Biron, M. (2016) Material Selection for Thermoplastic Parts - Practical and Advanced Information for Plastics Engineers - Elsevier William Andrew PLASTICS DESIGN LIBRARY (PDL) PDL HANDBOOK SERIES Series Editor: Sina Ebnesajjad, PhD ([email protected]) President, FluoroConsultants Group, LLC Chadds Ford, PA, USA www.FluoroConsultants.com The PDL Handbook Series is aimed at a wide range of engineers and other professionals working in the plastics industry, and related sectors using plastics and adhesives. PDL is a series of data books, reference works and practical guides covering plastics engineering, applications, processing, and manufacturing, and applied aspects of polymer science, elastomers and adhesives. 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Published by Elsevier Ltd. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-0-7020-6284-1 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress For information on all William Andrew publications visit our website at http://store.elsevier.com/ Publisher: Matthew Deans Acquisition Editor: David Jackson Editorial Project Manager: Peter Gane Production Project Manager: Susan Li Designer: Greg Harris Typeset by TNQ Books and Journals www.tnq.co.in Printed and bound in the United States of America Preface Engineers who work in many industrial segments search elsewhere complementary and corroborating that utilize plastic parts are not plastics experts. information. According to recent studies, about 60% of plastics Chapter 1 aims helping to define the problem, failures come from a wrong selection of the used pointing out the difficulty of a right choice of a grade. Time-dependent properties, environmental defined plastic material taking into account a broad stress cracking (ESC), chemical resistance, notched range of interactive parameters linked to the polymer rupture, thermal degradation, dynamic fatigue, properties, on the one hand, and surrounding stresses creep, and ultraviolet (UV) resistance are the main and media, on the other hand. issues. The aim of this book is to provide easy-to- Some thermoplastic features can surprise design- understand and easy-to-use tools for a systematic ers usually working with steels and other metals: the approach of a preliminary material selection. Of course, sensitivity to temperature, humidity, creep, chemi- this solution has the disadvantages of its simplicity cals, and viscoelasticity. The final choice results and cannot replace the knowledge and experience of from numerous iterations leading to a subtle balance plastics specialists. of technical requirements, economic considerations, To ease the work of the reader, innumerable ther- environmental issues, and targeted lifetime. moplastics grades (more than 30,000) are sliced into The ins and outs linked to the main interactions about 300 subfamilies. For each subfamily, about 20 between thermoplastics properties (mechanical, properties are assessed by a minimum and a maxi- physical, aging, sensorial), surrounding parameters mum values coming from a screening of industrial (temperature, time, stresses, chemicals, and so on), grades. (Of course, all the grades are not examined economics, regulations, green trends, and lifetimes and it is possible that other data exist.) As for all gen- are briefly examined. eral books, certain opinions may be unsuitable for A checklist of 125 good questions concludes this some cases and it is almost inevitable that errors and chapter. misconceptions have found their way in the mass of Chapter 2 makes the reader aware of some specific- data. ities of thermoplastics and helps clarify quickly some The selected subfamilies cannot be directly used particular features of the plastics language. Industrial and the reader must word deeper on the subject to plastics are based on organic macromolecules, which choose the suitable grade in the selected subfamilies lead to specific features such as viscoelasticity, various and use the actual data measured on this grade for levels of crystallinity, time and temperature depen- final computing, designing, economic study, etc. The dency, various levels of anisotropy, and so on. Apart advice of plastics specialists is irreplaceable, and from elemental composition, molecular weight, chain obviously, prototypes and tests under operating con- architecture, glass transition, and supramolecular ditions are essential. structure are also of high importance. Industrial grades This book is only one of the tools aiming to help are upgraded and customized mixtures of polymer(s) the preselection of thermoplastic materials for the and additives having specific roles. Main induced manufacture of thermoplastics parts. It proposes effects of additives include reinforcement thanks to an overview of the situation, a method of thinking glass and carbon fibers, minerals, and glass beads; among others for material selection, and property improvement of general behavior thanks to impact data allowing to lead to a first preselection. Obvi- modifiers, plasticizers, protective agents; optimization ously, it cannot cover all cases but it gives some start- of special features thanks to dedicated additives such ing points for innovative thinking of the reader to as fire retardants, electrically or thermally conductive, select information relating to his/her own case and to Antifriction, Magnetic and other additives. xiii xiv Preface Statistical analyses of some properties of more and office appliances; mechanical engineering; than 200 marketed thermoplastic grades give a more sports and leisure; medical market; furniture and precise idea of neat and reinforced thermoplastic bedding; and agriculture. grades. Chapter 5 aims to provide some information and Sensory properties (optical properties, touch, scratch examples to avoid some pitfalls leading to project fail- resistance, acoustic comfort, odor, taste, fogging) ures. Obviously, it is essential to fairly estimate part are examined before another burning issue, the requirements and to fairly understand the exact mean- dimensional stability linked to thermal expansion, ing of gathered properties of the used compound to mechanical stresses including residual ones, shrink- objectively fill the checklist. Difficulties include the age, warpage, water uptake, and releasing of organic selection of the useful mechanical properties: at break, additives. at elastic limit, at yield, after creep or relaxation. Chapter 3 helps clarify quickly the actual con- As for many other materials, provided properties sumption, uses, and costs of thermoplastics includ- are average data when failures are induced by weakest ing thermoplastic elastomer and bioplastics. After points that must be estimated from statistical results. an overview of the global plastics industry (up to Chemical behavior can hide several traps linked to 2020), the market shares of the various thermoplas- the nature of chemicals, test duration, temperature, and tic families, main concerned regions (Asia, Europe, so on without forgetting that ESC can worsen damages. America, BRIC), main application sectors, and Plasticization and decrease of insulating proper- importance of the various processing methods are ties by ambient moisture are also examined for cer- examined. tain plastics. Plastic costs are studied according to raw Designers must be aware of abrupt evolutions of material, additive and reinforcement costs, and some properties such as glass transition, yield, knees, processing costs. Some good reasons to use ther- frequency-dependent characteristics, leading to some moplastics and a few examples of success stories pitfalls linked to modeling and property compari- are examined. sons, very useful if carefully used but very hazardous Two important issues linked to costs and drying in other cases. up of crude oil are detailed through the modeling of Chapters 6–9 aim providing examples of densi- polymer cost and the potential use of bio-sourced ties, conventional mechanical and thermal properties plastics. for numerous subfamilies of thermoplastics includ- Finally, a table displays, without any warranty, ing neat grades, alloys, and special versions contain- price index hypotheses for 279 plastics. ing fibers, carbon nanotube, minerals, glass beads, Chapter 4 aims to provide tools for using a conductive additives, wood plastic composite, flame complementary preselection approach, generally retardant, etc. called, for example, design-by-analogy method Of course, density (Chapter 6) is of prime impor- or something like that. The concept is to search tance for weight of parts, costs per volume, and actual analogies with existing solutions solving an analo- weight savings. Density reduction is of a great inter- gous problem. Knowledge can be provided by the est and is briefly examined through structural foam designer experience, specialized databases, and all techniques and hollow parts. readily available information sources. This chap- For comparison, some property examples of ter is a specialized database providing more than traditional materials are quoted, pointing out the draw- 1500 couples of parts or products and the related backs of their higher densities. used thermoplastic(s). Analogies can concern the Chapter 7 warns designers that thermoplastics are product itself, the domain, or the functionalities not ideal materials obeying to simple physical laws of more or less similar products being of other and that testing methods are diverse, leading to pub- domains. lished data that can lead to common and important Parts or products come from the 10 top thermo- point of lack of understanding or misinterpretation. plastic domains, that is to say, packaging; building First of all, it is necessary to fully understand infor- and civil engineering; automotive and transportation; mation and make designer’s requirements under- electrical and electronics; household, entertainment, standable by plastics players. Preface xv This chapter provides data examples of usual Immediate retentions of strength and modulus are mechanical properties including tensile strength and extensively examined for temperatures above room strain at yield, tensile, and flexural moduli. Compres- temperature. Some examples relate to elongation sive properties, uniaxial compression, bulk compres- at break, tensile strength, and modulus at subzero sion, shear properties, and elongation work are also temperatures. briefly examined. Basic features of long-term resistance to heat Impact behavior (notched and unnotched Charpy aging and conventional accelerated aging tests in and Izod) and surface hardness (Rockwell M & air are examined with numerous examples of prop- R, Shore D) are also examined in detail with their erty retentions after aging. Examples of creep, stress numerous nonequivalent methods leading to difficult relaxation, and dynamic fatigue illustrate the time and hazardous comparisons. dependency of mechanical properties. Chapter 8 points out the temperature-dependent Tribological behavior is examined through coef- properties of thermoplastics with special behaviors at ficients of friction, PV factors, wear factors, Taber’s high and low temperatures. Plastics can be softened abrasion for tribological, and general purpose at temperatures as low as 40 °C and can be brittle at thermoplastics. subzero temperatures or even at a few degrees above Chapter 11 can surprise designers usually work- room temperature. ing with steels and other metals or glass. This chap- Several tables display numerous examples of ter aims to draw attention to some aspects of the fire glass transition temperatures, heat deflection tem- behavior of thermoplastics and requirements. Fire peratures (HDT or DTUL A and B), general assess- regulation is overabundant and always evolving: the ments concerning continuous use temperatures for designer has the responsibility to search elsewhere unstressed materials. More limited examples relate specific and general rules applicable to its own to UL relative temperature index and Vicat softening problem. temperatures. Oxygen indexes give a rough and sometimes mis- Low-temperature behavior is featured through leading idea of this fire sensitivity because, in the expected minimum service temperatures (more than end, all thermoplastics can burn with usual fire dam- 200 examples). More limited examples relate to Izod ages and, in addition, smoke emission of potential and Charpy impact tests at low temperatures and asphyxiating and corrosive gases. brittleness. Flame-retardant (FR) solutions, which pre- Chapter 9 is devoted to dimensional stability nega- vent a fire or limit its development, are examined tively affected by the viscoelastic behavior, low mod- as well as actual trends related to halogen-free ulus, high coefficient of thermal expansion (CTLE), FR suppressing emission of hydrogen halides, water and moisture uptake, possible release of ingre- which favors a reduction of toxicity and cor- dient, shrinkage, and warpage. Data examples of rosivity. Increasing flame, smoke, and toxicity usual dimensional properties include CTLE, mold requirements aim at reducing smoke opacity, tox- shrinkage, water uptake. Some effects of the struc- icity, and corrosivity. Properties of FR and general ture, the morphology, certain additives, orientation, purpose grades (28 examples) are compared when releasing of ingredients, relaxation, hysteresis, and possible. so on are also briefly examined. Chapter 12 deals with the most common applica- Sometimes it is forgotten that part sizes increase tions of thermoplastics that need electrical insula- with temperature, which can block a device and can tion but the most demanding uses relate to more or induce high stresses if the part has not a sufficient less conductive plastics. This chapter aims helping to space to expand. In the same way, cold temperatures define electrical requirements that must be selected reduce part sizes. among the most common electrical properties: Vol- Chapter 10 points out the specific time and tem- ume resistivity, permittivity or dielectric constant, loss perature dependency of polymer properties, atypical or dissipation factor, dielectric strength, arc resistance. Poisson’s ratios, and particular tribological behaviors. Electrostatic dissipative compounds are compared This chapter provides the basics and many examples to general purpose grades based on the same polymer (21 tables) for those advanced properties. for surface or bulk resistivity or resistance. xvi Preface Some examples briefly highlight the effects of fre- thermoplastics from commodities up to high-tech quency, temperature, and moisture on the main elec- resins through alloys and thermoplastic elastomers. trical properties. Chapter 15 is about ecodesign, life-cycle assess- At the end, a specific section gives information ment (LCA), environment, sustainability, pollution, concerning formulation to make thermoplastics and renewability that are rising concerns for design- conductive. ers, needing innovative thinking. Plastic sustainability Chapter 13 is about sensory properties that are is based on native resource preservation, renewable inevitable requirements for many applications. sources, energy saving, pollution and carbon footprint This chapter gives experimental data and ways of reduction, recycling, end cost optimization, and so on. thinking for optical properties, aesthetics, touch, Well-established routes relate to long-lasting odor, noise vibration harshness (NVH), and taste parts, design optimization by modeling, weight and transfer. Esthetics is a complex and subjective cost savings, and smart coatings. Repairing and use characteristic depending on the shape, color, gloss, of recycled plastics save money, energy, resources, clarity or opacity, surface quality, shaping defects, and pollution but must satisfy technical requirements aging, and more generally people’s opinion. Deg- and comply with specific regulations. radation of esthetics during service life can shorten Replacement of fossil polymers by bioplas- the lifetime as for the engineering properties. tics includes thermoplastic starch, polylactic acid, Grade selection, designing, modeling, simulation, cellulosics, aliphatic polyesters (polyhydroxyalkano- prototyping, processing enhancement, coloration, ate, polyhydroxybutyrate), liquid wood, proprietary decoration, and overmolding contribute to obtain a alloys, biocomposites. satisfying aesthetics and touch. Conventional polymers synthesized from bio- Odor, taste transfer, and NVH are other issues sourced chemical bricks offer more innovative more or less important according to the targeted ways including, i.e., polyolefins, polyamides, ther- application. moplastic polyesters, polyurethanes, and acrylics. Chapter 14 defines thermoplastics (as other Reinforcement with natural fibers and additives materials) are sensitive to chemicals, UV, light, from renewable resources contribute to higher and weathering. The goal of this chapter is to pro- biocontents. vide ways of thinking and practical information Thermoplastics versatility allows energy savings helping designers to do a basic selection and a pri- during the use phase, which is pointed out through mary rejection of thermoplastic families from this examples related to energy-efficient house, car indus- point of view. try, and packaging. Chemical behavior of more than 30 thermoplas- Main environmental indicators and benchmarks tics regarding immersion of unstressed samples in relating to LCA are reviewed in relation with the more than 60 chemicals representative of 14 chemi- impacts of polymer production, fiber production, cal functions are overviewed (hydrocarbons, oils polymer processing, end-product manufacturing, and and fuels, inorganic acids, organic acids, bases, recycling. amines, alcohols, aldehydes, ketones, esters, ethers, Once again, note this book is not an encyclope- phenols, chlorinated hydrocarbons, oxidants). dia for a definitive selection of thermoplastics but is Basics of ESC are examined and some assess- only one of the tools aiming to help the preselection ments are quoted for the main thermoplastics. of thermoplastics. Generally speaking, a single book Polymers do not rust but as other organic mate- cannot cover all situations and cannot replace the rials are sensitive to natural or artificial UV radia- intelligence of a team of designers and specialists of tions, light, and some are also sensitive to moisture plastic. Team is the ultimate decision maker and is and hydrolysis. After a review of the basics, assess- solely responsible for the final selection (Figures 1 ments relating to weathering concern more than 40 and 2). Preface xvii Performances Costs Environment Regula(cid:31)ons Source of Health & Mechanical Raw materials materials safety Source of Technical, Durability Processing energy environmental Aesthe(cid:31)cs Finishing Pollu(cid:31)on Sectorial Worldwide, Chemical Assembly Recycling, regional, local, disposal private Func(cid:31)on Carbon Miscellaneous integra(cid:31)on footprint Service costs Figure 1 Conclusion: Main requirements concerning plastics solutions. Technical, economic, Polymer, formula(cid:31)on, environment processing, design, requirements, sustainability regula(cid:31)ons Polymer Technical Economic Processing Regula(cid:31)ons Environment Design Sustainability Figure 2 Conclusion: Main possible interactions between parameters of production and requirements. Disclaimer This book is not an encyclopedia for a definitive any legal, or professional advice. The author is not selection of thermoplastics but gathers some prop- responsible for possible technical, economic, typo- erty data and suggests a method among others for graphical, or other errors. This book gives no warran- the material selection for thermoplastics parts. Obvi- ties either expressed or implied. ously, it cannot cover all cases and it is the responsi- Design, processing, and application of plastics bility of the reader to select information relating to and composites are professional activities needing his/her own case and to search elsewhere comple- specific skills and involving industrial and financial mentary and corroborating information. This book risks, health hazards, toxicity, fire hazards, regulation is only one of the tools aiming to help the preselec- conformity, etc. Readers must verify the technical tion of thermoplastics. The reader is the only respon- data and information, the economic figures, the pos- sible of his/her selection and, of course, he/she must sible suitability for the targeted application with their absolutely cooperate with polymer specialists for the own suppliers of raw materials or parts, the machin- selection of the definitive solution system. ery makers, and other current technical and economic All the information contained in this book, col- sources. Prototypes and tests under operating condi- lected from reliable documentation and verified as tions are essential. The reader is the sole responsible far as possible, is aimed at experienced professional of the chosen solutions. readers. We cannot accept responsibility for the It is the responsibility of the reader to determine accuracy, availability, timeliness, content, or com- the appropriate use of each product, processing pleteness of data, processing methods, machinery, method, machinery and ideas, and the compliance information and ideas. with processing rules, safety precautions, health haz- The characteristic data, economic figures, gen- ards, existing national laws and regulations required eral assessments, and indications concerning all the by countries of processing, commercialization, use, properties are not guaranteed and cannot be used for and application. The safety data, facts, and figures calculations, computations, or other operations to herein are provided for information only and are no determine design, cost-effectiveness, or profitability. substitute for the content of Material, Safety Data The quoted company names, trademarks, and Web Sheet, and other information from producers, com- sites are provided “as they are” and do not constitute pounders, converters, and other suppliers. xix