Flame -Retardant Polymeric Materials CONTRIBUTORS S. M. Atlas H. F. Mark Bronx Community College of the City Polytechnic Institute of New York University of New York Brooklyn, New York New York, New York Eli M. Pearce R. H. Barker Polytechnic Institute of New York Department of Textiles Brooklyn, New York Clemson University Clemson, South Carolina Daniel F. Quinn Department of Chemistry L. Benisek Wright State University International Wool Secretariat Dayton, Ohio Technical Center Ilkey, Yorkshire, England Sidney L. Reegen Wen-Hsuan Chang Polymer Institute University of Detroit Coating and Resins Division Detroit, MichiKan PPG Industries, Incorporated Allison Park, Pennsylvania T. H. Rogers Robert T. Conley Research Division Department of Chemistry Goodyear Tire and Rubber Company Wright State University Akron, Ohio Dayton, Ohio Ronald Blair Ross C. P. Fenimore Coating and Resins Division General Electric Research and Develop· PPG Industries, Incorporated ment Center Allison Park, Pennsylvania Schenectady, New York Roger L. Scriven Kurt C. Frisch Coating and Resins Division Polymer Institute PPG Industries, Incorporated University of Detroit Allison Park, Pennsylvania Detroit, Michigan Stephen B. Sello R. E. Fruzzetti J. P. Stevens & Company Research Division Technical Center Goodyear Tire and Rubber Company Garfield, New Jersey Akron, Ohio C. J. Setzer E. L. Lawton Fibers Department Fibers Department Monsanto Research and Development Monsanto Research and Development Corporation Corporation Research Triangle Park, North Carolina Research Triangle Park, North Carolina S. W. Shalab y Menachem Lewin Research Center Fiber Institute Ethicon Corp. Jerusalem, Israel Somerville, N. J. Flame - Retardant Polymeric Materials Edited by Menachem Lewin Israel Fiber Institute s. M. Atlas Bronx Community College of the City University of New York and Eli M. Pearce Department of Chemical Engineering Polytechnic Institute ofN ew York PLENUM PRESS· NEW YORK AND LONDON Library of Congress Cataloging in PUblication Data Main entry under title: Flame-retardant polymeric materials. Includes bibliographical references and index. 1. Fire resistant polymers. I. Lewin, Menachem. II. Atlas, Sheldon M. III. Pearce. EliM. THI073.F58 668 75-26781 ISBN-13: 978-1-4684-2150-7 e-ISBN-13: 978-1-4684-2148-4 DOl: 10.1007/978-1-4684-2148-4 ©1975 Plenum Press, New York Softcover reprint of the hardcover 1st edition 1975 A Division of Plenum Publishing Corporation 227 West 17th Street, New York, N. Y. 10011 United Kingdom edition published by Plenum Press, London A Division of Plenum Publishing Company, Ltd. Davis House (4th Floor), 8 Scrubs Lane, Harlesden, London, NWlO 6S£, England All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, otherwise, without written permission from the Publisher Preface Flammability has been recognized as an increasingly important social and scientific problem. Fire statistics in the United States (Report of the National Commission on Fire Prevention and Control. "America Burning:' 1973) emphasized the vast devastation to life and property--12.000 lives lost annually due to fire. and these deaths are usually caused by inhaling smoke or toxic gases: 300.000 fire injuries: 11.4 billion dollars in fire cost at which 2.7 billion dollars is related to property loss: a billion dollars to burn injury treatment: and 3.3 billion dollars in productivity loss. It is obvious that much human and economic misery can be attributed to fire situations. In relation to this. polymer flammability has been recognized as an in creasingly important social and scientific problem. The development of flame-retardant polymeric materials is a current example where the initia tive for major scientific and technological developments is motivated by sociological pressure and legislation. This is part of the important trend toward a safer environment and sets a pattern for future example. Flame retardancy deals with our basic everyday life situations-housing. work areas. transportation. clothing and so forth-the "macroenvironment" capsule within which "homosapiens" live. As a result. flame-retardant polymers are now emerging as a specific class of materials leading to new and diversified scientific and technological ventures. From the humble beginnings offlame-retardance treatments of existing polymers. the field is now developing into the design and engineering of new heat-resistant molecules. polymers. and commodities which are in herently flame-retardant. It is an interdisciplinary development and in volves several scientific. engineering. legal. medical. and sociological con sequences. The objective of this series is varied. In many cases it is to give an up-to-date summary of the state of the art in flame-retarding polymeric materials so as to be an aid to those involved in solving these problems. Interpretation as to mechanism and conjecture about future approaches \' VI Preface has been encouraged on the part of the authors. Since polymer degradation is the precursor to flammability, suitable importance has also been placed on this area. There will be occasional chapters which also deal with a specific test method, some of which may have historical importance. In the first volume, we have included a general article on the development of the oxygen index test because of its broad interest and significance. Future issues will also be concerned with similar subject areas. We are hopeful that through these means, meaningful solutions to a number of the flammability problems and their subsequent positive social ramifications will be accomplished. M. LEWIN S. M. ATLAS E. M. PEARCE Contents CHAPTER I Combustion of Polymers and Its Retardation H. F. MARK, S. M. ATLAS, S. W. SHALABY, AND E. M. PEARCE I. Introduction ................................................................. . 2. Brief Description of the Phases of Polymer Degradation and Combustion .................................................................. 2 2.1. Thermal Degradation of Polymers................................. 3 2.2. Thermal-Oxidative Degradation of Polymers .................. 3 3. Analysis of the Combustion Process and Pertinent Aspects of Flame Retardation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 7 3.1. Basic Features of Flame Retardancy .............................. 8 3.2. Additional Features of Flame-Retarding Compositions.. .... 9 3.3. Polymer Properties Which Affect the Heating and Combustion Processes. . . . . . . . . . . . . . . . . .. . . . . .. . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . II 4. Semiquantitative Evaluation of Polymer Flammability: The Limiting Oxygen Index (LOI) ............................................. 15 CHAPTER 2 Technology and Test Methods of Flameproofing of Cellulosics MENACHEM LEWIN AND STEPHEN B. SELLO I. Introduction .................................................................. 19 2. Nondurable Flame Retardants .......................................... 21 2.1. Group I ....... ....... ............ .... ........ ............................ 21 2.2. Group II .................................................................. 22 2.3. Group III . .............. ................ ............................ .... 25 3. Semi durable Flame Retardants .......................................... 25 3.1. Titanium and Antimony Compounds.............................. 29 VII VlIl Contents 3.2. Metallic Oxide and Halogenated Organic Binder Compositions.. .... ...... . ... . . ...... .... . . . ... . . . ..... . . .... .... .. . ..... 31 4. Flame-Resistant Cotton Flote........ ..................... ........ ........ 34 5. Durable Flame Retardants ................................................ 35 5.1. Phosphorylation ...................................................... 35 5.2. Sulfation.................................................................. 42 5.3. Combined Sulfation-Phosphory1ation ...... ............. ........ 43 5.4. Mesylation and Tosylation .......................................... 44 5.5. Phosphoric and Phosphorous Acid Derivatives ......... ...... 44 5.6. Phosphonitrilic Halides and Their Derivatives.................. 52 5.7. Phosphines and Phosphine Oxides ........................ ...... ... 54 5.8. Phosphonium Salts ................................................... 55 5.9. Phosphinic Acid and Its Derivatives .............................. 63 5.10. Phosphonic Acid Derivatives....................................... 64 5.11. Phosphorus-Containing Triazines................................. 70 6. Halogens as Flame Retardants .......................................... 74 6.1. Activity of Bromine and Chlorine Compounds.................. 75 6.2. Synergism .................. ........... ........ ..... ..................... 77 6.3. Brominated Lignin and Cellulose ......... ................. ....... 80 7. Flame-Retardant Treatment of Wood, Board, and Paper ... ...... 82 7.1. Flame-Retardant Requirements............... ... ............ ...... 82 7.2. Treating Processes...................................................... 83 7.3. Properties of Flame-Retardant Wood ...... ...... ............... 84 7.4. Recent Developments ... ............ ...... ..... ........... ... ... ..... 85 8. Testing Methods . ... ........ ............ .............. ....... ... ....... ..... 93 8.1. Textiles .................................................................. 94 8.2. Testing of Paper and Paper Laminates ........................... 112 8.3. Wood-Base Materials ................................................ 112 8.4. Need for Flammability Testing of Environment ............... 124 9. References..................................................................... 125 CHAPTER 3 Flame Retardance of Protein Fibers L. BENISEK 1. The Structure of Protein Fibers .......................................... 137 2. Flammability of Wool ...................................................... 139 3. Mechanism of Thermal Degradation and Combustion ............ 143 4. Smoke Emission and Toxic Fumes... ........ .... ...... ...... ............ 145 5. Mechanism of Flame Retardancy ...... .............. ...... ...... .... ... 148 6. Flame-Retardant Treatments ............................................. 152 6.1. Nondurable Treatments ............................................. 154 Contents IX 6.2. Phosphorus-Based Treatments .................. .................. 155 6.3. Metal Compounds........ ...................... ........................ 160 6.4. Chemical Modification of Wool.................................... 183 .. 6.5. Wool Flame-Resistant Man-Made Fiber Blends ..... .......... 184 7. References ...... ....... ..... ...... ...... ...... ...... .................. ......... 188 CHAPTER 4 Flarne-Retardant Polyethylene Terephthalate Fibers E. L. LAWTON AND C. J. SETZER 1. Introduction .................................................................. 193 2. Nonreactive Additives ...................................................... 196 2.1. Halogen .................................................................. 196 2.2. Phosphorus............................................................... 202 2.3. Phosphorus-Halogen Combinations ......... ........ .... ......... 207 2.4. Special Techniques ................................................... 210 3. Ethylene Terephthalate Copolymers ......... ...... ...... ..... .......... 211 4. Fiber and Fabric Treatments ...... ...... ............. ..... ............... 213 5. Fabric Flammability................................................... ...... 217 6. References..... ................................................................ 218 CHAPTER 5 Flame Retardance of Rubbers T. H. ROGERS. JR. AND R. E. FRUZZETTI 1. Introduction .................................................................. 223 2. Nature of Burning of Rubber............................................. 226 3. Flammability Testing ...................................................... 227 4. Smoke Generation.. ..... ....... .... ........ ..... ............................. 229 5. Flame Retardancy of Rubbers......... ............................... ..... 230 6. Commercial Rubbers ...................................................... 231 6.1. Natural Rubber (NR)................................................ 231 6.2. Synthetic cis-Polyisoprene .......................................... 231 6.3. SBR ..................................................................... 232 6.4. Poly butadiene Rubber ............................................. 232 6.5. Butyl..................................................................... 233 6.6. EPM and EPDM...................................................... 233 6.7. Nitrile ... ...... ...... ...... ..... ........ ..... ...... ........ .... ......... 233 6.8. Neoprene............................................................... 233 6.9. Thiokol ............... :... ..... ...... ........ ..... ........... .... ........ 234 6.10. Chlorohydrin Rubbers (ECO) ................ .... ... ...... ....... 235 x Contents 6.11. Silicone Rubbers (MQR) .......................................... 235 6.12. Hypalon Rubber (CSM)............................................. 235 6.13. Fluorocarbon Rubber (FKM) .................................... 235 7. Conclusion... ......... ... ........ ..... ..... ...... ... ......... .................. 236 8. References ..................................................................... 236 CHAPTER 6 Retardation of Combustion of Po lyam ides ELI M. PEARCE, S. W. SHALABY, AND R. H. BARKER 1. Introduction .................................................................. 239 2. Factors Affecting the Combustion and Related Processes of Polyamides............... .................. ............. ................. ...... 241 2.1. Heating .................................................................. 241 2.2. Transitions............................................................... 242 2.3. Degradation . .. . . . .. . .. .. . . . . .. . . . ... . . . . .. .. . . .... . . . . .. . ... . . . ... .. .. . 243 2.4. Decomposition ......................................................... 244 2.5. Oxidation ............................................................... 245 2.6. Ignition .................................................................. 246 2.7. Combustion ............................................................ 246 2.8. Propagation ............................................................ 247 3. Thermal and Thermal-Oxidative Degradation of Different Polyamides........ ...... .... ...... ...... ...... ......... ........................ 247 3.1. Nylon 6,6-6, and 6-10 ................................................ 248 3.2. Less Common Polyamides ........ ...... ...... .... .................. 256 4. Assessment of Physicochemical Changes in Degrading Polyamides 259 4.1. Thermogravimetric Analysis (TGA) .............................. 259 4.2. Differential Thermal Analysis (DTA )........................ ...... 259 4.3. Infrared Spectroscopy (IR) .... ..... ..... ......................... ... 260 4.4. Mass Spectrometry (MS) ............................................. 260 4.5. Pyrolysis-Gas Chromatography (P-GC) ........................ 260 4.6. Electron Spin Resonance (ESR) .................................... 260 4.7. Nuclear Magnetic Resonance (NMR) ........................... 261 4.8. Other Techniques ...................................................... 261 5. Stabilization Against Combustion ....................................... 261 5.1. Use of Additive-Type Stabilizers and Flame Retardants...... 262 5.2. Modification of Existing Polyamides .............................. 270 5.3. Synthesis of Structurally Modified Polyamides.................. 272 5.4. Synthesis of High-Temperature Polyamides ..................... 274 6. New Trends .................................................................. 279 7. Conclusion.... . . . . .. . . . . .. . . . . .. . . ... ..... . . . . ...... .. .. . . .... . . .. . .... ..... . .. 282 8. References ..................................................................... 283