Polymer Product Failure

Use of polymers in product design has continued to grow at a rate unrivalled by conventional materials such as metal, ceramics or glass. More polymeric materials are becoming available to the designer, and this report highlights the need for caution in new design work, for careful use of new materials, and for awareness of the product environment. An additional indexed section containing several hundred abstracts from the Rapra Polymer Library database gives useful references for further reading.

Plastics and rubbers together make up the most adaptable and varied class of materials available to product designers. They may be transparent or opaque, rigid or flexible, lightweight, insulating, and weatherproof. They are used in almost every industry, and in every part of the home. Applications range from the humble hot water bottle to the sheathing on a high voltage cable, and from a simple scrubbing brush to a tank for storing hydrochloric acid. Products may be disposable (e.g. packaging goods) or intended to last for decades, such as a buried sewage pipe. However, it is this very diversity which makes materials selection so difficult, and appropriate design so important. Indeed the one thing that all these particular products have in common is their presence in this book of failures. Failures due to degradation may result from exposure to the weather or an aggressive operating environment. Alternatively they may be caused by the introduction of an external agent unforeseen by the product designer. They may be rapid or very slow, and they may result from a combination of factors. In this book Dr. Wright describes the following mechanisms of polymer degradation, and then illustrates each failure mechanism with a number of case studies: Thermo-oxidation, Photo-oxidation, Degradation due to ionising radiation, Chemical attack, Environmental stress cracking, Other miscellaneous effects, including treeing, electrochemical degradation and biodegradation. Many of the case studies are based on Dr. Wrights own experiences whilst working at Rapra. In each case he describes the circumstances of the failure, and discusses both the consequences of the failure and the lessons that may be learned from it. Most of the failed products are familiar to us all, and his style is both readable and informative. Photographs are included where available. The book will be essential reading for designers, engineers, product specifiers and forensic engineers. Materials suppliers and processors will also benefit from the pragmatic analysis and advice it contains. It will also be of value to all students of polymer science and technology, providing an essential insight into the practical application of plastics and rubbers and the potential problems. Finally, it will be of interest to a much broader readership, including anyone who ever wondered why things break, and it should become a standard reference work in all technical libraries. This book was written with the support of the UK Department of Trade and Industry. It is intended to raise awareness of the causes and consequences of polymer product failures, in order to reduce the future incidences of such failures, and their considerable costs to industry

Degradation reactions grouped under the heading chemical attack include oxidation hydrolysis, halogenation and other reactions. They also include some purely physical interactions between materials and fluids, dominated by the absorption of fluid into the material or vice versa. One particular mechanism described in some detail is acid induced stress corrosion cracking, which is the most frequent cause of premature failure of GRP products, and where the principle degradation reaction is between the fluid and the glass fibres. An additional indexed section containing several hundred abstracts from the Rapra Polymer Library database gives useful references for further reading.

Ein Praxisleitfaden der Polymeranalyse für alle, die sich in Polymerlabors mit Analytik, Qualitätskontrolle oder Produktentwicklung beschäftigen. Der Autor erläutert, aus seinem umfangreichen Erfahrungsschatz, welche Probleme in welchen Situationen auftreten können. Viele Fallstudien helfen bei der Anwendung der Erkenntnisse im Laboralltag. Mit einer umfangreichen Datensammlung zu physikalischen Eigenschaften von Polymeren! (07/00)

Rubber components are used in many demanding applications, from tyres and seals to gloves and medical devices, and failure can be catastrophic. This review of Rubber Product Failure outlines and illustrates the common causes of failure, while addressing ways of avoiding it. There has been increasing pressure to improve performance so that rubbers can be used at higher temperatures and in harsher environments. For example, the under-the-bonnet temperature has increased in some vehicles and new medical devices require longer lifetimes in potentially degrading biological fluids. The expectations of tyre performance in particular are increasing, and retreads have been in the spotlight for failures. The definition of failure depends on the application. For example, a racing car engine seal that lasts for one race may be acceptable, but in a normal car a life span of 10 years is more reasonable. If appearance is critical as in surface coatings and paints, then discolouration is failure, whilst in seals leakage is not acceptable. Each rubber product must be fit for the use specified by the consumer. Failure analysis is critical to product improvement. the cause of the problem can be much harder to find. It can range from a design fault to poor material selection, to processing problems, to manufacturing errors such as poor dimensional tolerances, to poor installation, product abuse and unexpected service conditions. The rubber technologist must become a detective, gathering evidence, understanding the material type and using deductive reasoning. Testing and analysis of failed materials and components add to the information available for failure analysis. For example, stored aged tyres appeared superficially to be alright for use, but on drum testing small cracks grew more quickly than in new tyres leading to rapid failure in service. Quality control procedures such as product inspection, testing and material quality checks can help to reach 100 percent reliability. In critical applications such as electricians' gloves for high voltage working, gloves are inspected before each use, while engine seals may be routinely replaced before the expected lifetime to avoid problems. in the literature is not high. However, several reviews have been written on specific products and references can be found at the end of this review. Around 400 abstracts from papers in the Polymer Library are included with an index. Subjects covered include tyre wear and failure, seals, engine components, rubber bonding failure, rubber failure due to chloramine in water, tank treads, gloves and condoms, medical devices and EPDM roofing membranes.

Fractography in Failure Analysis of Polymers, Second Edition, provides a practical guide to the science of fractography and its application in the failure analysis of plastic components. In addition to a brief background on the theory of fractography, the authors discuss the various fractographic tools and techniques used to identify key fracture characteristics. The Second Edition includes additional material related to polymer life prediction testing and analysis. Case studies have been expanded, including a wide range of polymer types, new technologies, applications, and failure modes, as well as best practice guidelines enabling engineers to apply these lessons to their own work. Detailed images and their appropriate context are presented for reference in failure investigations. This text is vital for engineers who must determine the root causes of failure when it occurs, helping them further study the ramifications of product liability claims, environmental concerns, and brand image. This is also a valuable resource for all plastics professionals, including manufacturers, product designers, and consultants, forensic investigators, as well as educators in materials science. Presents comprehensive coverage of applied fractography, enabling improved reliability and longevity of plastic parts and products Includes case studies that demonstrate material selection decisions and how to reduce failure rates Provides best practice on how to analyze the cause of material failures, along with guidelines on improving design and manufacturing decisions

This book contains analysis of reasons that cause products to fail. General methods of product failure evaluation give powerful tools in product improvement. Such methods, discussed in the book, include practical risk analysis, failure mode and effect analysis, preliminary hazard analysis, progressive failure analysis, fault tree analysis, mean time between failures, Wohler curves, finite element analysis, cohesive zone model, crack propagation kinetics, time-temperature collectives, quantitative characterization of fatigue damage, and fracture maps. Methods of failure analysis are critical to for material improvement and they are broadly discussed in this book. Fractography of plastics is relatively a new field which has many commonalities with fractography of metals. Here various aspects of fractography of plastics and metals are compared and contrasted. Fractography application in studies of static and cycling loading of ABS is also discussed. Other methods include SEM, SAXS, FTIR, DSC, DMA, GC/MS, optical microscopy, fatigue behavior, multiaxial stress, residual stress analysis, punch resistance, creep-rupture, impact, oxidative induction time, craze testing, defect analysis, fracture toughness, activation energy of degradation. Many references are given in this book to real products and real cases of their failure. The products discussed include office equipment, automotive compressed fuel gas system, pipes, polymer blends, blow molded parts, layered, cross-ply and continuous fiber composites, printed circuits, electronic packages, hip implants, blown and multilayered films, construction materials, component housings, brake cups, composite pressure vessels, swamp coolers, electrical cables, plumbing fittings, medical devices, medical packaging, strapping tapes, balloons, marine coatings, thermal switches, pressure relief membranes, pharmaceutical products, window profiles, and bone cements.

The combined effects of oxidising media and heat result in degradation by thermo-oxidation. The principles and cases described in this review emphasise long term degradation in service. Two additional phenomena that influence thermo-oxidation are also described: catalysis by certain metal ions, and the influence of stress. An additional indexed section containing several hundred abstracts from the Polymer Library gives useful references for further reading.