Reinforced Plastics Durability

379 Pages·1999·4.366 MB·English

by  Geoffrey Pritchard

Contents i
Reinforced
plastics durability
Edited by
Geoffrey Pritchard
CRC Press
Boca Raton Boston New York Washington, DC
Cambridge England
© 1999, Woodhead Publishing Ltd
ii Contents
Published by Woodhead Publishing Limited, Abington Hall, Abington
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First published 1999, Woodhead Publishing Ltd and CRC Press LLC
© 1999, Woodhead Publishing Ltd
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© 1999, Woodhead Publishing Ltd
Contents iii
Contents
Preface ix
List of contributors xi
1 An introduction to plastics for non-specialists 1
GEOFFREY PRITCHARD
1.1 Durability 1
1.2 Cost effectiveness and product lifetimes 2
1.3 When does a fibre reinforced plastics product have to be
replaced? 3
1.4 Health and safety 3
1.5 What causes deterioration in fibre reinforced plastics? 4
1.6 Biodegradation 5
1.7 Terms 5
1.8 Thermoplastics and thermosetting resins 11
1.9 Blends 13
1.10 Commodity, engineering and high performance plastics 14
1.11 Crystallinity in thermoplastics 15
1.12 Stress–strain behaviour of unreinforced plastics 16
1.13 Glass transition temperature 20
1.14 Stress and time: viscoelastic behaviour 21
1.15 Predicting creep behaviour 23
1.16 Cracks and notches 25
1.17 Physical ageing 26
1.18 Reinforcements 27
1.19 Why use reinforcement? 28
1.20 Fibres combined with fillers 30
References 30
iii
© 1999, Woodhead Publishing Ltd
iv Contents
2 Fabrication, inspection and durability 32
GEOFFREY PRITCHARD
2.1 Fabrication of reinforced plastics products 32
2.2 Fibre reinforcement formats 33
2.3 Injection processes for thermoplastics
and thermosetting resins 36
2.4 Compression moulding and moulding compounds 37
2.5 Thermoforming and hot stamping 39
2.6 Filament winding 39
2.7 Hand lay-up and spray processes 40
2.8 New fabrication methods for long fibre thermoplastics 41
2.9 Quality control and non-destructive evaluation of
reinforced plastics during manufacture or in service 42
2.10 Property retention as a guide to durability 50
2.11 Moisture 50
2.12 Chemicals 55
2.13 Temperature 58
2.14 Outdoor use 58
2.15 Radiation (other than UV) 60
2.16 Mechanical stress 61
2.17 Joints 63
References 66
3 Durability of reinforced plastics in liquid environments 70
FRANK R JONES
3.1 Introduction 70
3.2 Hygrothermal conditions 71
3.3 Epoxy resins 78
3.4 Anomalous effects 82
3.5 Thermomechanical response of composite
to moisture absorption 88
3.6 Residual strains in laminates 91
3.7 Chemical durability of composite materials 96
3.8 Conclusions 108
References 108
4 Temperature–its effects on the durability
of reinforced plastics 111
JOHN J LIGGAT, GEOFFREY PRITCHARD
AND RICHARD A PETHRICK
4.1 Introduction 111
4.2 Physical mechanisms 115
© 1999, Woodhead Publishing Ltd
Contents v
4.3 Chemical mechanisms 125
References 147
5 Cyclic mechanical loading 151
KARL SCHULTE
5.1 Scope of chapter 151
5.2 Strain criteria 151
5.3 Mechanical properties of fibre reinforced plastics 153
5.4 Fatigue behaviour 158
5.5 Fatigue of continuous fibre reinforced polymers 162
5.6 Effect of heating 170
5.7 Environmental influences 176
5.8 Prediction of fatigue damage development 180
5.9 Conclusions 182
References 182
6 Weathering 186
JOHN LAYTON
6.1 Introduction 186
6.2 Natural weathering 187
6.3 Accelerated weathering 188
6.4 Unsaturated polyester resins 192
6.5 Phenolic resins 210
6.6 Epoxide resins 210
6.7 Other thermosetting polymers 211
6.8 Thermoplastics 212
6.9 Reinforcements 215
References 216
7 Review of the durability of marine laminates 219
TIM J SEARLE AND JOHN SUMMERSCALES
7.1 Introduction 219
7.2 Water absorption 225
7.3 Osmosis and blistering 229
7.4 Mechanical deterioration of FRP laminates
after sea water exposure 235
7.5 Stress corrosion and fatigue in water 242
7.6 Condition of US Navy FRP vessels and components
after service 245
7.7 Marine fouling and biodegradation 246
7.8 Cavitation erosion 248
7.9 Galvanic corrosion 253
© 1999, Woodhead Publishing Ltd
vi Contents
7.10 Concluding remarks 258
References 260
8 Survey of long term durability of fiberglass reinforced
plastics tanks and pipes 267
BEN BOGNER
8.1 Introduction 267
8.2 Composites 267
8.3 Fluid containment vessels – tanks and pipes 268
8.4 Pipe studies 274
8.5 Reinforced thermoplastics pipe 279
8.6 Concluding comments 281
References 281
9 Epoxy vinyl ester and other resins
in chemical process equipment 282
PAUL KELLY
9.1 Introduction 282
9.2 Raw materials 283
9.3 Resins 283
9.4 Glass 287
9.5 Laminate buildup 289
9.6 Postcure 289
9.7 Temperature limitations 290
9.8 Manufacturing processes 292
9.9 Longevity and maintenance of GRP 296
9.10 Use of GRP at Dow Stade 297
9.11 Ducts 300
9.12 Storage tanks and process vessels 302
9.13 Pipes 306
9.14 Gas absorbers (scrubbers) 309
9.15 Pultruded profiles 317
References 321
10 Repairs using fibre reinforced plastics 322
WING KONG CHIU AND RHYS JONES
10.1 Introduction 322
10.2 Repair of composite aircraft structures 323
10.3 Repair of ship structures with fibre reinforced plastics 327
10.4 Repair of concrete structures 329
© 1999, Woodhead Publishing Ltd
Contents vii
10.5 Conclusions 333
References 333
11 Fatigue performance: the role of the interphase 336
NIKHIL VERGHESE AND JOHN J LESKO
11.1 Introduction 336
11.2 Recent work 338
11.3 Conclusions and remarks 346
References 347
12 Computer models for predicting durability 349
SAMIT ROY
12.1 Introduction 349
12.2 Viscoelastic creep in a polymer 350
12.3 Diffusion in a polymer 351
12.4 Physical aging in resins and FRP 352
12.5 Durability models 354
12.6 Model verification examples 359
12.7 Summary and conclusions 366
References 367
© 1999, Woodhead Publishing Ltd
Contents ix
Preface
Primitive reinforced plastics products were known in the 1920s and 1930s,
but the more advanced fibre reinforced materials we know today only
became significant commercially as structural materials in the 1950s, and
even then, the more recent reinforcing fibres such as carbon/graphite,
aramid (e.g. Kevlar®, Twaron®) and polyethylene (e.g. Dyneema®) fibres
were all still completely unknown. The great majority of reinforced plastics
articles we use today have been manufactured since 1975.
Thus, we have a very limited number of case histories of structural
applications with which to prove the durability of fibrous composites
beyond dispute, although the evidence we have is very encouraging. This
promising start is not surprising because, except in a very few special
cases, they resist microbial organisms and are unaffected by electrolytic
corrosion.
As we reach the end of the present millenium, we notice a great expan-
sion of reinforced plastics into new fields such as load bearing parts of
buildings, bridges over highways and various infrastructure pipelines. A
mere 25 years of useful life will not suffice for these applications. In many
cases the target is 60, 75 or even 100 years. This is a longer period than the
entire previous history of reinforced plastics. The contribution that theory
can make to predicting the achievable lifetimes of reinforced plastics is
growing, but it is too early yet to base decisions entirely on conclusions that
are unsupported by any practical or experimental confirmation. Therefore
we have to use an amalgam of medium term laboratory research, case
histories and a knowledge of the theoretical principles of the main degrada-
tion processes.
Major studies are currently being undertaken into composites durability.
One of these programmes, the Composites Durability Study, is being car-
ried out in the USA by the Civil Engineering Research Foundation and the
Society of the Plastics Industry’s Composites Institute Market Develop-
ment Alliance, for the benefit of the design and construction industry and
the civil engineering profession. It is said that particular concerns include
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© 1999, Woodhead Publishing Ltd
xx CProenftaecnets
performance degradation in severe operating environments, fatigue life,
creep, fire resistance, weatherability and maintenance.
The problem with many technical books is that although they contain
valuable information, it is not always made sufficiently accessible to those
who most need it. This is often because of the failure to explain basic
terminology to readers from different backgrounds and specialties. The
editor has therefore made a considerable effort to ensure that at least the
early chapters of this book are readily understandable by people from
discipline areas other than composites science. It has not been possible to
eliminate altogether the chemical and mathematical equations which the
outsider often finds alienating, but they have been reduced to a minimum.
Those who wish that the subject matter had been treated more rigorously –
and no doubt there will be many – will find numerous references at the
end of each chapter, indicating further literature with a more specialized
orientation.
This book is therefore targeted at those concerned for the first time with
using reinforced plastics in building, highway engineering, offshore engi-
neering, civil and chemical engineering, marine and electrical areas. It is an
entry level book for engineers, architects, entrepreneurs, managers, design-
ers, and graduate students who have already completed courses in engi-
neering or science and who now need to be able to converse better with
consultants and specialists in the reinforced plastics world. If research
chemists, resin technologists or plastics process engineers should also find
something of interest, that will be a bonus.
The editor takes the blame for the frequent use of the phrase ‘reinforced
plastics’ rather than the increasingly favoured, up-market term ‘advanced
composites’. He recognizes that glass fibre reinforced composites are cus-
tomarily excluded from the advanced composite category in aerospace
circles, chiefly because of their relatively low modulus. But when their
technical qualities as a whole are considered, including their durability in
the broad sense, and when their cost effectiveness is also taken into account,
reinforced plastics scarcely need rebadging. They are among the best mate-
rials in the world in the context of durability.
© 1999, Woodhead Publishing Ltd
List of contributors
Chapter 1 An introduction to plastics for non-specialists
Geoffrey Pritchard, Emeritus Professor, Kingston University, Surrey, UK
Consultant, York House, Moseley Road, Hallow, Worcester WR2 6NH,
England
Chapter 2 Fabrication, inspection and durability
Geoffrey Pritchard, Emeritus Professor, Kingston University, Surrey, UK
Consultant, York House, Moseley Road, Hallow, Worcester WR2 6NH,
England
Chapter 3 Durability of reinforced plastics in liquid environments
Frank Jones, Department of Engineering Materials, Sir Robert Hadfield
Building, Sheffield University, Mappin Street, S1 3JD, England
Chapter 4 Temperature–its effects on the durability of
reinforced plastics
John J Liggatt* Geoffrey Pritchard** and Richard A Pethrick*,
*Department of Pure and Applied Chemistry, Strathclyde University, 295
Cathedral Street, Glasgow, G1 1XL, Scotland **See Chapter 1
Chapter 5 Cyclic mechanical loading
Karl Schulte, Technical University of Hamburg-Harburg, Polymer and
Composites Section, Denickestraße 15, D-21071 Hamburg, Germany
Chapter 6 Weathering
John Layton, The Ash, 23 Newtown Road, Raunds, Wellingborough,
Northants NN9 6LX, England
Chapter 7 Review of the durability of marine laminates
Tim J Searle and John Summerscales, Advanced Composites
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© 1999, Woodhead Publishing Ltd