Handbook of Plastics Analysis (Plastics Engineering) [1 ed.] 0824707087, 9780824707088

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HANDBOOK OF PLASTICS

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Hubert Lobo

DatapointLabs Itchaca, New York, U S A .

Jose W. Bonilla

ISP Chemicals Calvert City, Kentucky

MARCEL

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zyxwvutsrqponmlkjih MARCEL DEKKER, INC.

DEKKER

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

NEWYORK BASEL

Although great care has been taken to provide accurate and current information, neither the author(s) nor the publisher, nor anyone else associated with this publication, shall be liable for any loss, damage, or liability directly or indirectly caused or alleged to be caused by this book. The material contained herein is not intended to provide specific advice or recommendations for any specific situation. Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress. ISBN: 0-8247-0708-7 This book is printed on acid-free paper. Headquarters Marcel Dekker, Inc., 270 Madison Avenue, New York, NY 10016, U.S.A. tel: 212-696-9000; fax: 212-685-4540 Distribution and Customer Service Marcel Dekker, Inc., Cimarron Road, Monticello, New York 12701, U.S.A. tel: 800-228-1160; fax: 845-796-1772 Eastern Hemisphere Distribution Marcel Dekker AG, Hutgasse 4, Postfach 812, CH-4001 Basel, Switzerland tel: 41-61-260-6300; fax: 41-61-260-6333 World Wide Web http://www.dekker.com The publisher offers discounts on this book when ordered in bulk quantities. For more information, write to Special Sales/Professional Marketing at the headquarters address above. Copyright # 2003 by Marcel Dekker, Inc. All Rights Reserved. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher. Current printing (last digit): 10 9 8

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PRINTED IN THE UNITED STATES OF AMERICA

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Founding Editor

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Donald E. Hudgin Professor Clemson University Clemson, South Carolina

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1. Plastics Waste: Recovery of Economic Value, Jacob Leidner 2. Polyester Molding Compounds, Robed Burns 3. Carbon Black-Polymer Composites: The Physics of Electrically Conducting Composites, edited by EnidKeil Sichel 4. The Strength and Stiffness of Polymers, edited 6yAnagnostis E. Zachariades and Roger S. Potter 5. Selecting Thermoplastics for Engineering Applications, Charles P. MacDermott 6. Engineering with Rigid PVC: Processability and Applications, edited by 1. Luis Gomez 7. Computer-Aided Design of Polymers and Composites, D. H. Kaelble 8. Engineering Thermoplastics: Properties and Applications, edited by James M. Margolis 9. Structural Foam: A Purchasing and Design Guide, Bruce C. Wendle 10. Plastics in Architecture: A Guide to Acrylic and Polycarbonate, Ralph Montella 11. Metal-Filled Polymers: Properties and Applications, edited by Swapan K. Bhaitacharya 12. Plastics Technology Handbook, Manas Chanda and Salil K. Roy 13. Reaction Injection Molding Machinery and Processes, F. Melvin Sweeney 14. Practical Thermoforming: Principles and Applications, John Florian 15. Injection and Compression Molding Fundamentals, edited by Avraam 1. lsayev 16. Polymer Mixing and Extrusion Technology, Nicholas P. Cheremisinoff 17. High Modulus Polymers: Approaches to Design and Development, edited by Anagnostis E. Zachariades and Roger S. Porter 18. Corrosion-Resistant Plastic Composites in Chemical Plant Design, John H. Mallinson 19. Handbook of Elastomers: New Developments and Technology, edited by Anil K. Bhowmick and Howard L. Stephens 20. Rubber Compounding: Principles, Materials, and Techniques, Fred W. Barlow 21. Thermoplastic Polymer Additives: Theory and Practice, edited by John T. Lutz, Jr. 22. Emulsion Polymer Technology, Robert D. Athey, Jr. 23. Mixing in Polymer Processing, edited by Chris Rauwendaal 24. Handbook of Polymer Synthesis, Parts A and B, edited by Hans R. Kricheldod

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

25. Computational Modeling of Polymers, edited by Jozef Bicerano 26. Plastics Technology Handbook: Second Edition, Revised and Expanded, Manas Chanda and Salil K. Roy 27. Prediction of Polymer Properties, Jozef Bicerano 28. Ferroelectric Polymers: Chemistry, Physics, and Applications, edited by Hari Singh Nalwa 29. Degradable Polymers, Recycling, and Plastics Waste Management, edited by Ann-Christine Albertsson and Samuel J. Huang 30. Polymer Toughening, edifed by Charles B. Arends 31. Handbook of Applied Polymer Processing Technology, edited by Nicholas P. Cheremisinoff and Paul N. Cheremisinoff 32. Diffusion in Polymers, edited by P. Neogi 33. Polymer Devolatilization, edited by Ramon J. Albalak 34. Anionic Polymerization: Principles and Practical Applications, Henry L. Hsieh and Roderic P. Quirk 35. Cationic Polymerizations: Mechanisms, Synthesis, and Applications, edited by Krzysztof Matyjaszewski 36. Polyimides: Fundamentals and Applications, edited by Malay K. Ghosh and K. L. Mittal 37. Thermoplastic Melt Rheology and Processing, A. V. Shenoy and D. R. Saini 38. Prediction of Polymer Properties: Second Edition, Revised and Expanded, Jozef Bicerano 39. Practical Thermoforming: Principles and Applications, Second Edition, Revised and Expanded, John Florian 40. Macromolecular Design of Polymeric Materials, edited by Koichi Hafada, Tafsuki Kifayama, and Otto Vogl 41. Handbook of Thermoplastics, edited by Olagoke Olabisi 42. Selecting Thermoplastics for Engineering Applications: Second Edition, Revised and Expanded, Charles P. MacDennoliand Aroon V. Shenoy 43. Metallized Plastics: Fundamentals and Applications, edited by K. L. Mittal 44. Oligomer Technology and Applications, Constanfin V. Uglea 45. Electrical and Optical Polymer Systems: Fundamentals, Methods, and Applications, edited by Donald L. Wise, Gary E. Wnek, Debra J. Trantolo, Thomas M. Cooper, and Joseph D. Gresser 46. Structure and Properties of Multiphase Polymeric Materials, edited by Take0 Araki, Qui Tran-Cong, and Mitsuhiro Shibayama 47. Plastics Technology Handbook: Third Edition, Revised and Expanded, Manas Chanda and Salil K. Roy 48. Handbook of Radical Vinyl Polymerization, Munmaya K. Mishra and Yusuf Yagci 49. Photonic Polymer Systems: Fundamentals, Methods, and Applications, edited by Donald L. Wise, Gary E. Wnek, Debra J. Trantolo, Thomas M. Cooper, and Joseph D. Gresser 50. Handbook of Polymer Testing: Physical Methods, edited by Roger Brown 51. Handbook of Polypropylene and Polypropylene Composites, edited by Harutun G. Karian 52. Polymer Blends and Alloys, edited by Gabriel 0. Shonaike and George P. Simon 53. Star and Hyperbranched Polymers, edited by Munmaya K. Mishra and Shiro Kobayashi 54. Practical Extrusion Blow Molding, edited by Samuel L. Belcher

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55. Polymer Viscoelasticity: Stress and Strain in Practice, Evaristo Riande, Ricardo Diaz-Calleja, Margarita G. Prolongo, Rosa M. Masegosa, and Catalina Salom 56. Handbook of Polycarbonate Science and Technology, edited by Donald G. LeGrand and John T. Bendler 57. Handbook of Polyethylene: Structures, Properties, and Applications, Andrew J. Peacock 58. Polymer and Composite Rheology: Second Edition, Revised and Expanded, Rakesh K. Gupta 59. Handbook of Polyolefins: Second Edition, Revised and Expanded, edited by Cornelia Vasile 60. Polymer Modification: Principles, Techniques, and Applications, edited by John J. Meister 61. Handbook of Elastomers: Second Edition, Revised and Expanded, edited by Anil K. Bhowmick and Howard L. Stephens 62. Polymer Modifiers and Additives, edited by John T. Lutz, Jr., and Richard F. Grossman 63. Practical Injection Molding, Bernie A. Olmsted and Martin E. Davis 64. Thermosetting Polymers, Jean-Pierre Pascault, Henry Sautereau, Jacques Verdu, and Roberto J. J. Williams 65. Prediction of Polymer Properties: Third Edition, Revised and Expanded, Jozef Bicerano 66. Fundamentals of Polymer Engineering: Second Edition, Revised and Expanded, Anil Kumar and Rakesh K. Gupta 67. Handbook of Polypropylene and Polypropylene Composites: Second Edition, Revised and Expanded, edited by Harutun G. Karian 68. Handbook of Plastics Analysis, edited by Hubert Lob0 and Jose V. Bonilla

Additional Volumes in Preparation

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

Preface

Plastics are one of the enabling technologies of the 20th century. They are among the most complex engineering materials being used in the world today, with amazing properties that have revolutionized the way in which products are manufactured. They are used in almost every walk of life, ranging from the mundane to high-end applications in which no other material could serve as a replacement. In each of these applications, it has been crucially important to understand their behavior through various parts of their product life, from manufacture to utilization and eventually their reclaim or disposal. The tools and techniques used to develop this understanding are referred to as plastics analysis. Plastics analysis can be broadly grouped into two main categories. Physical analysis refers to the evaluation of the physical behavior of the material. Properties such as strength, thermal behavior, and flow properties fall into this category, as do failure and morphological characteristics. Chemical analysis seeks to evaluate the compositional characteristics of the polymer. The combination of these two broad approaches has been used successfully to correlate the behavior of plastics to their composition. A wide variety of modern tools are available to the plastics analyst. As the range of available tools continue to expand, it is necessary for the analyst to keep abreast of all these technologies so as to be able to apply the most appropriate technique to the solution of a particular problem. This handbook seeks to highlight the most prominent tools in use by providing information on these diverse techniques and their application, and provides guidelines on the analysis and interpretation of results. It also provides a ready source of detailed references to readers interested in a more complete understanding of the subject matter.

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

In order to maintain a practical focus, the book concentrates on an approach that is more phenomenological than theoretical. While not going into detailed derivations, the book sets forth the basic governing equations where necessary to provide a good theoretical understanding of the techniques. Through the use of case studies and illustrations, the reader will be aided in the understanding of possible outcomes of each analysis technique. A number of plastics analysis techniques are currently standardized to national and international norms. The book lists these norms in the form of reference tables and provides brief descriptions where necessary. The chapters contain: Introduction of the technique and a brief scientific basis; governing equations if applicable Illustrations of test instruments along with schematics to aid in the understanding of the techniques Detailed descriptions, including measurement method(s), highlighting differences in technique(s), if relevant, including merits and deficiencies of the technique Images of typical outcomes of the analysis A listing of applicable national and international standards Applications with typical case studies and corresponding results; these are intended to aid in the analysis and interpretation of results from the analysis Discussions Conclusion, including information on the latest advances in the field (noncommercial) so as to provide an indication of future potential of the technology References and additional reading The handbook will serve as a concise reference to practitioners in the industry, providing technical information about plastics analysis and descriptions of the technology used to perform the measurements. It is aimed at laboratory personnel who need to have a working knowledge of plastics analysis techniques and would like to keep abreast of the latest developments in the field. These will include laboratory managers, supervisors, and engineers. The book will also serve as a basic reference to research engineers and scientists who may be looking for techniques to solve problems or investigate behavioral phenomena. Hubert Lobo Jose V. Bonilla

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

Contents

Preface Contributors 1.

General Introduction to Plastics Analysis Hubert Lobo and Jose V. Bonilla

2.

Capillary Rheometry Burke Nelson

3.

Practical Uses of Differential Scanning Calorimetry for Plastics Andrew W. Salamon and Kenneth J. Fielder

4.

Thermogravimetric Analysis of Polymers Scott Kinzy and Robert Falcone

5.

Thermal Conductivity and Diffusivity of Polymers Hubert Lobo

6.

Thermomechanical and Dynamic Mechanical Analysis Kevin P. Menard

7.

Infrared and Raman Analysis of Polymers Koichi Nishikida and John Coates

8.

Plastics Analysis by Gas Chromatography Jose V. Bonilla

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9.

Nuclear Magnetic Resonance of Polymeric Materials Anita J. Brandolini

10.

Inorganic Analyses of Polymers John Lemmon and Galina Georgieva

11.

Liquid Chromatography of Polymers Gary J. Fallick and Rick Nielson

12.

Particle Size Measurement of Plastics and Polymers Using Laser Light Scattering Philip Plantz

Appendix: ASTM Methods for Analysis of Plastic and Rubber Materials

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

Contributors

ISP Chemicals, Calvert City, Kentucky, USA

Jose V. Bonilla

Anita J. Brandolini New Jersey, USA

William Paterson University of New Jersey, Wayne,

Coates Consulting, Newtown, Connecticut, USA

John Coates

Gary J. Fallick

Waters Corporation, Milford, Massachusetts, USA

Robert Falcone

ICI Fluoropolymers, Bayonne, New Jersey, USA

Kenneth J. Fielder USA Galina Georgieva Scott Kinzy

GE Medical Systems, Waukesha, Wisconsin, USA

ICI Fluoropolymers, Bayonne, New Jersey, USA

John Lemmon Hubert Lobo

PerkinElmer Instruments LLC, Shelton, Connecticut,

GE Corporate Research, Schenectady, New York, USA DatapointLabs, Ithaca, New York, USA

Kevin P. Menard PerkinElmer Thermal Laboratory, Materials Science Department, University of North Texas, Denton, Texas, USA Rick Nielson

Waters Corporation, Milford, Massachusetts, USA

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

Burke Nelson

Goettfert USA, Rock Hill, South Carolina, USA

Koichi Nishikida USA Philip Plantz

Thermo Electron Corporation, Madison, Wisconsin,

Microtrac, Inc., Largo, Florida, USA

Andrew W. Salamon USA

PerkinElmer Instruments LLC, Shelton, Connecticut,

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

1 General Introduction to Plastics Analysis Hubert Lobo DatapointLabs, Ithaca, New York, USA Jose V. Bonilla ISP Chemicals, Calvert City, Kentucky, USA

INTRODUCTION Plastics have undoubtedly been the wonder materials of the last century. They have fundamentally revolutionized the manner in which we conceptualize and implement new products. They are ubiquitous in today’s environment, appearing in ways that range from mundane to high-tech, from indispensable to completely wasteful. The manner in which these materials have been used has shaped our impressions of plastics as necessary evils as well as miracle materials. A lot of the negative impressions have come from the fact that the world was not prepared for materials of this complexity. In many ways, our inability to understand plastics affected the manner in which we used or misused them. Before the arrival of plastics, most materials were relatively simple, or if complex, natural. In both cases, either by the application of existing science or by long historical knowledge of their use, it was possible to use these materials in an effective manner. In the case of plastics, the converse occurred. The arrival of plastics heralded the onset of one of the most comprehensive periods of discovery in material science. The very nature

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

of plastics has demanded significant advances in our ability to understand polymers, analyze their composition, and characterize this behavior. These technologies, collectively termed plastics analysis techniques, have come a long way in helping us design novel materials for a better tomorrow. Our impression of plastics as miracle materials has also stemmed from an incomplete understanding of their complexity. Plastics analysis has allowed us to apply the rigorous application of scientific technique to deepen our knowledge of their behavior, replacing our previous wonder with a deep-rooted scientific understanding that permits us to truly appreciate the capabilities of these materials. Indeed, it is this knowledge that will shape our use of these truly amazing materials in the new millennium. The introduction of plastics requires us to apply a wide range of techniques to understand their behavior. Plastics exhibit complex molecular characteristics. From our understanding of molecular structure, we are now able to attempt to correlate behavior to structure. This ability, however, is still, far from an exact science. The complex manner in which polymer molecules interact still prevents us from developing strong structure–property relationship theories. Indeed, the disconnection between our understanding of molecular-level behavior and macro-level characteristics is one of the sharpest dividing lines between classical material science and polymer science. In the case of metals, it has been relatively easy to apply our atomic-level understanding of the material and its microstructure to its behavior. In sharp contrast, polymer molecules vary widely in molecular weight. The manner in which polymer molecules interact with each other depends to a great extent on the pendant groups that are attached to the chain. Most frustrating of all, even though we are able to understand these aspects, this still does not permit us to apply our knowledge to understand macro-level behavior. This has forced the simultaneous development of both chemical analysis and physical analysis to grapple with the problem. Chemical analysis techniques permit us to analyze molecular composition and molecular weight to allow us to characterize plastics precisely. Physical methods allow us to look at the behavior of plastics in response to a variety of influences such as temperature, pressure, and time. This understanding helps us to say how the plastics will behave in their lifetime. Plastics analysis may include identification and chemical composition, thermal properties, mechanical properties, physical properties, electrical properties, and optical properties, among others. Chemical analysis may include material identification and characterization by techniques including FTIR, NMR, GC, GC/MS, HPLC, and GPC. Thermal analysis does provide information such as melting point, glass transition, flash point, heat deflection temperature, melt flow rate, and Vicat softening point. Mechanical properties, on the other hand, provide critical information such as tensile

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

properties, flexural strength, impact strength, hardness, compressive strength, modulus, and fatigue. Recent advances in microscopy also permit us to peek into molecular structure. The atomic force microscope, for example, has truly revolutionized our ability to probe molecular behavior, promising us a startling new understanding of plastics. The past few years have been characterized by a large growth in development of new polymers and composite materials. Modern research and developments of high-technology materials have also driven the development of new analytical equipment and analytical technologies. As materials become more and more sophisticated and complex, so also must become the analytical techniques required for materials testing and materials characterization. Innovative, accurate, easy-to-use, performance, and reliability are the requirements that describe instrumentation needed in modern laboratories involved in materials research or materials manufacturing facilities. Instrumentation of this type is needed in order to deliver outstanding performance to downstream customers. Modern instruments, hardware, and software products are designed to support such requirements. This book covers some of the most significant techniques used in modern analytical technology to characterize plastic and composite materials. A short general introduction to some of them is provided here to the topics covered in more detail in later chapters. A general introduction is also given to other techniques that are not covered in extensive detail in this book but that are of significant use in characterization of certain critical properties of plastic materials. Much of plastics testing is done by methodology developed and validated in-house by analytical scientists to meet specific needs. There are also a large number of official testing methods developed by agencies such as the American Society for Testing Materials (ASTM). A reference list of ASTM methods used for analysis of plastic and plastic-related materials is included as an appendix at the end of this book. There are many applications of plastics analysis. It is useful to examine these applications using a life-cycle viewpoint. In each area, one is then able to see the importance of these vital techniques to the understanding and proper application of plastic materials in our lives and the environment. PLASTICS AND PRODUCT DESIGN Historically, product developers have had a great deal of difficulty working with plastics. They simply did not behave in the conventional manner. None of the conventional rules of behavior applied either in the manner in which the product was made or in the manner in which it behaved once it was

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

produced. There were serious contradictions to conventional design philosophies—for example, the concept that making it thicker did not necessarily make it stronger, or that once it was made, it did not necessarily want to stay that way. Factors such as stress relaxation and residual stresses played havoc with first-generation plastic products, giving plastics the bad reputation that years of continuous improvement have not been able to erase. A lot of improvement can be attributed to our current understanding of physical behavior. Plastics exhibit large nonlinear stress–strain behavior. Large recoverable deformation is, in fact, one of the defining characteristics of a plastic. This characteristic has been used unfairly to portray plastics as weak materials because they lack the stiffness and strength of metals. In fact, it means that a plastic part can undergo a large amount of recoverable deformation before it breaks. This characteristic has been exploited, for example, in the replacement of the metal automotive bumper with TPO. The stress–strain relationship of a plastic shows a continuously decreasing stiffness with larger strain. This is because, in contrast to metals, plastics do not undergo complete instantaneous recovery upon unloading. When the plastic is unloaded, the response is viscoelastic, with partial instantaneous ‘‘elastic’’ response and a component of ‘‘viscous’’ time-based recovery. The introduction of the dimension of time is therefore a serious complicating factor, presenting essentially a fourth dimension to be considered in design. Viscoelasticity, creep, and stress relaxation are some of the measures used to characterize this behavior. PLASTICS AND MANUFACTURING In conjunction with the injection molding process, plastics have revolutionized the manufacturing process over the past 20 years. Major economies in assembly were achieved by molding in features and incorporating subcomponents into a single part. For a very long time, however, injection molding was perceived to be a ‘‘black art’’ because of the extreme difficulty of making good parts. It took significant research in areas of polymer rheology, thermal properties, and mechanical behavior to develop the scientific understanding that guides modern injection molding. Other plastics processing methods have also benefited from these advances. Characterizations of viscoelastic behavior and extensional rheology guide modern blow molding and thermoforming, transforming this industry into a producer of highquality engineering products. PLASTICS AND THE ENVIRONMENT Just as steel rusts and wood rots, plastics degrade in the environment. This is in stark contrast to the picture of the 1960s, which presented plastic as both

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.

the wonder material that would never die and the terrible scourge that would be present on the earth unchanged long after people had disappeared. Neither of these extreme positions helps us understand plastics. Instead, the past 40 years have helped us develop a healthy perspective on the true characteristics of plastics. We now see that plastics are not as unaffected by the environment as we had hoped, or feared, and that the properties and appearance of these materials do change adversely with time. This has spawned widespread effort to develop an understanding of environmental effects on plastics. Today, detailed analyses are conducted by exposing plastics to a variety of environments. Lastly, the product life cycle of plastic does not end in the landfill. Materials recovery and recycling is becoming an important means to reuse rather than waste these valuable materials. As milk jugs are converted to automobile fuel tanks and old soda bottles to fleece sweaters, a brandnew area of plastics analysis arises, challenging us to find new ways to understand the factors that affect the recycling: issues of cross-contamination and material degradation and their effects on product performance; material identification and differentiation techniques to reduce crosscontamination; process monitoring systems that permit us to produce good products with a feed stream that is not very consistent. SEPARATION METHODS Gas Chromatography Gas chromatography (GC) instruments may be equipped with various detectors to accomplish different analytical tasks. Flame ionization and thermal conductivity detectors are the most widely used detectors for routine analyses, nitrogen-phosphorus detectors are used for the trace analysis of nitrogen-containing compounds, and electron-capture detectors are used for halogen-containing compounds. GCs may also be equipped with peripheral accessories such as autosamplers, purge and trap systems, headspace samplers, or pyrolyzer probes for special needs in sample introduction. High-Speed Gas Chromatography In recent years, the need for rapid GC analysis has led to the development of gas chromatographs with fast separation times. Several recent technologies have been developed to decrease analysis times in GC, such as using short, narrow-bore columns and optimizing flow rates, temperature rates, and sample focusing parameters. Two major requirements for successful fast GC are fast data acquisition rates and fast detector response.

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High-speed GC offers several benefits: Quicker results for timely decisions about sample or product fate Faster sample turnaround times Lower operating costs per sample analysis Ability to handle more samples with fewer pieces of equipment Three major types of commercially available systems provide high-speed GC. High-Speed GC Using a Standard Instrument High-speed GC analysis is now possible using recently developed GC equipment that allows rapid heating of the GC oven and precise control of the carrier-gas pressure. Although this is not yet a widely used approach in chromatography, it has already been demonstrated that this new technique can reduce analysis time by a factor of 5 or better, compared to conventional GC analyses. One of the many remarkable features of modern GC instruments is their ability to perform fast GC without special modifications or expensive accessories. These GCs offer the capability to carry out fast GC without the need for cryofocusing or thermal desorption devices that may limit the flexibility or performance of the instrument. Properly configured for fast GC, these systems can perform all types of analyses using existing detectors, injectors, and flow controllers. Minimal system requirements include electronic pneumatics control (EPC), off-the-shelf capillary columns, split/splitless or on-column inlets, standard detectors optimized for capillary columns, and a fast acquisition data system. At any time, users can switch from fast GC back to the original method without major difficulties, or optimize new methods to meet new analytical demands. Flash GC Flash temperature programming is a new technique for rapidly heating capillary GC columns. The technique utilizes resistive heating of a smallbore metal sheath that contains the GC column. This technology is based on the flash GC system, an innovative chromatographic system that accomplishes in 1–2 min what takes a conventional GC from 30 min to an hour or more. The flash- GC can be over 20 times faster than conventional GC, and can be more sensitive and far more versatile. Development of the flash GC began in the 1980s. The first application was for the detection of explosives. The basic concepts, the proof of principle, and the initial designs were initially classified by the U.S. Ggovernment. The patents were declassified in the early 1990s, and have been issued to produce this equipment for public use. The flash GC provides great speed and flexibility to the analyst for the characterization of a great variety of chemical compounds. This

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technology has been proven to work in conjunction with mass spectrometry. There is also an upgrade kit available to easily convert a conventional GC into a flash GC. It is called the EZ Flash. This kit converts a conventional GC to a flash GC, providing the benefits from the speed and accuracy of flash CC technology with minimal investment. EZ Flash columns mount inside the oven of a conventional GC, replacing the existing column. The system offers column heating rates up to 208C per second and a temperature control range of ambient to 4008C. Cryofocusing Technology Cryofocusing technology permits high-speed GC on already-existing GC equipment. Some GC manufacturers offer fast GC technology that enhances conventional capillary gas chromatographs with a novel sample inlet system to allow very rapid separations to take place. These are ideal for use in a wide range of applications including plastic materials, industrial chemicals, and environmental applications. Using a unique cryofocusing inlet system, samples can be preconcentrated and subsequently desorbed onto the analytical column in a very narrow band, thus eliminating the band broadening that occurs with conventional inlet systems. The instruments can also be interfaced to other automated sample introduction devices such as autosamplers, purge and trap, headspace, etc. Fast GC is extremely sensitive, capable of sub-parts-per-billion detection. This approach allows high-speed separations to be achieved using short lengths of conventional, 0.25-mm columns that provide increased sample handling capacity over microbore columns. A high-speed inlet system can deliver injection bandwidths of 5 ms. The main components include restrictor columns, solenoid valves, a source of hydrogen or helium carrier (CG), vacuum pump, detector, and split injector for sample introduction. Short lengths of 0.25-mm capillary columns are typically used at high linear velocities. This provides the maximum rate of plate production as opposed to number of plates. The cold trap consists of a metal tube with inert coating that is cooled using liquid nitrogen and rapidly heated using a capacitive discharge power supply. Gas Chromatography/Mass Spectrometry Mass spectrometry (MS) instruments are normally equipped with electron impact (EI) and chemical ionization (positive and negative CI) sources, and a solid probe. This type of equipment is used for product identification, and analysis of a variety of components in various polymer products and raw materials or any unknown compounds in laboratory samples. As an analytical technique, mass spectrometry offers special advantages over other techniques that derive from its properties as both a highly specific

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and universal detection method. It can be more sensitive than other analytical techniques. It can also be made highly specific for the analysis of a target component. This results in a high signal-to-noise ratio for an analyte, due to a reduction in the detection of unrelated background interference. The MS instrument can also be operated as a universal detector. Molecular fingerprint information can be derived from the structurally dependent fragmentation patterns produced and used to identify unknown compounds or to confirm their presence. All modern mass spectrometers have the following essential components: 1. 2. 3. 4. 5. 6.

Sample introduction or inlet system Ion source and ion focusing system Mass analyzer Vacuum system(s) Ion detection and signal amplification system Data handling system

Inlet System A sample inlet system is used to introduce the sample into the ionization chamber. The inlet system can range from a very simple solid probe to a highly sophisticated liquid interface that permits the introduction of nonvolatile molecules or high-molecular-weight polymeric materials. Inlets may also be static (one sample at a time) or dynamic (allowing for continuous analysis). In recent years the use of dynamic inlets in MS has greatly expanded, due to the enormous numbers of samples being generated by the applications MS can be used with. There are several alternative methods of introducing a sample into a mass spectrometer. Samples to be analyzed may come in a variety of different forms: solids, liquids and gases, either as single compounds or as mixtures. Each sample type brings its own unique handling problems. The type of inlet system used depends on the physicochemical properties of the sample and its thermal stability. Thermally stable gas and liquid samples with a high vapor pressure at room temperature are usually admitted to the MS via the static solid probe inlet or through a dynamic gas chromatography interface. Gas chromatography is commonly used to introduce medium- to highvolatility compounds. Often, other ancillary techniques are used in turn to introduce different types of samples into the GC. These ancillary techniques include headspace, purge and trap, thermal desorption, cryogenic concentrators, and thermal pyrolysis devices. Special applications using these devices are described in more detail in the chapter on GC. GC is most

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commonly used in conjunction with either electron impact, or chemical ionization MS ion sources. Compounds with little or no volatility, or thermally labile compounds, are normally introduced through a dynamic interface employing liquid chromatography (LC). The type of LC interface used is dependent on the nature of the process used to ionize the analyte and includes techniques such as particle beam, electrospray, and APCI. Static probe inlets such as Maldi, field desorption, desorption chemical ionization (DCI), and FAB can also be used. The details of the individual interfaces will be presented in the section on hyphenated techniques. Ion Source Ionization methods in mass spectrometry are divided into gasphase ionization techniques and methods that form ions from the condensed phase, either inside or outside of the MS. All ion sources are desired to produce ions without mass discrimination from the sample and to transport them into the mass analyzer. Ideally, ions should be produced with high efficiency (ion yield) and transported to the mass analyzer with no loss (high transport efficiency). Electron Impact Ionization Electron impact (EI) ionization is the most commonly used ionization method. Electrons are produced from the cathode of a resistively heated filament located perpendicular to the incoming gas stream and collide with the sample molecules to produce a molecular ion. The source normally operates with an electron energy of 70 eV, the optimum ionizing potential. This provides sufficient energy to cause ionization and the characteristic fragmentation of sample molecules. Some compounds do not produce a molecular ion in EI source. This is a disadvantage of this ionization mode, as is the low ionization efficiency (typically less than 0.01% of all neutrals admitted are ionized). The typical MS employing EI has an ion extracting and focusing system that operates at high vacuum, resulting in high transport efficiency for the ions that are formed. As a result, modern MS instruments have detection limits in the mid-femtogram (10–12 g) range in full-scan mode. Perfluoroalkanes are often used as calibration compounds in EI because they provide ions at known masses corresponding to the loss of CF, CF2 and CF3 groups. EI is widely used in MS for volatile compounds that are insensitive to heat and as a result are generally low in molecular weight (