Polymers on the Crime Scene

Polymers on the Crime Scene

Valerio Causin Polymers on the Crime Scene Forensic Analysis of Polymeric Trace Evidence

Valerio Causin Università di Padova Padova, Italy ISBN 978-3-319-15493-0 DOI 10.1007/978-3-319-15494-7 ISBN 978-3-319-15494-7 (ebook) Library of Congress Control Number: 2015935432 Springer Cham Heidelberg New York Dordrecht London Springer International Publishing Switzerland 2015 This work is subject to copyright. All rights are reserved 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, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper Springer International Publishing AG Switzerland is part of Springer Science+Business Media (www.springer.com)

Acknowledgements I am grateful to many people who, in different ways, helped me in the challenge of writing this book. First of all thank you Ania Levinson, Editor at Springer Business+Media, who supported me from the preparation of the proposal until the final submission of the manuscript. Thank you for all the patience and understanding, even when I missed some deadlines. Thank you Abira Sengupta, Assistant Editor at Springer Business+Media, for all the suggestions and the assistance on the editorial process. A big thank you is due to all my former colleagues in Carabinieri, for the fruitful discussion, for providing research ideas, for sharing casework, and for teaching me something on forensic science each time I visit them. Financial support for this book was provided by Università di Padova by Project CPDA128143 Polymer characterization in a forensic intelligence perspective. A final thank you is due to Gioia for her patience and encouragement throughout this project. v

Contents 1 Introduction... 1 References... 7 2 Polymers: An Overview... 9 2.1 Why Polymers Need Their Own Science?... 9 2.2 A Short History of Polymers... 11 2.3 The Fundamentals of Polymer Science: Some Definitions... 12 2.4 Polymerisation Reactions... 13 2.5 Average Molecular Weight and Molecular Weight Distribution... 16 2.6 Classification of Polymers... 21 2.6.1 Source-Based Classification... 21 2.6.2 Organic and Inorganic Polymers... 22 2.6.3 Thermoplastic and Thermosetting Polymers... 22 2.6.4 Application-Based Classification... 23 2.7 Describing Polymers: Constitution, Configuration, Conformation... 23 2.7.1 Constitution... 24 2.7.2 Configuration... 26 2.7.3 Conformation... 29 2.8 Commercial Polymers: A Round Up... 30 2.8.1 Polyethylene... 30 2.8.2 Polypropylene... 31 2.8.3 Polystyrene... 32 2.8.4 Polyacrylonitrile... 33 2.8.5 Polyacrylates... 33 2.8.6 Polyesters... 34 2.8.7 Polyoxymethylene, Polyoxyethylene, Poly(ethylene glycol) and Poly(propylene glycol)... 36 2.8.8 Polycarbonates... 37 2.8.9 Polysulphone... 37 vii

viii Contents 2.8.10 Polyamides... 37 2.8.11 Polyurethanes... 38 2.8.12 Poly(vinyl acetate) and Poly(vinyl alcohol)... 39 2.8.13 Poly(vinyl chloride) and Other Chlorinated Polymers... 40 2.8.14 Fluorinated Polymers... 41 2.8.15 Polyisobutylene... 42 2.8.16 Polyisoprene: Natural Rubber and Gutta-Percha... 43 2.8.17 Elastomers Derived from Butadiene and Its Derivatives... 44 2.8.18 Polychloroprene... 44 2.8.19 Formaldehyde-Based Resins... 45 2.8.20 Epoxy Polymers... 47 2.8.21 Silicone Polymers... 48 2.8.22 Cellulose and Derivatives of Cellulose... 48 2.8.23 Rayon... 49 2.8.24 Cellulose Acetate... 50 2.8.25 Other Cellulose Derivatives... 51 2.8.26 Proteins... 51 References... 52 Suggested Reading... 52 3 Polymeric Traces: Transfer, Persistence, Recovery, Analysis and Interpretation of Analytical Data... 53 3.1 Polymers as Sources of Evidence: Transfer, Persistence, Recovery... 54 3.2 The Development of an Analytical Method... 63 3.3 The Statistical Treatment of Analytical Data... 72 3.3.1 Comparisons... 72 3.3.2 Principal Component Analysis: The Basics... 75 3.3.3 Principal Component Analysis: Some Examples... 78 3.3.4 Clustering... 80 3.4 The Interpretation of Evidence... 86 3.4.1 The Frequency of Traces: Population and Target Studies... 87 3.4.2 The Levels of Proposition [78 80]... 88 3.4.3 The Bayesian Analysis of the Results... 89 References... 100 4 Polymers on the Crime Scene... 105 4.1 Textile Fibres... 105 4.1.1 A Classification of Fibres... 106 4.1.2 Technological Requirements for Textile Fibres... 107 4.1.3 Transfer and Persistence of Fibres... 108 4.1.4 Recovery of Fibres... 109 4.1.5 The Characterisation of Textile Fibres... 111 4.2 Paints... 113 4.2.1 The Composition of Paints... 114

Contents ix 4.2.2 Automotive Paints... 118 4.2.3 Recovery and Sampling of Paints... 119 4.2.4 The Characterisation of Paint Evidence... 121 4.3 Adhesive Tapes... 122 4.3.1 The Composition of Adhesive Tapes... 123 4.3.2 Recovery and Sampling of Adhesive Tapes... 124 4.3.3 The Characterisation of Adhesive Tape... 125 4.4 Rubber Gloves... 128 4.4.1 The Manufacturing of Rubber Gloves... 129 4.4.2 Recovery and Handling of Gloves... 130 4.4.3 Characterisation of Latex Gloves... 131 4.5 Tyre Rubber Traces... 132 4.5.1 Manufacturing of Tyres... 132 4.5.2 Sampling of Tyre Rubber Traces... 134 4.5.3 Characterisation of Tyre Rubber Traces... 135 4.6 Condom Lubricants... 136 4.6.1 The Composition of Condoms and Lubricants... 137 4.6.2 Collection and Handling of Condom-Related Traces... 138 4.6.3 The Characterisation of Condom-Related Traces... 138 4.7 Foam Fragments... 141 4.7.1 The Composition of Foams... 142 4.7.2 Collection and Handling of Foam Traces... 144 4.7.3 Characterisation of Foam Traces... 144 4.8 Plastic Bags... 147 4.8.1 Composition of Plastic Bags... 148 4.8.2 Sampling and Handling of Plastic Films... 148 4.8.3 Characterisation of Plastic Films... 148 4.9 Polymers in Documents: Paper and Toner... 149 4.9.1 Paper... 150 4.9.2 Toner... 152 4.10 Post-fire Traces... 153 4.10.1 The Identification of Pyrolysis Products in Fire Debris... 153 4.10.2 Post-fire Materials Identification... 155 References... 157 5 Formulation: Polymer Matrix, Fillers, Dyes, Pigments and Other Additives... 167 5.1 The Techniques: Spectroscopy... 170 5.1.1 UV Visible Spectroscopy... 173 5.1.2 Infrared Spectroscopy... 175 5.1.3 Raman Spectroscopy... 178 5.2 The Techniques: Atomic Spectrometry... 180 5.2.1 Optical Atomic Spectrometry... 181 5.2.2 Atomic Mass Spectrometry... 185 5.2.3 X-ray Fluorescence... 187

x Contents 5.3 The Techniques: Chromatography... 189 5.4 The Techniques: Pyrolysis... 196 5.5 The Techniques: Mass Spectrometry... 198 5.6 The Techniques: Thermogravimetric Analysis... 206 5.7 The Characterisation of the Matrix... 209 5.8 The Characterisation of the Fillers... 217 5.9 The Characterisation of Dyes and Pigments... 224 5.10 Characterisation of Other Additives... 238 References... 258 6 Synthesis-Dependent Parameters: Molecular Weight, Constitution and Configuration... 265 6.1 Average Molecular Weight and Molecular Weight Distribution... 266 6.1.1 The Techniques: Size Exclusion Chromatography... 269 6.1.2 Size Exclusion Chromatography: The Forensic Applications... 273 6.1.3 The Techniques: Mass Spectrometry for Measuring High Molecular Weights... 277 6.1.4 Other Methods for Molecular Weight Determination... 280 6.2 Comonomers... 281 6.3 Isotacticity... 290 6.4 Stereoregularity... 295 References... 296 7 Processing-Dependent Parameters: Structure and Morphology of Polymeric Materials... 301 7.1 Morphology... 302 7.2 Semicrystallinity... 307 7.2.1 The Techniques: X-Ray Diffraction... 311 7.2.2 The Techniques: Thermal Analysis Differential Scanning Calorimetry... 320 7.2.3 Other Methods for the Determination of the Degree of Crystallinity... 325 7.3 The Mobility of Macromolecules... 327 7.3.1 The Glass Transition Temperature... 328 7.3.2 The Techniques: Time Domain Nuclear Magnetic Resonance... 329 7.4 Orientation... 335 References... 341 Index... 345

About the Author Born in 1975, Valerio Causin received a Ph.D. in Chemical Sciences at the University of Padova in 2004. From 2001 to 2003, he was First Lieutenant at the Chemistry, Explosives, and Flammables section of the Forensic Branch of Carabinieri in Rome. Since 2015, he has been working as a researcher at the Department of Chemical Sciences at the University of Padova. His research interests are focused on the application of polymer characterization techniques to forensic sciences in collaboration with Carabinieri in Rome, Messina, and Verona. He served as a forensic consultant for the Court, for the Prosecutor, and for the Defense in over 100 civil and criminal cases. In 2009, he was awarded the AIM prize for young researchers in polymer science, and in 2011 he was elected a member of the Scientific Committee of POLYCHAR World Forum on Advanced Materials. An author of 75 papers in international journals, he was invited as a keynote speaker at a number of international conferences and in universities and research centres worldwide. xi