Re-envisioning Plastics Role in the Global Society: Perspectives on Food, Urbanization, and Environment 3031489446, 9783031489440

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Ololade Olatunji

Re-envisioning Plastics Role in the Global Society Perspectives on Food, Urbanization, and Environment

Re-envisioning Plastics Role in the Global Society

Ololade Olatunji

Re-envisioning Plastics Role in the Global Society Perspectives on Food, Urbanization, and Environment

Ololade Olatunji Geo Calibrations Lagos, Nigeria

ISBN 978-3-031-48944-0 ISBN 978-3-031-48945-7 https://doi.org/10.1007/978-3-031-48945-7

(eBook)

© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 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 Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Printed on acid-free paper

Preface

Humans have had over a century-long relationship with what was once “the miracle material.” That relationship has had its ups and downs. From images of households in the 50s falling in love with plastic Tupperware to some countries in the 2000s declaring national ban on plastics. Compared to materials like glass and iron which have been around for thousands of years, plastics are relatively newer. The world is now at the point where we are just learning how to better produce, use, and dispose of plastics. Thus far a more circular approach is looking better than the mostly linear approach we have adopted since the introduction of plastics. The environmental threat posed by plastics that has become more pronounced in recent years is not only due to problems inherent within plastic materials themselves. Rather, it is also due to the way humans over the years have chosen to produce, use, and discard plastics. A few decades ago, plastics were once welcomed as novel diverse, durable, and low-cost materials with seemingly unlimited applications. But today, plastics are often regarded as one of the shameful aspects of urbanization as images of millions, even billions of pieces of waste plastic floating in the oceans, gathered in heaps on dumpsites and other parts of the environment are seen across the world. Around 50% of plastics produced are single-use plastics. On the other hand, the other roughly 50% of plastics being produced have other applications that can extend for several decades or more. The plastic industry is an over half a trillion-dollar industry that also serves other sectors and almost every aspect of modern life. The recycled plastic market was valued at an estimated 47.6 billion USD as of March 2022 at 4.9% cumulative annual growth rate projected for next 10 years. It is estimated that over 8.3 billion tonnes of plastics have been produced worldwide. Around 78% of these plastics still exist in the environment, and the production of millions of tonnes of plastics still persists across the world. It is inevitable that plastics will still be around on the planet for some time in one form or another. A closer look into other existing and potential applications of various types of plastics suggests that plastics can have some far-reaching impacts when sustainably produced, effectively utilized, and efficiently managed. Therefore as the world v

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Preface

focuses on issues of food security, plastic waste management, and the environment as priority issues, it is essential to assess the present and future role of plastics in the world from different perspectives beyond the popular notion that plastics are simply bad. This book explores multiple plastics applications that are significant in food security, water resource management, and ecological conservation/restoration. It also explores frameworks for achieving a more sustainable plastic economy aligned with sustainable development goals. It provides a deep insight into how plastics have become so intricately woven into modern life and explores ways in which plastics can be used to achieve more sustainable development. It is intended to provide an insight for the plastic industry to develop plastic products that are better designed to fit into the global sustainable development agenda. Lagos, Nigeria

Ololade Olatunji

Contents

1

Global Society and Sustainable Development . . . . . . . . . . . . . . . . 1.1 Shift to a Global Society . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Global Sustainable Development Goals . . . . . . . . . . . . . . . . 1.3 Innovations Driving Sustainable Global Society . . . . . . . . . . 1.4 The Global Plastic Challenge . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . .

1 1 2 6 8 9

2

A History of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Modern Human and Plastics . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Plastics and Plastic-Like Materials in Nature . . . . . . . . . . . . . . 2.3 Development of Modern Plastics . . . . . . . . . . . . . . . . . . . . . . 2.4 Historical Development and Description of Some Plastic Processing Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.1 Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2 Blow Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 Injection Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 Rotational Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 Thermoforming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 Fiber Spinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 Plastics and the Environment . . . . . . . . . . . . . . . . . . . . . . . . . 2.10 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11 11 12 12

3

Plastics, Food Security, and Sustainable Urbanization . . . . . . . . . 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Growing More Food and Trees in Smaller Spaces . . . . . . . . . 3.2.1 Food Security Through Urban Gardens . . . . . . . . . . 3.2.2 Preserving Future Forests . . . . . . . . . . . . . . . . . . . . 3.2.3 How Much Food Can Be Grown in Plastic Containers? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14 15 17 18 20 21 22 22 24 24

. . . . .

27 27 28 28 33

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34

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3.2.4

4

5

Root Restriction for Improved Yield and Controlled Urban Greening . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.5 Green Walls and Vertical Planting . . . . . . . . . . . . . . . 3.3 Improving Access to Nature for Urban Residents . . . . . . . . . . 3.4 Supporting Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 Plastics in Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.1 Plastic as Soil Stabilizers for Construction . . . . . . . . . 3.5.2 Plastics in Agricultural Soil . . . . . . . . . . . . . . . . . . . . 3.6 Plastic Mulching and Advanced Irrigation Systems . . . . . . . . . 3.7 Plastics in Food Storage and Preservation . . . . . . . . . . . . . . . . 3.7.1 Polypropylene Sacks . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.2 Polypropylene Sacks with Improved Pest Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.3 Flexible Intermediate Bulk Bags . . . . . . . . . . . . . . . . 3.8 Malaria Prevention and Pest Management . . . . . . . . . . . . . . . . 3.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

51 51 52 53 53

Plastic in Water Safety Management, Distribution, and Conservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Water Desalination Membranes . . . . . . . . . . . . . . . . . . . . . . . 4.2 Artificial Floating Islands . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Artificial Ponds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Role of Plastics in Water Conservation in Agriculture . . . . . . . 4.4.1 Run-Offs into Water Bodies . . . . . . . . . . . . . . . . . . . 4.4.2 Plastics in Agricultural Mulch . . . . . . . . . . . . . . . . . . 4.5 Water Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Rain Water Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Plastic Water Pipes and Modern-Day Water Systems . . . . . . . . 4.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

59 59 61 62 63 63 64 65 65 68 69 69

Plastic as Fuel of the Future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Landfill Gas Capturing Prospects for Bioplastics . . . . . . . . . . 5.3 Plastic Incineration for Energy Recovery . . . . . . . . . . . . . . . 5.4 Chemical Recycling of Plastics . . . . . . . . . . . . . . . . . . . . . . 5.5 Purification/Dissolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6 Depolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6.1 Glycolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6.2 Solvothermal Liquefaction . . . . . . . . . . . . . . . . . . . 5.6.3 Chemical and Biological Depolymerization Combined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6.4 Hydrothermal Processing . . . . . . . . . . . . . . . . . . . . 5.7 Conversion or Thermal Cracking . . . . . . . . . . . . . . . . . . . . . 5.7.1 Pyrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

37 38 40 41 41 41 43 45 47 48

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73 73 74 75 77 78 78 79 80

. . . .

80 81 83 83

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5.7.2 5.7.3

Gasification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Low-Temperature Cracking Combined with Alkylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.8 Hydrogen and Syngas Production from Plastic Waste . . . . . . . 5.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Plastics in Sustainable Energy and Transportation . . . . . . . . . . . . . 6.1 Floating Photovoltaic Panels . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Plastics in Electric Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Plastics in High-Pressure Hydrogen Systems . . . . . . . . . . . . . . 6.4 Wearable Energy Generation . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 Plastics in Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 Plastics in Biogas Storage Airbags . . . . . . . . . . . . . . . . . . . . . 6.7 Walking Cities and Settlements . . . . . . . . . . . . . . . . . . . . . . . 6.8 Plastics in Water Transportation . . . . . . . . . . . . . . . . . . . . . . . 6.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

91 91 93 95 98 99 101 101 105 108 108

7

Assessing the Impact of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Life Cycle Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Mass Balance Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Materials Flow Through Industry Approach . . . . . . . . . . . . . . 7.4 Hazard Ranking Impact Assessment . . . . . . . . . . . . . . . . . . . . 7.5 Hazard Ranking of Microplastics . . . . . . . . . . . . . . . . . . . . . . 7.6 Material Input Per Service Unit . . . . . . . . . . . . . . . . . . . . . . . 7.7 Environmentally Extended Input–Output Analysis . . . . . . . . . . 7.8 Cost-Benefit Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9 Environmental Priority System . . . . . . . . . . . . . . . . . . . . . . . . 7.10 Sustainable Process Index . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11 Toward More Robust Tools for Impact Assessment of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.12 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

113 113 116 118 118 119 120 121 122 123 123

Plastics in Waste Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Plastics in Management of Sewage and Human Fecal Waste . . 8.1.1 Plastic as Filtering Media in Wetland-Type Waste Water Treatment . . . . . . . . . . . . . . . . . . . . . . . 8.1.2 Container-Based Sanitation and Compost Toilets . . . . Plastics in Oil–Water Separation in Industrial Waste Water 8.2 Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 Banknote Waste Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 Plastic Waste Disposal Containers . . . . . . . . . . . . . . . . . . . . .

131 131

8

86 87 87 87

124 127 127

131 132 134 134 135

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8.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 9

10

Some Non-plastic Materials and Their Environmental Impacts . . . . 9.1 Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1 Production and Processing . . . . . . . . . . . . . . . . . . . . 9.2 Impacts of Metal Production and Use . . . . . . . . . . . . . . . . . . . 9.2.1 Water Use and GHG Emissions . . . . . . . . . . . . . . . . . 9.2.2 Mine Tailings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.3 Red Mud Stockpiling . . . . . . . . . . . . . . . . . . . . . . . . 9.2.4 Metal Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.5 Open Cast Mines . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.6 Green Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 Cellulose and Cellulose-Based Materials . . . . . . . . . . . . . . . . . 9.4 Wood and Wood-Based Materials . . . . . . . . . . . . . . . . . . . . . 9.4.1 Applications of Wood . . . . . . . . . . . . . . . . . . . . . . . . 9.4.2 Wood Production . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.3 Environmental Impact of Wood Harvesting and Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.4 Sustainable Wood Products . . . . . . . . . . . . . . . . . . . . 9.4.5 Preserving Books and Art with Plastics . . . . . . . . . . . 9.5 Cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5.1 Production of Cotton . . . . . . . . . . . . . . . . . . . . . . . . 9.5.2 Environmental Impact of Cotton Production and Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5.3 Making Cotton More Sustainable . . . . . . . . . . . . . . . 9.6 Hemp (Cannabis Sativa L.) . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6.1 Applications of Hemp . . . . . . . . . . . . . . . . . . . . . . . . 9.6.2 Production of Hemp . . . . . . . . . . . . . . . . . . . . . . . . . 9.6.3 Environmental Impact of Hemp Production and Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.7 Gemstones and Precious Metals . . . . . . . . . . . . . . . . . . . . . . . 9.7.1 Applications of Gemstones . . . . . . . . . . . . . . . . . . . . 9.7.2 Production of Gemstones . . . . . . . . . . . . . . . . . . . . . 9.7.3 Environmental and Social Impact of Gemstone Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.7.4 The Potential of Plastic Jewelry as a Substitute for Gemstones and Precious Metals . . . . . . . . . . . . . . . . . 9.7.5 Buildings and Building Materials . . . . . . . . . . . . . . . 9.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

139 139 140 141 141 141 142 142 143 143 144 145 145 146 147 149 151 153 153 155 156 157 157 158 159 159 160 160 161 162 164 164 166

Sustainable Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 10.2 Renewable Synthetic Plastics . . . . . . . . . . . . . . . . . . . . . . . . . 172

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10.3 10.4 10.5

Synthetic Biodegradable Plastics . . . . . . . . . . . . . . . . . . . . . . Plastics from Organic Waste . . . . . . . . . . . . . . . . . . . . . . . . . Recycled Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.1 Thermomechanical Recycling . . . . . . . . . . . . . . . . . . 10.6 Chemical Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7 The Inherent Value of Used Plastics . . . . . . . . . . . . . . . . . . . . 10.8 Making Plastics Reusable . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9 Reducing Plastic Use in Product Design and Production . . . . . 10.9.1 Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9.2 Product Design, Process Optimization, and Materials Selection . . . . . . . . . . . . . . . . . . . . . . . 10.10 Global Policies and Commitments Toward Circular Plastic Economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.11 Plastic Bans across the World . . . . . . . . . . . . . . . . . . . . . . . . 10.12 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

174 175 176 177 179 180 183 185 185

11

Plastics and Space Exploration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Significance of Space Exploration to the Global Society . . . . . 11.2 Spacesuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 The Plastics in Spacesuits . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 The Parachute System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.5 Spacecraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6 Plastics from Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.1 Propene on Titan . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.2 Biomining and Biosynthesis of Plastics in Space . . . . 11.6.3 Scrap Plastic from Space Waste . . . . . . . . . . . . . . . . . 11.7 Radiation Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.8 Tracking Ocean Microplastics Using NASA Data . . . . . . . . . . 11.9 Plastics and Space Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.9.1 Global Agreement of Space Waste . . . . . . . . . . . . . . . 11.9.2 Space Debris Sensors . . . . . . . . . . . . . . . . . . . . . . . . 11.9.3 Self-Repairing Thermoplastics . . . . . . . . . . . . . . . . . . 11.10 Space Exploration and the Future of the Plastic Industry . . . . . 11.11 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

195 195 198 200 201 202 203 203 204 205 206 208 209 211 212 212 213 215 216

12

Plastics in Construction: Toward Green Buildings and Climate-Resilient Cities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 Recycled Plastic Roads . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Climate-Resilient Buildings . . . . . . . . . . . . . . . . . . . . . . . . . 12.3 Plastics in Green Roof Systems . . . . . . . . . . . . . . . . . . . . . . 12.3.1 The Layers of the Green Roof System . . . . . . . . . . . 12.3.2 Waterproof Layer in Green Roofs . . . . . . . . . . . . . .

219 219 222 224 224 224

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186 187 188 190 190

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12.3.3 Protection Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.4 Water Storage/Drainage Layer . . . . . . . . . . . . . . . . . . 12.3.5 Filter Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4 Floating Buildings for Flood Mitigation . . . . . . . . . . . . . . . . . 12.5 Plastics in Window Insulation . . . . . . . . . . . . . . . . . . . . . . . . 12.6 Recycled Plastics in Masonry . . . . . . . . . . . . . . . . . . . . . . . . . 12.7 3D-Printed Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.8 Eliminating Asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

226 226 227 227 229 230 234 235 237 237

Future Outlook, Conclusion, and Recommendations . . . . . . . . . . . . 13.1 Specialty Sustainable Plastics Optimized for Specific Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Understanding the Full Impact of Microplastics . . . . . . . . . . . . 13.3 Toward more Even Distribution in Global Waste Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.4 Size Matters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5 Design for Reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.6 A Pathway from Single-Use to Reusable Plastics Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.7 Biodegradable Lightweight Drones for Environmental Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.8 Traceable Value Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.9 Recycled Plastics in Urban Forests Schemes and Food Gardens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.10 Other Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.11 Conclusion and Recommendations . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Chapter 1

Global Society and Sustainable Development

Abstract This chapter is aimed at drawing the connection between technological advancement and sustainable global society. It begins with a review of the concept of a global society. Then an overview of the sustainable development goals is presented to refresh some background knowledge of these goals. This is important in shaping the understanding of the role of the plastic industry in a sustainable global society. The chapter then discusses the different categories of technologies that are helping to drive sustainable development in a global society. The final section discusses the plastic challenge and how plastics can be better integrated within a more circular economy.

1.1

Shift to a Global Society

Earlier years of global politics have focused on international relations. This was mainly centered around how a state’s governance and activities affect its relations with other countries, its position in the world, and access to support from other nations. Recent years have seen a shift toward the concept of global society (Barney and Sikkink 2009). This is evident in the new patterns of social, economic, and political interactions that have become more globalized over the years. This has been powered by technological advancement to a large extent. Advancement in information technology and communication as well as transportation systems and advanced supply chain and trade networks has made the world more interconnected than ever. The idea of a global society refers to a situation whereby all countries in the world exist within a single sociopolitical space (Bartelson 2009). It is said to be a consequence of globalization and increasing interconnectedness and intensified interaction between societies that cut across different boundaries. This has been significantly aided by technological advancement. Governance of a global society is guided by international organizations, transnational corporations, nongovernmental organizations, and new types of networks (Barney and Sikkink 2009). Information and knowledge have been said to be the main driving force of the globalized society as data generation, utilization, and integration increasingly become more important in modern life (Janakova 2018). For example, data on © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 O. Olatunji, Re-envisioning Plastics Role in the Global Society, https://doi.org/10.1007/978-3-031-48945-7_1

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resource availability in different locations is an important factor in local and international trade, data on plastic pollution across the ocean to guide global cleanup action and data on the health and well-being of a particular location to determine the best environment for optimal health. Information communication technology has been integrated into every aspect of modern life from mobile banking to virtual schools. Data-based technologies are now used in the management of smart cities, a concept developed to address the limitations of traditional city administration and governance (Amovic et al. 2021). From electronic touch cards on trains to tracked delivery robots. Goods and services have been able to spread across the world faster than ever. So much so that many products and service providers aim for global standards. Sustainability of the global society therefore requires shared ambitions and common goals among all the nations of the world.

1.2

Global Sustainable Development Goals

The sustainable development goals (SDG) is a set of 17 integrated goals for social, economic, and environmental sustainability for the world to achieve by a set date. It was introduced in 2015 by the United Nations. It is aimed as a global call to action for joint efforts toward eliminating poverty and hunger, protecting the earth, and achieving peace and prosperity for all. The current target date is 2030. Achieving the goals requires a joint effort from all the countries in the world acting toward these common goals. All members commit to the SDG and contribute their technologies, creativity, technical capacity, and financial resources. This section is based on the United Nations publication of the 17 SDGs (UN General Assembly 2015). They are summarized here to give an overview of the targets, strategies, and current status. There are four main indicators of climate change that have been identified. These are levels of greenhouse gas in the atmosphere, sea level rise, ocean temperature rise, and ocean acidification (ref). These are all indicators that are measured on a global scale since the atmosphere and earth’s waters are continuous mediums that are shared globally. The first SDG (SDG 1—no poverty) is aimed at eradicating all forms of poverty in the world by 2030. This has been identified as one of the greatest challenges facing the world. There has been substantial progress toward eliminating poverty. Between 1990 and 2015, the number of humans living in poverty dropped by more than 50%. Much of this drop in poverty is in China and India. South Asia and sub-Saharan Africa make up 80% of people living in extreme poverty across the world. Conflicts and climate change exacerbate poverty as people struggle with situations such as food insecurity, flooding, displacement, and pandemics. As of 2023, the UN reports that 1.3 billion people live in multidimensional poverty while 10% of the world lives in extreme poverty. Other than the fact that the definition of poverty can be quite broad, 736 million people in the world live in extreme poverty and this is still far behind considering that the goal is 0%.

1.2

Global Sustainable Development Goals

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The second goal of the SDG (Goal 2—Zero hunger) is related to the first goal. Indeed all the SDGs in one way or the other are interrelated and progress in one SDG does affect other SDGs. This relates to food for sustenance as well as nutrition for proper growth and development and thriving of every person from children to adults. Some progress has been made toward this goal as the past 20 years have seen some drop in the number of undernourished people. This is attributed to a rise in productivity in the agriculture sector and rapid growth in the global economy. Countries that have made the most progress toward eradicating extreme hunger include countries in the Caribbean, Latin America, and Central and East Asia. Despite this recent progress, extreme hunger, and malnutrition remain a challenge with around 821 million people still facing hunger and malnourishment as of 2017. Part of the strategies the UN proposes to address this includes promoting sustainable agricultural practices, providing people with access to land, access to technology such as food preservation technologies, access to markets, international collaborations to provide infrastructure and technology, and also make improvements to agricultural systems to improve productivity. The third SDG (SDG 3—good health and well-being). This is also associated with ensuring people live a good quality of life. The past century has seen significant advancement in health care. Discovery of drugs, treatments for diseases, discovery of the disease and its causes and diagnosis, development of diagnostic tools, production of artificial tissue scaffolds, and robotics for surgical procedures among others are some of the advancements we have seen in the field. Indeed life expectancy have markedly increased and mortality rates in infant and mothers have dropped significantly. Deaths from diseases like HIV, once uncurable disease, have now decreased by 50% of previous levels. However, 400 million people across the world do not have basic health care and 1.6 million people are living in fragile situations that put global health at serious risk. Such situations are exacerbated by protracted crises and weak health care institutions. Fourth SDG (SDG 4—quality education) aims to provide free, equitable, and quality education to all children at the primary and secondary levels. It also aims to provide access to preprimary education early childhood development and care that prepare these children for primary education by 2030. Beyond childhood, the goal extends to providing men and women access to affordable and quality education in technical, vocational, and university education. Having more educated people means more people who are empowered to advance society through various means such as trade, scientific development, and innovation. Thus far 91% of children in developing countries are enrolled in primary education. However, 57 million children who are of primary school age are out of school across the world. More the 50% of these 57 million out-of-school children are in sub-Saharan Africa. Around half of the children who are out of school are living in areas affected by conflict. Fifth SDG (SDG 5—Gender equality) is targeted at ending discrimination against females. Since women are around half of the population and in most cases they play the main role in child upbringing and home maintenance, educating, and empowering women is key to ensuring a sustainable global society. There has been significant progress in this area as now most regions have more girls in school

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than about a decade and a half ago and the number of girls enrolled in school are as much as the number of boys. Yet data suggests that 1 in 3 women have been victims of physical violence and/or sexual violence and only 13% of land owners are women. Underaged marriage is also still prevalent as 750 million living females married before the age of 18 years. The sixth goal (SDG 6—clean water and sanitation) aims to provide universal and equitable access to clean, safe, and affordable drinking water to every person in the world by 2030. This includes ending practices like open defecation and dumping of waste as these pose a danger to the natural water sources and aquifers. It also includes implementing systems for water resource management at all levels and restoration of aquatic ecosystems and the forests, mountains, wetlands, and other natural systems that affect water resources as well as achieving significant increase in the efficiency of water use by 2030. As of 2015, 5.2 billion people had access to safe drinking water. This still leaves 844 million people who do not have access to drinkable water. Goal 7 (SDG 7—Affordable and clean energy) is aimed at ensuring universal access to reliable, affordable, and modern energy services by 2030. It also extends to achieving a significant increase in the share of the global energy consumption that is renewable energy. Part of the strategies to achieve this is to improve energy efficiency such that more of the amount of the energy generated is actually available as useful energy. Part of the issues that have faced energy generation is how much of the energy available can be harnessed and how much of the harnessed energy can be used without being lost in transmission. Around 10% of people around the world do not have electricity. Half of them live in sub-Saharan Africa, mostly in the rural areas. The eighth goal (SDG 8—decent work and economic growth) is aimed at sustaining per-capital economic growth with regard to the circumstances of the nation. It is also aimed to achieve a minimum of 7% GDP growth yearly in the least developed countries in the world. This is expected to happen through innovation, technological advancement, high-value-added production and labor-intensive sectors which are expected to lead to increased economic productivity. As of 2018 around 172 million people, an estimated 5% of the global population, are unemployed. This number is said to increase by 1 million every year. This is partly attributed to increasing number of people joining the labor force every year. Despite having work, some 700 million employed people still remain in poverty as their earnings do not provide enough to meet their needs. The ninth goal (Goal 9—Industry, Innovation, and Infrastructure) targets quality, reliable, resilient, and sustainable infrastructure. This includes infrastructure across regions and across borders that contribute toward economic development and wellbeing of all people. It aims to achieve sustainable and inclusive industrialization by 2030 with a significant increase in employment and GDP that is aligned with the specific country’s circumstances. Infrastructure constraints reduce the productivity in some low-income African countries by 40%. This includes access to Internet, electricity, and infrastructure for processing agricultural produce.

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Global Sustainable Development Goals

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The tenth goal (SDG 10—reduce inequalities) aims to increase and sustain the increase of the income of the bottom 40% of the population at a rate above that of the national average by 2030. Strategies to achieve this include promoting social, economic, and political inclusion of all and adopting policies that help achieve greater equality. The UN states that in 2016 the top 1% received 22% of the income received across the world while the bottom 50% got 10% of the income received worldwide. This unequal distribution of income is partly attributed to the unequal ownership of capital as a result of the privatization of public wealth that has taken place across the world since the 1980s. Goal 11 (SDG 11—Sustainable cities and communities) aims to provide all people with safe, adequate, and affordable housing along with basic services and to upgrade the existing slums to meet the basic standard for housing. This includes providing adequate, safe, and affordable transport systems within and in and out of these communities. Taking into consideration the needs of those in vulnerable situations, persons with disabilities, and people in old age. It is estimated that 6.5 billion people will live in cities by 2050. As of 2018, this figure was 4.2 billion which was around 55% of the global population. More people living in urban areas means more demand for modern infrastructure. The twelfth goal (SDG 12—responsible consumption and production) aims to implement a 10-year framework for achieving sustainable consumption and production across the world led by the developed countries. The framework comprises a series of programs aligned with the goal. Part of this is to ensure natural resources are sustainably managed and efficiently utilized. In the area of food resources, for example, 1.3 billion tonnes of food gets wasted annually. Goal 13 (SDG 13—climate action) aims to improve the resilience and adaptation of all people to the effects of climate change. This is achieved through measures like integrating measures to mitigate against the effect of climate change into national policies, planning, and strategies. Although all countries in the world are affected by climate change, there are strategic efforts to support the places that are particularly vulnerable to the effects of climate change. Protecting the most vulnerable places has an impact on the whole world. For example, preventing a humanitarian disaster by protecting one climate-vulnerable city can help reduce the burden of immigration on bordering regions. The global temperature is said to have increased 1 °C higher than the pre-industrial global temperature. The fourteenth goal (SDG 14—life below water) and fifteenth goal (SDG—life on land) are aimed at protecting the life in the ocean and on land, respectively, by maintaining the right environment for them to thrive. Seventy-five percent of the earth’s surface is covered by water and around 200,000 species have been identified to exist in the world’s oceans. Millions more remain unidentified. However, today the ocean is facing pollution as 40% of the ocean is said to be polluted or affected by pollution. The UN set the goal to significantly reduce ocean pollution by 2025. Some progress has been made toward this, for example, The Ocean Cleanup recently reported to have removed 4,851,312 kg of plastic from the Pacific Ocean as of August 2023 (Company website). Although making up less of the surface area of the earth, the land is where all humans live and much of the food and resources required

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for food and other basic needs are produced on land. 2.6 billion people in the world live off agriculture directly. The forest is also of much importance. We are currently losing the earth’s forest at a rate of 13 million hectares per year. Whereas 80% of the animals, plants, and insects live in the forest. Goal 16 (SDG16—peace, justice, and strong institutions) aims for a significant reduction in all forms of violence and violence-related death rates all over the world. This includes ending all forms of abuse, exploitation, and trafficking of people and ending child torture and violence against children. This is achieved through promoting the rule of law at all levels and providing all people with equal access to justice. The UN has a set goal to combat all forms of organized crime and achieve a significant drop in illicit financial and arms flow by 2030. It also includes reducing bribery and corruption in all forms and develop institutions that are effective, transparent, and accountable across the world. Every year developing countries lose 1.26 trillion USD to bribery, corruption, and evasion of taxes. The seventeenth goal (SDG 17—Partnership for the goals) aims to foster global cooperation and partnership between countries to achieve the SDGs. This includes the developed countries providing support to the developing countries toward achieving. This includes policies that aid debt management for developing countries, promotion of international trade, and building fair and open trading systems to the benefit of all. The cost of achieving the SDGs is estimated to be between 5 and 7 trillion USD annually. Some of the SDGs mentioned here will be relevant to the applications of plastic discussed in the chapters to follow. This will range from the use of plastics in creating systems that facilitate food security to building climate-resistance homes and much more. Knowledge of all the goals is therefore important to be able to identify which SDG these applications apply to. In some cases, the application applies to more than one SDG. This is due to all the SDGs being interrelated.

1.3

Innovations Driving Sustainable Global Society

In this section, we explore the key technologies that have moved the world toward a more sustainable global society. The other chapters of the book assess how plastics as a class of materials contribute to some of these technologies and hence the role of plastics in ensuring a sustainable global society. Pollution from fossil fuel has been a key issue in modern economies due to the adverse impact on climate, environment, and human development. Researchers have identified some technologies that can play key roles in transitioning the countries of the world toward a sustainable development in terms of reducing environmental impact, providing clean energy, sustain economies, provide resilience against the impact of climate change, and ensure well-being of all people. The technologies that have been identified as key to building a sustainable global society are grouped into; technologies associated with renewable energy generation, renewable energy storage, technologies for CO2 capture and utilization, and technologies for sustainable

1.3

Innovations Driving Sustainable Global Society

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products and clean/green production processes. Of the technologies that were assessed, the existing technologies that are considered at the right level of maturity to be implemented in the market include carbon capture, storage, conversion, and utilization, offshore wind turbines, sustainable and energy-efficient ammonia production, cell culture technologies for agriculture and bio-based products like meat and biomaterials (Coccia 2023). Other technologies that show promise include blue hydrogen, green hydrogen, aluminum battery, floating photovoltaic systems, clean steel production, thermal energy systems, and wave power systems. The development of these technologies is affected by factors such as the cost of the research to advance the technology to the market, the cost of implementation, and the level of development of associated technologies to support the commercialization of the technology. Advancements in technologies associated with renewable energy generation have been significant in pushing the agenda to move away from fossil fuels. The existence of alternatives that are cheaper or at least cost the same, makes it more realistic for countries and regions to set more specific goals regarding switching to clean energy. For example, the EU’s goal is to shift to 42.5% renewable energy by 2030 (Payne 2023). Substitution of existing fossil-based technologies at such a large scale will require the existence of well-tested feasible alternatives. Another important factor in the advancement of technologies toward a sustainable global society is having a well-coordinated system for providing access to the world’s renewable resources as well as access to technical capacity for utilizing the resources. Fossil fuels have long been plagued with the “resource curse” whereby countries with an abundance of natural resources but without the knowledge and capacity to convert these resources into useful products tend to underperform economically (Tian and Feng 2023). This is partly attributed to the environmental degradation, human rights violation, corruption, and other issues that result from the extraction and processing of these resources such as crude oil and mineral ores. There is potential for green energy technologies to break this “resource curse” as these cleaner technologies avoid the associated issues of fossil technologies. Renewable energy storage is just as important as the generation of renewable energy. For some time renewable energy technologies have had to deal with the limitations of storage. For example, a solar-powered fan could only work when connected to the solar panel which only generates energy when there is sunlight. This limits its usefulness to daytime and during hot nights it cannot be used. Having a solar fan system that includes a battery and charging system, however, makes the solar fan much more useful. The batteries can be charged up during the day and powered directly by the sun during the day. At night the fan can operate using the energy stored in the battery. Similar applies to other forms of energy generation systems. The ability to store energy has been key to developing technologies such as electric cars and mobile phones. Devices no longer need to be connected to a home or industry power supply to function which allows for mobility. Current research and development in energy storage is getting energy storage systems to store more energy (Hutchinson and Gladwin 2023). This, for example, allows electric vehicles to go further before needing to stop to recharge the batteries.

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Global Society and Sustainable Development

The study into the impact of human activities on the environment has been well formulated since the second half of the eighteenth century (Boas 1904). Interest in the impact of human activity grew further after the first industrial revolution which has been followed by three other industrial revolutions, of which we are now in the fourth (Gumbo et al. 2023). These industrial revolutions have led to significant transformations in societies and economies and the driving force has been technological advancements. For example, the discovery of steam engines and mechanization was a driving force for the first industrial revolution. The electricity and the moving assembly line were key to the second industrial revolution, while the third industrial revolution was driven by advancements in automation and digital technologies. The fourth industrial revolution is driven by advanced application of information and communication technologies (ICT) to industry. Alongside the benefits they brought, these industrial revolutions have been marked by environmental degradation, pollution, and consumption of natural resources at an unsustainable rate. Although they contributed significantly to human development these industries have been largely powered by fossil fuel. The industrial revolutions also contributed to population growth, increased energy consumption and rising levels of greenhouse gases like CO2 and methane, and increased waste generation and pollution compared to post-industrial times. As technology kept people safer, more people stayed alive long enough to reproduce and with more people adopting more modern consumer lifestyles more resources were being consumed and more waste was being generated at an exponential rate. Deterioration of health has also accompanied industrialization and the mostly linear economy approach that has been adopted so far. Some argue that the rising CO2 level is not a new phenomenon, the level of CO2 in the atmosphere is said to have been rising since 6000 years ago (Ruddiman 2003). However, the period referred to as the Anthropocene era, an era marked by the beginning of human activities having an ecological and geological impact on the planet is mainly attributed to industrialization (Crutzen and Stoermer 2000; Steffen et al. 2007). The rise in CO2 is the main factor attributed to climate change. This has motivated the development of technologies to capture, store, and convert CO2 for utilization. Other than removing the CO2 from the environment another approach is to avoid producing CO2 in the first place. Since CO2 is produced from the combustion of fossil fuel, technologies to replace fossil fuels such as solar energy, green hydrogen, wind, and others are sustainable means to generate energy sustainably.

1.4

The Global Plastic Challenge

Where plastic waste is considered a waste management problem, this tends to be treated as a local issue where it is mainly municipalities that are responsible for addressing the problem of waste. However, plastic waste goes beyond the dumping of plastic waste, it is an issue of mismanaged resources that stems from a globally adopted linear economic approach. Furthermore, as images of plastic spread across

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oceans drifting long distances and impacting on global food chain, it becomes evident that plastic pollution is not limited to a country or region, rather it is a global challenge. The issues currently faced with plastics have challenged humanity to do better in the way we interact with the planet we inhabit and with each other. Technologies developed in one country can have an impact on the other side of the world and even across the world. Events occurring in London can be seen live all across the world and trigger actions in several countries thousands of miles apart. A PET bottle has become an essential item on the shelves of shops and supermarkets from New York to Dakar, a bottle of water or a carbonated drink packaged in a plastic bottle has become a global “staple.” The plastic industry is therefore faced with the challenge of developing sustainable production processes, applications, and end-of-life processing of plastics within a globalized society while adopting a circular economy approach. The process of producing, using, and disposing of plastic should not pose a threat to the environment or well-being of people and the entire planet. The rest of the book delves into applications of plastics in various technologies that drive the sustainable development of an increasingly globalized society beginning with a brief history of plastics.

References Amovic M, Govedarica M, Radulovic A, Jankovic I (2021) Big data in smart city: management challenges. Appl Sci 11(10):4557 Barney MN, Sikkink K (2009) From international relations to global society. In: The Oxford handbook of international relations. Academic, Oxford, pp 62–83 Bartelson J (2009) Is there a global society? Int Political Sociol 3(1):112–115 Boas F (1904) The history of anthropology. Science 20(512):513–524 Coccia M (2023) New directions of technologies pointing the way to a sustainable global society. Sustain Fut 5:100114 Crutzen PJ, Stoermer EF (2000) The anthropocene. Global IGBP Change Newsletter 41:17–18 Gumbo S, Twinomurinzi H, Bwalya K, Wamba SF (2023) Skills provisioning for the fourth industrial revolution: a bibliometric analysis 219:924–932 Hutchinson AJ, Gladwin DT (2023) Capacity factor enhancement for an export limited wind generation site utilising a novel flywheel energy storage strategy. J Energy Storage 68:107832 Janakova M (2018) Big data and simulations for the solution of controversies in small businesses. In: Encyclopedia of information science and technology (4th edn), pp 8–9. https:// doi.org/10.4018/978-1-52255-3.ch598 Payne J (2023) EU countries to finalise 42.5% renewable energy target. Reuters Ruddiman WF (2003) The anthropogenic greenhouse era began thousands of years ago. Climate Change 61:261–293 Steffen W, Crutzen PJ, McNeill JR (2007) The anthropocene: are humans now overwhelming the great forces of nature? Ambio 36:614–621 Tian Y, Feng C (2023) Breaking “resource curse” through green technological innovations: evidence from 286 cities in China. Resour Policy 85:103816 UN General Assembly (2015) Resolution adopted by the general assembly on 25 September 2015. Seventieth Session Agenda Items 15 and 116. A/RES/70/1

Chapter 2

A History of Plastics

Abstract Plastic-like materials have existed throughout history. Synthetic plastic saw much of its significant development during the second industrial revolution with chemical synthesis and mass production increasing during this period. The development of nylon fiber saw one of the greatest commercial successes as the most widespread product demonstrating the application of plastic material in everyday consumer products. Different plastic processing techniques were developed to meet the need for feasible processes to convert these plastic materials into products. Some of these processes were borrowed from other fields such as textiles, rubber processing, and metalworking. Many of the fundamental processes are still in use today despite having seen significant modification and advancement over the years. This chapter reviews some of the historical development of plastics and plastic processing techniques.

2.1

Modern Human and Plastics

Plastics, the polymeric material with a low yield strength that can be formed into various shapes when heated (thermoplastics) or prior to setting (thermoset plastics) and upon cooling or setting will retain the formed shape, have so far had a huge impact on the world from the twentieth to the twenty-first century. So much so that this period is being referred to as the “plastic age.” This class of polymeric materials has proven to be ubiquitous, wonderous as well as disastrous. From waking moment to sleep, from birth to death, modern humans cannot seem to do without plastics. Plastics are widely used in the clothes we wear, toothbrushes, shoes, medical devices, food packaging, baby feeders, electrical appliances, and much more. Plastics can be thermoplastics such as polypropylene, polystyrene, and polycarbonate. These can reversible flow upon heating to their softening and melting temperature and solidify upon cooling. They can also be thermosets. These are plastics that cannot be reversibly made to flow by heating. Examples are unsaturated polyesters, polyurethane, phenolics, and polyimides (Ratna 2022). Advanced polymer engineering has introduced a twist to this classification of polymers where some thermoset polymers can be modified to be thermoplastics and vice versa. Examples © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 O. Olatunji, Re-envisioning Plastics Role in the Global Society, https://doi.org/10.1007/978-3-031-48945-7_2

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are polyurethane and polyimide which can be made thermoset or thermoplastic (Ke et al. 2020).

2.2

Plastics and Plastic-Like Materials in Nature

Although synthetic nonbiodegradable plastics account for around 99% of plastic produced globally (Zhao et al. 2020), plastic materials or plastic-like materials exist in nature. Examples of naturally occurring plastic or plastic-like materials include amber, shellac, gutta-percha, ebonite, and ivory (Brydson 2016). Amber, for example, is a fossilized resin from a conifer tree, that has taken 30–60 million years to form. The resin is formed and fills cavities within the trees, from which it is then deposited in the forest soils. Under dry and aerated conditions, the resin hardens. Over time the resin is washed into the water basins where it is exposed to alkaline silt water containing potassium and eventually forms amber. These are typically obtained by mining and they are obtained in the form of irregular rocky pieces of amber around 3 cm in diameter (Vikhareva et al. 2016). These processes under which amber is naturally formed occur over millions of years thus making amber a nonrenewable resource. The amber deposits on Earth can be used up much faster than the rate at which they are formed in nature. Amber is mainly used in jewelry and decorative applications. The limited application is linked to the limited processibility. Although amber grains and pieces can be formed into blocks through the application of heat and pressure, the material in its natural form does not melt and flow as well as synthetic thermoplastics, and is prone to degradation as it approaches its melting point. Similarly, many of the other naturally occurring plastic and plasticlike materials tend to have limited applications due to their limited processibility. Many of the naturally occurring plastic and plastic-like materials have been replaced by synthetic fossil-derived plastic since the 1950s. For example, shellac which was once used as a coating (Brydson 2016) is now largely replaced by plastics like PMMA and polyvinyl acetate.

2.3

Development of Modern Plastics

The earliest fully synthetic plastic was celluloid. It was obtained by chemical modification of cellulose nitrate (nitrocellulose) using camphor (Rasmussen 2021). Cellulose nitrate was technically the first manufactured plastic. It was one of the early attempts at obtaining plastic-like materials by modifying naturally occurring materials. It was obtained by reacting cotton fibers with nitric acid and sulfuric acid. A modified version of cellulose nitrate which was obtained by mixing with vegetable oil was introduced in 1860 and patented with the name “Perkesine” in 1862 by Alexander Parkes (Rasmussen 2021).

2.3

Development of Modern Plastics

13

Although not plastics, the 1840s also saw the development of another category of polymers, rubber, particularly vulcanized rubber introduced by Charles Goodyear. The invention of vulcanized rubber was key to the development of modern bicycles, motorbikes, cars, and other vehicle tires. Around 1897, casein plastics were invented by Krische and Spitteler who obtained the plastic from reacting milk protein with formaldehyde. The earliest application of this plastic was in white blackboards in Germany. They are still used today in the production of buttons used in garments. By 1859 more formaldehyde-derived plastics were introduced. This is evidently due to the highlighted ability of formaldehyde to react with other materials to form resinous compounds. 1872 saw the introduction of phenol-aldehyde-based polymers. With the first patented in 1899 by Arthur Smith. 1907 saw the first of many phenol-aldehyde plastics patented. Such that the phenolic plastics were among the earliest truly synthetic polymers to be commercialized. Bakelite Xylonite Company, Celluloid Manufacturing Company, Carbide and Distillers organizations, and British Industrial Plastics were among the earliest companies in the plastic industry. Pakesine derived from cellulose nitrate blended with modified oil was developed by Alexander Parkes in 1860. In 1870, celluloid was introduced by John Wesley Hyatt (Rasmussen 2021). Around 1924 urea-formaldehyde resins were introduced and their applications were being explored. This later became widely used in adhesives, textiles, and paper industry. Cellulose acetate was developed around the same period. In its unplasticized form, it was used for the production of fibers and aircraft dope. By 1927 plasticized cellulose acetate was introduced and became an alternative to celluloid. Cellulose acetate found use in several injection molded products and replaced celluloid in many applications (Brydson 2016). In 1907 bakelite was developed by Leo Baekeland, a Belgian chemist. Bakelite was regarded as the first fully synthetic plastic and the first to be obtained fully from fossil fuels. It was produced by the reaction between formaldehyde and phenol under heat and pressure. Bakelite led the way for a deluge of fossil-derived modern plastics, many of which are still in use today. Examples include polyethylene, polyvinyl chloride, polyesters, nylon, and many others. World War 2 contributed immensely to the rise of the plastic industry. During the war plastics were used in applications such as bulletproofs, radar insulations, water resistance casings, lightweight containers for easy carrying, and rugged and lightweight vehicle parts that could be produced fast and cheaply. When natural resources like wood and metal ores were, there was a need for cheaper alternatives to materials like paper, metal, and glass. After the war in 1945, the demand for plastics fell as there was less need for the products the plastics were being used to produce. In order to maintain the production rate, the manufacturers sought to create new demands for the plastics. They sought to produce consumer goods made out of plastics. By 1948, products like Tupperware and plastic toys were being mass produced from fossilderived plastics. This was also during the second industrial revolution, the age of mass production. The inventions of the different types of plastics also fueled the rise in the consumer goods market and perhaps the rise of a consumer-based economy. Plastics,

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2 A History of Plastics

which could be synthesized and processed cheaply made it possible to produce large quantities of goods such as combs, radios, and sunglasses cheaply. Plastics quickly replaced more scarce materials like ivory and tortoise shells in the production of such goods. Plastics also had to impact on preventing the extinction of animals like elephants which were hunted and killed for their tusks. Later companies like Dow Chemicals, BASF, DuPont, and ExxonMobil entered the plastic industry as major players in the twentieth century and they still remain major players today as primary manufacturers of plastics. They supply secondary producers who then make use of these plastic resins to produce plastic products such as films, colored resins, premolds, or finished plastic products like plastic cutleries, pieces of furniture, kayaks, and others. The oil and gas industry was a source of by-products like ethylene gas which served as the raw material for the plastic polyethylene. This plastic today is the most produced plastic in the world (Statista 2023). Nylon was the first plastic to experience huge commercial success. In the 1950s, Dupon company was the first to commercialize nylon-based products in the form of nylon leggings which saw phenomenal commercial success. Despite the several plastics introduced in the 1800s and into the early 1900s, it was not until the 1920s that a scientific explanation for the macromolecular chemistry of plastics was presented (Billmeyer 1981). This was when the existence of polymers as a separate category of materials was presented. Table 2.1 lists some plastics and their year of invention/ introduction into the market based on various sources as discussed within the section (McKeen 2011; Zhang et al. 2021; Billmeyer 1981; Sanchez et al. 2021; Riedl and Kaboorani 2015; American Chemistry Society 1999). The years reported for different plastics may vary from the different texts as in some cases the distinction is not made between the year of discovery year of patenting and the year of commercialization.

2.4

Historical Development and Description of Some Plastic Processing Techniques

Other than the properties of plastics like their relative inertness, lightweight, durability, and water repellency, the ease of processing of plastics has also been a great contributor to their enormous success over the decades since their invention. Therefore, the historical development of plastic processing techniques is just as important as the history of the plastics themselves. Some of the plastic processing techniques have been borrowed or adapted from the processing techniques used for other materials like metal and glass. Some of the processes are also used for processing other materials. On the other hand, some of the processing techniques are only applicable to thermoplastics and not thermoset plastics. A given plastic type can be processed using a variety of techniques to produce a wide range of products. Many of these techniques are mass reproducible allowing for

2.4

Historical Development and Description of Some Plastic Processing Techniques

15

Table 2.1 Some plastics, year of invention, and example applications Plastic Polypropylene (PP) Polyethylene (PE) Polyester (PES) Polyvinyl Chloride (PVC) Polyether ether ketone (PEEK) Nylon 66 Polycarbonate (PC) Polystyrene (PS) Polylactic acid (PLA) Polymethyl methacrylate (PMMA) Polyacrylonitrile (PAN) Polyvinyl alcohol (PVA) Cellulose nitrate/nitrocellulose Low-density polyethylene (LDPE) Parkesine Celluloid Cellulose acetate Urea-formaldehyde Bakelite Teflon Polyethylene terephthalate (PET) Polyhydroxy butyrate (PHB)

Year of invention/introduction 1957 1934 1930 1933 1978 1935 1898 1929 1920 1932 1946 1912 1860 1936 1862 1870 1924 1924 1907 1930s 1941 1926

optimization of production cost through economy of scale. PET, for example, can be processed through melt spinning into polyester fibers used in textiles, it can also be processed into films for packaging using blown film extrusion, and using blow molding it can be processed into bottles for packaging and storage of drinking water. The following subsections provide some historical accounts and brief descriptions of some plastic processing techniques. Table 2.2 lists some plastic processing techniques, and the year of the invention based on various sources (Wiley 1944; Zhao et al. 2020; Kronholm 1954; Tucker et al. 2012; Andersen et al. 2009; Belcher 2017; Gajdosik 1958; De la Mora 2013; Konica Minolta Inc. 1977; Hyatt and Hyatt 1872; Giles et al. 2005; Cadden 1928) and the products commonly processed using these techniques.

2.4.1

Extrusion

Extrusion is one of the fundamental plastic processing techniques. It is used at different stages of plastic product development. The first patent on a single screw extruder was in 1885 (Andersen et al. 2009). Prior to this extrusion was already

16

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A History of Plastics

Table 2.2 Plastic processing techniques and year of invention Plastic processing method Injection molding Single screw extrusion Blown film extrusion Blow molding Rotational molding Thermoforming Solvent casting Melt spinning Wet spinning Electro spinning Calendaring

Products Molded parts with diverse geometry Simple continuous profiles Thin films Hollow parts with closed base Hollow parts with complex geometry Thin-walled large parts Plastic films Fibers Fibers Fibers Continuous sheets

Year of invention 1872 1885 1954 1930 1940–1950 1930–1950 1977 1883 1943 1900 1928

being used in the processing of rubber. The process described in the first patent is still being used today although there are advancements in the systems used to achieve each stage. The process involves melting and mixing plastic under shear and releasing it through a die. Upon release from the die the plastic is immediately solidified as it passes through a cooling channel in the case of thermoplastics (Billmeyer 1981). Thermoset plastics may solidify upon release from the die as a result of reaction completion. The shearing force is achieved by the action of the plastic pellets being forced between a rotating screw inside a barrel. Heat is generated as a result of viscous dissipation. Additional heat is obtained from heaters connected to the barrel to meet the melting point of the thermoplastic or the reaction activation energy of the thermoset. Other plastic processing techniques like blow molding, calendaring, and melt spinning are preceded by extrusion. The extrusion process is the key process used to produce the plastics pellets or resins which serve as the feedstock for the processing of plastics into other products. The extrusion serves as the fundamental process of other plastic processing technologies. Extrusion can be applied to both thermoset and thermoplastics. Processing of thermoplastics requires the melting of the plastic pellet/resin as it moves along the barrel. Processing of thermoset by extrusion may involve introducing the feed monomer, oligomer, or uncured polymer in liquid form and precise timing of the reaction to ensure that the product does not solidify before exiting the die. Extrusion of plastics and polymers in which reactions such as crosslinking, grafting, polymerization, and co-polymerization occur during the reaction process is referred to as reactive extrusion (Giles et al. 2005). There are different types of extrusion. The extrusion types can be categorized according to the type of products like profile extrusion, wire extrusion, and blown film extrusion. The extrusion can also be categorized based on the design of the equipment like the twin screw extruder and single screw extruder. Each process needs to be configured such that the settings are appropriate for the specific plastics

2.4

Historical Development and Description of Some Plastic Processing Techniques

17

to be processed. Parameters to be considered for different plastic types include temperature settings along the barrel, the screw type, the rpm of the screw, lengthto-diameter ratio, etc.

2.4.2

Blow Molding

Blow molding process involves inflating a thermoplastic melt tube (parison) within a closed mold cavity by passing air through a blow pin such that the melt stretches and forms a hollow object taking the shape of the mold cavity. The melt is then allowed to solidify and cool, retaining the formed shape (Belcher 2017). Blow molding can be adapted to small bench-scale production for producing a few pieces for a small market or for research or custom applications. They can also be large machines taking up several meter squares of space in a factory. Blow-molded parts can range from centrifuge bottles of around a few cm3 to large storage tanks of thousands of m3 volume. There are several variations of the blow molding process that have been developed over the years. These came about as the need to modify the prior blow molding process to meet specific product design specifications. Blow molding processes include injection blow molding where a preform with thicker walls gets injection molded first prior to inflation in a blow mold (Kazmer 2011), free extrusion blow molding where an extruder drops a parison in between the two halves of a mold cavity through a die head followed by blowing (Maack et al. 2022), stretch blow molding where a preform is stretched to improve the properties before blowing into desired hollow shape (Greene 2021) and co-injection of co-extrusion blow molding where multiple layer hollow articles are produced using multiple parison or preforms and multiple extruders (Kazmer 2011). The blow molding process itself dates further back than modern-day fabric. Blow molding originates from the glass-blowing process which is said to date back to the first century AD with evidence of glass blowing by Romans and Syrians. However, the development of blow molding in the plastic industry only began in 1930 with the molding of cellulose acetate and cellulose nitrate items using a blown injection molding process. Thus was introduced by the Fernplas Company. In 1935, a joint venture of the Owens-Illinois and the Emhart Corporation was started with the goal of adopting the glass-blowing process for the production of plastic hollow objects and containers. The blow molding of modern plastics as we know it today really took off in 1946 with the blow molding of LDPE (Belcher 1989). The earliest application of blowmolded LDPE was as squeeze bottles for deodorants. The flexibility of the LDPE bottles allowed the flexibility required to create a container that could be squeezed to push out deodorants as a spray. The production of these deodorant spray bottles began in 1947 and reached sales of 5 million bottles by 1949. LDPE gradually replaced glass and metal in applications such as edible oils, detergents, and antifreeze. LDPE had a lower melting point and higher flexibility than glass. It could

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2 A History of Plastics

also achieve the transparency of glass and can be blown into different shapes more easily. Blow molding of PET also joined in 1976. These were primarily used as bottles for packaging and storing carbonated soft drinks. The PET bottles were very successful and became competitive with the aluminum two-piece cans which previously dominated the carbonated drinks packaging. By 1987, PET bottle production for soft drinks packaging was over 5.3 billion. Overall 19.6 billion blow-molded containers of different kinds and applications were produced in 1987. Blow-molded plastic production continued to rise at approximately a 5–7% growth rate between 1987 and 1991 (Belcher 1989). In 2008, 12.8 billion pounds of HDPE plastics were produced in the United States and a large fraction (estimated 40%) of the HDPE was used in blow molding, particularly extrusion blow molding (Belcher 2017). HDPE is mostly used in large blow-molded articles like large oil gallons, drums, and tanks.

2.5

Injection Molding

Injection molding is the process whereby plastics are mixed and melted under heat and shear pressure and then injected into a mold cavity where they are formed into desired shapes. The mold is then cooled which allows the plastic to harden retaining the shape of the mold, after which the product is ejected from the mold. The melting and shearing are achieved by forcing the plastic pellets through the gap between a rotating screw placed within a heated barrel. The equipment used to facilitate this process is called an injection molding machine. Although there are several variations of injection molding machines, the fundamental principles remain consistent for all injection molding processes. Injection molding is the most widely used plastic processing technique. It came at a time when there was a growing demand for mass production of quality products at low cost. The process of injection molding was first patented in 1872 by John Wesley Hyatt and Isaiah Hyatt (Hyatt and Hyatt 1872). Hyatt’s venture into plastic processing was motivated by an advert in New York offering a reward of 10,000 USD to anyone who could offer a replacement material for ivory. Ivory was then used for the production of billiard balls to the extent it threatened the population of elephants in the world. This quest led to the creation of a company with his brothers and several other inventions in the plastic industry as well as injection molding (White 1999). The first injection molding machine had a basic operation that involved ramming molten viscous plastic into a mold, holding it under pressure to allow cooling, and then releasing the molded product. The process was referred to as ram injection molding and was developed with the aim of processing celluloid into molded products. Advancements in the injection molding process over the years gradually led to the injection molding machine as it is today. The injection molding process advanced through the introduction of the rotating screws within a heated barrel, the limit

2.5

Injection Molding

19

switch triggered injection, multi-cavity injection systems, to automated systems to the numerous other advancements and variations of the injection molding process. Injection molding is so far the most widely used plastic processing technology. With injection molding, bioplastics can be processed into a variety of complex parts in a mass-reproducible way. Injection blow molding also allows the production of hollow containers and parts. Plastic injection can be done at different scales from small bench-top production of a few parts as needed to large-scale processes making hundreds of cycles daily. There are several classifications of injection mold based on different characteristics (Frizelle 2017). Prototype injection molding is injection molding dedicated to production of prototypes. Here the goal is to produce one or just a few of a product for the first time. Since the product design might change, the goal is not primarily to develop a set injection molding process yet. One of the key features of prototype injection molding is the mold. Rather than using a long-lasting material like stainless steel 306, the operator might go for a weaker metal like aluminum. This material might not last more than a few runs, however, this is just sufficient for a prototype. While in the long run, this is a very expensive practice, for a prototype, this is the cheapest way to produce a prototype by injection molding. This limitation of injection molding in the production of prototypes is partly attributed to the success of 3D printing over the years. A 3D-printed prototype will require a mold to be fabricated by CNC machining. The mold design itself is a rather complex discipline. There are engineers whose specialty is in mold design alone. A 3D printer mainly requires the CAM file and a suitable ink material or filament. 3D printing can achieve faster prototyping compared to injection molding. Another classification of injection molding is based on the orientation of the setup. Vertical injection molding is where the assembly is set vertically as the name implies. The clamp action and mold opening and closing occur vertically and the orientation allows gravity-enhanced mold filling. To someone not familiar with injection molding process, this might not seem so relevant, since from first impression it is simply the same thing just turned downward. However, this change in orientation allows a little more to be done and can significantly improve efficiency. For example, multiple molds can be used and over-molding is more effective in vertical injection molding. Because of the orientation, ejected parts do not fall out of the molds. They are removed by hand or by a robot. This has advantages in some processes like insert molding where an insert which is typically metal material is placed in the mold over which the melt is injected. Injection molding can also be classified based on the number of shots. Two-shot injection molding is where within a single cycle, two shots are released rather than one. Two molds are also used per cycle. The first shot fills the first mold. This is cooled and the formed product is transferred into the second mold. The second shot fills the second mold and the cycle repeats as the first shot fills the first mold. This is used in overmolding where two types of materials are molded in a product. The first shot and second shot are two different materials from different barrels (Wei et al. 2023). There are several other types of injection molding processes. The several

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2 A History of Plastics

variations of injection molding further makes it a very versatile processing technology.

2.6

Rotational Molding

Also referred to commonly as roto-molding or roto casting was introduced in the 1940s and was industrial production began in the 1950s where some of the earliest applications of the process included, the production of doll heads, toys, and other articles (Nugent 2017). It is used to create a diverse range of products from small pipette bulbs of a few milliliters to large tanks of 20,000 l (Beltran et al. 2012). The common theme for rotomolded products is hollow and seamless designs. These include parts for aerospace, road cones, armrests in cars, storage boxes, water tanks, fuel tanks, kayaks, and other products. The process is said to be borrowed from the ceramic rotational casting and for the production of hollow chocolate eggs by the Swiss. It involves charging the plastic in powdered form into a mold, closing the mold, and allowing it to heat to the desired temperature. The mold is then rotated biaxially to allow the plastic to melt and spread covering the inner walls of the mold. In so doing the plastic forms a hollow shape according to the shape of the mold. The mold is allowed to cool and once hardened the product is released (Beltran et al. 2012). A schematic description of roto-molding is presented elsewhere in this book in the chapter on plastics in sustainable energy and transformation. There the application of roto-molding in the production of kayaks is also presented. PVC was the first plastic to be used in rotational molding. However, with the introduction of powdered polyethylene, it became the plastic type most processed using the rotational molding method (Beltran et al. 2012). Their melt properties, shrinkage, and mold release properties are well suited for roto-molding. Today a wider range of plastics has also been used in rotational molding polycarbonate, polypropylene, nylon polyesters, and ABS. Recent development includes the development of methods for rotational molding of containers with multiple layers (De la Mora 2013). Other areas of development include a reduction of cycle time since rotational molding is a relatively slow cyclic process compared to other plastic processing methods like injection molding. Rotation speeds are typically between 2 and 20 rpm (Beltran et al. 2012). The process is also a low-shear process since there is no need to apply pressure or squeeze a plastic melt through nozzles.

2.7

2.7

Thermoforming

21

Thermoforming

Thermoforming saw its early development between 1930s and 1950s (DuBois 1972). The earliest applications of thermoforming were in the production of acrylics used in airplane canopies. Later applications of thermoforming made use of rigid vinyl than other plastics like polystyrene, acetate, and copolymers of styrene. Hot oil, steam, and water were previously used as heating and cooling medium and later hot air as a cooling medium was introduced. Various patents were released between the 1930s and 1950s which showed different methods of forming articles from plastic sheets to obtain thin-walled plastic articles. A 1939 patent for example presented a method for forming hollow articles using both mechanical and fluid pressure from plastic sheets or strips (Kopitke 1939). In 1944 another patent was filed presenting a method of deep drawing to be implemented in the thermoforming process. This claimed to achieve more even wall thickness and is applicable to a variety of plastics included cellulose acetate, polystyrene, vinyl chloride, and other plastics (Wiley 1944). In 1950, the thermoforming process was further advanced to include a method for designs in fine detail on the thermoformed articles to great depth (Winstead 1950). This eliminated the need for additional, time-consuming processes to apply details to thermoformed plastic objects. In 1958, a patent was filed for the thermoforming process which included pre-stretching of the plastic sheet and the use of a male mold the achieve uniform thickness of the walls and less reduction in thickness from the sheet to the formed product (Gajdosik 1958). The process of thermoforming generally involves forming of plastic sheets into parts with relatively thin walls. These are usually relatively large parts like buckets, equipment parts, and swimming pools. The main types of thermoforming are mechanical, air, and vacuum. The process begins with the plastic being molded in the form of a sheet. This sheet is clamped onto a female mold and then heated and stretched. In the mechanical thermoforming, a male mold is used to form the heated and stretched film into the desired shape. This is followed by cooling after which the product is released. In air thermoforming a plunger is used to stretch the heated film toward the female mold. After this air pressure is used to stretch the heated plastic sheet to form the shape of the female mold. This is followed by cooling and release. In the vacuum thermoforming process a vacuum is used to pull the heated sheet into the female mold. This is maintained until the product is formed and cooled after which the vacuum is removed and the product is released. The different processes used in the industry vary with the types of systems used to achieve each stage such as heating, pressure, and cooling, and the level of control over the processes. The material is often moved from one stage to the other until the process is complete.

22

2.8

2

A History of Plastics

Fiber Spinning

Prior to plastics, fibers have been made out of natural sources such as cotton, silk, and hemp. Artificial fibers go as far back as 1734 when artificial filaments were produced from varnishes (Kauffman 1993). The first plastic fiber to be spun was nitrocellulose which was used to produce filaments used in light bulbs in 1883 (Spear 2013). In 1938, nylon 6,6 was introduced by Wallace Carothers as the first plastic fiber to be commercially melt spun (Hufenus et al. 2020). This was followed by the development of nylon 6 in the same year. Melt-spun PET fibers followed in 1941 and by 1957 polyolefin fibers were being spun commercially (Hufenus et al. 2020). The fiber spinning process involves creating a melt or solution of plastic within a container. This is then drawn into fibers through a spinneret. The fiber is then passed through a nonsolvent in case of wet spinning or through quenching/cooling air/liquid medium. This allows the fiber to solidify. The formed fiber is further drawn to improve its properties through rollers. Further washing, drying and other postprocessing may follow. The finished fiber is then wound up into spools. Other variations of the fiber spinning process include electrospinning, melt-blowing, spun bonding, and gel spinning. Melt spinning has been the most commercially applied fiber spinning method (Hufenus et al. 2020).

2.9

Plastics and the Environment

With plastics finding countless applications in almost every aspect of life, this class of material quickly gained a reputation as the wonder material. Its use also increased drastically and consequently so did its disposal. A class of durable, seemingly indestructible materials was largely being used as low-cost disposable materials. This spelled the beginning of a pollution problem. The mechanism of degradation of plastics is not yet fully established. Plastics are said to require up to several millennials to degrade under normal environmental conditions. Part of this degradation is the disintegration of the plastic piece into micron-sized particles referred to as microplastics (Boucher and Friot 2017). These are fragments of plastics having a size within the micron range, typically 5000 microns or less. Impacts of the microplastics on human health and the ecosystem are still being unraveled. Some already visible impacts are already manifested in the form of the accumulation of microplastics in aquatic animals that are consumed as food by humans (Yan et al. 2022). The late 1980s saw the first commercial production of polyhydroxybutyrate (PHB), a bioplastic from bacteria, a polyhydroxyalkanoate with a tradename, Biopol (Kariduraganavar et al. 2014). This is the first feasible biodegradable plastic developed by the then Imperial Chemicals Industry (ICI). Although PHB was first discovered in 1925, its commercial production was not really investigated until the

2.9

Plastics and the Environment

23

1970s. This was a period when the availability of cheap oil was threatened by the Iran–Iraq war, the Arab Oil Embargo between 1973 and 1974, and some scientists’ concerns about marine pollution (Sanchez et al. 2021). It can be said that the early development of bioplastics was motivated more by uncertainties in the supply of crude oil than environmental concerns. One of the limitations of most commercially available biodegradable plastics today is that they require specialized industrial composters for them to biodegrade. If such plastics end up in the domestic composts, landfills, or other parts of the environment they are unlikely to biodegrade any faster than conventional synthetic plastics. Thus defeating the point of such plastics. Other biodegradable plastics such as PLA, PHA, and thermoplastic starch have also been developed over the years. Some of these like PHA are compostable, however, factors such as inferior mechanical properties and higher cost compared to conventional plastics limit their wider commercial application. Bioplastics are covered in more detail in a separate chapter of this book on sustainable plastics. Although mechanical plastic recycling has been established as an effective way to reduce the environmental impact of plastics, this comes with several limitations. Most plastics deteriorate after each recycling such that the application and performance of recycled plastics are limited. Sorting and purity are also other issues in mechanical plastic recycling as this requires additional cost, manpower, and technology. Other than the separation of different plastic types, it is often also necessary to separate different product types made from different plastics. This is because different manufacturers may use different types of additives to achieve specific properties of the same plastic type to meet different applications. For example, while a carbonated drink bottle and a grapefruit packaging box may both be made of PET, different additives could be used to make the PET suitable for packaging carbonated drinks that are not used for the PET used in the grapefruit packaging box even if the colors are the same. Mixing these two can result in the melt with inconsistent melt flow properties that do not allow for good processing. While sophisticated methods to achieve high efficiency in the separation and purification of plastics in recycling have been introduced, these are yet to be economically viable for large-scale application. Such that much of the sorting is done manually. Although the earliest plastics like cellulose nitrate and cellulose were obtained from cellulose, a natural, abundant, and renewable resource, the fossil-derived plastics have since dominated production. This leads to another concert, the depletion of nonrenewable fossil resources. There is also the environmental concern associated with the emissions and risk of oil spills associated with crude oil production. This has motivated efforts to find alternative sources for producing conventional plastics like polyethylene. Such that in cases where the use of these synthetic, nonbiodegradable plastics cannot be avoided, the problem of fossil raw material can at least be addressed. To this effect, technologies have been developed to produce plastics such as polyethylene terephthalate from plant sources (Rorrer et al. 2019), which are regarded as more sustainable sources. The sugar in the feedstocks which can be sugarcane for example is converted to ethanol through fermentation by microbes. The ethanol is then converted into ethylene which is the starting

24

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A History of Plastics

compound for the production of polymers like polyethylene and polyethylene terephthalate. These are chemically identical to fossil-derived counterparts and can be processed in the same way for the same applications. Today these bio-derived plastics are already in the market in the form of PET bottles used in the packaging of carbonated drinks.

2.10

Conclusion

The historical development of the plastic industry began during a period when there was a demand for low-cost materials to replace those that were either not easily available or did not meet the demand of the time effectively. Plastic processing methods also emerged as means to process plastics into a wide range of products. In the age of mass production methods that could produce good quality parts cheaply and fast took precedence. Some of the methods such as injection molding were first introduced as simple crude methods but have seen significant advancement since with the development of improved machinery, automation, and digital technology. As we advance further into the age of artificial intelligence and Industry 4.0, it is expected that these plastic processing techniques will see further development.

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Hufenus R, Yan Y, Dauner M, Kikutani T (2020) Melt-spun fibers for textile applications. Materials (Basel) 13(19):4298 Hyatt JS, Hyatt JW (1872) Improvement in process and apparatus for manufacturing pyroxyline. US Patent 133,220 Kariduraganavar MY, Kittur AA, Kamble RR (2014) Polymer synthesis and processing. Nat Synthetic Biomed Poly:1–31 Kauffman GB (1993) Rayon: the first semi-synthetic fiber product. J Chem Educ 70:887–893 Kazmer D (2011) Design of plastic parts. In: Applied plastics engineering handbook. William Andrew, pp 535–551 Ke H, Zhao L, Zhang X, Qiao Y, Wang G, Wang X (2020) Performance of high-temperature thermosetting polyimide composites modified with thermoplastic polyimide. Polym Test 90: 106746 Konica Minolta Inc (1977) Process for preparing cellulose triacetate films. United Kingdom Patent GB2013559A Kopitke WH (1939) Process and apparatus for forming articles from organic plastic material. US Patent. 2282423A Kronholm CA (1954) Plastic film extruder. US patent US2844846A Maack RF, de Puiseau CW, Sokolova A, Atsbha H, Tercan H, Meisen T (2022) Reducing the Sim2Real-gap in extrusion blow molding using random forest regressors. Manufact Lett 33: 843–849 McKeen LW (2011) Environmentally friendly polymers. Permeability properties of plastics and elastomers, 3rd edn. William Andres, pp 287–304 Nugent P (2017) Applied plastics engineering handbook (2nd edn): processing, materialism and applications. Plastics design library, pp 321–343 Rasmussen SC (2021) From Parkesine to celluloid: the birth of organic plastics. Angew Chem 133(15):8090–8094 Ratna D (2022) Chemistry and general applications of thermoset resins. In: Recent advances and applications of thermoset resins, 2nd edn. Elsevier, pp 1–172 Riedl B, Kaboorani A (2015) Mechanical performance of polyvinyl acetate (PVA)-based composites. In: Biocomposites: design and mechanical performance, pp 347–364 Rorrer NA, Nicholson S, Carpenter A, Biddy MJ, Grundi NJ, Beckham GT (2019) Combining reclaimed PET with bio-based monomers enables plastics upcycling. Joule 3:1006–1027 Sanchez TP, O’Flaherty V, Lens PNL (2021) Polyhydroxyalkanoate bio-production and its rise as biomaterial of the future. J Biotechnol 348:10–25 Spear B (2013) Let there be light! Sir Joseph Swan and the incandescent light bulb. World Patent Inf 35:38–41 Statista (2023) Global Polyethylene demand and capacity 2015–2022. https://www.statista.com/ statistics/1246675/polyethylene-demand-capacity-forecast-worldwide/. Accessed 5 June 2023 Tucker N, Stanger JJ, Staiger MP, Razzaq H, Hofman K (2012) The history of the science and technology of electrospinning from 1600 to 1995. J Eng Fibers Fabrics 7:63–73 Vikhareva AS, Melnikov AG, Otyev OM (2016) Technology for melting amber chips to produce a solid block. Mater Sci Eng 124:012147 Wei J, Sun L, Sun J, Pan W (2023) Mesoscale failure analysis of the hybrid structure by injection overmolding after compression process. Eng Fail Anal 146:107145 White JL (1999) Fifth of a series: pioneer of polymer processing John Wesley Hyatt (1837-1920). Int Polym Process 14(4):314–314 Wiley FE (1944) Method of deep drawing organic plastic sheets. US Patent 2468697A Winstead TW (1950) Method for forming and embossing thermoplastic materials. US Patent 2702411A Yan Z, Liu Y, Zhang T, Zhang F, Ren H, Zhang Y (2022) Analysis of microplastics in human feces reveals a correlation between fecal microplastics and inflammatory bowel disease status. Environ Sci Technol 56(1):414–421

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Zhang N, Liu P, Yi Y, Gibril ME, Wang S, Kong F (2021) Application of polyvinyl acetate/lignin copolymer as bio-based coating material and its effects on paper properties. Coatings 11(2):192 Zhao L, Rong L, Zhao L, Yang J, Wang L, Sun H (2020) Plastics of the future? The impact of biodegradable polymers on the environment. In: Microplastics in terrestrial environment. Springer Nature, Cham. https://doi.org/10.1007/698_2020_462

Chapter 3

Plastics, Food Security, and Sustainable Urbanization

Abstract Ending poverty and zero hunger are listed as the first and second sustainable development goals (SDG). Other sustainable development goals such as building sustainable cities are also linked with food security and sustainable urbanization. Plastics have been widely used in various systems to achieve the goals of urban farming that seeks to grow as much food within the limited spaces in urban areas as possible. This is achieved using vertical structures and other urban farming innovations to improve yield per area. Plastics are also key materials in innovations that are used to improve conventional agricultural yield, food storage and shelf life improvement, pest management, and improved livelihoods. These topics are covered in this chapter. This in-depth review of the plastic application is significant in assessing the role of the plastic industry in the development of products that can positively contribute to global food security and sustainable urbanization goals.

3.1

Introduction

Considering the current dominant image of plastics in the general public, the last thing one might associate with plastics would be food security or anything sustainable. However, plastics have become so ubiquitous that every aspect of modern living involves plastics in one form or the other. With the rising population fast adopting an urban lifestyle and over 50% of the global population living in urban areas either by choice or otherwise, urbanization seems inevitable. By 2030, it is estimated that 60% of people in the world will live in cities. Although only around 0.51% of the total land area is covered by cities, these cities generate around 82% of the global GDP. At the same time, these cities also consume around 80% of the global energy and generate 70% of the global greenhouse gases (UNDP 2016). Cities are also major contributors to waste generation. An estimated 3 billion city dwellers globally generate 1.3 billion tonnes of waste annually (World Bank 2012). These include plastic waste. Urbanization has both positive and negative impacts and one way to avert the potential adverse impacts of urbanization is to take measures toward sustainable urbanization.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 O. Olatunji, Re-envisioning Plastics Role in the Global Society, https://doi.org/10.1007/978-3-031-48945-7_3

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Within the scope of this book sustainable and in line with other accepted definitions, sustainable urbanization refers to urbanization that does not result in damage to the environment and health of the people and does not deny future generations the ability to live the same or better quality of life. Urbanization refers to the movement of people into cities or the transition of rural or other non-urban areas into cities. The definition of urban areas or cities varies depending on the factors considered. This can be the availability of modern infrastructures like paved roads and electricity grid per capita, the population density, and/or other factors used to characterize cities. According to the United Nations World Urbanization Prospects published in 2014, cities are broadly defined based on population within a given geographical location (UNDP 2016). Cities are said to comprise 500,000 to 10 million people. Cities with a population of around 500,000 are categorized as small cities while those with a population over 10 million are classified as megacities. Medium-sized cities have a population size of around five million. Violence and crimes have been stated as one of the major challenges associated with an increasing urban population (UNDP 2016). This is partly attributed to the intrinsic limited direct access to basic needs of life in urban areas. These basic needs include food, shelter, and clothing as well as other needs such as transportation and communication. As the world becomes increasingly urbanized various innovations have been developed to provide food and other necessities and conveniences for the increasing urban population. When we look at these different innovations, we see that many of these rely on the use of plastics in different ways to be feasible, affordable, and/or efficient. While there is yet to be a well-established life cycle assessment to fully establish and quantify the sustainability of urban greening and farming systems such as vertical garden systems, several indications suggest some positive environmental impact (Rowe et al. 2022). This varies significantly with the type of system.

3.2 3.2.1

Growing More Food and Trees in Smaller Spaces Food Security Through Urban Gardens

Urban gardens contribute ecosystem services in the form of providing needed products and other natural resources, supporting life, regulating ecological systems, and creating healthy sustainable cultures within the communities (Nur et al. 2022). Examples of ecosystem services include trees taking up CO2 and in doing so regulating the levels of greenhouse gases in the atmosphere, trees providing shelter for birds’ nests hence supporting their nurturing, plants like vegetables serving as sources of food to humans and the physical and mental health benefits gardeners gain from working on the garden. The rapid rate of urbanization also puts a strain on the resources and capacity to govern and provide for such fast-growing cities (UNDP 2016). Introducing low-cost

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and easily implementable measures, as simple as growing food in plastic containers serves as a means for people to meet these basic needs for themselves.

3.2.1.1

Transferable Food Asset

In urban areas, most of the grounds are paved and access to earth ground and fertile soil is often limited for people living in urban areas. In addition to this, many of the properties in urban areas are often rentals, some without garden spaces and some are multi-floor apartments. Even where gardening spaces exist, investing the time to prepare the soil, and grow food, particularly perennials and fruit trees in garden spaces in a rented temporary home may not be as appealing. This is because the effort invested is not transferable and the next resident or owner may decide to cut down the tree and clear the garden. Therefore, a better option would be to grow trees and other plants in pots that can be moved around. This ensures the time and resources invested are transferable. Various texts in literature have presented an archive of edible, ornamental, and medicinal plants and trees that can be grown in containers for long periods. These include tomatoes, blueberries, peppers, tiger nuts, beans, potatoes, a wide range of leafy vegetables, fruit trees, and other tree seedlings (Fang et al. 2022; Salisu et al. 2018; Ott et al. 2011). This provides residents in urban areas the option to grow food and ornamental plants within limited spaces which they can take along with them if and when they relocate. Plastics used in these containers range from commercially available planters made from polypropylene, High-density polyethylene, or composites of plastic and fiberglass to repurposed plastic containers.

3.2.1.2

An Alternative to Address the Impact of Wars and Conflict

Wars and conflicts have threatened food security in recent years. The most recent of that in Europe is the war between Russia and Ukraine which has disrupted the supply of food and energy resources across the world. Together Russia and Ukraine are said to produce around 30% of the wheat traded across the world and 12% of the calories supplied to the world (El-Haiba and Behnassi 2022). These two countries also produce a significant amount of the world’s corn and barley. Russia is also a major producer of fertilizers which is necessary for improving crop yield in conventional modern large-scale farming systems. The war between these two countries has resulted in a sharp increase in the prices of food and fertilizers since it began. In parts of Africa the war in Tigray, Ethiopia has severely disrupted food production. There are reports of soldiers threatening farmers with death if they carried out any farming activity including plowing or harvesting (De Waal 2021). Some farmers in remote villages are said to do some plowing at night and have people on the lookout for soldiers. In Nigeria, the insecurities resulting from kidnapping and armed herders attacking farmers in the north of the country and other regions have caused disruption to food production due to farmers fleeing their lands (Fadare et al. 2022).

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Where farmers are forced to flee their farmlands, the farming cycle is disrupted; seeds are not planted when they need to be and those that have been planted cannot be tended to and the foods ready to harvest are abandoned to spoil and therefore are wasted. Destruction of facilities such as irrigation systems, water storage tanks, food storage housing, and others can cause disruption to food production. Where there is an ongoing war, the movement of products across further could cease cutting off supply to other parts of the country or the world. Further in countries like Nigeria, most of the farming areas are in rural areas and remote villages where the federal or state security are not very active or not well equipped to prevent attacks. This discourages youths and active adults from pursuing agriculture as most flee to the urban areas where land is more expensive. Growing food in containers in urban areas could reduce total dependency on particular regions for food for survival. It also provides individuals and families with enough healthy foods to survive or at best supplement the food they can afford to buy or store. Where people are displaced to camps, vegetables, and seedlings can be started in containers and then moved to farmlands when the conflicts get resolved. This could play a role in reducing the impact on food security in cases of wars and regional conflicts. Where it is optimized, food grown in containers in urban areas may serve to temporarily support affected regions. The ability of urban dwellers to produce food in containers provides more diverse options for food sources and could reduce the scarcity of certain foods and other food insecurity issues. A study of rooftop gardens in Bangladesh observed that most urban gardens either make use of containers filled with soil or beds made out of concrete. The containers are often made out of plastics and other materials such as terra cutter clay pots, concrete, or wood. The beds are also often lined with plastics before filling with soil (Nur et al. 2022). The plastic lining helps to limit drainage or where undesired, prevent the penetration of plant roots into the ground or the staining of the ground. Other factors such as inflation which occurs as a result of the interplay of factors may reduce the purchasing power of consumers which may force them to opt for less healthy foods. Studies reported in the literature (Fang et al. 2022) and trials carried out for the purpose of this book suggest that a significant amount of foods can be grown in plastic containers of different sizes. These include commercially available plastic planters such as the 40-m3 planter shown in Fig. 3.1 used for growing African eggplant (Solanum aethiopicum L.) and tomatoes (Solanum lycopersicum). Singleuse plastic containers such as ice-cream bowls, and plastic shopping bags, and other plastic packaging like polypropylene sacks have also been observed used for growing edible plants such as those shown in Fig. 3.2 used in growing food crops such as peppers, beans, and vegetables.

3.2.1.3

Improved Crop Yield and Water Retention in Containers

Commercial farmers and horticulturalists have also resorted to growing some plants in containers for various reasons. For example, recent years have seen increasing use of containers to grow Southern highbush blueberry in order to reduce the cost

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Fig. 3.1 Vegetables grown in commercially available plastic planters. Original image by author

Fig. 3.2 (a) Food crops growing in different plastic containers including various repurposed plastic containers such as plastic shopping bags and polypropylene sacks. (b) Green pepper plant fruiting in a repurposed 70 cl PET water bottle. Original image by author

required to amend the soil to the special requirement of the plant and to improve yield (Fang et al. 2022). The plant requires soil with high organic matter, low pH, and good aeration. These conditions are easier to achieve within a container than out in the field. Due to their lightweight and relatively low cost and water resistance, plastics are a preferred choice for such applications where the soil composition and growth condition need to be controlled.

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Growing plants in containers has also been shown to significantly improve yield by allowing farmers to increase planting density. Containers can be stacked closely together in greenhouses or in the field without their roots competing with each other. Although the exact mechanism by which plant growth is affected by growing in the limited space in containers is not completely established, it is thought to train the plant to spread its roots within the container space and focus on yielding fruit rather than competing with neighboring plant roots. Techniques like hydroponics and aeroponics achieve increased yield in various ways like eliminating the competition with surrounding soil biomass and the risk of pest infestation and diseases from the soil since these techniques make use of no soil and closed environments. Container-based rooftop gardens have been shown to increase rainwater retention. A study in Taipei City found that the container rooftop gardens retained 50,550.7 m3 of rainwater in 2019 over 133.142 m2 total area of cultivated rooftop food gardens (Chen and Chen 2021). This was higher than the case of concrete rooftops without gardens which have almost no water retention and are often designed to ideally have no water retention.

3.2.1.4

Moving Crops During Pest Invasion

Other benefits of such a method of growing include the ability to more easily separate plants with diseases or pests from other plants, limiting their spread. Plants can also be moved to safer locations in cases of pest invasion. For example, the locust invasion of 2020–2021 spread across the Horn of Africa and Yemen. These desert locusts have been identified as the most destructive migratory pest in the world and a serious threat to food security. Within a day, a swarm of these pests is capable of devouring an equivalent amount of food, enough to feed 35,000 people (FAO 2022). Part of the action that was taken to address the upsurge of desert locusts was to monitor the migration of these pests and provide early warning signs to allow farmers to prepare. Although the main method used in the management of this particular desert locust upsurge was spraying of pesticides and insect growth regulators, with plants grown in containers, part of this preparation to avert such a crisis could be moving the plants to a safe location or ensuring the shelter in which the plants are grown are insect proof once the warning is received. This can significantly reduce the scale of damage suffered from pest invasion, particularly for small-scale growers.

3.2.1.5

Integrating Food Growing in Unconventional Places

Plastics allow the flexibility required to achieve the goals of urban farming that seeks to grow as much food within the limited spaces in the city using vertical structures and other urban farming innovations to improve yield per area. For example, one company in Tokyo uses various vertical structures and structures hanging from

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building ceilings within an office space to allow workers to grow food at work (Park 2023). There are also several examples of trays and pipes used to construct vertical structures for optimizing space usage for urban farming. The lightweight nature of plastics also makes them ideal candidates for constructing farming systems in space crafts and space stations (Minjuan et al. 2019). With such systems astronauts therefore only need to carry seeds and then grow the food they need on arrival at their station or in transit using technologies like aeroponics. Much of this requires the use of plastics. Even the LED lights used for indoor planting make use of plastics.

3.2.2

Preserving Future Forests

Plastic containers of different types are also widely used in growing tree seedlings prior to transplants. These range from plastic bags to rigid root trainers made out of polypropylene of varying sizes (Salisu et al. 2018). In many of the tree-planting images published by organizations such as FAO, plastic containers used in growing seedlings are visible. Although larger trees planted in the ground are likely to capture more CO2 compared to smaller trees planted in containers, a tree’s CO2 capturing rate has been shown to increase with size and age (Stephenson et al. 2014). Trees grown in containers serve as potential forest trees. Many trees can last several years in containers after which they can be transferred into the ground either on farms, urban areas, forests, or other locations. Indeed trees grown in containers are considered as one of the nature-based solutions for sustainable urbanization and climate change adaptation as part of urban forest development (Scheuer et al. 2022).

3.2.2.1

Preserving Trees Using Bonsai Practice

The ancient practice of bonsai trees is centered around keeping trees small in containers for long periods, most times, permanently. Bonsai exhibitions have presented trees that have been kept alive in a container for centuries. The practice is said to be thousands of years old originating in China and spreading to Japan and to the Western world. Keeping the tree in a container limits the growth of the tap root as the plant naturally adapts to the limited space. Continuous root pruning also affects the growth of fine roots such that trees started in containers tend to perform better when transplanted into the ground than those trees that are directly planted into the ground (Wang et al. 2020). Although bonsai trees are typically grown in artistically appealing containers, plastic containers are also used. The concept of keeping trees alive and thriving in containers can be adopted from this ancient practice for container urban gardening.

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3.2.2.2

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Integrating Planted Forests into Urban Areas

Here we are considering growing trees in containers within urban areas as opposed to not having any trees in these areas at all. Therefore even where potted trees may not capture as much carbon as bigger trees are grown in the ground in urban areas or in the forest, they still serve a significant purpose in CO2 sequestering. In one report, it is estimated that skyscrapers integrating 1100 trees and 2500 cascading plants and shrubs planned for vertical forest in the city of Nanjing China (Hutt 2017) can absorb around 25 tonnes of CO2 annually and release 60 kg of oxygen daily. Recently, construction of what is declared as the world’s tallest green building is being built in Zanzibar in Tanzania (Mitchell 2023). The building is named the Burg Zanzibar. It is planned to be 96 m tall and comprises 28 floors constructed using wood. One of the key features of the building plan is the rooftop and balcony gardens. These are most likely to be constructed using plastic as part of the main material. For example, plastics used in the piping of aquaponic or aeroponic gardens or plastic used as waterproof material between rooftop raised beds and the wood floor. So far only around 7% of the world’s forest is characterized as planted forest. The remaining roughly 93% are naturally regenerating forests (FAO 2020). Although the rate of loss of total area of forest is decreasing indicating that we are not losing forest land as much as we were in previous years since 1990, the world is increasingly losing these naturally regenerating forests. There is therefore need to explore innovative ways to increase the amount of planted forests that can potentially become naturally regenerating forests in the future.

3.2.3

How Much Food Can Be Grown in Plastic Containers?

Most times when the subject of food security comes up, the discussions seem to always hover around improving the efficiency of large-scale farming systems and large-scale food processing, and fertilizers, or addressing inefficiencies in the local and/or global food supply chain. For example, one study on small- and large-scale production in the Khorasan Razavi province in Iran concluded that growing wheat on large farms compared to smaller ones resulted in higher yields per unit area of farmland compared to smaller farms, despite consuming more resources and being less environmentally and financially sustainable (Fallahinejad et al. 2019). The region produces 25% of the global wheat production and has 34% of the 72,000 ha of land growing wheat globally. In the said study, small-scale farms consumed 1.39 × 1016 sej per hectare per year while large-scale farms over 15 hectares consumed 2.16 × 1016 sej per hectare per year total energy. The share of renewable and nonrenewable natural inputs per farm area was higher in smaller farms compared to large-scale farms while the share of purchase inputs per farm area where higher in large-scale farms. Such findings suggest that the yield and inputs

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required for growing food are not necessarily correlated to the area available for growing. Furthermore, considering the success of different innovations in farming it is important to take a closer look at food security on a more individual level. One possible answer to the question of how we are going to feed the projected 9.7 billion population predicted for the year 2050, and 10.4 billion by 2080 (United Nations, Department of Economic and Social Affairs, Population Division 2022), is to empower people to produce their own food sustainably. A large fraction of the food produced from large-scale farming gets exported rather than for local consumption. This is especially so in developing countries. Some small-scale farmers go hungry or malnutrition, this is not mostly because they do not have enough space to grow food, rather, it is because they spend the available limited resources and water to grow crops for export in order to earn money to purchase food and pay for other needs. The cash crops grown have higher market value than if they were to grow edible nutritious food crops for their own consumption. Some of the cash crops grown may not be edible or nutritious. Examples are coffee, cocoa, and cotton. Such that the availability of space is not the only limitation to food availability. For the purpose of this book, to answer this question, a model urban garden where a variety of foods are grown in plastic containers of different types is built. The garden is a private garden set up to provide vegetables, nuts, fruits, and other food needs for the single dweller of the household. The garden covers an estimated total area of 18 square meters which includes the spacing between the containers to allow walking and working around the plants. Images of the garden are shown in Figs. 3.1 and 3.2. The garden also yields other useful plant and nonplant products such as biomass from dead branches and leaves that can be used in compost or for fire. The growing medium used in the garden is a mix of soil purchased from horticulture shops and soil from surrounding dormant land. Rainwater collected in a 150-L drum is used for watering as well as direct rainfall. Data was collected on the amount of food obtained from the garden between October 2022 and December 2022. This is summarized in Table 3.1. During the period of observation, the garden produced an estimated 14.18 kg of edible plant-based food. These included protein-rich foods such as tiger nuts and peanuts, carbohydrate bulk foods like potatoes and beans, and foods rich in vitamins and minerals like leafy green vegetables. A herb, clove basil (Ocimum gratissimum) which is used as a condiment and also shown to have therapeutic properties (Martins et al. 2021), is also grown in a container in the garden. Some of these foods such as tiger nuts and clove basil are sun-dried and lasted for several weeks. Others like onions and ginger have inherent long shelf lives and were stored for up to 3 weeks. Leafy vegetables are picked, washed, and eaten fresh and remain in continuous supply throughout the months observed. The fruit trees grown in containers were papaya, mangos, oranges, apples, avocados, cashews, African cherry, dates, African almond nut tree, and camel foot tree all within 6 months to 3 years of growth. Four of the papaya trees were transplanted onto the ground after 1–4 months of growth and 3 yielded fruits within a year of their growth while one

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Table 3.1 Data on the harvest from the garden between September 2022 and December 2022 Food items harvested from garden African egg plant vegetable Water leaf Ginger Tigernuts (wet weight) Pinto beans (with husk) Lagos spinach Clove basil Onions Aleo vera (estimate for leaves) Pigweed Garlic Sweet potatoes (interrupted growth) Tomatoes (interrupted growth) Chilli peppers Peanuts Total

Quantity in weight as harvested (kg) 1.500 4.300 0.200 2.500 0.100 1.100 0.100 1.000 1.000 2.000 0.010 0.020 0.050 0.100 0.200 14.180 kg

tree died several months after transplant. For the purpose of this book, this serves as an observation of fruit-bearing plants started in plastic containers and continuing their growth and yielding fruit after transplant into earth ground. Other trees that were transplanted into the ground and continued to thrive included, mango, orange, lemon, avocado, and date. However, these can take several years. Some fruit trees like oranges do produce fruits while in the containers if well cared for and watered regularly (Brara and Spann 2014). Therefore to answer the question posed at the beginning of this section, an 18-m2 garden comprising plants grown in plastic containers can provide an estimated 14.18 kg of edible plant-based food within 3 months in a tropical climate region in West Africa, Nigeria, Ogun State between the months of October and December 2022. Figure 3.3 shows images of some of the foods harvested from the garden. This region of the country experiences an annual rainfall of around l200 mm on average and a mean temperature between 21 and 27 °C (World Bank Climate Change Knowledge Portal). The plants were exposed to around 11 h of sunlight daily. Occasionally compost from household waste and plant debris was applied to the soil. No additional fertilizers, pesticides, or herbicides were used. The yield from such space could be further optimized by implementing vertical gardening structures to optimize yield per square meter and the use of more controlled growing practices.

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Fig. 3.3 Some food products from plants grown in plastic containers in the model garden observed (a) tigernuts, (b) ginger, (c) onion, (d) leafy green vegetables, and (e) peppers. Original image by author

3.2.4

Root Restriction for Improved Yield and Controlled Urban Greening

Many trees over the years tend to spread their roots in order to reach for water and nutrients. Some of these roots extend above ground. While growing trees within the cities is a great way to create shade, absorb CO2, and introduce nature into the urban areas as well as other benefits of trees, however, when the roots become invasive they may cause some damage such as breaking of the pavement, extending into buildings and damaging structures, pipes, and cables, it may become necessary to cut down the trees, losing the benefits. A way to prevent this is the use of root restriction. The most common technique for achieving this uses root restriction bags which are often made of plastics such as polystyrene and polypropylene. Root restriction works by placing the plant within a container which, as the term implies, restricts the growth of the root to the volume of the container. In some designs, the container base is made of unperforated plastic while the sides are made of porous fabric. This allows some roots to spread beyond the container volume, however, due to the small size of the pores of the fabric, these are limited to fine roots. In other cases, the entire container is nonporous (except for water drain holes). This completely restricts root growth to the container volume (White 1995). Root restriction bags have been produced using various plastic types including polypropylene, polyvinyl chloride, and polystyrene. While the mechanism by which root restriction affects plant growth is not fully understood, some studies have shown that fruit production efficiency (number of fruits per area covered by tree canopy) and fruit quality can be improved by using root restriction albeit reduction in plant size (Byers et al. 2004; Mataa and Tominaga 1998). When the mango (Mangifera indica) cv. Chokanan, tree growth was studied in containers which caused root restriction and water stress when compared to those grown under unrestricted growth. The study revealed that the mango plants grown under restricted root and water stress showed higher abscisic acid and proline concentrations in the leaf. When rewatering ABA concentration dropped and the

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stomatal conductance increased and so did leaf water for both mangos with roots restricted and those whose roots were not restricted. It was found that mangos with restricted roots had compacted cells which indicated that the restricted roots caused the plant to “shrink” itself physiologically and morphologically by altering gene expression (Zaharah and Razi 2009). This could mean the ability to grow more of such trees within a given space. More recent studies on grapes grown under root restriction suggested that the quality of fruits is improved by root restriction. This improved fruit quality under fruit restriction although not fully understood, analysis shows that ABA and associated genes may be responsible for this plant phenomenon (Li et al. 2021a, b). Earlier studies of fruit restriction in apples (Malus x domestica Borkh. cv. “fuji”) grown in fabric fruit restriction bags showed higher fruit productive efficiency compared to unrestricted growth (White 1995). “Yonda” Ponkan mandarin (Citrus reticulata Blanco) trees also showed improved fruiting efficiency and fruit quality in the form of total soluble solids and fruit color index when planted in 20 l root restriction bags (Mataa and Tominaga 1998). Albeit reducing the tree height, canopy volume, girth and leaf area were significantly reduced by root restriction, the photosynthesis, transpiration, water potential, and leaf carbohydrate content were not affected by root restriction. This suggests that restricting the growth of trees to meet the limited spaces in urban areas does not necessarily remove their benefits as trees such as CO2 capture and production of biomass. The ability to grow more trees in smaller spaces with improved fruit quality is particularly relevant in current times as more of the world population now lives in urban areas. Increased population and increased demand for food mean less space available for growing plants. Restricting the size of plants like mango trees which grow wide canopy when unrestricted makes more room available to grow more crops. The wide canopy means less direct sunshine available to other crops around the trees which leaves a lot of unused land space. One of the reasons for trees being removed or avoided in urban areas is the dangers that may be posed to the trees or to the people and structures within these areas. Where trees exist in urban areas, if not well managed, the trees pose a risk as they tend to extend their roots into pavements and surrounding buildings. These may lead to the destruction of the pavements and walls and obstruction of paths. Damage to tree roots, branches, and trunks during construction and other activities may result in the tree getting damaged and eventually falling which may result in casualties or damage to infrastructure around the tree (Institute of Wood Science and Technology 2019). Restriction of such tree roots is one way to accommodate trees within urban spaces without damage to life and properties or to the tree itself. The root restriction containers are typically made from plastics such as polypropylene and polystyrene.

3.2.5

Green Walls and Vertical Planting

The integration of plants within inhabited buildings goes as far back as 700 BCE when what is commonly known as the Hanging Gardens of Babylon was constructed

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by the engineer, Philo of Byzantium as one of the seven wonders of the ancient world (Dalley 2013). Urban gardening and farming in recent years have seen rising interest in vertical planting as a way to optimize the limited space available in urban areas. The incorporation of green facades and green walls has also been investigated for their energy saving and environmental impact (El Gizawy 2016). Green walls have been shown to be a good way to reduce the environmental impact of urban areas. All the heat and greenhouse gas emissions from the activities within the urban areas and those outside the urban areas are required to meet the demands of the urban areas like mechanized agriculture and energy and emissions from transportation to meet the demand for food, and deforestation to meet the demand for wood and land space for agriculture, can be balanced by integrating the growing of plants which will have a cooling effect, reduce the demand for imported food, restore some plant population and capture carbon dioxide. The retrofitting of green walls within existing buildings has also been used to reduce the environmental and visual impact of the building. For example, in one study, a school in Italy was retrofitted with green walls made of high-density polyethylene (HDPE) profiles and the resulting design allowed the building to blend into the green environment in addition to the environmental impacts of the plants (Perini 2013). The study also compared the use of HDPE profiles and modular grids with steel meshes as supporting structures for the green wall and established that the HDPE profiles and modular grids had a lower environmental burden than the steel ones. Various vertical planting concepts have been introduced over the years with the general goal of growing plants in a vertical manner rather than the conventional horizontal manner on the ground as done in conventional farming. This means that within the same given floor space, more plants can be grown. There are some urban farms in cities that have adopted this technique to grow vegetables within urban areas for commercial and private purposes. Vertical planting and green walls can be made from a range of materials. The most common are rigid plastics of felt. The felt material is commonly made of layers of woven polypropylene thermally pressed to form a single layer and constructed into planters. Other designs consist of polypropylene molded into vertical planters or assembled into vertical structures. Low-cost constructions are achieved using repurposed plastic bottles. When the life cycle assessment of felt-based green wall systems was compared with plastic-based green wall systems, results indicated that the felt-based systems have a higher environmental impact than the plastic-based system (Reyhani et al. 2022). The assessment considered the environmental impact of both systems from the production stage up to the usage and maintenance stage. In another study that compared a multilayered felt-based living wall system comprising layers of polypropylene, polyamide, and polyethylene with another living wall system made of high-density polyethylene molded into the living wall structure, it was found that the felt-based living wall system had a higher environmental impact (Mannan and Al-Ghamdi 2022). The environmental impact of the felt-based vertical green wall system is further increased by the need to use steel and/or Polyvinyl chloride (PVC) as structural support materials. Since the HDPE has sufficient

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rigidity to support the weight of the plants, no additional materials were required to provide support.

3.3

Improving Access to Nature for Urban Residents

Forests are said to cover around 30% of the land on Earth. However, not very many people have access to these forests. Around 54% of the world’s forest is located in five countries; the United States, Brazil, Russia, Canada, and South America (FAO 2020). Some forests are privately owned while some are legally protected limiting access. From observations in cities like Lagos and Accra, for example, while some green spaces exist, there is limited access to parks, forests, and other open green spaces in the city. The literature reviewed suggests that access to nature is an issue across many cities in the world (Alexander and Brooks 2022; Jarvis et al. 2020; Shanahan et al. 2014). Very few city dwellers have access to green spaces within walking distance. Retrofitting buildings with green walls and container-grown plants is one way of bringing the natural environment closer to the urban residents. Furthermore during periods of insecurity, even where public parks exist, people are unable or unwilling to access them as such places become risky. The only access individuals may have to nature is within their homes. Access to nature implies not just being able to see and touch natural plants or to visit natural spaces. It includes a person being able to interact with nature (Jarvis et al. 2020; Alexander and Brooks 2022). Therefore, the ability to grow a plant and tend to a plant albeit in a container, might have more health impact than simply visiting a park or forest. Having plants in containers can serve as a way to connect to nature for those in urban areas where there is limited access to green spaces. Furthermore, in situations where individuals or whole communities are forced to remain in their homes for long periods, such as in the case of a pandemic, the ability to grow plants in containers provides some contact with nature. Considering the benefits that being in the natural environment has been proven to have on mental well-being and health of people (Liu et al. 2022), having less of the “concrete jungle” appearance and more of nature within the city can also improve the well-being or those residing in these urban areas. Some homes and public places have been observed to make use of artificial plants made of plastics to create a natural environment. Indeed artificial plants have been shown to have similar psychological effects on people as natural plants based on studies on patients in hospital waiting rooms (Beukeboom et al. 2013). This is thought to be mainly due to the aesthetically pleasing perception of the natural environment the artificial plant creates. However, artificial plants come without the benefits natural plants have on the environment and air. Figure 3.4a, b shows some examples of the application of plastic containers for adding greenery to private and commercial urban spaces. The latter shows an example of epoxy a thermoplastic plastic reinforced with glass fiber (Rahman and Rahman 2022). These types of composite plastic planters have emerged to meet the demand for planters with the

3.5

Plastics in Soil

41

Fig. 3.4 Plants grown in containers (plastic and plastic composite) to add greenery in (a) private residence (b) Public space (c) a terrace on a multistory building (d) a vertical garden on an outdoor wall. Lagos Nigeria 2023. Original image by author

desirable properties of plastics (such as lightweight ease of processing into various shapes) and yet have the glossy elegant aesthetic appeal of materials like painted ceramic or metal.

3.4

Supporting Biodiversity

For every building in an urban area, a portion of the world’s natural habitat gets lost. Clearing of land and sometimes permanently paving previously earth grounds leaves little room for nonhuman life forms to thrive unassisted. Urban greening techniques such as container gardening can help retain some level of biodiversity by providing habitats for some organisms such as caterpillars and butterflies. Garden snails of various sizes have been observed in the garden, especially during the peak rainy seasons. Flowering plants and orange trees attract butterflies which drop caterpillars that feed on the orange tree leaves have also been observed in the garden. Other pollinators and other life forms that promote biodiversity and contribute to the environment in different ways have also been observed. Figure 3.5 shows a variety of lifeforms observed within a container garden using plastic containers.

3.5 3.5.1

Plastics in Soil Plastic as Soil Stabilizers for Construction

Urbanization is linked with the construction of buildings, roads, and other infrastructures. One of the several ways to achieve sustainable urbanization is the use of more sustainable options when choosing construction materials in construction. This can be the use of biodegradable materials like hemp or the use of recycled plastics. Researchers have explored various ways to reduce, reuse, and recycle plastics over

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Fig. 3.5 Different wildlife observed on plants growing in plastic containers in an urban garden (a) garden snail around waterleaf plants (b) Brown insect on a mango tree (c) Yellow caterpillar on African eggplant vegetable (d) a butterfly around an orange tree (e) a praying mantis on an orange tree (f) A bird nest woven into the leaves of a mango tree. Original image by author

the years. One of the applications for used plastics is soil stabilization. This is where plastics, mostly in the form of fibers achieved by shredding or cutting waste plastics into small pieces, are added to soil to improve its physical properties thereby making it better suited for geotechnical applications like use in pavements (Kassa et al. 2020). Some soil types particularly, clayey soils tend to show significant variation in volume as a result of moisture content changes. When dry the soil shrinks and hardens, making the soil and structures around it prone to cracking and deformation. When wet the soil absorbs moisture and volume increases which could exert pressure on surrounding structures also leading to deformation. This is undesirable. To address this conventional methods for stabilizing soils include the use of limestone, bitumen, and cement. However, these are nonrenewable resources and increasing demand as a result of increasing urbanization means there is a need for more sustainable alternatives. Plastic wastes such as polypropylene, polyethylene terephthalate, and HDPE can be processed into fibers and mixed in with the soil prior to compaction. This has been

3.5

Plastics in Soil

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shown to improve the mechanical properties of soil to make it better suited for geotechnical applications (Hassan et al. 2021). Plastic fiber is typically added varying between 0.5% and 4% and the fibers are between 0.75 and 2 cm long (Hassan et al. 2021; Kassa et al. 2020; Gangwar and Tiwari 2021). The effect of the plastic fiber content varies with the type of plastic used and the size of the fibers used. However, most study reviews report general improvement in the properties of the soil with the addition of plastic fibers. The use of plastics in this way keeps plastics in use and within the cycle for long periods. Since plastics are currently so abundantly available that they are constituting environmental nuisance this can be said to be a more sustainable alternative to less renewable and more costly materials like limestone and bitumen in the same application. Construction of roads is also a high-priority need particularly in developing economies where, for example, the African continent, it is estimated that only around 10,000 km of road networks exist for the transportation of goods within the continent compared to the estimated 60,000–100,000 kilometers of road network required for effective transport and trade (Gwilliam et al. 2008). Therefore having a sustainable, low-cost material for the construction of roads would have a significant economic impact.

3.5.2

Plastics in Agricultural Soil

While there exists the application of plastics in improving the geotechnical properties of soil for the purpose of construction, the presence of plastics in soil could have an unintended impact on the properties of soil and plant growth for agriculture. Routes by which plastics get into the soil include the release of microplastics into the soil from different sources such as textile washing, paints, tires, and others (Boucher and Friot 2017; Paruta et al. 2021). The use of plastic mulch in agriculture is also a source of plastics getting into the soil as well as plastic debris from discarded plastics getting washed up by rain or blown by the wind onto farmlands. Various research groups have looked at the different ways in which the presence of plastic in soil, alters the properties of the soil, and affects plant growth and microbial growth, and activity in the soil. There are also efforts to understanding the mechanisms by which plastics have such effects on plant and microbial growth as well as soil properties. Residues from the use of plastic film as mulch have been reported to lead to depletion in the organic carbon and nitrogen stocks in the soil (Li et al. 2021a, b). This results in a loss of soil fertility which affects crop yield and/or increases the amount of fertilization needed. This loss of carbon and nitrogen socks as a result of plastic residue in the soil has been attributed to the permeability, water content, and nutrient absorption of the soil and loss of moisture from seed as a result of the physical presence of the plastics since the plastics such as polyethylene and polypropylene films used are impermeable to water. While most plastics themselves are chemically inert, these plastics also contain toxic compounds that are used at different stages of their production to act as catalysts or to modify their properties

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such as UV resistance. Examples of such additives are bisphenol A and diphthalate (2-ethylhexyl)–phthalate, which is used as additives in the production of plastics. They are also able to absorb some compounds from the soil thereby disrupting the ecological balance in the soil. In an experiment carried out on soybeans grown in pots under field conditions, when meso plastic debris of polyethylene films was introduced into the soil at levels varying from 0.1% to 1% w/w with particle size ranging from 0.5 to 2 cm, the results showed that the presence of polyethylene plastic debris in the soil reduced the germination viability of the soybeans by as much as 74% where 1% w/w polyethylene debris was present in the soil (Li et al. 2021a, b). The effect of plastic on the soybean germination rate was dependent on the level of plastic contamination. Where the level of polyethylene was 0.1% the germination rate was decreased by about 18%. Other growth properties; plant height, culm diameter, and leaf area were also reduced by the presence of plastic debris in the soil. Research on the effect of surgical mask fragments on plant growth has been carried out recently. This was motivated by the rise in the amount of personal protective gear, particularly surgical face masks during the COVID-19 pandemic of 2019 where governments across the world made the use of face masks while in public mandatory. This resulted in a large number of face masks being improperly discarded resulting in another waste management issue. These masks are largely made using polypropylene. When discarded these masks tend to break down into fragments of polypropylene which end up in different parts of the aquatic and terrestrial environment. A study on the effect of these polypropylene fragments on the growth of rapeseed (Brassica napus L) indicated that the presence of polypropylene fragments from face masks significantly affected the development of the plant (Meszaros et al. 2022). Large fragments of polypropylene face masks (>1 cm) caused an increase in lateral root development as the concentration of the large fragments increased. Interestingly, however, a different relationship between lateral root development and polypropylene fragment concentration in the soil is observed for smaller fragments of polypropylene face masks (10 cm exist from human activity in space. Fragments less than 10 cm are said to be over hundreds of thousand pieces and minute fragments estimated to millions in number. Some of these debris eventually fall back to earth within years or centuries. Others may remain in orbit even longer. While not all of these are plastics, plastics pose particular problem since they will take even longer to degrade in space. When plastics do degrade that is another problem. When exposed to radiation plastics undergo photodegradation. This causes the polymer chains to be broken down into shorter chains. Although plastics themselves are relatively inert, when they break down at this molecular level, they no longer retain the same chemical identity and they become more reactive. In a complex environment such as space,

11.9

Plastics and Space Waste

211

they can react with anything and turn into anything. The chances of these being toxic compounds that can be detrimental to humans, the environment, and other life forms exist. One of the main causes of space debris is collision of satellites. The first hypervelocity collision of two large satellites in history was that of the Iridium 33 satellite which was launched in 1997 and Cosmos 2251 which was launched earlier in 1993 (Hobbs et al. 2019). The Iridium was still in service as global communication satellite; there were 66 other satellites in a constellation, while Cosmos 2251 was an out of service Russian communication satellite. The collision occurred over Siberia in 2009. Two satellites collided at an altitude of 790 km causing the formation of an estimated 2000 fragments of sizes larger than 10 cm and thousands of fragments of sizes less than 10 cm. After this there have been several reports of damages caused to satellites and spacecraft including to the International Space Station due to space debris. This not only damages equipment but also puts the lives of astronauts at risk and threatens the sustainability of space travel and exploration. For example if the solar arrays get damaged this affects the power supply of the mission where everything from communication to earth to food supply may be at risk. A crack in the window of a space capsule from space debris can result in air leakage which is life-threatening. Space debris can also cause damage to electronic circuits and conduits which can result in the failure of the entire spacecraft (Tang et al. 2023), so that a single piece of plastic object floating around in space can end an entire space mission. Considering the impact, one can say that a piece of plastic waste in space can be more dangerous than a piece of plastic waste in the ocean.

11.9.1

Global Agreement of Space Waste

Currently, it seems all there is a nonbinding agreement among countries not to pollute the environment in space. While we still deal with having binding agreements regarding plastic waste in the ocean, agreements regarding plastic waste or waste, in general, in space have made less progress. Despite the existence of the Outer Space Treaty (UN Office of Outer Space Affairs 1966), there still exists no legally binding agreement or structure regarding waste management in space. Part of the reason for this is that this treaty existed before the discovery of space debris. There are certain provisions in the treaty that relate to taking responsibility for damage caused by activities during a space mission. Some of the complications with cleaning up space waste include the fact that the objects from a spacecraft are still the legal property of the party that launched it into orbit. Therefore, removing such objects requires the permission of the owner (Inglezakis 2016). There are active efforts to address plastic waste in space. These include missions to extract broken down satellite from orbit and allow them to be demolished on re-entry and capturing and deorbiting space debris using tether, among other strategies. Most of these are at an experimental stage. As a preventive measure NASA

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published a detailed list of guidelines for mitigation against space debris in 1995 for US space missions. All space missions from the United States are to meet the guidelines before being allowed to launch. Other countries have since published similar guidelines and the United Nations also has endorsed an inter-agency guideline to mitigate against space debris in 2008. ISO standards also exist that clearly define space debris and methods for mitigation. However, this is not legally binding except there is a legal requirement for space missions to adhere to the standard (Inglezakis 2016). Therefore, the prevention of space debris is down to good intention and goodwill of the space mission.

11.9.2

Space Debris Sensors

Timely detection of space debris collision can save equipment, spacecraft, human life, and an entire mission. Here sensing technologies for detecting hypervelocity collisions such as that which occurs between space debris and spacecraft are employed. These include thermal imaging, acoustic emission, electromagnetic wave emission, acceleration signal, and optical camera surface detection technologies, among others. Thus far, the acoustic emission-based sensors are the most commonly used. However due to limitations such as bulkiness and poor adaptability to the environment, researchers have sought alternatives. NASA developed the Space Debris Sensor that is based on a combination of resistance grating and piezoelectric detection technologies. Such systems are able to detect space debris as small as 50 um. The velocity, direction, size, and density of the space debris can be obtained using this method. A key component of this technology is the piezoelectric sensing material. One of the recent sensing technologies under development is a sensor based on a polyvinylidene fluoride (PVDF) piezoelectric film (Tang et al. 2023). This high-performance thermoplastic already has found applications in a wide range of industries which include petrochemical, nuclear power engineering, aviation, radio engineering electronics, electrical engineering, construction, pharmaceutics, automotive, and aerospace, among others (Dallaev et al. 2022).

11.9.3

Self-Repairing Thermoplastics

Self-repairing thermoplastic polymers have found usefulness in building spacecraft that are more resilient to collision with space debris. Polyethylene-co-methacrylic is one of such plastics that have shown potential for applications as self-healing materials for hypervelocity collision resistance (Haramina et al. 2021). It has been specifically studied for application in spacecraft to mitigate against space debris collision (Pernigoni et al. 2021). The mechanism of such material is based on the transfer of the energy from the hypervelocity collision into heat which is absorbed by

11.10

Space Exploration and the Future of the Plastic Industry

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the material causing it to melt. This melting then causes thermal rewelding of the area that was hit; this closes the hole that would have been created by the collision otherwise; hence, it self-repairs. The use of this material is currently limited by its weak mechanical properties. Efforts to improve the mechanical properties of selfhealing polyethylene-co-methacrylic include reinforcing with carbon fiber (Haramina et al. 2021). Addressing the issue of space debris or space waste can be a combination of all the factors discussed above. These include; developing self-healing materials that make for a more resistant spacecraft, having advanced detection systems that aid in timely detection of the location and extent of impact of space debris, removing the space debris, and preventing them from occurring in the first place by having legally binding agreements and standards for space missions.

11.10

Space Exploration and the Future of the Plastic Industry

Thus far, it is evident that plastics are key materials in space exploration. There is increased interest in space exploration, although so far only a handful of countries are actively involved in space missions (United States, Russia, China, and India). More recently, private companies like SpaceX have actively joined space exploration. This is very promising for a niche industry for plastics. A future where plastic companies can specialize in the production of specific plastic parts and production technologies for space application seems feasible. For example where private and public space agencies are engaged in more frequent manned trips to the moon or other parts of deep space, demand for space helmets parts is bound to increase. A company can specialize in producing visors for space helmet, where plastics used as radiation shield are outfitted on the spacecraft as individual flat panels which are then joined due to the size. A more efficient way could be to use plastic processing techniques like vacuum thermoforming. This can be a modified large-scale vacuum thermoforming process that is dedicated to producing such large relatively thin parts for specific design of spacecraft. While there currently might be no applications to justify employing that type of thermoforming, space exploration opens the door for plastic processors to specialize in it. This allows advancement through specialization. The cost of production of parts of spacesuits and spacecraft could be significantly reduced as more space missions are embarked upon. In fact, significant reduction in the cost per kg of space mission is reported to have decreased from an estimated 18,000 USD per kg between 1970 and 2000 to 2.720 USD per kg by 2023 (MessaArango et al. 2023). With companies specializing in specific plastic processing technologies optimized specifically for specific aspects of space exploration, the process becomes more efficient and parts are easier to source. Rather than a spacesuit manufacturer having to source the equipment for in-house production of parts. This

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aspect is outsourced to other companies who are able to advance their capabilities and dedicate research and development in the specific area. Helmet visors for example are produced using injection molding (Krevor et al. 2003), considering that spacesuits are not yet mass produced, This significantly adds to the production cost as the payback in injection molding is economy of scale. Considering that the spacesuits are made to custom fit each astronaut with precision could mean having a different mold for each helmet visor. Molds can be around 40% of the injection molding cost. Developing plastic parts specific for space mission has already led to the development of some plastics that then found applications in other industries. For example, Teflon gets used in spacesuits and is also used for household applications like nonstick cooking pots thanks to its heat resistance. As humanity explores further into space, new challenges are expected and polymer scientists will be challenged to develop new plastics and polymers and the processing techniques to meet new applications, thus further advancing the field making it more dynamic. As humans go deeper into space and visit other planets, moons, and asteroids and beyond, the demands on the spacesuits and spacecraft are bound to become more diverse. For example a spacesuit that might be designed to make the journey to and meet the conditions on Mars might not be suitable to make the journey to farther planets. The astronaut will require more protection from more extreme temperatures and should be able to hold enough oxygen and water and other life support to make longer journeys while still remaining reasonably compact. For example, SEM images of used and unused Teflon fabric from an Apollo 12 spacesuit showed signs of wear in the used Teflon fabrics (Rezende et al. 2020). This suggests a deterioration in the fabric within a period of 10 days the mission lasted for. Therefore for missions lasting longer and possibly harsher environments, the suits need to provide better durability. This could mean improving the yarn or fabric, developing another type of Teflon, or a different material entirely. Space tourism is already a reality albeit currently highly priced. The first space tourist was Dennis Tito, an American businessman who self-funded his 20 million dollars trip to the International Space Station. Others who followed include Gregory Olsen, Maezawa Yusaku, Richard Garriott, and Mark Shuttleworth, among several others. In 2021, Richard Branson funded a full crew on a suborbital flight. Blue Origins made the first commercial flight to space on July 20, 2021. The passengers on board included Jeff Bezos, Mark Bezos, Wally Funk, and Oliver Daemen. In the same year, SpaceX also launched an orbital tourism mission. So far more than 600 people have traveled to space (Messa-Arango et al. 2023). Space exploration offers an avenue for polymer scientists to justify further advancement of a material or technology beyond requirements for earth application. After developing a material to meet the highest requirements on earth, a polymer scientist can reach further into the skies and optimize the material further for applications in space exploration. This will contribute significantly to technological advancement. Potential for finding raw materials for plastic production like propylene on Titan in future could mean space exploration funded by plastics industries to explore the

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Conclusion

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potential for extracting propylene from Titan and having on-site plastic production to meet the demands of space missions already there. The International Space Station has been in operation for over 2 decades. Considering this is a relatively early stage of human space exploration, production facilities stationed in outer space are not too far-fetched. Already SpaceX has launched a few resupply payloads from earth to the International Space Station. Among the supplies sent were vehicle hardware, scientific supplies, supplies for the crew, and perovskite solar cells. The potential for producing perovskite solar panels in space is actively being considered (Brown et al. 2022). These will require use of some plastic components. Currently, most of the plastics used in space application are the nonbiodegradable fossil-derived plastics. Exploring bioplastics for space applications such as bioplastics that can offer comparable or better radiation protection becomes important in addressing the issue of plastic waste in space. Furthermore, the biodegradability of these plastics in different space environment also needs to be studied. Since different bioplastics such as PLA and PHA offer biocompatibility, this could lead the way to exploring bioplastic formulations that can be applied directly on the skin surface of astronauts to serve as additional radiation protection coating.

11.11

Conclusion

Considering the extent to which plastics are used in space aircraft, spacesuits, helmets, parachutes, and other space equipment and tools used in space exploration, it is safe to say that space exploration as we know it might not have been successful without plastics. From polyethylene, commodity plastics used in everyday life in articles like plastic grocery bags to the high-performance plastics like Kevlar used in bulletproof vests on earth, plastics have followed humans into space. Plastics have in fact taken humans into space and protected them while there as garments, as radiation shields, and as helmet and have even brought humans back safely as the parachutes that facilitate soft landing. Space debris pose significant threat to future of space exploration if not addressed. Plastics are among the materials which make up space debris. Therefore, the plastic industry can potentially assist and benefit from helping to address this issue. Already plastics like PVDF have been employed in the different technologies developed to address and mitigate against space waste. As more private and public organizations show increased active interest in space exploration, it is expected that the frequency of space missions will increase in the coming years. With plastics having vast applications in space exploration, the niche industry for space plastics is likely to see significant growth in the new space age.

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Krevor D, McNelly G, Skubon J, Speirs R (2003) Development and manufacture of visor for helmet mounted display. Proceedings of SPE:optical manufacturing and testing V. 5180. Stahl P (Ed). Bellingham WA. USA. 0277-786X/03 Learn JR (2021) The Nebra sky disk is the world’s oldest star map really a map at all? Astronomy Leonard R, Williams ID (2023) Viability of a circular economy for space debris. Waste Manag 155: 19–28 Lloyd V (2023) Spacesuit for NASA’s Artemis III moon surface mission debuts. NASA https:// www.nasa.gov/feature/spacesuit-for-nasa-s-artemis-iii-moon-surface-mission-debuts/. Accessed Aug 2023 Lombardo NA, Nixon CA, Achterberg RK, Jolly A, Sung K, Irwin PGJ, Flasar FM (2019) Spatial and seasonal variations in C3Hx hydrocarbon abundance in Titan’s stratosphere from Cassini CIRS observations. Icarus 317:454–469 Messa-Arango R, Jaramillo JP, Araujo DSA, Bi J, Basva M, Viti F (2023) Missions and factors determining the demand for affordable mass space tourism in the United States: a machine learning approach. Acta-Astronautica 204:307–320 Mohamed MMP, Holynska M, Weiss P, Gobert T, Chouard Y, Singh N, Chalal T, Sejkora N, Groemer G, Schmied S, Schweins M, Stegmaier T, Gresser GT, Das S (2020) Planetary exploration textiles (PEXTEX)- materials selection procedure for surface EVA suit development. 71st International Astronomical congress (IAC)–the CyberSpace edition. 12-12 October. The international Astronautical federation Narici L, Casolino M, Fino LD, Larosa M, Picozza P, Rizzo A, Zaconte V (2017) Performances of kevlar and polyethylene as radiation shielding on-board the international space station in high latitude radiation environment. Scientific Reports. 1644 Nechitailo G, Kondyurin A (2023) First long-term station Salyut 1: first steps to establish a space garden. Biological experiments in space: 50 years investigating life in space Orbit. pp 1–58 Nixon CA, Jennings DE, Bezard B, Vinatier S, Teanby NA, Sung K, Ansty TM, Irwin PGJ, Gorius N, Cottini V, Coustenis A, Flasar FM (2013) Detection of propene in Titan’s stratosphere. Astrophys J Lett 776:L14 Parks J (2023) How many astronauts have died in space? Astronomy. www.astronomy.com/spaceexploration/how-many-astronauts-have-died-in-space/. Accessed 21 Aug 2023 Pernigoni L, Sardelli AP, Lafont U, Grande AM (2021) Self-healing system for hypervelocity impact protection, repair and debris mitigation. Proceedings of the 8th European Conference on Space Debris (virtual). Darmstadt, Germany 20–23 April. ESA Space Debris Office. Flohre et al (editors) Rezende J, Moiseev N, Souza D, Santos D (2020) Spacesuits: challenges and research. 50th international conference on environment systems, 12-16 July, Lisbon, Portugal Siddiqi AA (2018) Beyond earth: a chronicle of deep space exploration, 1958–2016. NASA History Program Office Statista (2023) Oil demand for plastics production worldwide in 2019, 2050 and 2060. Statista Research Department Tang E, Xie C, Guo K, Han Y, Chen C, Chang M, He L (2023) Analysis of space debris impact source localization based on PVDF piezoelectric film. Adv Space Res 71:390–407 UN office for Outer Space Affairs (1966) Resolution adopted by the general assembly. 222(XXI). Treaty on principles governing the activities of states in the exploration and use of outer space, including the moon and other celestial bodies. 1499th plenary meeting Uri J (2022) 55 years ago: the Apollo 1 fire and its aftermath. NASA History wwwnasagov/feature/ 55-years-ago-the-apollo-1-fire-and-its-aftermath. Accessed 21 Aug 2023 Walsh A, Vernon W (2023) Russia’s Luna-25 spacecraft crashes into moon. BBC News www.bbc. co.uk/news/world-europe-66562629.amp. Accessed 21 Aug 2023 Washburn SA, Blattnig SR, Singleterry RC, Westover SC (2015) Active magnetic radiation shielding system analysis and key technologies. Life Sci Space Res 4:22–34 Wilson JW, Simonsen LC, Shinn JL, Kim MHY, Cucinotta FA, Badavi FF, Atwell W (1999) SAE Technical papers. Paper 1999-01-2173

Chapter 12

Plastics in Construction: Toward Green Buildings and Climate-Resilient Cities

Abstract As more of the world becomes urbanized, more infrastructures and buildings are being constructed. Implementation of green buildings and infrastructure is vital to achieving sustainable urbanization and population growth. Plastics play a key role in this regard. This is primarily through the implementation of sustainable plastics and the use of plastics to reduce or eliminate the use of more toxic and less environmentally friendly materials like asbestos. Plastics have also proved to have better performance in some applications in construction than conventional materials like steel while offering cost savings. Plastics have been key materials in constructing affordable homes by cutting time and material use, thereby reducing cost through their compatibility with techniques such as 3D printing and the reduced transportation cost due to their lightweight nature. We also look at how plastics can be used in constructing buildings and infrastructure that are better fit to withstand the challenges from climate change and environmental pollution such as adapting buildings to flooding and heat waves.

12.1

Recycled Plastic Roads

Bitumen is a key ingredient in road construction. It serves as the binding agent which holds the other materials used in the road structure. The latest innovation is the use of recycled plastics in road construction. This is aimed at addressing the issue of plastic waste as well as bringing down the cost of road construction, particularly in places where bitumen is not available in abundance, without compromising on the quality and durability of the roads. Styrene-butadiene-styrene is already being widely used as a butadiene modifier in conventional road construction materials such that thermoplastic materials have always been used in road construction (Li et al. 2022). The plastics that have been tested for road construction include LDPE, PP (Ibrahim et al. 2023), and PET (Veropalumbo et al. 2023). Annually the world accumulates around 150 million tons of plastic waste (Ibrahim et al. 2023). These are largely nonbiodegradable, are fossil derived, and can potentially release toxic additives into the environment if not properly handled. Recycling has been seen as one of the solutions to address plastic waste. Organization have dedicated time and © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 O. Olatunji, Re-envisioning Plastics Role in the Global Society, https://doi.org/10.1007/978-3-031-48945-7_12

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resources to remove millions of tons of plastics from the ocean. The question is after recovering all these plastics from the ocean, where will they then go? One of the policy instruments that have been used to address plastic pollution is to set legally binding requirements for recycled plastic contents in products. Certification programs that certify products’ ocean plastic or recycled plastic content have been implemented. Even where not legally binding, the increased public awareness of plastic pollution problem makes acquiring certification for including recycled plastic content in a product a good marketing strategy. Considering the scale of existing plastic waste relative to the available market, applications of recycled waste that require large quantities of plastic will aid in faster removal of plastic waste that has accumulated in the environment. Furthermore considering that the plastic economy to date is mainly based on the linear economic model rather than a circular economic model, applications that can accommodate plastic waste from untraced sourced and do not require high purity are more feasible. Chemical recycling processes which include gasification and pyrolysis can convert large quantities of plastic waste into fuel and chemical products. However, these processes are not fully advanced enough to prevent the release of potentially harmful compounds during the chemical recycling (Kwon et al. 2022). The complexity and cost of implementing these on a large scale is also a limiting factor especially with countries with low budget on waste management and limited technical capacities. A key feature in urban areas are roads. Asphalt roads are important for accessibility and ease of transportation. The smoothness provided by well-paved roads can significantly reduce fuel consumption and limit damage to vehicles compared to unpaved bumpy earth roads. They also reduce the rate of erosion of the road compared to unpaved roads. Paved roads are aesthetically pleasing, neat, and convenient. However, they require a significant amount of investment to build and to maintain. Bitumen, the key material used as binder in roads, is the most expensive of the ingredients (Anas et al. 2021). Approaches to bringing down the cost have included blending with crumb rubber or devulcanized crumb rubber. These are most often crumb rubbers derived from used tires at the end of their lifespan. The use of waste materials seeks to combine the potential for improved performance with reduced cost. Bitumen modified with crumb rubber from waste tires indeed shows improved resistance to fatigue cracking and rutting (Ibrahim et al. 2023). Despite this crumb rubber-modified bitumen is limited by high processing temperature requirement due to the higher viscosity. This can be contradictory to the goal of using waste rubber as it leads to higher energy consumption for processing and increased greenhouse gas emissions. There have been a lot of effort to reduce the energy consumed in road construction. This is with the goal of bringing down the cost and the environmental impact of the process. The main approach has been to modify the concrete bitumen mixture that is used to achieve a mix that can be efficiently layered and compacted at lower temperature and requires less energy, without compromising on quality. Some reduction in processing temperature has been achieved using for example synthetic wax as bitumen modifier (Chomicz-Kowalska et al. 2017).

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Recycled Plastic Roads

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While still employing the strategy of waste utilization, researchers have turned to waste plastics as alternative modifiers for bitumen. Polyethylene and polypropylene are the main candidates for this application. They are among the cheapest commodity plastics and among the most available as waste plastics. Due to their low melting point compared to other plastics like polyethylene terephthalate and nylon, they pose significant advantage in bitumen modification as they can be mixed and melted using the existing blending equipment. Polyethylene and polypropylene blended bitumen show improved properties compared to the neat bitumen (Nadupuru et al. 2022). However, these types of bitumen blends still require further development to achieve standard performance for practical application. Phase separation due to poor compatibility between the plastics, bitumen, and other components of the asphalt blend still remains a problem in most formulations reported. Polypropylene and polyethylene are nonpolar linear polyolefins which form weak secondary bonds with bitumen, hence the poor compatibility of such blends. Measures to improve compatibility between these polyolefins and bitumen include using low-density polyethylene rather than high-density polyethylene. This is because low-density polyethylene shows better compatibility compared to high-density polyethylene. This is likely due to low-density polyethylene having branched chains with lower melt viscosity. The use of processing agents like compatibilizers, plasticizers, and cross-linkers has also been shown to significantly improve the properties of plastic and bitumen blends for road construction application. Further improvement is achieved by blending devulcanized rubber crumbs with either polypropylene or polyethylene and bitumen. Devulcanized rubber crumbs have the advantage of including chemical agents that are used in the devulcanization process. When included alongside polypropylene or polyethylene in the bitumen blend, they have been shown to promote improved storage stability of the blend (Ibrahim et al. 2023). Devulcanized rubber is produced by passing rubber crumbs from used tires through an extruder. Compatibilizers, plasticizers, and other reagents are added to grind and devulcanize the rubber crumbs. The devulcanized rubber is then mixed with pelletized waste plastics, plasticizers, compatibilizers, and reagents in a second extruder which blends the components to a devulcanized rubber/plastic blend. The plastic can be either polyethylene or polypropylene. The polyethylene is either low-density polyethylene or high-density polyethylene (Ibrahim et al. 2023). Neat bitumen is then heated to a temperature of 180°C. The devulcanized rubber/plastic blend was then added and mixed at 3000 rpm for 2 h. At experimental condition this is carried out on a heating mantle with the temperature maintained. On an industrial scale other high shear heating apparatus is used such as a melt mixer. After the initial mixing the mix is transferred into a low-shear mixer at a reduced mixing speed of 700 rpm for 1 h adding 0.25% powdered sulfur which served as a cross-linker halfway through the mixing. For road production application, this bitumen is then applied alongside other components such as sand and concrete used in road construction. An example composition of bituminous concrete mix used for asphalt roads comprises 5.8% paving bitumen mix, 37.7% coarse aggregate of 4/8 mm

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gabbro, 15.1% coarse aggregate of 2/5 mm gabbro, 34.8% of crushed fine continuously graded limestone aggregate of 0/2 mm, and 6.6% limestone aggregate filler (Chomicz-Kowalska et al. 2017). When using recycled plastics in road construction, the process and other composition can be maintained with the plastic component within the bitumen mix being the main modification, such that the process is still carried out using the same equipment with potentially reduced operating temperature. Another important environmental impact of using plastics in road construction as bitumen modifiers is that they can potentially decrease the chances of these plastics breaking down in microplastics or nanoplastics that will then get into the environment. One study shows that this can be up to 93% reduction (Veropalumbo et al. 2023), since the plastics are bonded with the bitumen in a way they are immobilized within the road structure and shielded from the environmental conditions which typically lead to plastic pieces breaking down into microplastics. This is considering the case where the bitumen plastic mix is well compatibilized and the road is built to good standards whereby erosion is avoided and the road retains its integrity for several years. Microplastics can also be used directly in hot asphalt mixture for road construction as a recent study has shown. At just 0.3% composition, polypropylene microplastics improved the performance of the bitumen mix significantly. For example the flow rate based on STAS 174–197 was increased from 2 mm for the standard bitumen mix with no polypropylene to 4 mm when 0.3% polypropylene microplastics were added (Buruiana et al. 2023). This process takes advantage of the large surface area posed by microplastics. This significantly reduces the processing requirements for recycling the plastics using an extruder before adding to the bitumen mix. The temperature of the hot asphalt is sufficient to melt the microplastics as less heat is lost through transfer over larger surface area. Here the plastic used is polypropylene microplastics; however, there is potential for other plastics or a mixture of microplastics. Since in reality microplastics occur as a mixture of different types of plastics dispersed in air, water, or soil, the practicality of using microplastics in road construction will also depend on being able to use a mix of microplastics. Having a reasonably low-cost method for recovering microplastics from the environment will also further determine the feasibility of this application of microplastics.

12.2

Climate-Resilient Buildings

Recent years have seen the highest temperatures ever recorded in human history. This rise in temperature has been attributed to extreme environmental conditions such as floods, hurricanes, cyclones, and wildfires. These are occurring with increased frequency all across the world. Building and construction industries therefore have a significant role to play in helping societies survive and thrive through this changing climate through homes, public spaces, and structures that

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Climate-Resilient Buildings

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can withstand this era of changing climate. Around 38% of global CO2 emissions from energy use is attributed to the building construction industry. The building construction industry also consumes 35% of global energy (UNEP 2020). The Global Alliance for Buildings and Construction (GLOBALABC) was founded as COP21. It has more than 150 members; this includes 30 countries with others being non-country members. It has a common vision of achieving efficient and resilient buildings and the construction sector with zero emission. GLOBALABC is dedicated to create synergies between key players, initiatives, and platforms with the goal of boosting their scale, pace, and impact toward achieving zero-emission building and construction industry (UNEP 2020). It has helped set targets and track progress and actions for decarbonization of the building and construction industries globally. GLOBALABC is also a platform for knowledge sharing and guidelines for good practices for countries, organizations, and other stakeholders. GLOBALABC introduced the building’s climate tracker. It is a tool for tracking global decarbonization progress based on 7 global indicators. Recent evidence provided by the buildings climate tracker shows that the rate of decarbonization of the buildings and construction industry slowed between 2016 and 2019. Therefore, measures to improve decarbonization of the building and construction industry are pertinent. Part of the measures to achieve this is through improving climate resilience of buildings. The World Bank estimates that the world can save 4.2 trillion USD from investing in buildings and infrastructure that are more climate resilient (Hallegatte et al. 2019). The importance of the building and construction industry is effectively highlighted in the report’s main title “Lifelines.” The building and construction industry does indeed to some extent represents lifelines for global society. Making buildings more climate resilient is key to the world adapting and surviving through this climate change period. Whether it is individual homes, community shelter, schools, or other buildings, climate-resilient buildings can play key roles in the survival and sustenance of people through climate crisis in terms of water, food, warmth, protection, financial earnings, and more. There are different ways to make a building climate resilient, just as there are different climate factors a climate resilient building will have to withstand. These include flooding, heatwave, cyclones, and other forms of extreme weather that occur as a result of climate change. Improving climate resilience of buildings can refer to modifying existing buildings to make them more climate resilient or designing and constructing new buildings that are more climate resilient. UNEP presents 5 ways to achieve climate-resilient buildings in its 2021 report (UNEP 2021). These are (1) making buildings resilient to heatwaves, (2) droughtresilient buildings, (3) flood-resilient buildings, (4) buildings that are resilient to cyclones and strong winds, and (5) buildings that are resilient to cold. The type of climate-resilient system implemented in a building depends on the climate where the building is located. Since the world is currently experiencing climate change, it is important that building construction takes into consideration the extreme weather prediction for the location rather than just making designing and construction decisions based on the usual climate of the region.

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A good climate-resilient building would combine more than one feature to aid climate resilience. For example, one climate-resilient building design incorporates floating house structure, wind tolerance, a vertical garden, rainwater harvesting system, a poultry bio-digester unit, renewable energy systems, and cage fishing (Bhattacharjee and Mukherjee 2017). The following subsections review some of the applications of plastic in climate-resilient building construction.

12.3

Plastics in Green Roof Systems

Roofs serve as one of the most important parts of buildings. The common expression of having a roof over one’s head highlights the importance of the roof in a building. For a long time, conventional materials for rooftops have included ceramics, metal, thatch, and others. Furthermore, besides the unintentional purpose of serving as landing spots for birds and other creatures, roofs have for long been vacant spaces that served the sole purpose of providing a cover. As requirement for better waterproofing and more innovation in buildings grew, plastics have found applications in roofs. The following sections review the use of plastics in roofing tiles and as waterproof in green roofs.

12.3.1

The Layers of the Green Roof System

While the specific design may vary depending on the design of the building, the following is a general description of the different layers of a green roof. The green roof layers begin with the structural support. This is most often the concrete material of the roof. This is typical material used in building construction intended for green roofs. However, if the roof is not a concrete deck roof other structural materials like wood apply. It is important to ensure that the roof structure can hold the green vegetation and all the layers. The structural support layer is then covered by an antiroot membrane layer followed by or integrated into a waterproof layer. Above the waterproof layer is a protection layer. This is followed by a drainage layer and then the filter layer. The substrate for planting is then placed over the filter layer. Some of these layers are made of plastics and they are discussed in the following section.

12.3.2

Waterproof Layer in Green Roofs

Rooftops are largely vacant all year round. They have the best sunlight and rainfall access in the building and are particularly important planting spaces in the urban areas. Placing vegetation on roofs and rooftop, i.e., green roofs, is one of the ways proposed by the UN for making buildings more climate resistant. Green roofs serve

12.3

Plastics in Green Roof Systems

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as heat absorbers to reduce the heat island effect of urban areas (Fang et al. 2023). Plants serve as carbon storage and absorb CO2, thereby reducing the heating effect of the greenhouse gas. Plants grown on green roofs can be either edible or nonedible; they can vary from ornamental plants to vegetables to fruit trees. Where edible plants are grown they serve as food source to the household. They can also serve as a source of income whereby the excess food plants, ornamental plants, seedlings, exotic species, and others can be sold. Green roofs also serve as a way to support biodiversity and presence of wildlife in the cities by extending the purpose of rooftops from landing spots for birds to serving as habitat for a host of lifeforms such as pollinators like bees (Wooster et al. 2022). Therefore, green roofs contribute to sustainable cities in diverse ways. Achieving green roof goes beyond just placing plant on the roof. For optimal functionality and to reap all the benefits from green roofs they must be designed with technical soundness. Poorly designed and constructed green roof can lead to damage of the roof over time. A key feature in green roof system is the waterproof membrane. It functions as a protective layer from moisture. Even where the roof is made of concrete, over time water and plants root system can cause significant damage if not properly done. Since the key role of the membrane is to protect from water it must be made from a water-resistant material. The material must also be leakproof. There also needs to be excellent adhesion between the waterproof membrane and the bearing structure. The waterproofing membrane used in green roofs is similar to that used in conventional roofs. The main difference is the waterproofing membrane in green roofs has to withstand exposure to microbes and chemicals used in cultivating green vegetation such as fertilizers and pesticides. Since it is covered by vegetation and other layers in between, the waterproof membranes in green roofs are, however, protected from solar radiation, temperature fluctuations from nighttime to daytime, and hail shocks that conventional roofs are exposed to. The materials typically used for waterproof in green roofs are elastomeric membranes, plastomeric membranes, and elasto-plastomeric membranes (Cascone 2019). The elastomeric membrane is a blend of bitumen and an elastomeric polymer. It offers excellent elasticity as its key advantage. The plastomeric membrane is a blend of bitumen and a plastomeric polymer. It offers the advantage of UV resistance and higher stability at elevated temperatures. A third type of waterproof membrane is the elasto-plastomeric membrane. This is a blend of elastomeric and plastomeric polymers, thus combining the advantage of both materials. The selection of material for waterproofing in green roofs depends on factors such as the location, climate, design specifics, intended duration of use of the green roof, and budget. The reinforcement materials typically used are polyester or glass. The plastic can also be applied as an additional protective layer. A single layer or double layer can be used, and the thickness typically varies between 3 ands 4 mm (Cascone 2019). Recent innovations in plastomeric bitumen make use of recycled plastics as the plasticizing component and graphene as a filler (D’Angelo et al. 2022). These achieved properties are superior to those of plain bitumen. Therefore, green roofs can potentially be made more sustainably using waterproof layers that incorporate recycled plastics.

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Besides protecting the roof from moisture, the waterproof layer must also retain dimensional stability over the wide range of temperatures it gets exposed to throughout its life span. It needs to also retain dimensional stability under the load exerted on it by the rest of the green roof. It should be noted that the waterproof layer can be penetrated by the plant roots over time. Therefore, a layer of anti-root membrane is necessary. This prevents the plants’ root system from penetrating the waterproof membrane. If the plants are able to penetrate the waterproof membrane, without an anti-root layer, they would then much easily penetrate the concrete beneath. Antiroot membranes are typically made using metal sheets (Cascone 2019). It important that this does not rust or release toxins to the plant.

12.3.3

Protection Layer

While waterproofing protects the roof from moisture, the anti-root system protecting the waterproof membrane itself needs protecting from the rest of the green roof layers. The protection layer must be able to bear load and stress throughout the life span. It is placed above the anti-root system. Polystyrene is commonly used as the material for the protection layer. Geogrids and geotextiles, which are typically made from polyester, polypropylene, polyethylene, nylon, PVC, or fiberglass, are used as the protection layer. The protection layer typically has a minimum thickness of 3 mm (Cascone 2019). If this material absorbs water it is not a problem as the water can be released to the plants on hot days. Furthermore, plastic materials can be modified to have properties such as controlled release of nutrients or antimicrobial agents (Wang et al. 2024).

12.3.4

Water Storage/Drainage Layer

Plants and soil need drainage. Most plants do not like their roots immersed in water all the time and too much damp and poor aeration in the soil can lead to root rot. In the natural environment, the soil self-drains into lower layers of the earth. However, a green roof has limited depth and if excess water is not managed it collects and the plants and substrate become waterlogged. The lower layers of the green roof are also prone to damage from waterlogging and the excessive load undrained water adds. Therefore, a drainage system needs to be implemented in the green roof design. The drainage layer collects the water and channels it into a water storage system. The drainage system also provides aeration which is necessary for plant and soil health. Modular panels made of polyethylene and polystyrene are lightweight options for drainage systems in green roofs. These are between 2.5 and 12 cm thick. Some may also use granular materials like pumice, expanded perlite, expanded slate, crush bricks, or other materials. However, modular plastic panels are better suited for large-scale green roof installations and ones with slopes (Cascone 2019). This is

12.4

Floating Buildings for Flood Mitigation

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thanks to plastics being lightweight. Designing the green roof to slope enhances drainage into storage systems. The specific type of drainage layer employed depends on the rainfall in the region. Factors such as compaction and deformation should be considered.

12.3.5

Filter Layer

The substrate can be garden soil or other plant growth medium like perlite which is around 9 times lighter than soil (Abdelfattah et al. 2023). This is likely to contain small particles and debris from the substrate, vegetation, and other particles that could reach the green roof from the wind. If these particles get into the drainage layer, they could cause blockage. Hence a filter is placed between the substrate and the drainage layer. The role of the filter layer is to prevent these small particles from getting to the drainage layer. The filter is a perforated material that allows fluid to penetrate through but not particles. It is more permeable than the substrate; therefore, it will not be the limiting layer for water permeation such that it does not disrupt water permeation through the layers. While granular materials like pumice, crushed bricks, expanded perlite, expanded clay, expanded slate, and other materials can be used as filter layer, non-woven geotextiles are the preferred candidates (Cascone 2019).

12.4

Floating Buildings for Flood Mitigation

The destruction caused by flooding can be massive and sometimes fatal. Flooding is a natural process that is embedded in the natural system. When controlled flooding can even be beneficial to a region. For example, flooding of rivers allows the seasonal flow of water across streams and other water channels that are important to the flora and fauna of a region. Much of the challenge modern society faces with flooding is a result of building structures that obstruct the flooding process. With a better understanding of the flooding process over the years, technologies that allow buildings and other structures to better adapt to flooding have been developed. It is estimated that 40 million hectares which represents around 10.2% of total geographical area face the risk of flooding. In India over the past 3 decades, 4000 lives have been lost due to flooding (Tiwari et al. 2023). The problem of flooding is associated with a rising population which results in poorly planned settlements that disrupt the geographical water flow system. It is estimated that 680 million people across the world live in coastal areas. This is projected to increase to 1 billion people by 2050 (UN 2023; McMicheal et al. 2020). Much of the building and construction systems have been designed to create barriers to water flow. More sustainable building and construction strategies now look to design systems that allow humans to live in harmony with the natural water flow.

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When flooding occurs and people are forced to move from their homes into temporary shelters, they require food and water and depend on charity. Furthermore where there is limited space and people are forced to gather closely, there is an increased risk of contracting communicable diseases. Conflicts are also more likely to occur where people have to flee from flooded places and into dry land that is most likely already inhabited. This is particularly the case in low-income areas and areas generally lacking infrastructure and sufficient support. This further exacerbates the situation. Where buildings are flood resistant people are more likely to stay in their homes safely while the situation eases. They would be in a better position to be selfreliant and higher chances of surviving. Amphibious homes as the name implies are homes that are suited for both land and water. They are specifically designed to rest on land but float in the situation of a flood while remaining in the same horizontal position. Example design on an amphibious house that is constructed using lightweight materials is presented by a group of researchers from the Civil Engineering Department of the Shri Ramswaroop Memorial College of Engineering and Management Lucknow in India. The house with a 10 m × 10 m dimension is estimated to cost Rs 2,11,799 as of July 2023 around the period of publication of the research (Tiwari et al. 2023). A low-tech design is presented for amphibious buildings in Bangladesh. Three locations were chosen as potential sites to test the feasibility of floating houses in Bangladesh (Bhattacharjee and Mukherjee 2017). These were Sakhipur, Char Bhaga, and Tarabunia. These are areas that are highly exposed to flooding and are particularly vulnerable to the effects of climate change. In this particular study, the floating house design mimics a tree. The house also includes other climate adaptation features. A vertical garden will provide food for the dwellers even during periods of flooding. With a garden placed on a floating structure, there is reduced chances of losing harvest from flooding as the produce does not get washed away or submerged in the flood water where it gets spoilt. The loss of soil nutrient can also be reduced. The floating house also incorporates a rooftop rainwater harvesting system. This allows the rainwater from the roof to be stored in tanks. This water can be treated and made suitable for household use. The house can generate energy through solar panels and biodigesters which digest the household waste into biofuel. A fish cage that is submerged in water but hangs from the building platform serves as a source of food and potentially a source of income for the household. The houses are designed for collaborative learning between the community and researchers. Based on this concept, floating houses can be designed to provide the inhabitants all the energy, water, and food to survive through flood crisis period without need for external help if such is unavailable. Although different floating/amphibious buildings have various floatation mechanisms, a key feature of any amphibious building is the buoyant substrate. Some floating buildings have used fiberglass cylinders to facilitate floating of the structure (Varkey and Philip 2022). Fiberglass uses plastics like polyester, epoxy, and vinyl esters as the matrix within which the fiberglass is reinforced (Naqvi et al. 2022). Other floating house constructions have used styrofoam. In dry conditions, the amphibious house remains on the ground. When the flood sets in, the entire house

12.5

Plastics in Window Insulation

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is raised onto the dock. A vertical guiding feature ensures that the house only moves vertically to float over the flood water; it does not drift away horizontally (Varkey and Philip 2022). Flood-resilient houses have been constructed over a thousand years. Materials such as bamboo have been used as floatation substrates. With more advanced materials such as plastics, the design and construction of these buildings has advanced over the years. The plastics used in this application need to meet the requirement for strong, resilient materials that are also lightweight.

12.5

Plastics in Window Insulation

Another way to make a building climate resilient is to implement features that can insulate against heat loss. This can be achieved in multiple ways. Walls can be insulated and designed to absorb heat during the day and release the heat at night by radiation. The building design can take into consideration the sun’s movement in order to maximize sun exposure to the building for optimal natural solar heating. Dark wall colors can also be used to radiate heat (UNEP 2021). Other sections of this chapter have reviewed insulation of the roof through green roofs and the insulation provided by some building materials used for the walls. This section reviews the applications of plastics in double glazing of windows toward climate-resilient buildings. This specifically applies to building in regions that are prone to extreme cold weather or abnormally long cold seasons than usual due to climate change. Conventional windows can be a significant source of heat loss to the building. This is attributed to the conductive nature of glass. On the other hand, radiation from the sun can provide some heating. Letting sunlight into the building can also reduce the amount of electrical lights required for brightness during the day or for indoor plants. In addition to this, a well-lit room is aesthetically pleasing and calming. Therefore, the transparent glass window offers some advantages alongside the disadvantage of conductive heat loss. Properly insulated windows can significantly save heating cost. This is especially important with recent rise in energy cost that has exerted pressure on households. This rise in energy cost was to a large extent triggered by the war between Ukraine and Russia. Household expense on energy is set to increase by up to 112.9% in the near future (Guan et al. 2023). Households account for ~35% of global energy consumption as of 2021 (Lianwei and Wen 2021), and 40% of the heat loss from the building envelope occurs through the windows (Li et al. 2023). One of the most widely used method of insulating windows against cold weather today is double glazing. Advanced glazing is relatively expensive; therefore; researchers have sought to develop a low-cost alternative. A key material in the low-cost alternative doubleglazed window is polycarbonate plastic films (Li et al. 2023). These are very transparent polycarbonate films that serve as the interval layers in double-glazed windows. This type of assembly results in superior insulation without compromising on light transmission compared to other advanced double glazing. It achieves

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Plastics in Construction: Toward Green Buildings and Climate-Resilient Cities

between 60 and 70% visible light transmittance, whereas the lower grade window glazing barely achieves around 60% light transmittance. These windows glazed with the polycarbonate layer achieve heat gain coefficient and are therefore able to keep the room warm in severe cold than lower grade glazing. Polycarbonate has the advantage of low thermal conductivity compared to glass. It is also lighter than glass. The relative ease of processing polycarbonate compared to glass brings down the cost of producing a double-glazed window using polycarbonate compared to glass. The windows also weigh less (Li et al. 2023). Wide windows are currently a desirable feature in buildings for aesthetic appeal. However, this may come at the cost of increased surface area for heat loss to the external of the building if not well insulated. Plastics are frequently applied as transparent insulation materials in double-glazed windows. Example of such plastics include polymethyl methacrylate, polycarbonate, polytetrafluoroethylene, polyester carbonate, polyethylene, and fluorinated ethylene propylene polytetrafluoroethylene (Ming et al. 2022). The properties that make these materials suitable for such application is that they have higher visible light transmittance than glass, as well as lower thermal conductivity. Generally, they all have thermal conductivity less than 0.5 W/m.K., while glass has thermal conductivity around 1 W/m.K. Glazed windows used in cars are often made with sheets of laminated annealed glass that has been coated with polyvinyl butyrate to make it shatter proof. Polycarbonate is also considered as an alternative for glazed car windows due to its ductility and high impact resistance. While they have lower scratch resistance than glass, an anti-scratch coating can be applied to polycarbonate windscreens and windows to improve their resistance to scratch Mallick (2021). Such applications of plastics in car windows may become important in vehicles where weight reduction is required to accommodate the weight of other gadgets for optimal fuel efficiency. Another innovation in window insulation is the integration of Parallel Slats Transparent Insulation Materials into double-glazed systems for windows. These materials increase resistance to heat flow of the system and helps retain the heat in the room. An advancement of this is to integrate Parallel Slats Transparent Insulation Materials combined with thermotropic materials in the glazed window system (Ming et al. 2022). In these advanced glazed window systems, thermotropic hydrogels are integrated within polymethyl methacrylate plastic slats that are placed between the double glass windowpanes. The thermotropic materials can change from clear at low temperatures to translucent at higher temperatures to control the amount of sunlight that passes through the window.

12.6

Recycled Plastics in Masonry

One of the aspects of making homes affordable is utilizing low-cost building materials that perform as well or even better than the conventional materials. The bricks and blocks make up the bulk of the building structure. The roof is constructed with a variety of materials. Typically roofing tiles are made using conventional

12.6

Recycled Plastics in Masonry

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materials like ceramics, slate, cedar wood, and clay. While aesthetically pleasing and effective in their function as roof cover, they are relatively expensive. The roofing can be up to 40% of the building construction cost (Adesogan 2018). Similar aesthetics and function can be achieved using roofing tiles made from recycled plastics. Roofing materials made from bitumen modified with different plastics are already widely used in construction. For example atactic polypropylene has been used as a bitumen modifier in roofing felts. Similarly bitumen modified with styreneethylene-butylene-styrene and styrene-butadiene-styrene has been used in roofing materials (Luczak et al. 2021). Plastics have already been used in different aspects of conventional building construction. Recently, there have been increased interest in using plastics in building construction. This is of particular interest because it offers an avenue to divert a large amount of plastics into applications where they will potentially remain for decades or even longer. This is in addition to other advantages such as potentially reducing the amount of concrete required in building construction. Since concrete has a high greenhouse gas emission, the use of plastics in some building construction also reduces the use of toxic materials such as asbestos. Traditionally bricks and blocks are made of cement or concrete. The production of cement comes with some burden to the environment such as destruction of land flora and fauna, noise pollution, and land erosion during extraction of resources and the greenhouse gas emission during processing (Mohamad et al. 2022). It is also desirable to reduce its cost. In an attempt to incorporate waste plastic in building construction, waste PET blended into foundry sand has been explored. To achieve this, scrap waste PET was mixed with foundry sand to test the application in block making. Foundry sand varied from 60 to 80% weight composition, while scrap waste plastic composition varied from 20 to 40%. The bricks with 70% foundry sand and 30% scrap waste plastic showed the best performance with a tensile strength of 9.51 MPa and compressive strength of 38.14 MPa (Aneke and Shabangu 2021). Similarly the combination of recycled PET and crushed glass enhanced the strength of clay bricks (Lamba et al. 2022). Unfired clay bricks with HDPE and PET grains of 1 mm were made to a bulk density of