Failure of Plastics and Rubber Products. Causes, Effects and Case Studies Involving Degradation

Failure of Plastics and Rubber Products. Causes, Effects and Case Studies Involving Degradation

Author: D.C. Wright
ISBN 978-1-85957-517-8 

Pages: 412, Figures: 139, Tables: 52
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 ionizing radiation,
  • Chemical attack,
  • Environmental stress cracking,
  • Other miscellaneous effects, including treeing, electrochemical degradation and biodegradation.
Many of the case studies are based on Dr. Wright's 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. Colored 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

1 Failure Analysis - A Personal Perspective
1.1 Introduction
1.2 Identification of strategic weaknesses
1.3 Identification of human and material weaknesses
1.4 Identification of product testing weaknesses
1.5 Priorities for future consideration

2 Thermo-oxidation
2.1 Introduction
2.2 The influence of polymer chemistry
2.3 The efficacy of stabilising additives
2.4 Metal catalysis
2.5 The influence of stress
2.6 The oxidising medium
2.7 Oxidation and stabilisation of polyvinyl chloride
2.8 Case studies

  • 2.8.1 Low density polyethylene insulation covers
  • 2.8.2 Rubber expansion joints
  • 2.8.3 Vehicle tyres
  • 2.8.4 Flexible hose (example 1)
  • 2.8.5 Flexible connectors
  • 2.8.6 Lift pump diaphragms
  • 2.8.7 Hot water bottle
  • 2.8.8 Flexible hose (example 2)
  • 2.8.9 Polypropylene laminated steel sheet
  • 2.8.10 Acrylic bulkhead light covers

    3 Photo-oxidation
    3.1 Introduction
    3.2 The severity of exposure
    3.3 The influence of polymer chemistry
    3.4 Stabilisation
    3.5 Material and application examples
    3.6 Case studies

  • 3.6.1 Polyethylene irrigation pipe
  • 3.6.2 Polyvinyl chloride power line insulation
  • 3.6.3 Colour instability of pigmented polymers
  • 3.6.4 Low density polyethylene tube
  • 3.6.5 Acrylonitrile-butadiene-styrene pipework
  • 3.6.6 Crosslinked polyethylene (XLPE) pole terminated waveconal cable
  • 3.6.7 High impact polystyrene jug handle
  • 3.6.8 Artificial ski slope filaments
  • 3.6.9 Polyvinyl chloride shrouds
  • 3.6.10 Polypropylene starter units
  • 3.6.11 Polyvinyl chloride running rails

    4 Degradation Due to Ionising Radiation
    4.1 Introduction
    4.2 Degradation mechanisms
    4.3 Radiation resistance of polymers
    4.4 Performance of specific materials
    4.5 Failure examples

    5 Chemical Attack
    5.1 Introduction
    5.2 Solvation effects
    5.3 Oxidation
    5.4 Acid induced stress corrosion cracking
    5.5 Hydrolysis
    5.6 Case studies

  • 5.6.1 Polyvinylidene fluoride in dry chlorine
  • 5.6.2 Acrylonitrile-butadiene-styrene in hydrochloric acid
  • 5.6.3 Acetal in chlorinated water
  • 5.6.4 Stress corrosion cracking of acetal (1)
  • 5.6.5 Stress corrosion cracking of acetal (2)
  • 5.6.6 Thermoplastic elastomers in hot water
  • 5.6.7 Solvent attack: cables in ducts and contaminated soil
  • 5.6.8 Glass-reinforced plastic in sulphuric acid
  • 5.6.9 Corrosion cracking of composite insulators
  • 5.6.10 Acetal pipe fittings
  • 5.6.11 Polyurethane oil seals
  • 5.6.12 Degraded polycarbonate mouldings
  • 5.6.13 Glass-reinforced plastic in hydrochloric acid
  • 5.6.14 Polyvinyl chloride lined rinsing tank

    6 Environmental Stress Cracking
    6.1 Introduction
    6.2 Crazing and cracking in air
    6.3 Crazing and cracking in active fluids
    6.4 Performance of specific materials
    6.5 Case studies

  • 6.5.1 Noryl fire extinguisher head
  • 6.5.2 High density polyethylene screw caps
  • 6.5.3 Crazing of an acrylic sight glass
  • 6.5.4 Polycarbonate instrument housing
  • 6.5.5 Nylon 6 fire hose valve
  • 6.5.6 Polyethylene agrochemical container
  • 6.5.7 Noryl electrical plugs
  • 6.5.8 Acrylonitrile-butadiene-styrene pipe fittings
  • 6.5.9 Motorised wheelchairs
  • 6.5.10 Pin hinged polystyrene mouldings
  • 6.5.11 Polyethylene wire insulation
  • 6.5.12 Polystyrene scrubbing brushes
  • 6.5.13 Blow moulded polyvinyl chloride bottles
  • 6.5.14 Polyvinyl chloride pressure pipe
  • 6.5.15 Fracture of an acrylic sight glass
  • 6.5.16 Rotationally moulded polyethylene wine coolers
  • 6.5.17 Polycarbonate mixing bowls and jugs
  • 6.5.18 Acrylonitrile-butadiene-styrene rotary switches
  • 6.5.19 Vacuum moulded sweets dispenser
  • 6.5.20 Acrylonitrile-butadiene-styrene pipe
  • 6.5.21 Polycarbonate filter bowls
  • 6.5.22 Noryl rotary switches

    7 Other Miscellaneous Effects
    7.1 Electrical treeing and water treeing

  • 7.1.1 Introduction
  • 7.1.2 Minimising the risk of failure
    7.2 Electrochemical degradation
    7.3 Biodegradation
  • 7.3.1 Body fluids
  • 7.3.2 Micro-organisms
    7.4 Diffusion, permeation, and migration
    7.5 Physical ageing
    7.6 Case studies
  • 7.6.1 Water treeing failure of crosslinked polyethylene power cable insulation
  • 7.6.2 Loss of polyvinyl chloride plasticiser
  • 7.6.3 Marring in contact with polyvinyl chloride covered wiring
  • 7.6.4 Shrinkage of ethylene-propylene-diene hose
  • 7.6.5 Diffusion of chlorine through polyvinylidene fluoride
  • 7.6.6 Cracking of a Nylon 6 outsert moulding
  • 7.6.7 Nylon 66 drive coupling
  • 7.6.8 Blistering of a glass-reinforced plastic laminate
  • 7.6.9 Polysulphone filter bowl
  • 7.6.10 Polyvinyl chloride skylights
  • 7.6.11 Polypropylene scooter wheels
  • 7.6.12 Epoxy flooring
  • 7.6.13 Valve sleeves

    Abbreviations and Acronyms


  • During his 30 years with Rapra, until his recent retirement, Dr. Wright specialized in the failure of plastics materials and products, researching into critical issues of materials durability, such as creep, fatigue and environmental stress cracking. He published around 90 technical papers and 3 books and was involved in the diagnosis of some 5,000 product failures, making him a leading expert in this field.