replacing all other materials in a variety of applications [1]. The most commonly used polymer materials are carbon-based polymers (CFRP), glass-based polymers (GFRP), Kevlar fibres etc., Numerous joint designs are described in the research; the most widely used ones include single-lap joints, steplap joints, scarf joints, and double-lap joints. The joggle bend lap joint, which is frequently used to attach aircraft fuselage halves, patches, and the L-section joints, which are used to connect internal structure to the outside coverings of wings, are other, less explored forms that have also been employed [2, 3]. Many researchers have worked on the different joint parameters till now, and based on that, some are presented with varying adherend thickness, width, and adhesive thickness, which give the best performance in improving the bond shear strength. Matsuzaki et al. [4] performed the experimentation on the shear properties and fatigue strength of the aluminium alloy A-5052 F and found that it improved shear strength by 1.8 times compared to conventional co-cured joints. Adhesively joining and mechanically fastening are combined to create hybrid composite joints, which are considered to combine the benefits of both joint types. Three different methods are adopted to increase the strength of joints: adhesive bonding, bolting, and bondingbolting composite joints [5]. An experimental investigation was conducted on a flatjoggle-flat joint, and the results showed a 90% improvement in failure load compared to a single-lap joint [6]. Dhilipkumar et al. [7] look over the influence of multi-wall carbon nanotube (MWCNT) and co-cure technique on the shear parameters of a single-lap joint, and the results showed that the addition of 0.25 wt% of MWCNT improved the shear properties by 104.25 and 88.2% as compared to co-bonding and secondary-bonding joints. Due to their fascinating features, graphene-based 2D nanoparticles have promise for a variety of sensing and biosensor solutions [8]. The weakest components of a structure determine its ability to support loads. Thus, in bonded composite joints, it is preliminary action to consider the interaction among adherends, adhesive in consideration of stress and strength under specified loading conditions. With the advent of numerous surface preparation methods, including

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sandblasting, anodizing, sandpaper abrading, and plasma treatment, their appropriateness for various types of materials has now been thoroughly investigated, which defines enough interface strength among the laminates [9]. Somehow, because of the poor transversal strength of the composites and the notable peel stress that develops in the composite joints, the bonding of composite laminates is extremely vulnerable to delamination, a prior failure mechanism in which the composites crack between the laminates. When both the failure happens at the same time, the maximum shear strength can be obtained [10]. Due to the fact that construction is often associated with structural loads and settling demands, geotechnical conditions, and a specific site, deep foundations are frequently recommended and also use composite materials [11]. Delamination, particularly in joints with higher overlapping lengths, is one of the primary failure mechanisms as well as one of the performance-restricting variables of bonded joints using adherends. In continuation to successfully enhance the load-bearing capacity of adhesive material connections using composite adherends and postpone the onset of delamination, fresh materials and procedures must be applied. The demand for strong and long-lasting joints is rising as adhesive joints are increasingly used in high-stakes structures. Concerning the strength prediction methodologies and strength influencing variables, numerous evaluations have been written [12]. The limitations of the current methods for enhancing the strength of adhesive junctions with composites adherends are thoroughly examined in this research. These methods typically focus on strengthening composite adherends while lowering the strength intensity of the adhesives as well as the adherends. The benefits of thermoplastic composite materials over composite materials include enhanced fracture toughness, less moisture absorption, the possibility of lowered life cycle costs, and renewability [13]. The current work provides an overview of recent changes to the key parameters, i.e. joint configuration, adherend and adhesive selection, material property, surface preparation, environmental conditions, failure mode, and nano-fillers in joints, which enhance the tensile load and shear behaviour of the adhesively bonded composite joints.

2 Impact of Different Parameters on Bond Strength 2.1 Bonding Technique Some of the issues to consider while creating a bonded joint are related to the bonding technique. The bonding technique has an impact on most metrics including the failure mode, failure process, and joint strength [14]. Co-bonding, secondary bonding and co-curing, and are the three fundamental manufacturing bonding procedures used to form the bonded connections between composite substrates.

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Fig. 1 Different bonding technique of composite materials a Secondary-bonding, b Co-bonding, c Co-curing [7]

Co-curing is the technique of concurrently bonding a composite laminate to another uncured material while allowing it to cure, the technique of curing two or more components simultaneously while ensuring that at least one of them is fully cured and the other isn’t is known as co-bonding, in secondary bonding process when two or more pre-cured composite pieces are joined together via adhesive bonding, the only chemical or thermal reaction taking place is the adhesive curing itself. Due to the decreased number of components and curing cycles, co-bonding or co-curing is typically preferred than secondary bonded joints, Consequently, this technique is the one that is most frequently employed to repair composite constructions. The effects of various bonding techniques under tensile stress, including co-cured joints, co-bonding, and secondary bonded joints as illustrated in Fig. 1. Mohan et al. [15], discussed the influence of different bonding methods and found that co-cured joints have less shear properties compared to co-bonded joints, because moisture from the layup was liberated while curing and dispersed throughout the adhesive layer, the interfaces were weakened, and the co-cured joints’ strength was reduced [16]. It needs to be emphasised that while fabricating bonded composite joints, consideration should be given to moisture content prior to joining as well as other variables such as cure temperatures and adhesive material. Hence, it’s crucial to choose the manufacturing bonding process carefully, particularly when using the composite restoration damage identification process [16]. Numerous studies looked into how inter-bonding affected strength properties and they discovered that it had a favourable impact on how well bound structures performed. Consequently, intelligent material selection is the solution to building lighter structure.

2.2 Laminate Surface Composing In pursuit of enhancement the quality of the adhesive joints, surface preparation also has a significant impact. The adherends’ surface treatment must meet the necessary features in order to produce a robust and resilient joint: the elimination of all pollutants on the surface of the adherends, wettability, and surface energy. There have

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Fig. 2 Surface image of composite adherends [18]

been numerous physical and chemically effective surface treatments available, and choosing them is a very critical issue [17]. Initially a surface preparation is needed using abrasive paper, or by any peep-ply methods, as shown in Fig. 2 [18], it can prevent contamination like dust or humidity. Azari et al. [19] focuses on how surface finish affects the behaviour of fractures and wear in adhesive materials. In mode I and mixed mode fatigue loading a notable dependency was observed on surface roughness, so it very important to overcome the issue on improving the fatigue parameters of the composite joints.

2.3 Geometrical Factors 2.3.1

Configuration of Joints

The joint configuration should evenly distribute stress so that it does not increase local stress concentration and fail prematurely. There are many factors that affect the joint structure, like peel stress and interfacial stress. Different types of joint configuration were discussed and have been used for current engineering applications [20]. The joint strength of the composite joint will reduce because of stress concentration at the overlap end, to overcome this issue many researchers have discussed different

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joint configurations. Kishore and Prasad [6] introduced the new proposed design of the flat-joggle-flat joint over the single-lap joint to minimise the eccentricity, due to the joggle bend, and increase the failure load up to 90%. Several techniques has been introduced to lower the peel stress by many researchers like edge filleting of the joint ends, tapered sections, adherend width, thickness and various adhesives, the tapered geometry and bi-adhesive improves the joint strength and get rid of singularities [21]. Internal tapering and filleting can reduce peel stress, but producing the specimens by hand lay-up is extremely difficult [22]. Ply orientation and stacking sequencing are also critical in improving the failure load in composite joints as well as low-velocity impacts [23]. Comprehensively, different joint parameters like adherend thickness, adherend width, tapering of adherends, stacking sequence, etc., play an effective role in enhancing the composite joint’s performance. Over-Lap Length As the overlap length escalate, the strength of the composite joints also improves, because of the enlargement in the bonding area. The adhesive and adherend have a direct impact on bonding strength improvement. The enhancement in the failure load was improved up to certain limit as the over-lap length increased in adhesive material, some of the cohesive failure in composite joints was also observed within the over-lap length between 10 and 20 mm, than next inter-laminar failure began [24]. The proper over-lap length will directly effect on the failure load shear strength of the composite joints. Adhesive Thickness The influence of adhesive thickness on composite bonded joints was studied by many researchers, based on experimental method, analytical methods, finite element analysis methods. The strength of the joint will decrease as the thickness of the adhesive is increased, because there will be more defects in the bond-line region like pores, cracks, and high interfacial stress [25]. Fracture energy in the composite joints will grow as the ductile adhesive thickness is increased whereas for brittle adhesive it will decreased the energy, whereas numerical analysis results also confirmed the same [26]. According to appearances, toughness appears to rise with adhesive thickness and peak at a particular thickness, say 1, 1.5, and 2 mm [27], above that it will adhesively fracture. To summarize, it’s crucial to take the adhesive qualities, geometrical factors, and loading types into account while attempting to maximise the adhesive thickness. Bond-line surface of adherends as shown in Fig. 3.

2.4 Selection of Materials Adhesive Material The majority of the manufacturing industries need innovative adhesive material with enhanced qualities that should meet the criteria needed for a particular application,

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Fig. 3 Co-cure joint surface a bond-line smooth surface b bond-line rough surface [28]

Innovative adhesive materials with more advanced capabilities are developed to meet the desired requirements. Despite the availability of numerous adhesive materials on the market, selecting the right adhesive material for the specific purpose is a difficult task because it is dependent on a number of criteria (curing time, temperature, atmospheric conditions, bonding property) [29]. In the present condition, the common usage of adhesives joining in manufacturing is a significant development, but the reprocess of joined parts poses key difficulties, mostly due to environmental considerations, to address this issue, the adhesive joining should be easily dis-bonded without causing damage to the structure [30]. Chemical foaming compounds and thermally expanding particles (TEPs) have attracted increasing interest since they may be simply included in current adhesive formulations. There have been numerous recent advancements in the elegant adhesive materials, including self-healing and dis-bonding sticky polymers, Smart epoxy materials with self-healing capabilities can enhance structural lifespan and are often less expensive than repairing damaged structures [31]. The fracture toughness has been improved in polymer composite by adopting the micro capsules, and dicyclopentadiene self-healing method was also adopted [32]. However, studies involving the use of self-healing material in adhesive joints are still in their early phases, and there remain plenty of technological obstacles to overcome before the principles of self-healing can be implemented in the bonded joints. One more innovation is the invention of impact-resistant adhesives that are more deformable than traditional epoxies and have higher strength and impact resistance, such adhesives were especially important in the manufacturing industry. Numerous researchers present research on the application of reinforcing particles and strategies to enhance the toughness and several parameters of structural adhesive [33]. Adherend Material Particular care must be given when selecting the adherends because various materials react independently and have an impact on how well joints function in the end, when joints were bonded using various adherend materials under similar circumstances, a substantial variance in strength was seen [34]. Additionally, due to its benefits over other adherend joints of the same nature, the multi-material adherend joining approach is becoming more and more popular, the adherend material should enough to withstand the load.

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3 Environmental Effects on Joints The major environmental factors that affect the composite joints are temperature and moisture, due to this effect the bond strength of the joint will decreased. Moisture is the main issue where it can directly effect on performance of the joint. Pre-bond moisture research examines how the substrate’s moisture concentration affects the joint’s ability to operate mechanically after bonding [35]. A composite structure’s ability to absorb moisture over the service term depends on the different factors, including the adhesive, adherend, bonding procedure, exposure factors and timing, cure temperature, etc. [36]. Moisture can affect the adhesive, adherend and its mechanical properties along with producing more cracks, plasticization and down in transition temperature, on the opposite side, resin have been shown to become more ductile when exposed to moisture, although their toughness and elastic modulus both decreased. Moisture was predicted to extract the resin and plasticize it, resulting in the loss of adhesive ductility after repeated exposure to moisture [37]. Another main aspect crucial to the long-term endurance of adhesive junctions is the interfacial adhesion’s resistance to moisture, it is frequently discovered that the breakdown of the content is substantially greater than that of the epoxy [38]. Many researches were carried out on the impact of moisture and found the deterioration of adhesive joints as a result of moisture and the ageing process [39], the reduction in the strength depend on exposing to environmental scenario, exposed time and joints combination, Low interfacial failure and adhesion plasticization are two potential causes of the decline in strength [16], and completely drying is the good option to regain the strength. Therefore, it is crucial to take these factors into account while designing and repairing a particular adhesively joined composite material under the influence of various moisture conditions.

4 Impact of Nano-fillers 4.1 Carbon Nano-tubes (CNT) Based The fibre and the matrix are the main aspects that improve the mechanical parameters as well as the strength of the fibre-reinforced polymer composites. In order to enhance the characteristics of those FRP composites, researchers employed short and long fibre reinforcements as well as nanofillers such as graphene, nano-clay, alumina and carbon nanotubes (CNTs) [40]. Yip et al. [41] Reported that there was an improvement in flexural strength of 9.2% with the inclusion of 0.75 wt% CNT. The effect of nano-clay as well as CNT on the impact strength of Kevlar-epoxybased composite laminates was studied, and the results showed that, in contrast to graphene, nano-clay improved the resistance by 26.8% [42].

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Fig. 4 Tensile test of neat and CNT based composite joints. a Load versus displacement b tensile strength versus CNT wt% [43]

To enhance the load-bearing capabilities of tensile test specimens made using various production techniques, CNTs having six distinct weight ratios (0.25, 0.5, 0.75, 1.0, 1.25, and 1.25 wt%) were utilised. Figure 4a showed that the load-bearing ability of co-cured composite was enhanced when CNTs were used in composite laminates as opposed to co-cured composite without CNTs, An exciting finding from Fig. 4b was that the tensile strength and load-bearing capacity of a composite made using a co-curing technique with 1 wt% CNT reinforcement were improved, whereas they were lower for a co-cured composite without CNT reinforcement [43].

4.2 Graphene Nano Particle Nanoparticles enable thin bond line thickness and, as a result, reduce the embrittlement threat in large epoxy materials, which can increase joint efficiency. The electrical, thermal, and mechanical behaviour of polymeric materials has been improved by using graphene as a reinforcing material [44]. The introduction of specific nanoparticle compositions can improve an epoxy’s adhesion strength by enhancing the epoxy’s cohesive strength and decreasing residual strains at the interphase, the lap strength can be enhanced by 50% using CNT or grapheme [45]. Bali and Topkaya [46] investigated fatigue behaviour of single lap joint using different graphene nano-particle wt% like 0.25, 0.5, and 1 wt%, and results revealed that improvement in tensile strength and 0.5 wt% GNP showed maximum fatigue life. Çetkin [47] worked on various ratios of GNP (0.1, 0.2, and 0.3%) and nano-fibres on double over lap bonded joints, and results found maximum tensile load of 19,258 N was achieved.

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Fig. 5 Force and displacement of the joints using 0.1 and 0.2% GNP and nano fibre [47]

The addition of GNP and nano fibres in adhesive enhances the load bearing ability and shear properties in the composite joints, Fig. 5 shows the improvement in the tensile load in 0.2% of GNP and nano fibre as compared to 0.1%. There is no much improvement in only addition of GNP, but along with GNP plus nano fibre gives weightage to the joints [47]. The above discussion disclosed that, the addition of GNP in any ratios in the adhesives gives the good results as compared to neat composite joints.

5 Methods to Analyse the Composite Joints The analysis of composite joints has been carried out by different methods, say, analytical methods and FE methods. Analytical methods are easy, time-consuming, require experimentation, and have high perfection but are difficult for complex types of geometries. While finite element analysis can handle complex geometries, different models, and so on, the only drawback is that analysis time is longer.

5.1 Analytical Methods An analytical method can be used for the early development of bonded joints, reducing the expense of testing and assessment of the joints. Many researches have been conducted on analytical and numerical methods of adhesively bonded joints. Icardi and Sola [48] generated improved 3-D zigzag plate models with hierarchic descriptions of displacements throughout the thicknesses that precisely recorded interlaminar stress with minimal computation effort. It is widely recognised that

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the interfacial stress gradients in the adhesive layers can be greatly influenced by the boundaries and loading circumstances. There are currently no easily accessible, practical techniques for determining interfacial stress distributions. Timoshenko’s beam theory and the energy technique were used to provide a unique mathematical method for composite joints are subjected to a range of boundary and loading conditions. Depending on the thickness of the adhesive layer, shear stress distribution changes significantly, especially close to the ending points [49].

5.2 Finite Element Method Finite element analysis, in addition to the design of the joints, the materials’ characteristics and other boundary constraints also have an impact on how adhesively joined joints behave mechanically. Finding an entire framework of governing equations for forecasting the physical properties of bonded joints is becoming more challenging due to the growing complexity of joint design and its three-dimensional nature. Additionally, it is challenging to include material non-linearity resulting from plasticity behaviour in systems since the analysis and mathematical formulation become highly complicated. However, the investigations are frequently expensive and timeconsuming. So, it is advisable to use mathematical solutions produced by FEMs. The research contains a number of approaches for finite element analysis (FEA) of adhesive joints.

6 Challenges and Prospects The cost-effectiveness, dependability, and adaptability of adhesive bonding make it an appealing approach that is continuously expanding for attaching materials and structures. In certain cases, it is chosen over alternative mechanically connecting methods like riveting and bolting because it can join a wide variety of materials and reduce the stress concentrations in the pieces to be joined. Owing to its ongoing need for lightweight, more durable, and ecologically friendly materials, the automobile industry has made adhesive bonding one of the most important industrial areas in recent years. Consequently, it is very important to continue to improve this type of bonding by creating functionally graded adhesive connections. compositional and/or structural change is continuous throughout a position, enabling a more even distribution of stress along its bondline. Mostly because of their potential for significant levels of modification, which might provide additional design alternatives and solutions, such joints have a lot of promise for use.

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7 Conclusion A number of different methods, parameters, and techniques have been studied in this review work. Joint geometries have the greatest impact on joint strength because they directly influence how adherends and adhesives are loaded, despite the fact that they are typically required in specific situations. The other parameter is material selection, which will influence the mechanics of the joints, the adhesive and its behaviour under loading conditions, and the bond-line thickness between them to improve the joints’ strength. Environmental effects, specifically moisture before and after bonding the joints, and their behaviour in the impact of bond strength enhancement as well as composite joint repair Failure modes in the joint structure like adhesive failure, cohesive failure, and debonding between them under loading conditions. The influence of nano-fillers in enhancing the strength of composite joints, especially 1 wt% MWCNT, enhances the shear strength as compared to other combinations. Graphene nano-filler improves the fatigue life as well as the tensile load with a 0.5 wt% addition in the adhesives. Different types of adhesives are constantly being developed. Nonetheless, given their traits and qualities, there is still room for improvement in terms of adaptability. Self-healing adhesives, as an illustration, have a bright future. The most effective way to optimise the design parameters would’ve been analytical. This provides prompt findings that may be rapidly modified in response to variations in size, shape, and material qualities. This review effort examined the most recent approaches, difficulties, and opportunities in creating composite joints. The outcomes of each method were positive, with significant increases in a number of mechanical characteristics, including maximum strength and failure load. Acknowledgements The authors appreciate the kind support of the SMEC and the VIT management (VIT, Vellore) for providing facilities for carrying out research work.

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Preparation and Characterization of Biodegradable Polyester-Based Shape-Memory Polymer N. W. Mohd Rusli , N. Adrus , N. J. Jusoh, N. A. Hamidon, A. A. Bowo Leksano, J. Jamaluddin , and S. A. Samsudin

Abstract The primary goal of this research is to investigate the shape memory performance of a new biodegradable polyester-based polymer, poly (1,8-octane diolglycerol-1,12-dodecanedioic acid) (POGDA) blended with polylactic acid (PLA) and polycaprolactone (PCL). The presence of functional groups in the polyester and polyester blend was determined using Fourier transform infrared (FTIR) spectroscopy. FTIR results revealed that the existence of preferential specific interaction via hydrogen bonding between the hydroxyl and acid molecules detected the reaction between the monomers. POGDA polymer was further blended with PLA and PCL. The blended samples are then characterized for morphological structure and shape memory ability. The physical appearance and FESEM revealed that the smooth surface of the compatible mixture was observed compared to the uncompatibilized blend samples without EPO. PCL/POGDA (80:20) had a rough surface compared to PCL/POGDA (90:10). Meanwhile, the shape fixity of blended samples showed above 90%. Sample recovered its permanent shape at about 24 °C and regained 50% of its permanent shape at approximately 32 °C. When the Tm (39.8 °C) of pure POGDA and the Tm (40.2 °C) of PCL/POGDA reached, the polymer successfully regained around 90% of its shape and recovered around 43 °C. The shape recovery of PCL/POGDA with EPO (cPCL/POGDA (90:10)) was higher than PCL/POGDA (90:10) without EPO. Pure POGDA had a good recovery rate, while pure PLA can only recover its permanent shape up to 65% of the time. In conclusion, this study proves that incorporating POGDA into PCL polymer influences the shape memory ability of the blended samples. Keywords Biodegradable polymer · Shape memory polymer · Polyester-based polymer · Shape-memory polyester-based

N. W. Mohd Rusli · N. Adrus (B) · N. J. Jusoh · N. A. Hamidon · A. A. Bowo Leksano · J. Jamaluddin · S. A. Samsudin Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_25

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1 Introduction Biodegradable shape memory polymers (SMPs) form an important class of polymeric smart materials. SMPs can respond to environmental stimuli such as heat, light, pH, electricity, moisture, etc. [1, 2]. They have a memory effect that allows them to transition between “original-temporary-original” shapes [3, 4]. SMP necessitates the use of a polymer network architecture that includes both net points (hard) that establish the permanent shape and switching (soft) segments that keep the temporary shape. Polyester is a polymer with a main chain ester functional group. Many researchers have previously studied polyester-based SMPs such as polylactic acid (PLA) and polycaprolactone (PCL) for their easily adjustable properties, biodegradability, biocompatibility, excellent shape memory effect, and non-toxicity [2, 5]. Introducing crosslinking in shape memory polyesters may enhance the shape memory effect, recoverable strain, and final recovery rate [6]. Polycaprolactone (PCL) and polylactic acid (PLA) have gained a significant deal of interest as biodegradable and biocompatible candidates, particularly for biomedical and tissue engineering applications, due to their relatively low melting temperature and slower breakdown rate [7]. Generally, PLA is naturally brittle and has a relatively low glass transition temperature (Ttrans ) of roughly around 60 °C, rendering it unsuitable for body temperature applications because it would remain its glassy state when the temperature did not rise over its Ttrans [8]. Meanwhile, PCL acts as semi-crystalline polymer with a crystalline switching segment for shape memory, which is triggered by a thermal melting temperature that can be adjusted from 45 to 60 °C as molecular weight concentration increases [7, 9]. Furthermore, PCL-based SMPs have piqued the interest of researchers due to its flexibility, non-toxic and less expansive [10]. Despite their many advantages, the characteristics of pure PLA and PCL are insufficient to produce a highly effective SMP, particularly for biomedical applications. With a few exceptions, single polymers tend to exist as either thermoset (Polyurethane) or thermoplastic (PCL and PLA), resulting in pure polymers with networks for either permanent or switching shapes respectively. In the case of PLA, tuning the transition temperature towards the human body (37 °C) with a single polymer is most likely difficult. PLA has been studied in conjunction with other elastomeric polymer such as PCL and polyurethane (PU). Research efforts have been directed towards enhance the mechanical and thermal properties of the PLA, including modifying of PLA with plasticizer [11], blending with other polymers [3], copolymerizing chemicals [12], and incorporating fillers [13]. Among to others, polymer blending with a selected existing flexible or elastic polymers component is a cost-effective method and convenient strategy for improving the toughness of PLA. The properties of the resulting polymer blends are also tunable in shape-memory and mechanical properties by changing components and compositions of blend [8]. To improve the miscibility of the blends, epoxidized palm oil (EPO) was usually added to the blend’s polymers. EPO has been proven to act as a plasticizer that increased

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the elongation at break and impact strength of the blends polymer [14]. Epoxidized vegetable oils such as epoxidized linseed oil and epoxidized soybean oil are a sustainable and environmental friendly alternative to petroleum-based conventional plasticizer [15]. According to Silverajah et al. [16] and Ramli et al. [14], 1 wt% of EPO is sufficient to improve the strength and the flexibility of neat PLA with significant increase in the thermal stability by 27%. So far, only a few SMPs that operate at body temperature have been reported [17]. Therefore, multi-material systems, such as blending, can incorporate multiple functions in a single body structure while avoiding intricate and complicated synthesis [18, 19]. To address the issues and achieve the goals of SMP in biomedical applications, a new thermoset based on biodegradable polyester will be developed by involving numerous diacids and diols. First, polycondensation reaction will be performed to obtained the pre-polymer using 1,12-dodecanedioic acid (DA), 1,8-octanediol (Oct) and glycerol (Gly). The paradigm shifts in replacing petroleum-based polymers with those derived from bio-based. These diacids and diols were chosen for their ability to lengthen the backbones, which responsible for the shape memory effect, as well as the fact that they are derived from biobased resources. In order to improve the thermomechanical properties as well as shape memory properties, the new polymer called as POGDA will be blends with PLA and PCL polymer using a polymer blending technique. Introduction of EPO in blends PCL/POGDA polymer is expected to react with polymers and helped in improving the toughness of the blends. To date, no study on the effect of EPO in PCL/POGDA blends can be found in literature to the best author’s knowledge. The preparation of blend PLA/POGDA and PCL/POGDA polymer blend was carried out using an environmentally friendly technique via internal melt, where is no existing of solvent use through the process [16]. There is various technique for the fabricating of PLA as a SMPs, such as hot-press molding [20], electrospinning [21], freezer drying and 3D printing [22]. The hot press molding technique was used to produce the samples in this study. In comparison to the other existence methods, this method is simplest and most cost effective [23]. A series of analysis and testing has been conducted in order to characterize the properties relating to their chemical properties, morphology, and shape memory effect of the blend.

2 Methodology 2.1 Materials PLA pellets with a commercial grade 3251D with 1.25 g/cm3 density, were purchased from Nature Works LLC (Minnetonka, MN, USA). PCL pellets used were Capa® 6800, purchased from Perstorp AB. Epoxidized palm oil (EPO) content of 3.2%, can

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be obtained from the Malaysian Palm Oil Board (MPOB). In this investigation, 1-8octanediol (Oct), glycerol (Gly) and 1,12-dodecandioic acid (DA) were purchased from Sigma-Aldrich and used as monomers to produce POGDA.

2.2 Synthesis and Preparation of POGDA Polymer According to previous study, POGDA was synthesized with the polycondensation polymerization technique without solvent or catalyst [24]. To avoid moisture and oxygen interfering with the reaction, the synthesis was carried out under a dry nitrogen atmosphere in a 500 ml round-bottom reaction glass with stoichiometry of reactant 0.5:0.5:1 of Oct:Gly:DA. Oct and DA powder were placed into a reaction flask equipped with mechanical stirrer and melted in a 140 °C oil bath until the mixture was entirely melted. The temperature was subsequently reduced to 120 °C before the Gly added to the flask. The mixture was continuously heated and stirred to form the prepolymer PODGA, for 24 h. Lastly, the POGDA polymer sample was casted into a pre-heated polytetrafluoroethylene mould (16 × 18 × 1 mm3 ) and cured for 7 days at 120 °C in a universal oven.

2.3 Preparation of Blends Polymer Prior to the blending process, both PLA and PCL pellets were dried in a vacuum oven at 50 °C for 48 h to remove any excess moisture retained in the pellets. PLA/POGDA and PCL/POGDA were blended in various composition (shown in Table 1) using a Brabender Plasticorder internal melt-mixer at 180 °C temperature, 50 rpm rotor speed and 15 min process time [20]. Hot-press compression molding was performed at 200 °C on a 150 × 150 × 1 mm3 metal mold, which was then cut to a sample size of 80 × 6 × 1 mm3 for characterization. Table 1 Composition of blending POGDA Composition labels

Composition (wt%) PLA

Composition labels

POGDA

Composition (wt%) PCL

POGDA

PLA100 /POGDA0

100

–

PCL100 /POGDA0

100

–

PLA90 /POGDA10

90

10

PCL90 /POGDA10

90

10

PLA80 /POGDA20

80

20

PCL80 /POGDA20

80

20

PLA70 /POGDA30

70

30

PCL90 /POGDA10 /EPO

90

10

PLA0 /POGDA100

–

100

PCL80 /POGDA20 /EPO

80

20

PCL0 /POGDA100

–

100

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3 Characterization of Polymer 3.1 Fourier Transform Infrared Spectroscopy (FTIR) FTIR Spectrometer (FTIR—ThermoFisher Nicolet 6700) fitted with a universal attenuated total reflectance (UATR) accessory was used to analyze the chemical structure of blends. The spectra were captured at frequencies ranging from 4000 to 650 cm−1 , with a spectral resolution of 6 cm−1 . The data is then replotted and analyzed using the program OriginPro Software.

3.2 Field Emission The fragmented morphology of cross-sectional samples was investigated using a FESEM (Zeiss Gemini 500) at a 3 kV accelerating voltage. To avoid electrostatic charge during electron irradiation, the specimen was coated with an ultra-thin Platinum sputter layer using a high vacuum sputter coater (EMITECH K550X).

3.3 Shape Memory Properties Assessment A conventional bending test was performed to evaluate the blend’s shape memory effect (SME). Initially, the blend samples were heated for 15 min at 60–70 °C, just above the blend’s thermal deformation temperature, to convert the glassy-state polymeric blend samples to their rubber-like state. While the sample specimens softened due to the heating process, an external force was applied to bend the samples in half and generate the largest maximum deformation angle (θ0 ). The unloading of the external stress was recorded and provided as θi . The sample was then immersed in a cooled bath for 15 min. Then, the sample is subsequently heated over its transition point (60–70 °C) for a second time to restore its original shape, when the folded sample continued to bend backwards until it reached its maximum bending recovery, denoted as θf . The form memory effect is examined using two key parameters: Shape recovery (Rr ) and the shape fixity ratio (Rf ). Rr indicates the ability of the blend to recover to its initial shape, whereas Rf indicates the ability to maintain the temporary programmed shape. The Rr and Rf were determined by the following equations: Rr =

θi − θ f × 100% θi

(1)

θi × 100% θ0

(2)

Rf =

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3.4 Rheological Characteristics The flow curve rotational rheometer was employed in this characterization using a 25 mm parallel plate geometry. The tests were carried out at 100 °C in a nitrogen environment with the shear rate set to default.

4 Results 4.1 Chemical Functional Group Analysis Figure 1 shows the FTIR spectra of all the samples of blends and pure PLA, and POGDA. From the FTIR spectra for pure PLA and blends PLA/POGDA, it is shown the peaks within the range of 3650 to 3200 cm−1 of were assign to –OH stretching vibration. Meanwhile, sharp peaks appearing between 3200 cm−1 to 2875 cm−1 in every spectrum were attributed to the C–H stretching, which common in carbon compound. Another peak is between 1840 and 1640 cm−1 were assigned to vibration of C=O bond [25]. The aliphatic polyesters PLA and POGDA is known to have almost similar structures [24, 25], and this is clearly shown in the nearly identical relative positions of characteristic peaks obtained. Several differences were also discovered, with some peaks in one polymer but not the other. The peak at 870 cm−1 was apparent in pure PLA, but undefined in pure POGDA. It also detected at 3650–3200 cm−1 represented –OH stretching vibration, which is present in POGDA spectra but not in pure PLA. In the instance of PLA/POGDA blends, it clearly seen that entire blend composition represented the combined identity peak of pure PLA and pure POGDA. This means that there was a chemical reaction between the two parts and that they mixed well. The only changes that could be seen were the different intensities of the peaks and small changes in the blend’s spectral composition. Meanwhile, from the Fig. 2, the FTIR spectra shown for the results of pure PCL, PCL/POGDA and PCL/POGDA with EPO, the peaks within the range of 3500– 3300 cm−1 were assigned to the stretching of O–H; 3000–2800 cm−1 were assigned to stretching vibration of CH2 ; 1800–1650 cm−1 were assigned to the vibration of C=O group; 1620–1570 cm−1 were assigned to the vibration stretching of –COO group; and 1200 cm−1 were assigned to the C–O stretching [26]. From seeing the spectra briefly, the comparison of FTIR spectra of pure PCL, POGDA, and the PCL/ POGDA/EPO blends revealed that the relative positions of characteristic peaks are nearly identical to one another. The resemblance in the spectra can be explained since PCL and POGDA are polyesters type. Nonetheless, numerous significant variations in the spectra of the pure PCL and POGDA remained, with some peaks present in one polymer and absent in the other. For example, the peaks at 3444 cm−1 and 3350 cm−1 were apparent in pure PCL, but undefined in the IR spectra of pure POGDA. Another notable finding was a distinct peak in the spectra of pure PCL but nor pure POGDA

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Fig. 1 FTIR spectra analysis for pure PLA, POGDA and blends PLA/POGDA

from 1620 to 1570 cm−1 . Other peaks at ~1200 cm−1 were also observed in pure POGDA but not in pure PCL. All the peaks in pure PCL and POGDA could be seen in PCL/POGDA/EPO blends, showing that the blending worked. The only differences that could be seen were changes in the peak intensities and slight shifts in the spectra of combinations that were incompatible with each other and those that were. As a result, the chemical structure of PCL/POGDA in the presence of EPO compatibilizer is unlikely to have changed significantly.

4.2 Morphological Analysis Figure 3 shows field emission scanning electron micrographs taken at a magnification of 500× for all samples of pure PLA, pure PCL, pure POGDA, and blends of PLA/

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Fig. 2 FTIR spectra analysis for pure PCL and POGDA, blends PCL/POGDA and PCL/POGDA with EPO

POGDA, PCL/POGDA, and PCL/POGDA with EPO. The pure PLA and PCL sample cross-section is uniform, smooth, and homogeneous because it only has one part. There is no separation of phases. In contrast to the PLA and PCL morphologies, the pure POGDA samples had a clumpy texture but remained homogeneous as onephase morphologies. This clumpy shape contributed to POGDA’s sticky property. Even though the surface appearance of the blended sample was nearly identical, there was a slight change in composition. The morphological identity of all the mixed samples was blended. As the POGDA content of blend samples increases, the appearance of a clumpy-like surface grows. Despite this, the physical appearance after cured process of all the samples shows differences. Compared to the uncompatibilized blend without EPO, the smooth surface of the compatible mixture was visible. Another discovery was that PCL/POGDA (80:20) had a rough surface compared to PCL/POGDA (90:10).

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POGDA POGDA

PLA

PLA

POGDA

PCL PCL

PLA

PLA90/POGDA10

POGDA PLA80/POGDA20

POGDA PLA70/POGDA30

POGDA PCL90/POGDA10 PCL90/POGDA10

PCL80/POGDA20

PCL90/POGDA10/EPO PCL90/POGDA10/EPO

PCL80/POGDA20/EPO PCL80/POGDA20/EPO

Fig. 3 FESEM figure with 500× magnification for pure PLA, PCL, POGDA, blends sample of PLA/POGDA, PCL/POGDA and PCL/POGDA with EPO

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When compared to blends that have not been “compatibilized” (without EPO), the “compatibilized” (with EPO) blend has a much smoother and better-mixed surface.

4.3 Shape Memory Assessment A simple bending test was used to determine the shape-memory behaviour of all samples. Figures 4 and 5 show the shape fixity rate and shape recovery rate for PCL/POGDA. The fixity rate of all blended samples could remain above 90%. The distorted sample recovered its permanent shape at about 24 °C. The sample regained 50% of its permanent shape at approximately 32 °C. When the Tm (39.8 °C) of pure POGDA and the Tm (40.2 °C) of PCL/POGDA mixes were reached, the polymer successfully regained around 90% of its previous shape and recovered around 43 °C. A polymer must have both hard and soft segments to have shape memory. Lee et al. [24] say that the polymer’s permanent shape is set by the rigid part, while the soft part adds to the polymer’s temporary shape. Only PCL/POGDA exhibited temperaturesensitive shape-memory behaviour, preserving a briefly distorted shape and restoring its permanent shape following heating. When compared to pure PCL, PCL/POGDA (90:10) has superior form recovery. The shape recovery of PCL/POGDA with EPO (cPCL/POGDA (90:10)) is higher than PCL/POGDA (90:10) without EPO. However, the addition of 20% POGDA in PCL causes a decrease in shape recovery. When EPO is added to a PCL/POGDA (80:20) blend, shape recovery fails, and the sample cannot fold without cracking. It can be concluded that EPO is only effective in increasing shape recovery when the mix composition is optimized. Meanwhile, Table 2 shows that pure POGDA has a good recovery rate, while pure PLA can only recover its permanent shape up to 65% of the time. The PLA/POGDA blend polymer could not keep its temporary distorted shape because its structure did not have a soft segment that was crystallized. The blend polymer degraded due to the high Tm gap between PLA and POGDA. This bending test result supported La Mantia et al. deteriorations of polymer mix theory [27].

4.4 Rheological Characterization Figure 6 shows that the rheological data link the exact concentration ratio of the blend’s parts and the qualities of the final product. According to the data, pure PCL exhibits conventional Newtonian flow behaviour in the low-frequency zone, with minor shear thinning beginning at 10 rad/s, pure POGDA showed consistent viscosity with a rising shear rate. Except for blends PCL/POGDA, all the blends samples’ viscosity goes down as the shear rate increases. As a result, all samples exhibit normal shear thinning or pseudoplastic behaviour. With or without EPO as a compatibilizer, blends with 10% POGDA and Newtonian flow properties like PCL and viscosities between those of pure PCL and POGDA.

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100 99

Shape Fixity (Rf) (%)

98 97 96 95 94 93 92 PCL/POGDA (100:0)

PCL/POGDA (90:10)

PCL/POGDA (80:20)

PCL/POGDA/EPO (90:10)

PCL/POGDA/EPO (80:20)

Samples

Fig. 4 Shape fixity rate of pure PCL, blends PCL/POGDA and PCL/POGDA/EPO

50

Shape Recovery (Rr) (%)

40

30

20

10

0

PCL/POGDA (100:0)

PCL/POGDA (90:10)

PCL/POGDA (80:20)

PCL/POGDA/EPO (90:10)

PCL/POGDA/EPO (80:20)

Samples

Fig. 5 Shape recovery rate of pure PCL, blends PCL/POGDA and PCL/POGDA/EPO

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Table 2 Summary of shape memory assessment for pure PLA, POGDA and blends PLA/POG Pure PLA

Sample

Pure POGDA

PLA/POGDA

Permanent shape (initial)

Temporary shape (after folded into half and cooling)

Recovery shape (after 2nd heating)

Aborted due to sample break

Achieve 65% of recovery rate

Remarks

Achieve 100% of recovery rate

PLA/POGDA blend break while bending—0% recovery rate PCL POGDA PCL/POGDA (90:10) PCL/POGDA (80:20) PCL/POGDA/EPO (90:10) PCL/POGDA/EPO (80:20)

140000 120000

Viscosity [mPa·s]

100000 80000 60000 40000 20000 0 0

100

200

300

400

500

600

Shear Rate [1/s]

Fig. 6 Viscosity versus shear rate of pure PCL, POGDA, blends PCL/POGDA and PCL/POGDA/ EPO

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In contrast, blends with up to 20% POGDA exhibit pseudoplastic behaviour and complex viscosities. From the complex viscosity data, we can figure out how the shapes of blends with POGDA vary. The flow behaviours of blends are well known to be influenced by their morphologies, which are defined by the viscosity ratio of the constituent polymers and their content [28]. When the morphology included both dispersed and continuous phases, the flow behaviours of the blends were regulated by the continuous-phase polymer. The excellent viscosity polymer regulates the behaviour in continuous phase morphology. The higher the POGDA content in a PCL blend, the lower the viscosity of the blend. This is owing to glycerol’s diluent effect in POGDA [29]. Using EPO was also found to reduce the viscosity of the blend.

5 Conclusion • Hot-press moulding process and internal melt blending was also used to generate blends POGDA/PLA, POGDA/PCL and POGDA/PCL/EPO successfully. • The results of the FTIR, FESEM, and shape memory tests show that the properties of POGDA can be changed by changing the proportions of the blends. • FTIR showed that the peak at 870 cm−1 was apparent in pure PLA, but undefined in pure POGDA. It also detected at 3650–3200 cm−1 represented –OH stretching vibration, which is present in POGDA spectra but not in pure PLA. In the instance of PLA/POGDA blends, it clearly seen that entire blend composition represented the combined identity peak of pure PLA and pure POGDA. This means that there was a chemical reaction between the two parts and that they mixed very well. • For POGDA and PCL, all the peaks in pure PCL and POGDA could be seen in PCL/POGDA blends and PCL/POGDA/EPO, showing that the blending worked. The only differences that could be seen were changes in the peak intensities and slight shifts in the spectra of combinations that were incompatible with each other and those that were. As a result, the chemical structure of PCL/POGDA in the presence of EPO compatibilizer is unlikely to have changed significantly. • Another discovery was that PCL/POGDA (80:20) had a rough surface compared to PCL/POGDA (90:10). When compared to blends that have not been “compatibilized” (without EPO), the “compatibilized” (with EPO) blend has a much smoother and better-mixed surface. • In terms of shape memory performance, pure POGDA demonstrated an excellent SME with a 100% recovery rate, while pure PLA possess a 65% recovery rate. • The fixity rate of all blended samples could remain above 90%. The distorted sample recovered its permanent shape at about 24 °C. The sample regained 50% of its permanent shape at approximately 32 °C. • However, this study found that all the PLA/POGDA blends inhibits SME characteristics by breaking into two parts as soon as they were bent, resulting in a 0% recovery rate and fixity. The large melting temperature difference between PLA and POGDA caused incompatibility. High temperatures during the mixing

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process cause the POGDA polymer to degrade and destroy its shape memory properties. • Adding EPO improved blend miscibility, improving PCL mixes’ shape memory with optimal composition. Acknowledgement This study was supported by the Fundamental Research Grant Scheme (FRGS/ 1/2021/TK0/UTM/02/2) by the Ministry of Higher Education Malaysia.

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Design and Development of Light Weight Antenna Using Polydimethylsiloxane (PDMS) for Biomedical Applications T. A. Karthikeyan , M. Nesasudha , and S. Saranya

Abstract In this paper a Lightweight flexible antenna operating at 2.45 GHz has designed and fabricated. Three layer flexible patch antenna contains ground, substrate and radiating layer. The ground and radiating layers consists of Copper material with 0.035 mm thickness and the substrate layer is PDMS (Polydimethylsiloxane) with the thickness of 1 mm, dielectric constant of 2.71 and loss tangent of 0.0134. The Polydimethylsiloxane substrate is flexible and it is used for wearable biomedical applications. For analysis FEM based HFSS software is used. The factors such as S11 , voltage standing wave ratio, E and H field, Current distribution across the radiating elements and the SAR (Specific Absorption Rate) are analyzed over and done with the simulation platform. The obtained Specific Absorption Rate value is below 1.6 W/ Kg per 1 g of tissue as per FCC Standards. The same has been fabricated by preparing Polydimethylsiloxane as substrate and the corresponding results are analyzed. The antenna performance metrics are analyzed and compared for fabricated as well as simulated results at a frequency of 2.45 GHz giving a return loss of − 20 dB. The performance of antenna is analyzed using metrics and skin tumor can be detected by positioning the antenna on top of the human phantom. The difference in E-field and H-field ideals of phantom with tumor and without tumor can be used to find the tumor. Keywords Lightweight antenna · Polydimethylsiloxane (PDMS) · Flexible substrate · Tumor detection · Biomedical applications

T. A. Karthikeyan (B) · M. Nesasudha Department of Electronics and Communications Engineering, Karunya Institute of Technology and Sciences, Coimbatore 641114, India e-mail: [email protected] S. Saranya Department of Electronics and Communications Engineering, Sri Ramakrishna Engineering College, Coimbatore 641002, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_26

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1 Introduction The next generation is driven by the era of flexible electronics in view of their Excellency in nature of bending, behavioural characteristics, and electrical ability [1]. Recently this technology is being used in the wearable antennas, sensors, filters which depends mainly on the polymeric materials [2] for the substrate requirements. The means of fabrication for these materials are done by using the traditional methodologies like photolithography and also by recent trends like screen and inject printing [3–5]. The key operating element in the wearable electronics or flexible electronics is an antenna which is capable of establishing a nominal communication among the operators. IEEE 802.15.6 has been created as an international standard for WBAN to accommodate both wideband and narrowband communications [6]. As previously said, WBAN (wireless body area networks) can fall under a vast category of trending applications in the thrust sector, such as physical fitness observation [7]. The above mentioned standard provides several frequency bands, such as ISM band, dedicated to a frequency of 2.4 GHz and ultra wideband (UWB) ranging which covers a spectrum of 3.1–10.6 GHz are predominantly chosen for research. Furthermore, the substrate chosen for WBAN applications must be conformal in nature and should not be sensitive to the desirability of human clothing [8]. Henceforth the designed antenna should be lightweight and flexible in nature to ensure the stretch [9] or bent ailment when the human body is exposed to different body postures [10]. The survey results shows clearly that there are several researchers working in the development of different flexible antennas which can be applicable for the Internationally protected areas of the radio spectrum for ISM bands which excludes telecommunications applications [11, 12]. A planar inverted-F antenna (PIFA) antenna empowering the WBAN Applications of 4.96–5.9 GHz and dual antenna mode which is dependent on fabric substrate material to operate at 2.4 GHz is proposed in [13, 14]. A radio frequency identification (RFID) tag antenna of extremely small size made of polyimide film and features a closed-loop structure. As a result, it could be contained within a two-layer plastic cylinder ring the size of a racing pigeon [15] UWB antennas with a low profile for wearable applications was proposed in [16]. The antenna’s impedance bandwidth performance enhancement was based on a customized radiator (dewdrop-inspired radiator) and a (DGS) defective ground structure. The flexibility of antennas is examined using different substrates like sapphire, polyester, polystyrene, polyamide and quartz [17]. On a flexible polyethylene terephthalate (PET) substrate, an inkjet-printed monopole UWB (ultra wide band) antenna with circular-shaped slot and powered by the CPW feed structure demonstrates working in all the directions throughout the impedance bandwidth [18]. The antenna bending properties of a flexible antenna operating in the different bands such as WLAN/4 GHz to 8 GHz/8–12 GHz were investigated [19]. The skin helps us regulate our body temperature, protects us from microbes and the elements, and allows us to feel touch, heat, and cold. The epidermis, dermis, and hypodermis are the three layers of skin. Skin cancer affects nearly one in five

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people at some point in their lives. If detected and treated early, nearly all types of skin cancer can be cured. Excision, chemotherapy, and radiation are the treatments. When skin cells grow and multiply uncontrollably, they form a tumor. Normally, new skin cells form when cells die or become damaged, but when this process doesn’t work right, they grow quickly. Overexposure to sunlight and frequent chemical contact are the main causes of skin cancer. The difference between the Electric field, Magnetic field, current distribution can indicate the presence of the tumor. The difference in values is much greater in this paper, making it much simpler to identify the tumor. The difference between the permittivity values for the E-field, H-field, and J-surf will vary for the phantom with and without tumor. The substrate characterisation by using different polymers based materials have been reviewed and listed [20]. The Variation in electromagnetic interaction due to causes of physical, chemical and various biological factors may affect the radiation properties of antenna thereby resulting in sensing applications at the microwave frequencies. The same was studied and analysed using different shapes and properties of split ring resonators with CPW feed [21]. A paradigm shift in the material nature of substrates has evolved from choosing polymer based ones of synthetic and natural hybrid composite to complete natural way of fibers which are completely ecofriendly and sustainable [22]. This work describes a flexible ground radiating antenna properties that meets a variety of biomedical implantable antenna needs [23]. To assess the performance of the antenna, simulation is performed in a single layered tissue model and compared to a multilayered tissue model. Furthermore, the flexible antenna offers low profile features and a broad axial ratio bandwidth. A 14 GHz microstrip grid array antenna (MGAA) with conducting patch made of rubber layer and a substrate of Polydimethylsiloxane (PDMS) layer is shown [24]. All of the suggested antenna’s requirements qualify it as a viable contender for the next generation flexible and conformalLTE applications. A FMG based antenna designed on Polydimethylsiloxane (PDMS) exhibits minimal sensitivity to stress and strain effect occurring on the flexible material which operates at designed frequency of 15 GHz [25]. A PDMS based indium tin oxide patch shows good versatility and translucent characteristics at 2.4 GHz which can be focussed for wearable antenna design [26].

2 Antenna Design The proposed antenna shape as well as its optimum dimensions is shown in Fig. 1. ANSYS Electronic desktop v19.2 is used to design and model the proposed antenna. One of the most often used and readily available conductive layers is copper sheets. We utilised a copper sheet with a thickness of 0.035 mm, and the copper foil was cut according to design using the EDM process. After preparing the PDMS of thickness 1 mm, the conducting sheets are correctly attached to create a flexible PDMS antenna.

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Fig. 1 Structure of antenna a Top view b Bottom view c Side view

C /

W = 2f ∈ ref f =

(∈r +1) 2

( ) 1 h −2 ∈r +1 ∈r −1 + 1 + 12 2 2 W

c √ 2 f ∈ ref f ( ) (∈ r e f f + 0.3) Wh + 0.264 ) ( ΔL = 0.412h (∈ r e f f − 0.258) Wh − 0.8 Le f f =

L = Le f f − 2ΔL Fi =

6h 2

(1)

(2) (3)

(4) (5) (6)

where W is width of the patch, ∈ r e f f is substrate dielectric constant, H is height of substrate, L is radiating patch length, C is velocity of sunlight, Fi is feed line length, f is operating frequency.

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Figures 2 and 3 shows the return loss characteristics of the simulated antenna and VSWR. The antenna working at 2.45 GHz with s11 of − 20 dB and the obtained VSWR is 1.32 which is less than 2.

Fig. 2 Return loss characteristics of antenna

Fig. 3 VSWR

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Fig. 4 Antenna on top of skin phantom

Table 1 Material properties of skin phantom (niremf.ifac.cnr.it) [26]

Thickness (mm) Skin Fat

2 5

Permittivity (F/m)

Loss tangent

38.007

0.28262

5.2801

0.14524

Muscle

10

52.729

0.24194

Bone

10

11.381

0.2542

3 Evaluating Antenna Performance on Body The designed patch antenna is placed on the top of Skin Phantom and phantom is made up of four layers as shown in the Fig. 4. The distance between the phantom and the patch antenna is 10 mm. The material properties and thickness of the skin phantom is shown in Table 1.

4 Results and Discussion The designed antenna is placed on the top of the skin phantom. The simulated outcomes for both the phantasm and the one lacking tumour are analysed, and the related findings are listed in Table 2. It shows that Electric field value for phantom without tumor is less when compare to Electric field, value for phantom with tumor, Fig. 5 shows the Electric field of antenna without tumor and with active tumor. From the table it is observed that the presence of tumor can be easily detect by the difference in value of Electric field, Magnetic field and J-surf values for phantom without tumor and with tumor. Table 2 Comparison of field overlays for phantom without tumor and accompanied by tumor Phantom

E-field (V/m)

H-field (A/m)

J-surf (A/m)

SAR (W/Kg)

Without tumor

2635

46.49

46.10

0.9452

With tumor

3378

64.84

64.99

0.9342

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Fig. 5 E Field value of phantom without tumor and with tumor

The antenna is positioned on top of the skin mimic where the tissue layer meets the ground. The mimic and the antenna are isolated by 10 mm. Figure 6 illustrates the determined Specific Absorption Rate (SAR) of 0.9452 W/Kg per 1 g of tissue, which is less than 1.6 W/Kg.

Fig. 6 Specific absorption rate

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Fig. 7 Fabricated antenna a Top view b Bottom view

5 Antenna Fabrication The ground and patch layers are build-up of Copper foil with 0.035 mm thickness. These foils are cut and treated by the EDM (Electrical discharge machining) method to get the sought after dimensions. The substrate layer is then made up of PDMS (Polydimethylsiloxane) material with the chunk of 1 mm thickness, relative permittivity of 2.71 and loss tangent of 0.0134 as depicts in Fig. 7. The radiating surfaces and ground made up of copper are glued with PDMS. The simulated and fabricated return loss depicts in Fig. 8. The deviation between fabricated antenna and simulated antenna is due to the fabrication method, it includes attaching the SMA connector with the microstrip feed of the radiating surface by soldering method, and placing the substrate material between the patch and ground, and the Fig. 9 depicts measuring setup of Vector Network Analyzer and Weighing Scale. The antenna is 4.281 g in weight.

6 PDMS (Polydimethylsiloxane) The base and curing agent for Sylgard 184 silicon elastomers are used in a 10:1 ratio. For instance, if 20 g of base and 2 g of curing agent are thoroughly mixed for ten minutes with a head stirrer, bubbles can be eliminated with vacuum desiccators. Once the bubbles have been removed, the liquid mixture can be poured into the molds.

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Fig. 8 Simulated and fabricated reflection coefficient

Fig. 9 Antenna with a Vector network analyser measuring setup b Weighing scale measuring setup

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Glass materials are used to prepare the molds, which measure 65 × 44 × 1 mm. After the molds are annealed in an oven to set the liquid form of PDMS to the substrate, we can peel it for use as a substrate.

7 Conclusion The proposed light weight antenna using PDMS is designed to find the skin tumor. The antenna operates at 2.45 GHz at the ISM band with an improved return loss of − 20 dB. The presence of tumor can be easily detect from the difference in the value of Electric field, Magnetic field and J-surf values between phantom with tumor and without tumor. The obtained values of phantom without tumor for E-field, H-field and J-surf is 2635 V/m, 46.49 A/m, 46.10 A/m respectively whereas the obtained values of phantom without tumor for E-field, H-field and J-surf is 3378 V/m, 64.84 A/ m, 64.99 A/m respectively. Different parameters are obtained VSWR of 1.2, return loss of − 20 dB, and 0.9 W/Kg of SAR are analysed. The future scope is that to design an antenna which can be analysed by placing on top of the full body phantom and to create a mimicking phantom.

References 1. Kirtania SG, Younes BA, Hossain AR, Karacolak T, Sekhar PK (2021) Cpw-fed flexible ultrawideband antenna for iot applications. Micromachines 12(4). https://doi.org/10.3390/mi1204 0453 2. Qu H, Wang Z, Cang D (2019) Flexible bandpass filter fabricated on polyimide substrate by surface modification and in situ self-metallization technique. Polymers (Basel) 11(12). https:// doi.org/10.3390/polym11122068 3. Abi N (2020) A compact wearable 2.45 GHz antenna for WBAN applications, pp 184–187. https://doi.org/10.1109/ICDCS48716.2020.243577 4. Sreemathy R, Hake S, Sulakhe S, Behera S (2020) Slit loaded textile microstrip antennas. IETE J Res:1–9. https://doi.org/10.1080/03772063.2019.1709572 5. Janapala DK (2019) Specific absorption rate reduction using metasurface unit cell for flexible polydimethylsiloxane antenna for 2.4 GHz wearable applications. no. April, pp 1–12. https:// doi.org/10.1002/mmce.21835 6. Hussain AM, Ghaffar FA, Park SI, Rogers JA, Shamim A, Hussain MM (2015) Metal/ polymer based stretchable antenna for constant frequency far-field communication in wearable electronics. Adv Funct Mater 25(42):6565–6575. https://doi.org/10.1002/adfm.201503277 7. Sairam S. A review on substrate requirements and characteristics of wearable antenna, pp 861–868 8. Bai Q, Langley R (2010) Bending of a small coplanar textile antenna, no. November, pp 329–332 9. Deepa C, Rajeshkumar L, Ramesh M (2022) Preparation, synthesis, properties and characterization of graphene-based 2D nano-materials for biosensors and bioelectronics. J Mater Res Technol 19:2657–2694. https://doi.org/10.1016/j.jmrt.2022.06.023 10. Prakasam NCV, Meghana R, Sravani A, Karishma SK, Divya B (2021) Tumor detection in skin using electromagnetic band gap structure antenna. Int Res J Eng Technol 8(8):1552–1556

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11. Shueai A, Alqadami M, Jamlos MF (2014) Design and development of a flexible and elastic UWB wearable antenna on PDMS substrate, pp. 8–10 12. Singh R, Arora M, Dubey YM, Kumar V, Sahu G (2020) RT/Duroid 5880-based Hook slotted multi frequency low profile patch antenna for WBAN applications. Mater Today: Proc 13. Sugumaran B, Balasubramanian R, Palaniswamy SK (2021) Reduced specific absorption rate compact flexible monopole antenna system for smart wearable wireless communications. Eng Sci Technol an Int J 24(3):682–693. https://doi.org/10.1016/j.jestch.2020.12.012 14. Kaur G, Kaur A (2019) Breast tissue tumor detection using ‘S’ parameter analysis with an UWB stacked aperture coupled microstrip patch antenna having a ‘+’ shaped defected ground structure 15. Sim CYD, Chen CC, Chen BS, Liang SY (2017) Compact size flexible UHF RFID tag antenna for racing pigeon ring applications. Int J RF Microw Comput Eng 27(9):1–7. https://doi.org/ 10.1002/mmce.21144 16. Thangarasu D et al (2022) On the design and performance analysis of flexible planar monopole ultra-wideband antennas for wearable wireless applications. Int J Antennas Propag 2022. https://doi.org/10.1155/2022/5049173 17. Ramesh M, Rajeshkumar L, Balaji D, Bhuvaneswari V (2023) Sustainable and renewable nano-biocomposites for sensors and actuators: a review on preparation and performance. Curr Anal Chem 19(1):38–69. https://doi.org/10.2174/1573411018666220421112916 18. Abdu A, Zheng HX, Jabire HA, Wang M (2018) CPW-fed flexible monopole antenna with H and two concentric C slots on textile substrate, backed by EBG for WBAN. Int J RF Microw Comput Eng 28(7). https://doi.org/10.1002/mmce.21505 19. Lee H, Park YB (2022) Wideband ring-monopole flexible antenna with stub for WLAN/C-band/ X-band applications. Appl Sci 12(21):10717. https://doi.org/10.3390/app122110717 20. Fu Y, Lei J, Zou X, Guo J (2019) Flexible antenna design on PDMS substrate for implantable bioelectronics applications. Electrophoresis 40(8):1186–1194. https://doi.org/10.1002/elps. 201800497 21. Ramli MR, Rahim SKA, Rahman HA, Sabran MI, Samingan ML (2017) Flexible microstrip grid array polymer-conductive rubber antenna for 5G mobile communication applications. Microw Opt Technol Lett 59(8):1866–1870. https://doi.org/10.1002/mop.30645 22. Ramli RM, Abdul Rahim SK, Sabran MI, Yong WY, Pon LL, Islam MT (2019) Polymer conductive fabric grid array antenna with pliable feature for wearable application. Microw Opt Technol Lett 61(2):474–478. https://doi.org/10.1002/mop.31585 23. Saranya S, Aparna S, Karthiyayini R, Aruna R (2016) Design methodology to reduce loss due to mismatch in patch antenna using ANSOFT HFSS for ultra wide band applications. 2(2):560–563 24. Harnsoongnoen S. Microwave sensors based on coplanar waveguide loaded with split ring resonators: a review 25. Oladele IO, Omotosho TF, Ogunwande GS, Owa FA. A review on the philosophies for the advancement of polymer-based composites: past, present and future perspective 26. Janapala DK, Nesasudha M, Mary Neebha T, Kumar R (2022) Design and development of flexible PDMS antenna for UWB-WBAN applications. Wirel Pers Commun 122(4):3467– 3483. https://doi.org/10.1007/s11277-021-09095-7

Design Optimization of Kapton Polyimide Based Wearable Antenna for Biosensing Application S. Saranya

and B. Sharmila

Abstract The development of light weight antennas operating at higher frequencies with reconfigurable nature are the necessity of current need in the field of noninvasive biomedical applications. The availability of inexpensive, flexible and ease of fabrication polymers which can act as a substrates can pave way to the next generation wearable electronics. In this manuscript, a versatile and space-saving microstrip patch antenna is created using a 200 μm kapton polyimide substrate that has a dielectric constant and loss tangent of 3.5 and 0.002 respectively. The ANSYS high frequency structure simulator (HFSS) is utilized to simulate and optimize the antenna, resulting in multi-band resonance frequencies of 2.2 GHz, 3.9 GHz, and 5.4 GHz, which correspond to reflection coefficients of −17.4 dB, −19.2 dB, and − 14.18 dB, respectively. Additionally, the antenna complies with FCC standards by satisfying SAR properties of less than 1.6 W/kg. The design novelty includes the Split ring resonator structures (SRR) which can act as meta-material inspired antennas having the unique property of negative permeability and permittivity thereby helps in sensing the bio signals by the change in the permittivity of the sensing elements. The influence of Split ring resonator structures aids in improving the return loss and producing resonance at higher frequencies hence improving the overall performance gain of the antenna. The SAR properties analysed using the human arm model and head model will be of greater help in the field of non-invasive biosensing application. Keywords Split ring resonator · Meta-materials · Specific absorption rate · Microstrip patch antenna · High frequency structure simulator

S. Saranya (B) Department of Electronics and Communication Engineering, Sri Ramakrishna Engineering College, Vattamalaipalayam, Coimbatore 641022, India e-mail: [email protected] B. Sharmila Department of Electronics and Instrumentation Engineering, Sri Ramakrishna Engineering College, Vattamalaipalayam, Coimbatore 641022, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_27

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1 Introduction The terminology flexible electronics refers to electronics circuits made on flexible substrates that can keep them working properly even when they are bendable and stretchy in nature. This nature of the flexible substrate opens up new ways and paradigms for the current era of wearable technology which cannot be made possible with the conventional and commercially available substrates like semiconductors. These aforementioned substrates are said to satisfy following attributes such as flexibility/stretchability, lightweight, cost effectiveness and less ruggedness in appearance which can revolutionise the current era of electronics. The flexible electronics can be of any of the following from like flexible solar cells, flexible Integrated circuits, flexible batteries (thin film solid state batteries), smart clothing (which could monitor brain, muscle and respiratory activity as a part of health care management) and flexible sensors (like finger print sensors, thin film sensors, flexible RFIDs and so on) which are manufactured by the multilayer approach [1] as shown and listed in Fig. 1. The RFID and flexible electronics supports in dealing with huge strain of pathogens, less time consuming and helps with tracking the test samples. Recent advances in multilayer flexible electronics have mostly focused on optoelectronics, robotics, biomedicine, and energy devices. Health data collecting, artificial intelligent acquired therapy, electronic skin (e-skin) for bioelectronics applications [2], human–machine interface systems, ferro magnetic and shape memory polymeric applications [2]. A diverse production technologies including hydro printed electronics, laser printing, Hydrographic methods and so on while also enabling layering interconnections and multilayer electronic circuits. The future era of electronics focuses predominantly on human machine interaction [3] which has its applications in the health monitoring, prosthesis, Robotic technology, safety monitoring and so on. These applications of the devices extends their technological needs in the devices which satisfies the properties like self-healable, biocompatible, imperceptible, stretchable and flexible substrates. Polymeric substrates offer a high potential for advancement in non-invasive biosensing, which is one of the applications described above. When selecting a polymer-based composite for antenna design, several factors should be considered, including the dielectric constant, loss tangent, thermal stability, and moisture absorption. These properties can affect the antenna’s radiation pattern, impedance matching, and overall performance. The antenna serves as a critical sensing component, relying on human physiological fluids such as sweat, urine, and saliva, or on haemoglobin, oxygen, and glucose for fluid-free non-invasive oximeter devices [4]. The antennas designed for wearable application have material requirements such as light weight thin flexible, non-conducting substrates and radiating patch element. It also highlights the importance of understanding the electromagnetic interactions between substrates and antennas, as well as the effects of physical, chemical, and biological factors on radiation properties [5]. The use of split ring resonators with CPW feed for sensing applications at microwave frequencies, exploring how different shapes and properties of these resonators can affect performance [6]. Recent research has

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Fig. 1 Possible Manufacturing techniques deployed in multilayer flexible electronics. Reprinted with permissions from Elsevier [1] (with License Number 5472510057419)

focused on developing polymer-based composites with tailored dielectric properties for specific antenna applications. It also suggests a shift towards using natural fiberbased substrates that are eco-friendly and sustainable, moving away from synthetic polymer-based materials [7]. In general it appears to provide a comprehensive overview of recent developments in substrate characterization and its application in microwave sensing [8]. Overall, polymer-based composites offer a promising substrate option for antenna design, and ongoing research is exploring ways to optimize their properties for specific applications. The suggested antenna, which is made of kapton polyimide and has a miniaturised size, functions as a non-invasive biosensing [9] element that may be used as a wearable device.

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2 Literature Survey A low-profile, low-cost electromagnetic biosensing microstrip patch is constructed and proven to operate efficiently on 8.6 GHz using an AMC structure to increase the antenna’s frequency selectivity [10]. CST is used to build a MEMS-based UWB antenna constructed on a kapton polyimide-based substrate to give good functioning in the S band. This antenna is suitable for WBAN applications, with a gross return loss of −32 dB at an operating frequency of 3.5 GHz [11]. The spiral antennas with circular polarisation made from a kapton polyimide-based transparent substrate with a thickness of 0.375 mm aid in the imaging of human breast cancer [12]. For breast cancer diagnosis, a sixteen-element array with conformal and low-profile criteria has been designed. Body worn wearable antenna for improved health care monitoring made of copper conducting material on a polymeric substrate is designed to function on the 2.45 GHz frequency band and is flexible in nature [13]. The conformal antenna designed on a indium tin oxide (ITO) patch with a PDMS substrate is a best choice for transparent and wearable antenna operating at ISM band [14]. Ring shaped flexible monopole antenna working on a wider bandwidth has novel multiple step shaped ground plane to achieve better impedance match and provide good return loss characteristics. This design is also powered by CPW feeding technique which is fabricated on a polyimide substrate [15]. The implantable antenna designed with low profile characteristics operating at a bandwidth of 2.28–2.53 GHz is tested on a multi layer tissue model like skin, fat, bone and blood to best suit for a biosensing antenna [16]. The polymer based grid antenna array is designed to work in 12–18 GHz range of frequency to best suit for 5G application [17]. The flexible antenna developed using the PDMS and copper fabric which is tested for conformal nature with the help of Styrofoam works goof for 15 GHz with improved gain characteristics of 14 dBi [18]. Flexible PET antenna created using inkjet printing technology is capable of resonating at a UWB range with a centre frequency of 10 GHz supplied by coplanar waveguide at various feed line cut lengths yielding varying reflection coefficient values [19].

3 Antenna Design The metamaterial inspired antenna are artificially manmade structures which have the potential to possess γ dispersion principle and each elements of the unit cell can behave as a individual electrically paired dipole elements with electrically very small size compared to the wavelength of the antenna. In addition to these the metamaterial inspired antennas have negative permittivity and permeability characteristics [20]. The material behaviour in biosensing application is completely dependent on the parameters ε and μ (permittivity and permeability respectively). MMinspired resonators consist primarily of SSRs (Split Ring Resonators) and CSRRs

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(Complementary Split Ring Resonators). SRRs are created by etching two concentric metallic rings on a dielectric substrate and dividing them by slits on opposite sides. The proposed technique involves creating a compact SRR antenna inspired by MM on a flexible 200 μm kapton polyimide substrate with a dielectric constant and loss tangent of 3.5 and 0.002, correspondingly. The ring structures in circular Split ring resonator antenna has average loop length of Ln which is calculated using the following expressions given in Eq. (1). Ln = 2π × rn − S

(1)

 The  frequency of resonance for each loop is calculated based on half wavelengths λg by Eq. (2) 2 fn =

C √ 2Ln εe f f

(2)

where n represents the number of split rings available in the structure of metamaterial antenna. The proposed design comprises 3 split ring which contributes n value as 3.

3.1 Substrate Selection The design requirements in microstrip antenna suited for wearable application should address few metrics like size compatibility, permeability and permittivity characteristics, flexible in nature to withstand the bending and twisting effects of wearable device, proximity effect of human body corresponding to the near field effect and specific absorption rate as per the FCC standards. Based on these factors the substrate selection for wearable device can drastically fall under composite material such as family of polymers like polystyrene, Polydimethylsiloxane (PDMS), Polytetrafluoroethylene (PTFE), TFT deposited parylene polymers, kapton polyimide, sapphire and so on. The dielectric constant and Loss tangent values of the suitable polymeric substrates [13, 21] have been reviewed and are listed as shown in Table 1.

3.2 Design Idea The conventional microstrip patch antenna is comprised of metallic patch and a ground plane at the bottom. A new compact, broadband CPW-fed monopole antenna with SRR-loaded substrate is reported in this approach. The usage of an SRRloaded substrate resulted in increased bandwidth. The impedance bandwidth has been raised from 32 to 80%. The antenna designed using Split Ring Resonator is capable of producing multiple resonance frequencies based on the number of split

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Table 1 Characteristics of different polymeric substrates Substrate material

Dielectric constant

Loss tangent

Polydimethylsiloxane (PDMS)

2.7

0.134

Kapton polyimide

3.5

0.002

Polytetrafluoroethylene

2.1

0.0004

Polystyrene

2.4–2.7

0.0004

Polyolefin

2.30

0.0003

Polyphenylene

2.55

0.0016

Sapphire

9.4, 1.6

0.0001

Glass microfiber: 4E-4

rings deployed in the design. The kapton polyimide based circular SRR comprises of 3 rings resulting in triple resonating bands. The antenna geometry is mentioned in Fig. 2 and its corresponding equivalent circuit model is represented in Fig. 3b. The design parameters such as substrate radius, CPW radius, Radius of the feed, Radius of 3 SRR structures, split gap, feed width and its corresponding dimensions are listed in Table 2. The thickness of the substrate is optimised to 200 μm so it can act as a flexible and lightweight base for the biosensing operation. Fig. 2 Geometry of multiband antenna suitable for wearable application

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Fig. 3 a SRR (split ring resonator structure) b equivalent circuit representation of SRR

Table 2 Design parameters of proposed antenna in mm

Parameter

Dimension (mm)

Substrate radius (RS)

27

CPW radius (R-CPW)

26

R fed

17

Radius srr1 (R1)

16

Radius srr2 (R2)

13

Radius srr3 (R3)

10

Width (W)

2

Split gap

3.2

Feed width (FW)

5

CPW feed (CF)

16

X sub (XS)

18

3.3 Results and Discussion The antenna performance in general is evaluated by few performance metrics like return loss, VSWR, Radiation pattern and bandwidth measurement. The proposed SRR is specifically planned for light weight and flexible substrates used in biosensing hence the SAR (Specific Absorption Rate) has to be considered as a key element of testing since the near field radiation of antenna can cause some adverse effects on human body. The return loss signifies the power dissipated at the load and reflected back to the system and is typically expressed in decibels (dB). When the return loss is high, it implies that a greater amount of power is lost at the load. VSWR (voltage standing wave ratio), on the other hand, measures the efficiency of RF power transfer and is represented as a ratio of the highest to lowest amplitude (voltage or current) of the corresponding field components that occur on a line feeding an antenna. The simulation is done with Ansys HFSS (3D electromagnetic (EM) simulation software) that is employed to develop and analyze high-frequency electrical devices such as antennas. The SRR designed in HFSS platform is shown in Fig. 4 (a) top view (b) bottom view.

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Fig. 4 SRR based metaresonator antenna—simulated using Ansys HFSS platform a top view b bottom view

Return Loss and VSWR The Return loss characteristics is a plot of frequency versus S11 parameter (reflection coefficient) as shown in Fig. 5 which produces triple resonating band of operation at 2.2 GHz, 3.9 GHz and 5.4 GHz which corresponds to reflection coefficient of − 17.4 dB, −19.2 dB and −14.18 dB respectively. The value of VSWR at the resonant bands maintains its limit below 2 which hold good for wearable antenna operating at higher bands. Recent advancements in wireless body area networks aim for increased frequency of operation, which may be accomplished using various configurations of SRR and its unit cells. There are two methods of optimization former method involves adjusting the width of the split ring, whereas the later involves varying the gap between two successive rings. This can assist us in raising the resonance frequency to a higher

Fig. 5 Return loss of metaresonator antenna with 3-SRR

Design Optimization of Kapton Polyimide Based Wearable Antenna … Table 3 Optimization by varying the split ring width

Table 4 Optimization by varying the space between two consecutive rings

371

Split width (mm)

Resonant frequency

3.2

1.8 GHz, 5.7 GHz

4.2

5.5 GHz, 6.7 GHz

4.6

5.7 GHz, 7.5 GHz

Spacing between two adjacent SRR (mm) Resonant frequency 2

1.8 GHz, 5.7 GHz

3

2.9 GHz, 5.5 GHz

order band. The value of capacitance falls as the split gap rises, resulting in a decrease in total capacitance, and a decrease in capacitance raises the resonate frequency. The mutual induction and capacitance are reduced as the space between the rings increases. The resonant frequency rises as inductance and capacitance fall. The parameter optimization was done for the basic design with the 2 split ring resonator resulting in dual operating bands when the split width is initially assigned as 3.2 mm the resonant frequencies produced are 1.8 GHz and 5.7 GHz when the width increases to 4.2 mm and 4.6 mm the resonance is shifted to a higher order mode of 5.5 GHz, 6.7 GHz and 5.7, 7.5 GHz respectively as shown in Table 3. The Spacing between two adjacent SRR also plays an important role in shifting the frequency band to higher order modes as shown in Table 4. Initial spacing of 2 mm results in 1.8 GHz, 5.7 GHz and when its increased to 3 mm it results in 2.9 GHz, 5.5 GHz band. Radiation Pattern The 3D representation of radiation pattern expressing the gain in terms of decibel and the E field concentration in volts per metre is shown in Fig. 6.

Fig. 6 a 3D representation of radiation gain b E field distribution

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When operating at the initial resonant frequency of 2.2 GHz, the current flows from the feeding point through the outer ring’s edge in a 3 SRR configuration, then couples to the inner ring and travels along the inner ring’s edge, resulting in an overall electrical length proportional to the corresponding resonant frequency’s wavelength. Similarly, the frequency bands of 3.9 and 5.9 GHz are created by the Metaresonator element’s successive outer rings, with current flowing only along the outer ring’s edge, and the length of this path is proportionate to the resonant wavelength. Specific Absorption Rate (SAR) SAR stands for Specific Absorption Rate. It is the amount of radiation or electromagnetic energy that a human body absorbs when in contact with a wireless communication device or medium. It is an important factor that has to be analysed when designing an antenna for a wearable device. According to FCC regulations, the value of SAR must be less than equal to 1.6 W/kg. To analyse the SAR properties of the proposed antenna design, a 4-layer model representing the human arm was designed using ANSYS HFSS and simulated. The model was designed with four layers consisting of skin, fat, muscle, and bone. An object list was created with these four layers and the SAR value was analysed. From Fig. 7, it can be seen that the SAR values are appreciable and well complying with the FCC standards, thus making our antenna suitable for integrating into a wearable device. The Specific absorption rate is also measured by testing the designed antenna with the human arm model and human head phantom model for more accuracy. The

Fig. 7 SAR analysis—4-layer model representing the human arm

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SAR simulation results of the same are shown in Figs. 8 and 9 respectively making it more suitable for the wearable biosensing application.

Fig. 8 SAR analysis—with human arm phantom model

Fig. 9 SAR analysis—with human head phantom model

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4 Conclusion and Future Work A unique SRR inspired metaresonator is constructed with a 200 m thick kapton polyimide substrate fed with coplanar waveguide feeding and tested in several techniques of wearability testing. This resonant biosensor operates in several resonances of higher frequency bands including 2.2, 3.9, and 5.4 GHz, is low in weight, and has good SAR values satisfying the FCC standards. The SAR value is tested for three different arrangements initially it was tested under 4 layer skin model which proved to be effective and the value was 0.11 W/kg only at the outer edge of radiating patch and much lesser in the other radiating surfaces. The antenna was also tested with human arm and human head phantom model which also resulting in 0.11 W/ kg. These radiating elements can also be helpful in frequency reconfiguration by optimizing the split ring width and the spacing between the adjacent SRR elements. The future work of this proposed wearable antenna may be examined for the bending effect and flexibility test to confirm the antenna’s conformal nature, which is an added advantage for wearable applications.

References 1. Wang Y, Xu C, Yu X, Zhang H, Han M (2022) Multilayer flexible electronics: manufacturing approaches and applications. Mater Today Phys 23. https://doi.org/10.1016/j.mtphys.2022. 100647 2. Lopes PA, Paisana H, De Almeida AT, Majidi C, Tavakoli M (2018) Hydroprinted electronics: ultrathin stretchable Ag-In-Ga E-skin for bioelectronics and human-machine interaction. ACS Appl Mater Interfaces 10(45):38760–38768. https://doi.org/10.1021/acsami.8b13257 3. Deng L, Wang G (2020) Quantitative evaluation of visual aesthetics of human-machine interaction interface layout. Comput Intell Neurosci 2020. https://doi.org/10.1155/2020/981 5937 4. Falk M, Psotta C, Cirovic S, Shleev S (2020) Non-invasive electrochemical biosensors operating in human physiological fluids. Sensors (Switzerland) 20(21):1–28. https://doi.org/10.3390/s20 216352 5. Potejana P, Seemuang N (2021) Fabrication of metallic nano pillar arrays on substrate by sputter coating and direct imprinting processes. Appl Sci Eng Prog 14(1):72–79. https://doi.org/10. 14416/j.asep.2019.09.001 6. Harnsoongnoen S (2019) Microwave sensors based on coplanar waveguide loaded with split ring resonators: a review. Appl Sci Eng Prog 12(4):224–234. https://doi.org/10.14416/j.ijast. 2018.11.006 7. Ramesh M, Rajeshkumar L, Balaji D, Bhuvaneswari V (2023) Sustainable and renewable nano-biocomposites for sensors and actuators: a review on preparation and performance. Curr Anal Chem 19(1). https://doi.org/10.2174/1573411018666220421112916 8. Oladele IO, Omotosho TF, Ogunwande GS, Owa FA (2021) A review on the philosophies for the advancement of polymer-based composites: past, present and future perspective. Appl Sci Eng Prog 14(4):553–579. https://doi.org/10.14416/j.asep.2021.08.003 9. Deepa C, Rajeshkumar L, Ramesh M (2022) Preparation, synthesis, properties and characterization of graphene-based 2D nano-materials for biosensors and bioelectronics. J Mater Res Technol 19:2657–2694. https://doi.org/10.1016/J.JMRT.2022.06.023 10. Hamza MN, Abdulkarim YI, Saeed SR, Altınta O, Mahmud RH (2022) Low-cost antennaarray-based metamaterials for human body

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11. Afyf A, Elouerghi A, Afyf M, Sennouni MA, Bellarbi L (2020) Flexible wearable antenna for body centric wireless communication in S-band. In: 2020 international conference on electrical and information technologies (ICEIT 2020), pp 48–51. https://doi.org/10.1109/ICEIT48248. 2020.9113217 12. Saeidi T et al (2020) Miniaturized spiral UWB transparent wearable flexible antenna for breast cancer detection. In: 2020 international symposium on networks, computers and communications (ISNCC 2020), pp 19–24. https://doi.org/10.1109/ISNCC49221.2020.929 7255 13. Bahrami H, Porter E, Santorelli A, Gosselin B, Popovic M, Rusch LA (2014) Flexible sixteen monopole antenna array for microwave breast cancer detection. In: 2014 36th annual international conference of the IEEE engineering in medicine and biology society (EMBC 2014), pp 3775–3778. https://doi.org/10.1109/EMBC.2014.6944445 14. Hussain AM, Ghaffar FA, Park SI, Rogers JA, Shamim A, Hussain MM (2015) Metal/ polymer based stretchable antenna for constant frequency far-field communication in wearable electronics. Adv Funct Mater 25(42):6565–6575. https://doi.org/10.1002/adfm.201503277 15. Lee H, Park YB (2022) Wideband Ring-monopole flexible antenna with stub for WLAN/ C-band/X-band applications. Appl Sci 12(21):10717. https://doi.org/10.3390/app122110717 16. Fu Y, Lei J, Zou X, Guo J (2019) Flexible antenna design on PDMS substrate for implantable bioelectronics applications. Electrophoresis 40(8):1186–1194. https://doi.org/10.1002/elps. 201800497 17. Ramli MR, Rahim SKA, Rahman HA, Sabran MI, Samingan ML (2017) Flexible microstrip grid array polymer-conductive rubber antenna for 5G mobile communication applications. Microw Opt Technol Lett 59(8):1866–1870. https://doi.org/10.1002/mop.30645 18. Ramli RM, Abdul Rahim SK, Sabran MI, Yong WY, Pon LL, Islam MT (2019) Polymer conductive fabric grid array antenna with pliable feature for wearable application. Microw Opt Technol Lett 61(2):474–478. https://doi.org/10.1002/mop.31585 19. Kirtania SG, Younes BA, Hossain AR, Karacolak T, Sekhar PK (2021) Cpw-fed flexible ultrawideband antenna for iot applications. Micromachines 12(4). https://doi.org/10.3390/mi1204 0453 20. Salim A, Kim SH, Park JY, Lim S (2018) Microfluidic biosensor based on microwave substrateintegrated waveguide cavity resonator. J Sens 2018. https://doi.org/10.1155/2018/1324145 21. Janapala DK, Nesasudha M, Neebha TM, Kumar R (2019) Flexible PDMS antenna backed with metasurface for 2.4 GHz wearable applications. In: 2019 IEEE 1st international conference energy systems and informations process (ICESIP 2019), pp 1–3. https://doi.org/10.1109/ICE SIP46348.2019.8938235

Experimental Analysis on Mechanical Properties of Hemp/Rice Cereal Fibre Reinforced Hybrid Composites for Light Weight Applications J. Venkatesh , M. Bhuvaneshwaran , and P. Jagadeesh

Abstract This work includes hemp fibres, rice cereal stalk fibres as reinforcement materials, and epoxy resin as matrix materials. Composites samples were prepared by using hand layup followed by compression-molding techniques. Four different composites were fabricated based on the rules of hybridization by modifying the weightiness proportion of fibre material in each set. After that, the mechanical characteristics of the composites were evaluated, as well as morphological investigations through SEM analysis. The result obtained by analyzing the fractured tensile test specimen using scanning electron microscope revealed that the characteristics of hybrid composite were superior when compared to that of the individual fibre composite. Keywords Natural fibre · Hybrid composites · Mechanical properties · SEM

1 Introduction The demand for the composite made of natural fibre or on the upward trend due to their readily affordable, biodegradable environmentally acceptable characteristics [1–3]. Natural-fibre-reinforced composite materials have found use in a broad range of industries, especially construction, biomedical, sports goods, marine applications, automotive, and aerospace [4]. Natural plant fibres, such as those derived from date palm, banana, pineapple, bamboo, jute, okra, cotton, hemp, and silk, have shown promise as are employed as reinforcement in elastomers and plastic polymer composites and have a diverse range of uses. Both the reinforcing and matrix components of a composite material are essential [5, 6]. J. Venkatesh (B) · M. Bhuvaneshwaran · P. Jagadeesh Department of Mechanical Engineering, K.S.R. College of Engineering, Tiruchengode, Tamil Nadu 637215, India e-mail: [email protected] M. Bhuvaneshwaran e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 S. Mavinkere Rangappa and S. Siengchin (eds.), Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23), Springer Proceedings in Materials 32, https://doi.org/10.1007/978-981-99-5567-1_28

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The thermoset polymers and thermoplastic polymers constitute the matrix materials. Thermoplastic materials may be utilized again even after they have been cured, but this requires the right process. Because of their excellent adhesive qualities, minimal shrinkage, quick drying time, and ease of use, thermoplastic polymers such as polyester, polypropylene, nylon, and Teflon are widely used. However, thermosetting polymers depending on adhesive bonding agents have garnered the most focus [7, 8]. The fundamental benefit of hybridization is that many methods, such mixed constant fibres, small fibres, broken fibres, and loose-matter fibres, may be used to combine the reinforcements. The vast majority of hybrid compositions combine natural fibres along with synthetic fibres like glass and carbon fibres, and they provide a number of advantages over composites made of individual fibres [9, 10]. As a consequence, their composition is usually expressed in terms of maximum and lowest values. The amount of cellulose and the type/ratio of natural fibres both have a significant impact on mechanical performance. According to several researches, fibre combinations reinforced with plant-based natural fibres with high cellulose content, such as cannabis, linen, and banana, outperform composites reinforced with lower cellulose concentration natural fibres. As a result, hemp and rice cereals fibres were employed as reinforcement in the current research to examine how the fibre ratio affected mechanical performance. Neves et al. [11] looked into the mechanical properties for hemp biocomposites manufactured using various polymer matrices. Researchers compared the properties of polyester resin with epoxy resin, and they asserted that these composites may be used in military applications. Sapuan et al. [12] revealed that the hybridization procedure might improve the mechanical properties of natural fibres and assorted the same with the help of tensile test and flexural test on over epoxy composite reinforced by banana fibres which might set high in the direction of matrix phase of usual fibres hybrid composite.

2 Materials and Methods 2.1 Materials Hemp and rice cereals stalk fibres were obtained from Tanjore, Tamil Nadu, India, for use in the current study. Covai Seenu & co, Coimbatore, Tamil Nadu, India, supplied the epoxy resin (LY556) and hardener (HY951). For the preparation of mould material, teak wood was employed.

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Table 1 Composites sample weight fraction for epoxy matrices Composites

Hemp (%)

Rice cereals stalk fibre (%)

Total matrix (%)

10H/30R

10

30

60

25H/15R

25

15

60

30H/10R

30

10

60

20H/20R

20

20

60

2.2 Reinforcement and Composite Material Preparation The fibres were cleaned with distilled water after being processed with a 5% NaOH. The fibres were pre—heated after alkalization and prepared for the production process. As a matrix and hardener, epoxy resin was employed in the fabrication process. The desired quantity of hardening agent and resin were blended in a plastic container in the ratio of 10:1.

2.3 Preparation of Composite Specimen This explains the preparation of a sample material by merging two or more fibre hybrid composites with the same epoxy at a 40 wt% concentration [13, 14]. In this study, hemp (H) and rice cereals stalk (R) fibres hybrid composites are created in uses of epoxy resin. The hand lay-up method was used followed by compression molding technique. Table 1 shows the reinforcement composition of Hemp and Rice cereals fibers.

2.4 Characterization Methods A universal testing device was used to assess the flexural parameters of composite samples, like flexural strength. Because the outer force acts in the centre of a composite, resulting in consistent load transfer, the triaxle flexible test was chosen over the 3-point bends test to test the samples. The test was performed on five samples at a continuous uniaxial speed of 2 mm/min, and the average flexural strength of composites was estimated. ASTM D-790 [15] was used to evaluate samples. As per the recommendation of the ASTM D638-03 [16] the test were conducted on five specimens to find the mean result which with the help of computer controlled Kalpak universal testing machine with head speed of 2 mm/min. ASTM D 256-05 [17] was used to execute by Izod impact testing. The impact resistance of five specimens was determined, and the average impact strength of composites was estimated. The marked-bar impact testing method utilized resulted in a rapid fracture with a quick stress rise at the notch and gave information under

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high velocity loading circumstances. The entire experiment was conducted at ambient temperature. SEM, model VEGA3 TESCAN, was employed to study interfacial characteristics such as fibres matrix bonding, fibres breaking, and fibres pull-out on the failure surfaces of Hemp and rice cereals stalk fibres epoxy composites.

3 Results and Discussion In this work, processed hemp and Rice cereals stalk are combined with epoxy to form hybrid composite laminates. The test specimens are then produced in accordance with ASTM standards. Table 2 displays the results of the experiment of the tested composite material.

3.1 Flexural Strength Analysis Figure 1 depicts the flexural strength of different composition of hemp and rice cereals stalk epoxy hybrid composites. In this condition, hybrid composites better than conventional composites in terms of flexural characteristics of Individual fibres composites. This represents hybridization’s effect on composite materials. The flexural strength of the epoxy matrix 30H/10R were the greatest, while the 10H/30R composites were the lowest. According to the findings of these studies, the matrix has a substantial influence on the mechanical performance of the composites [18]. Flexural strength of four varied composites are shown in Table 1.

3.2 Tensile Strength Analysis Tensile characteristics were determined for the four varied composite samples and results are shown in Table 1. Figure 2 depicts a tensile strength comparison of four combinations of hybrid composites. According to the graph, 30H/10R reinforced composites perform better than the other composites tested, with a tensile strength of Table 2 The hybrid composite samples experimental results Sample name

Flexural strength (MPa)

Tensile strength (MPa)

Impact strength (Joules)

10H/30R

22.5

34.5

6.75

25H/15R

35.25

43.4

7.6

30H/10R

39.75

47.25

8.6

20H/20R

31.5

40.5

6.9

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Fig. 1 Flexural strength of H/R hybrid epoxy composites

Fig. 2 Tensile strength of H/ R hybrid epoxy composites

47.25 MPa, followed by 25H/15R reinforced composites with a strength of 43.4 MPa. Hemp fibres reinforcing in a mixture also boosts strength more than any other natural fibres [19]. As a result, the composite material is more tensile than single-fibre composites.

3.3 Impact Strength Analysis The impact test is carried out to evaluate the impact capabilities of four different composites and the results are presented in Table 1. Izod test equipment is used to

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Fig. 3 Impact strength of H/ R hybrid epoxy composites

determine the energy lost. Figure 3 summarizes the amount of energy received by each specimen when struck by a powerful impact. The various ratio of the fibres has been discovered to be more essential than composition in affecting impact toughness [20]. Figure 3 depicts a comparison of the impact strength of four different composite samples. The results showed that 30H/10R reinforced hybrid composites with impact strength of 8.6 J have the highest impact strength. The 25H/15R reinforced composites and 20H/20R fibres reinforced composites can sustain impact strength of 7.6 J and 6.9 J, respectively. The combination of hemp and rice cereals stalk has the maximum impact strength because hybrid fibres are stronger than single fibre composites [21].

3.4 Scanning Electron Microscopy Analysis Morphological investigation was used to conduct by scanning electron microscope. The fractured surface of the composite materials were studied the use of SEM once the testing was completed. SEM images efficiently depict the interfacial bonding with the matrix and the fibres. Figure 4a depicts a scanning electron micrograph of the hemp/rice cereals stalk combination of tensile test, from the figure fibres breakage and fibres pullouts are shown. The impact-tested samples depict of large and small debris of hemp and rice cereals stalk reinforced composite in Fig. 4b [22].

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Fig. 4 (a) Tensile test of hemp and rice cereals stalk reinforced epoxy matrix composites, (b) impact test of hemp and rice cereals stalk reinforced epoxy matrix composite

4 Conclusion • The scientific community is working hard to develop new and advanced materials, particularly non-naturally biodegradable polymers. The process of degrading such wastes is inefficient and will result in the development of hazardous substances. Because of the above mentioned ground, it is preferable to reinforce polymers with natural fibres. A novel category of polymer composites reinforced with preserved hemp and rice cereal fibres has been developed. • The mechanical properties depends on the composition of hemp/rice cereals stalk reinforcement in epoxy composites. Thus, the mechanical capabilities of hybrid fibres reinforced epoxy composites outperform other traditional fibre reinforced polymeric materials, potentially expanding their use in the automobile and construction industries.

References 1. Bhuvaneshwaran M, Sampath PS, Sagadevan S (2019) Influence of fiber length, fiber content and alkali treatment on mechanical properties of natural fiber-reinforced epoxy composites. Polimery 64(2):93–99. https://doi.org/10.14314/polimery.2019.2.2 2. Balu S, Sampath PS, Bhuvaneshwaran M, Chandrasekar G, Karthik A, Sagadevan S (2020) Dynamic mechanical analysis and thermal analysis of untreated Coccinia indica fiber composites. Polimery 65(5):357–362. https://doi.org/10.14314/polimery.2020.5.3 3. Selvaraj M, Akash S, Mylsamy B (2023) Characterization of new natural fibre from the stem of Tithonia Diversifolia plant. J Nat Fibre 20(1):2167144. https://doi.org/10.1080/15440478. 2023.2167144 4. Sinha AK, Narang HK, Bhattacharya S (2017) Mechanical properties of natural fibre polymer composites. J Polym Eng 37(9):879–895. https://doi.org/10.1515/polyeng-2016-0362 5. Vaisanen T, Batello P, Lappalainen R, Tomppo L (2018) Modification of hemp fibers (Cannabis Sativa L.) for composite applications. Ind Crops Prod 111:422–429. https://doi.org/10.1016/j. indcrop.2017.10.049

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6. Mochane MJ, Mokhena TC, Mokhothu TH, Mtibe A, Sadiku ER, Ray SS, Daramola OO (2019) Recent progress on natural fiber hybrid composites for advanced applications: a review. eXPRESS Polym Lett 13(2):159–198. https://doi.org/10.3144/expresspolymlett.2019.15 7. Sanjay R, Madhu P, Jawaid M, Senthamaraikannan P, Senthil S, Pradeep S (2018) Characterization and properties of natural fiber polymer composites: a comprehensive review. J Clean Prod 172:566–581. https://doi.org/10.1016/j.jclepro.2017.10.101 8. Singha AS, Thakur VK (2008) Synthesis and characterization of pine needles reinforced RF matrix based biocomposites. E-J Chem 5(S1):1055–1062. https://doi.org/10.1155/2008/ 395827 9. Messana A, Airale AG, Ferraris A, Sisca L, Carello M (2017) Correlation between thermomechanical properties and chemical composition of aged thermoplastic and thermosetting fiber reinforced plastic materials. Mater Sci Eng Technol 48(5):447–455. https://doi.org/10.1002/ mawe.201700024 10. Cartie DDR, Irving PE (2002) Effect of resin and fibre properties on impact and compression after impact performance of CFRP. Compos A Appl Sci Manuf 33(4):483–493. https://doi.org/ 10.1016/S1359-835X(01)00141-5 11. Neves ACC, Rohen LA, Mantovani DP, Carvalho JP, Vieira CMF, Lopes FP, Monteiro SN (2020) Comparative mechanical properties between biocomposites of epoxy and polyester matrices reinforced by hemp fiber. J Market Res 9(2):1296–1304. https://doi.org/10.1016/j. jmrt.2021.02.064 12. Sapuan SM, Leenie A, Harimi M, Beng YK (2006) Mechanical properties of woven banana fibre reinforced epoxy composites. Mater Des 27(8):689–693. https://doi.org/10.1016/j.mat des.2004.12.016 13. Gupta MK, Ramesh M, Thomas S (2021) Effect of hybridization on properties of natural and synthetic fiber-reinforced polymer composites: a review. Polym Compos 42:4981–5010. https://doi.org/10.1002/pc.26244 14. Khan MZ, Srivastava SK, Gupta MK (2018) Tensile and flexural properties of natural fiber reinforced polymer composites: a review. J Reinf Plast Compos 37(24):1435–1455. https://doi. org/10.1177/0731684418799528 15. Aji IS, Zainudin ES, Abdan K, Sapuan SM, Khairul MD (2013) Mechanical properties and water absorption behavior of hybridized kenaf/pineapple leaf fibre-reinforced high-density polyethylene composite. J Compos Mater 47(8):979–990. https://doi.org/10.1177/002199831 2444147 16. Li X, Tabil LG, Panigrahi S (2007) Chemical treatments of natural fiber for use in natural fiber-reinforced composites: a review. J Polym Environ 15(1):25–33. https://doi.org/10.1007/ s10924-006-0042-3 17. Atmakuri A, Palevicius A, Vilkauskas A, Janusas G (2022) Numerical and experimental analysis of mechanical properties of natural-fiber-reinforced hybrid polymer composites and the effect on matrix material. Polymers 14(13):2612 18. Chong A, Miller F, Buxton M, Friis EA (2007) Fracture toughness and fatigue crack propagation rate of short fiber reinforced epoxy composites for analogue cortical bone. J Biomech Eng 129(4):487–493. https://doi.org/10.1115/1.2746369 19. Mylsamy K, Rajendran I (2011) The mechanical properties, deformation and thermo mechanical properties of alkali treated and untreated Agave continuous fibre reinforced epoxy composites. Mater Des 32(5):3076–3084. https://doi.org/10.1016/j.matdes.2010.12.051 20. Tang J, Swolfs Y, Longana ML, Yu H, Wisnom MR, Lomov SV, Gorbatikh L (2019) Hybrid composites of aligned discontinuous carbon fibers and self-reinforced polypropylene under tensile loading. Compos A Appl Sci Manuf 123:97–107. https://doi.org/10.1016/j.compositesa. 2019.05.003

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21. Anand P, Anbumalar V (2015) Mechanical properties of cellulose-filled epoxy hybrid composites reinforced with alkali-treated hemp fiber. Polymer (Korea) 39(1):46–55. https://doi.org/ 10.7317/pk.2016.40.6.836 22. Vijaya Ramnath B, Sharavanan R, Chandrasekaran M, Elanchezhian C, Sathyaarayanan R, Niranjan Raja R, Junaid Kokan S (2015) Experimental determination of mechanical properties of banana jute hybrid composite. Fibers Polym 16(1):164–172. https://doi.org/10.1007/s12 221-015-0164

Mechanical and Wear Behavior of Halloysite Nanotubes Filled Silk/Basalt Hybrid Composites Using Response Surface Methodology S. M. Darshan , B. Suresha , B. Harshavardhan , Mohan B. Vanarotti , Sunil Waddar , Shijo Thomas , and L. Francis Xavier

Abstract The aim of this study is to develop bio-friendly light weight polymer nanocomposites for load bearing applications and to evaluate the influence of halloysite nanotubes (HNTs) on mechanical as well as wear behavior of silk fiber (SF) and basalt fiber (BF) reinforced epoxy (Ep) composites. HNT filled biocomposites were fabricated using vacuum bagging technique. The Box-Behnken design (BBD) of experiment with Response surface methodology (RSM) was used to conduct the dry-sliding wear tests on a pin on disc apparatus. Tribo-mechanical properties and worn surface micrographs of hybrid composite samples were analyzed. Hardness, tensile strength and wear resistance behavior of SF + BF/Ep hybrid composites were substantially improved with the incorporation of HNTs. It was observed from the confirmation test that there is a strong agreement between the experimental findings as well as the predicted values, with a minimum reported error of