Pvc Degradation and Stabilization

516 Pages·2020·23.253 MB·English

by  George Wypych

PVC

Degradation
and Stabilization
4th Edition
George Wypych

Toronto 2020
Published by ChemTec Publishing
38 Earswick Drive, Toronto, Ontario M1E 1C6, Canada
© ChemTec Publishing, 2008, 2015, 2020
ISBN 978-1-927885-61-1 (hardcopy); 978-1-927885-62-8 (epub)
Cover design: Anita Wypych
All rights reserved. No part of this publication may be repro-
duced, stored or transmitted in any form or by any means without
written permission of copyright owner. No responsibility is
assumed by the Author and the Publisher for any injury or/and
damage to persons or properties as a matter of products liability,
negligence, use, or operation of any methods, product ideas, or
instructions published or suggested in this book.
Library and Archives Canada Cataloguing in Publication
Title: PVC degradation and stabilization / George Wypych.
Names: Wypych, George, author.
Description: 4th edition. | Includes bibliographical references and index.
Identifiers: Canadiana (print) 20190145110 | Canadiana (ebook) 20190145145
| ISBN 9781927885611
(hardcover) | ISBN 9781927885628 (PDF)
Subjects: LCSH: Polyvinyl chloride-Deterioration. | LCSH: Stabilizing agents.
Classification: LCC TP1180.V48 W96 2020 | DDC 668.4/236-dc23
Printed in Australia, United States, and United Kingdom
Table of Contents iii
Table of Contents
1 1 Chemical Structure of PVC 1
1.1 Repeat structures and their basic organic chemistry 1
1.1.1 Bronsted acid source with controllable emission 7
1.2 Molecular weight and its distribution 8
1.2.1 Kuhn-Mark-Houwink-Sakurada 9
1.2.2 Fikentscher K number 9
1.2.3 Chain length 9
1.3 Prediction of formation of irregular segments 10
1.3.1 Ab initio 10
1.3.2 Monte Carlo 12
1.4 Irregular segments 12
1.4.1 Branches 12
1.4.2 Tertiary chlorine 14
1.4.3 Unsaturations (end chain – vinyl, in-chain – vinylene) 15
1.4.4 Oxygen containing groups 18
1.4.4.1 Ketochloroallyl groups 18
1.4.4.2 α- and β-carbonyl groups 18
1.4.5 Head-to-head structures (1,2-dichloro groups) 18
1.4.6 Initiator rests 19
1.4.7 Transfer agent rests 20
1.4.8 Defects introduced during processing 20
1.4.9 PVC having increased stability 21
2 PVC Manufacture Technology 25
2.1 Monomer 25
2.2 Basic steps of radical polymerization 27
2.2.1 Initiation 27
2.2.2 Propagation 29
2.2.3 Termination 29
2.2.4 Chain transfer to monomer 30
2.3 Polymerization technology 31
2.3.1 Suspension 31
2.3.2 Paste resin manufacturing processes 34
2.3.3 Bulk 36
2.3.4 Solution 37
2.3.5 Living polymerization 37
2.4 Polymerization conditions and PVC properties 38
2.5 Optimal operation of Industrial PVC dryer 45
iv Table of Contents
3 PVC Structure and Morphology 47
3.1 Molecular weight of polymer (chain length) 47
3.2 Configuration and conformation 51
3.3 Chain folds 58
3.4 Chain thickness 60
3.5 Entanglements 60
3.6 Crystalline structure 63
3.7 Grain morphology 68
3.7.1 Stages of morphology development during manufacture 68
3.7.1.1 Suspension polymerization 68
3.7.1.2 Paste grades manufacture 73
3.7.1.3 Bulk polymerization 74
3.7.1.4 Nonaqueous polymerization 74
3.7.2 Effect of morphology on the degradation 75
4 Principles of Thermal Degradation 79
4.1 The reasons for polymer instability 79
4.1.1 Structural defects 79
4.1.1.1 Branches 79
4.1.1.2 Tertiary chlorine 79
4.1.1.3 Unsaturations 81
4.1.1.4 Oxygen containing groups 83
4.1.1.5 Head-to-head structures 84
4.1.1.6 Morphology 84
4.1.2 Polymerization residue 84
4.1.2.1 Initiator rests 84
4.1.2.2 Transfer agent rests 85
4.1.2.3 Polymerization additives 85
4.1.3 Metal derivatives 86
4.1.3.1 Metal chlorides 86
4.1.3.2 Copper and its oxide 92
4.1.4 Hydrogen chloride 93
4.1.5 Impurities 97
4.1.6 Shear 97
4.1.7 Temperature 98
4.1.8 Surrounding atmosphere 101
4.1.9 Electrical breakdown (space charge formation) 103
4.1.10 Additives 103
4.2 Mechanisms of thermal degradation 103
4.2.1 Molecular mechanism 103
4.2.2 Amer-Shapiro mechanism 104
4.2.3 Six-center concerted mechanism 105
4.2.4 Activation enthalpy 106
Table of Contents v
4.2.5 Radical-chain theory 107
4.2.6 Ionic 108
4.2.7 Polaron 109
4.2.8 Degenerated branching 111
4.2.9 Transition state theory 112
4.2.10 Recapitulation 113
4.3 Kinetics 113
4.3.1 Initiation 113
4.3.2 Propagation 116
4.3.3 Termination 118
4.4 Results of thermal degradation 125
4.4.1 Volatiles 125
4.4.2 Weight loss 126
4.4.3 Char formation 127
4.4.4 Ash content 127
4.4.5 Thermal lifetime 128
4.4.6 Optical properties 128
4.4.6.1 Color change 128
4.4.6.2 Extinction coefficient 129
4.4.6.3 Absorbance 129
4.4.7 Molecular weight 130
4.4.8 Mechanical properties 131
4.4.9 Electric properties 132
4.5 Effect of additives 132
4.5.1 Blend polymers 132
4.5.1.1 ABS 132
4.5.1.2 ASA 133
4.5.1.3 Chlorinated polyethylene, CPE 133
4.5.1.4 Epoxidized butadiene/styrene block copolymer 133
4.5.1.5 Epoxidized natural rubber 134
4.5.1.6 Ethylene vinyl acetate, EVA 134
4.5.1.7 High impact polystyrene, HIPS 135
4.5.1.8 Methylmethacrylate-butadiene-styrene 136
4.5.1.9 Methylmethacrylate-isoprene-styrene, MIS 136
4.5.1.10 Nitrile rubber, NBR 137
4.5.1.11 Oxidized polyethylene, OPE 137
4.5.1.12 Polyacrylate 137
4.5.1.13 Polyacrylonitrile 138
4.5.1.14 Polyamide 138
4.5.1.15 Poly(ε-caprolactone), PCL 138
4.5.1.16 Polyaniline, PANI 139
4.5.1.17 Polycarbonate, PC 139
4.5.1.18 Polyethylene, PE 140
vi Table of Contents
4.5.1.19 Poly(ethylene oxide), PEO 140
4.5.1.20 Poly(3-hydroxyalkanoate), PHA 140
4.5.1.21 Poly(methyl methacrylate), PMMA 140
4.5.1.22 Poly(N-vinyl-2-pyrrolidone), PVP 142
4.5.1.23 Polysiloxane 142
4.5.1.24 Polystyrene, PS 142
4.5.1.25 Polythiophene 143
4.5.1.26 Polyurethane 143
4.5.1.27 Poly(vinyl acetate), PVAc 144
4.5.1.28 Poly(vinyl alcohol), PVA 144
4.5.1.29 Poly(vinyl butyral), PVB 144
4.5.1.30 SAN 145
4.5.2 Antiblocking 146
4.5.3 Antistatics agents 146
4.5.4 Biocides and fungicides 146
4.5.5 Blowing agents 147
4.5.6 Fillers 147
4.5.7 Flame retardants 149
4.5.8 Impact modifiers 150
4.5.9 Lubricants 150
4.5.10 Pigments 150
4.5.11 Plasticizers 151
4.5.12 Process aids 157
4.5.13 Solvents 157
4.5.14 Stabilizers 158
5 Principles of UV Degradation 169
5.1 Reasons for polymer instability 171
5.1.1 Radiative energy 171
5.1.2 Radiation intensity 173
5.1.3 Radiation incidence 174
5.1.4 Absorption of radiation by materials 175
5.1.5 Bond structure 176
5.1.6 Thermal history 176
5.1.7 Photosensitizers 176
5.1.8 Wavelength sensitivity 177
5.1.9 Thermal variability 177
5.1.10 Pollutants 178
5.1.11 Humidity 178
5.1.12 Stress 178
5.1.13 Laboratory degradation conditions 178
5.2 Mechanisms of degradation 179
5.2.1 Radical mechanism 179
Table of Contents vii
5.2.1.1 Photooxidation mechanism 179
5.2.1.2 Mechanistic scheme 182
5.2.1.3 Conformational mechanism 183
5.2.1.4 Electronic-to-vibrational energy transfer 184
5.2.1.5 Other contributions to the mechanism of photodegradation 185
5.3 Kinetics 187
5.3.1 Initiation 187
5.3.2 Propagation 187
5.3.3 Termination 189
5.4 Results of UV degradation 190
5.4.1 Photodiscoloration 190
5.4.2 Mechanical properties 191
5.4.3 Other properties 193
5.5 Effect of additives 194
5.5.1 Biocides and fungicides 194
5.5.2 Fillers 195
5.5.3 Flame retardants 196
5.5.4 Impact modifiers 196
5.5.5 Lubricants 196
5.5.6 Pigments and colorants 196
5.5.6.1 Titanium dioxide 196
5.5.6.2 Zinc oxide 200
5.5.6.3 Iron-containing pigments 201
5.5.7 Plasticizers 202
5.5.8 Polymer blends 203
5.5.9 Solvents 203
5.5.10 Stabilizers 204
5.5.11 PVC modification 204
6 Principles of Degradation by γ-Radiation 207
6.1 The reasons for polymer instability 207
6.2 Mechanisms 207
6.3 Kinetics 209
6.4 Results 209
6.5 Effect of additives 210
6.5.1 Plasticizers 210
6.5.2 Fillers 213
6.5.3 Stabilizers 213
7 Degradation by Other Forms of Radiation 217
7.1 Argon plasma 217
7.2 β-radiation (electron beam) 218
7.3 Corona discharge 220
viii Table of Contents
7.4 Lightning arc 220
7.5 Ion (proton) beam 220
7.6 Laser 222
7.7 Metallization 224
7.8 Microwave 224
7.9 Neutron irradiation 225
7.10 Oxygen plasma 226
7.11 X-rays 227
7.12 Ultrasonic 228
8 Mechanodegradation 231
9 Chemical Degradation 237
9.1 Methods of chemical dehydrochlorination 237
9.2 Kinetics and mechanisms of reaction 240
10 Analytical Methods 247
10.1 Heat stability test 247
10.1.1 Sample preparation 247
10.1.2 Kinetic studies of dehydrochlorination 250
10.1.3 Dehydrochlorination rate and optical changes 254
10.1.4 Degradation in solution 256
10.2 Thermogravimetric analysis 256
10.2.1 Differential scanning calorimetry, DSC 256
10.2.2 Mass loss 256
10.3 Combustion 258
10.4 Optical properties 259
10.5 Spectroscopic methods 261
10.5.1 Atomic absorption, AAS 261
10.5.2 Auger 262
10.5.3 Electron spin resonance, ESR 262
10.5.4 Fourier transform infrared, FTIR 262
10.5.5 Laser photopyroelectric effect spectrometry 264
10.5.6 Mass, MS 264
10.5.7 Mossbauer 265
10.5.8 Near-infrared, NIR 265
10.5.9 Nuclear magnetic resonance, NMR 265
10.5.10 Positron annihilation lifetime spectroscopy, PAS 267
10.5.11 Inductively coupled plasma emission spectroscopy 268
10.5.12 Raman 268
10.5.13 Time-of-flight secondary ion mass spectrometry, ToF-SIMS 270
10.5.14 X-ray analysis 270
10.5.14.1 Small angle x-ray scattering, SAXS 270
Table of Contents ix
10.5.14.2 Wide angle x-ray scattering, WAXS or WAXD 270
10.5.14.3 Wide-angle neutron diffraction, WAND 271
10.5.15 X-ray photoelectron spectroscopy, XPS 271
10.5.16 UV-visible 272
10.6 Chromatographic methods 273
10.6.1 Gas chromatography 273
10.6.2 Liquid chromatography 274
10.7 Mechanical properties 275
10.8 Morphology 276
10.9 Other essential methods of testing 278
10.9.1 Action spectrum 278
10.9.2 Coulter counter 278
10.9.3 Gel content 278
10.9.4 Ozonolysis 279
10.9.5 Peroxide titration 279
10.9.6 Rheological studies 279
10.10 International standards 280
11 Principles of Stabilization 297
11.1 Functions of PVC stabilizers 297
11.1.1 Hydrogen chloride binding 297
11.1.2 Removal of reactive chlorine 300
11.1.3 Reactions with metal chlorides 303
11.1.4 Reactions with isolated unsaturations 304
11.1.5 Reactions with conjugated unsaturations 305
11.1.6 Decomposition of hydroperoxides 305
11.1.7 Removal of reactive radicals (chain-breaking function) 306
11.1.8 UV screening 307
11.2 Theories 309
11.2.1 Frye and Horst 309
11.2.2 Application of the Debye-Hückel theory 311
11.2.3 Kinetic model of PVC stabilization 312
11.3 Stabilizer groups 321
11.3.1 Metal soaps 322
11.3.1.1 Barium/zinc 322
11.3.1.2 Calcium/zinc 327
11.3.1.3 Magnesium/zinc 335
11.3.1.4 Potassium/zinc 337
11.3.1.5 Barium/cadmium 339
11.3.1.6 Barium/cadmium/zinc 342
11.3.1.7 Lanthanum soaps 344
11.3.2 Lead stabilizers 345
11.3.2.1 Properties and applications of commercial stabilizers 346