The Application of Textiles in Rubber

The Application of
Textiles in Rubber
David B. Wootton
Rapra Technology Limited
Shawbury, Shrewsbury, Shropshire SY4 4NR, United Kingdom
Telephone: +44 (0)1939 250383 Fax: +44 (0)1939 251118

Textiles Title Page etc. 31/7/01, 11:34 am1
First Published in 2001 by
Rapra Technology Limited
Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK
©2001, Rapra Technology Limited
The right of David Wootton to be recognised as the author of this work
has been asserted by him in accordance with sections 77 and 78 of the
Copyright, Designs and Patents Act 1998.
All rights reserved. Except as permitted under current legislation no part
of this publication may be photocopied, reproduced or distributed in any
form or by any means or stored in a database or retrieval system, without
the prior permission from the copyright holder.
A catalogue record for this book is available from the British Library.
Typeset by Rapra Technology Limited
Printed and bound by Polestar Scientifica, Exeter, UK
ISBN: 1-85957-277-4
Textiles Title Page etc. 31/7/01, 11:34 am2
1
Preface
Rubber and textiles have been used together, each working with the other to give improved
performance in a very wide range of applications, since the earliest days of the rubber
industry in the more developed areas of the world.
For many years, rubber companies of reasonable size, using textile reinforcement, would
employ their own textile technologist working alongside the rubber technologists. Over

the last third of the twentieth century, faced with global competition and the need to
control and reduce total costs, this luxury has largely disappeared apart from the largest
companies (particularly the tyre companies). Most organisations now rely on their textile
suppliers to provide technical knowledge and expertise. As a result, the textile component
for many applications is now considered in much the same way as the other raw materials,
that is as an existing product, which only requires introducing into the manufacturing
process, without any special knowledge or understanding, and is supplied against an
agreed specification, which was probably drawn up by the textile manufacturer anyway.
The aim of this current work is to provide a general background to and a basic awareness
of the technology of textiles, to give the rubber technologists an improved understanding
of the uses, processes and potential problems associated with the use of textiles in
rubber products.
The most important and by far the largest use of textiles in rubber is in the tyre industry.
This area is not covered in this book, as the field covers such a wide range that it
would require a volume on its own. In addition, most tyre companies have their own
textile specialists and have developed their own technologies, shrouded in the mysteries
of ‘trade secrets’.
The first part of this volume covers the basic technology of the textile fibres and the
processes used in preparing these ‘ready made’ raw materials for rubber reinforcement.
Particular attention is given to various aspects of adhesion, adhesive treatments, the
effects of rubber compounding and processing and the assessment of adhesion.
In the second half of the book, the major applications of textiles in rubber are described;
the aim here is to illustrate the way that the textile component can be designed and
engineered to obtain the optimum reinforcement and performance for each particular
application. These descriptions are not intended to be definitive technological theses on
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The Application of Textiles in Rubber
2
the different applications. However, they indicate the balance of properties required and
how these can be obtained in the textile component by selection of the fibres used, the

physical form of the reinforcement and the processes and treatments required.
Over the years since the earliest days of Hancock, Goodyear and Macintosh, there have
been many significant breakthroughs and developments, in both textile and rubber
technologies. Originally, there were only cotton and natural rubber, now there are wide
ranges of both synthetic rubbers and of man-made fibres. There have been great advances
in the technologies of vulcanisation and of adhesive treatments; the service requirements
have become more stringent and operating conditions more severe, but these issues have
largely been overcome by improving expertise and knowledge.
However, over the last two decades, there has been relatively little advance in the general
technologies of textiles or rubbers; most developments have been targeted either at cost
containment or at very high performance (and consequently very high cost) applications,
particularly aerospace, with only minor spin-offs for everyday terrestrial applications.
Where possible, the general content of the chapters has been kept as simple and practical
as possible but where there is a more theoretical discussion of certain aspects, these have
been separated into appendices, at the end of the relevant chapters. The general discussion
can thus be read without the intrusion of the more theoretical aspects, but these are still
available, if desired. A glossary of terms has been included to assist the reader.
I wish to thank all those at Rapra who have encouraged and assisted me in the preparation
and publication of this book, in particular Clair Griffiths and Steve Barnfield, for their
work in preparing the manuscript for publication.
David B. Wootton
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i
Contents
Preface 1
1 Historical Background 3
Introduction 3
1.1 The Textile Industry 3
1.2 The Rubber Industry 6
1.3 Textile and Rubber Composites 10

References 13
2 Production and Properties of Textile Yarns 15
Introduction 15
2.1 Production Methods for Textile Fibres 15
2.1.1 Cotton 15
2.1.2 Rayon 21
2.1.3 Nylon 24
2.1.4 Polyester 26
2.1.5 Aramid 28
2.2 General Characteristics of Textile Fibres 30
2.2.1 Cotton 30
2.2.2 Rayon 32
2.2.3 Nylon 33
2.2.4 Polyester 34
2.2.5 Aramid 35
2.3 General Physical Properties of Textile Fibres 36
2.3.1 Cotton 36
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ii
2.3.2 Rayon 38
2.3.3 Nylon 39
2.3.4 Polyester 40
2.3.5 Aramid 40
References 40
3 Yarn and Cord Processes 41
Introduction 41
3.1 Yarn Preparation Methods 41
3.1.1 Twisting 42
3.1.2 Texturing 49

3.2 Warp Preparation 52
3.2.1 Direct Warping 53
3.2.2 Sectional Warping 54
3.3 Sizing 57
4 Fabric Formation and Design of Fabrics 59
Introduction 59
4.1 Fabric Formation 59
4.1.1 Weaving 59
4.1.2 Knitting 64
4.1.3 Non-Woven Fabrics 68
4.2 The Design of Woven Fabrics 70
4.2.1 Physical Property Requirements 70
4.2.2 Selection of Fibre Type 71
4.2.3 Selection of Fabric Construction 74
5 Heat-Setting and Adhesive Treatments 83
Introduction 83
5.1 Heat-Setting Machinery 83
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iii
Contents
5.2 Heat-Setting 90
5.3 Adhesive Treatment 94
5.3.1 Cotton 94
5.3.2 Rayon 95
5.3.3 Nylon 98
5.3.4 Polyester 99
5.3.5 Aramid 101
5.4 The In Situ Bonding System 102
5.5 Mechanisms of Adhesion 103
5.6 Environmental Factors Affecting Adhesion 107

Appendix V Interfacial Compatibility 109
References 112
6 Basic Rubber Compounding and Composite Assembly 113
6.1 Compounding 113
6.1.1 Polymers 113
6.1.2 Curing Systems 114
6.1.3 Fillers 116
6.1.4 Antidegradants 117
6.1.5 Other Compounding Ingredients 117
6.2 Processing 117
6.3 Composite Assembly 118
6.3.1 Calendering 118
6.3.2 Coating 124
References 127
7 Assessment of Adhesion 129
Introduction 129
7.1 Cord Tests 129
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The Application of Textiles in Rubber
iv
7.1.1 Pull-Out Tests 130
7.1.2 Cord Peel Test 130
7.2 Fabric Test Methods 133
7.3 Testing and Interpretation of Results 138
7.4 Adhesion Tests for Lightweight Fabrics and Coatings 140
7.5 Peeling by Dead-Weight Loading 142
7.6 Direct Tension Testing of Adhesion 143
7.7 Adhesion and Fatigue Testing 145
7.8 Assessment of Penetration into the Textile Structure 146
Appendix VII: The Physics of Peeling 148

References 153
8 Conveyor Belting 155
Introduction 155
8.1 Belt Construction and Operation 160
8.1.1 Carcase 160
8.1.2 Insulation 161
8.1.3 Covers 162
8.2 Belt Design 165
8.2.1 Plied Belting 167
8.2.2 Single-Ply and Solid-Woven Belting 171
8.2.3 Steel Cord Belting 172
8.3 Belting Manufacture 172
8.3.1 Belt Building 173
8.3.2 Pressing and Curing 173
8.3.3 Belt Joining 178
8.4 Belt Testing 182
8.4.1 Tensile Strength and Elongation 182
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Contents
8.4.2 Gauge 183
8.4.3 Adhesion 183
8.4.4 Abrasion 183
8.4.5 Troughability 183
8.4.6 Fire Resistance 183
References 184
9 Hose 187
Introduction 187
9.1 Hose Manufacture 188
9.1.1 Braiding 188

9.1.2 Spiralling 190
9.1.3 Wrapped Hose 191
9.1.4 Knitted Hose 192
9.1.5 Oil Suction and Discharge Hose 192
9.1.6 Circular Woven Hose 193
Appendix IX 195
i. Neutral Angle 195
ii. Bursting Pressure 196
10 Power Transmission Belts 199
Introduction 199
10.1 Main Types of Power Transmission Belts 200
10.1.1 V-Belts 200
10.1.2 Timing Belts 203
10.1.3 Flat Belting 203
10.1.4 Cut-Length Belting 205
10.2 Manufacture of Power Transmission Belting 206
10.2.1 Manufacture of V-Belts 206
10.2.2 Manufacture of Timing Belts 209
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vi
10.3 Effect of the Textile Reinforcement on Belt Performance 209
References 212
11 Applications of Coated Fabrics 213
Introduction 213
11.1 Inflatable Structures 214
11.1.1 Inflatable Boats 214
11.1.2 Oil Booms 218
11.1.3 Inflatable Dams 219
11.1.4 Inflatable Buildings 220

11.1.5 Dunnage Bags 221
11.2 Non-Inflated Structures 222
11.2.1 Reservoir and Pond Liners 222
11.2.2 Flexible Storage Tanks 223
11.2.3 Supported Building Structures 223
References 224
12 Miscellaneous Applications of Textiles in Rubber 225
Introduction 225
12.1 Hovercraft Skirts 225
12.1.1 Types of Skirt 226
12.2 Air Brake Chamber Diaphragms 229
12.3 Snowmobile Tracks 230
References 231
Abbreviations and Acronyms 233
Glossary 234
Index 239
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3
1
Historical Background
Introduction
The modern world relies to a great extent, on textile/polymer composites, the majority
of which are rubber/textile compositions. In fact, it is difficult to imagine the functioning
of modern everyday life without the use of such products. It is only necessary to consider
the need for transport systems (relying on textile/rubber tyres), materials handling systems
(relying on textile/rubber conveyor belting) and mechanical drive systems (using rubber/
textile drive belts) to see the important role played by such materials.
Whereas textiles have been produced and used for many thousands of years, it was only
some 500 years ago that rubber was introduced to Europe and really only in the last two
hundred years that textiles and rubber have been used together in this region. Since then,

however, there has been very great development in the design and use of these materials.
Within the last 75 years, there has been a great move away from natural materials (natural
rubber and cotton) to synthetic products, both as regards the fibres and the polymers
used, resulting in a very wide diversity of engineered composites, to meet many and
varied performance requirements.
1.1 The Textile Industry
The origin of the textile industry is lost in the past. Fine cotton fabrics have been found
in India, dating from some 6-7000 years ago, and fine and delicate linen fabrics have
been found from two to three thousand years ago, at the height of the Egyptian
civilisations. More recent archaeological excavations, among some of Europe’s oldest
Stone Age sites, have found imprints of textile structures, dating back some 25,000 years,
but in the humid conditions obtaining in these more northerly areas, all traces of the
actual textiles have long disappeared, unlike those from the dry areas of India and Egypt.
Until more recent times, the spinning of the yarns and the weaving of the fabrics were
generally undertaken by small groups of people, working together – often as a family
group. However, during the Roman occupation of England, the Romans established a
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The Application of Textiles in Rubber
‘factory’ at Winchester, for the production, on a larger scale, of warm woollen blankets,
to help reduce the impact of the British weather on the soldiers from southern Europe.
In the family context, it generally fell to the female side to undertake the spinning,
while the weaving was the domain of the men. Spinning was originally done using the
distaff to hold the unspun fibres, which were then teased out using the fingers and
twisted into the final yarn on the spindle. In the 1530s, in Brunswick, a ‘spinning
wheel’ was invented, with the wheel driven by a foot pedal, giving better control and
uniformity to the yarns produced. Often, great skill was developed, as shown by the
records of a woman in Norwich, who spun one pound of combed wool into a single
yarn measuring 168,000 yards, and from the same weight of cotton, spun a yarn of
203,000 yards. In today’s measures this is equivalent to a cotton count of 240, or

approximately 25 decitex. Cotton count is the number of hanks of 840 yards (768
metres) giving a total weight of 1 lb (453.6 g). A Tex is a measurement of the linear
density of a yarn or cord, being the weight in grams of a 1,000 m length; a decitex is
the weight in grams of a 10,000 m length.
By the eighteenth century, small co-operatives were being formed for the production of
textiles, but it was really only with the mechanisation of spinning and weaving during
the Industrial Revolution, that mass production started.
Up to this time, both spinning and weaving were essentially hand operations. Hand-
looms were operated by one person, passing the weft (the transverse threads) by hand,
and performing all the other stages of weaving manually (see Chapter 4 for a description
of the weaving process). In 1733, John Kay invented the ‘flying shuttle’, which enabled a
much faster method for inserting the weft into the fabric at the loom and greatly increased
the productivity of the weavers.
Until the advent of the flying shuttle, the limiting factor in the production chain for
fabrics was the output of the individual weaver, but this now changed and with the more
rapid use of the yarns, their production became the limiting factor in the total process. In
1764, this was partly resolved by the invention, by James Hargreaves, of the ‘Spinning
Jenny’, which was developed further by Sir Richard Arkwright, with his water spinning
frame, in 1769, and then in 1779, by Samuel Crompton, with his ‘spinning mule’.
Alongside these developments in spinning, similar changes were taking place in the weaving
field, with the invention of the power loom by Edmund Cartwright, in 1785.
With this increase in mechanisation of the whole industry, it was logical to bring the
production together, rather than keeping it widely spread throughout the homes of the
producers. Accordingly, factories were established. The first of such was in Doncaster in
Chapter 1 31/7/01, 11:34 am4
5
Historical Background
1787, with many power looms powered by one large steam engine. Unfortunately, this
was not a financial success, and the mill only operated for about 3 or 4 years.
Meanwhile, other mills were being established, in Glasgow, Dumbarton and Manchester.

A large mill was erected at Knott Mill, Manchester, although this burnt down after only
about 18 months. The first really successful mill was opened in Glasgow in 1801.
However, this industrialisation was not to everyone’s liking; many individuals were losing
their livelihoods to the mass production starting to come from the increasing number of
mills. This led to a backlash from the general public, resulting in the Luddite Riots in
1811-12, when bands of masked people under the leadership of ‘King Ludd’ attacked
the new factories, smashing all the machinery therein. It was only after very harsh
suppression, resulting in the hanging or deportation of convicted Luddites in 1813, that
this destruction was virtually stopped. However, there were still some outbreaks of similar
actions in 1816, during the depression following the end of the British war with France,
and this intermittent action only finally stopped when general prosperity increased again
in the 1820s.
Following this, the textile industry expanded considerably, particularly in the areas where
the raw materials were readily available. For example, the woollen mills in East Anglia,
where there was good grazing for the sheep, and in West Yorkshire and Eastern Lancashire,
where either coal was available for powering the new steam engines, or where fast flowing
streams existed to provide the energy source for water-powered mills (particularly in
central Lancashire). The main woollen textile production developed in Yorkshire, as it
was easier and cheaper to transport the raw wool there, than to carry the large quantities
of coal required to power the mills to the wool growing areas. In Lancashire, with the
ports of Liverpool and Manchester close by for the importation of cotton from America,
the cotton industry grew and flourished. However, in the 1860s, due to the American
Civil War, the supply of cotton from America dried up and caused great hardship among
the cotton towns of south and east Lancashire.
On account of this, and with the great strides being made in chemistry, research was
begun to try to find ways of making artificial yarns and fibres. The first successful artificial
yarn was the Chardonnet ‘artificial silk’, a cellulosic fibre regenerated from spun
nitrocellulose. Further developments lead to the cuprammonium process and then to the
viscose process for the production of another cellulosic, rayon. This latter viscose was
fully commercialised by Courtaulds in 1904, although it was not widely used in rubber

reinforcement until the 1920s, with the development of the balloon tyre.
Research continued into fibre-forming polymers, but the next new fully synthetic yarn
was not discovered until the 1930s, when Wallace Hume Carothers, working for DuPont,
discovered and developed nylon. This was first commercialised in 1938 and was widely
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The Application of Textiles in Rubber
developed during the 1940s to become one of the major yarn types used. Continuing
research led to the discovery of polyester in 1941, and over the ensuing decades, polyolefin
fibres (although because of their low melting/softening temperatures, these are not used
as reinforcing fibres in rubbers) and aramids.
As the chemical industry greatly increased the types of yarns available for textile applications,
so the machinery used in the industry was being developed. Whereas the basic principles of
spinning and weaving have not significantly changed over the millennia, the speed and
efficiency of the equipment used for this has been vastly been improved. In weaving, the
major changes have been related to the method of weft insertion; the conventional shuttle
has been replaced by rapiers, air and water jets, giving far higher speeds of weft insertion.
Other methods of fabric formation have similarly been developed, such as the high speed
knitting machines and methods for producing fabric webs known as ‘non-wovens’.
1.2 The Rubber Industry
Whereas the basic properties of rubber, or caoutchouc as it was then called, were known
to the natives of South America, the first reports of it in Western Europe were given by
Christopher Columbus in 1492 and then more detailed accounts were given by Gonzalo
Fernandez d’Ovideo y Valdas, in his Universal History of the Indies [1], in which he
describes the game of ‘batos’ as like a game of balls, ‘But played differently and the balls
are of other material than those used by Christians’.
Later, Juan de Torquemada [2] describes the use of elastic balls from the sap of the Ulaqahil
tree, which juice was also used for painting on linen fabrics, to protect the wearer from the
rain; water did not penetrate but the sun’s rays ‘had an evil effect on the coating’.
In 1731 the French government sent the geographer Charles Marie de La Condamine to

South America on a geographical expedition. In 1736 he sent back to France a report to
the Paris Academy, together with several rolls of crude rubber and a description of the
products fabricated from it by the people of the Amazon Valley. In this report, he stated
that the resin (caoutchouc) from the Hévé tree was used, in the province of Quito, to
cover linen material, which was then used like oilcloth. Fresnau, an engineer, later reported
more fully on this use and suggested other possible applications, such as waterproof
sails, divers’ hoses and bags for keeping food, etc. He also commented, however, that
such goods could only be produced in those areas where the trees grew, as the juice dries
very quickly and looses its fluidity.
During the 18th century, small quantities of rubber were sent to Europe and found
some limited applications. For example, in 1770, Joseph Priestly drew attention to the
Chapter 1 31/7/01, 11:34 am6
7
Historical Background
fact that small pieces of caoutchouc could be used for rubbing out pencil marks. Since
1775, small pieces have been available in stationers’ shops for this purpose, called
‘India Rubbers’, by which name this material has been known ever since, in English
speaking countries.
More important uses were found for this material, however, and in spite of the comments
by Fresnau some fifty years earlier, one of these earlier applications was for coating
fabrics, to render it waterproof, where the ‘loss of fluidity’ was overcome by solution of
the rubber in turpentine; this was the subject of one of the earliest patents for the use of
rubber, granted to Samuel Peal in 1796 [3].
All the rubber available at this time, was, of course, wild rubber, gathered from the rain
forests of Central and Southern America. This rubber was mainly in the form of ‘bottles’,
from the wooden formers on which the latex was dried and smoked, or roughly spherical
‘negro-heads’, consisting of many small lumps of dried rubber stuck together. Originally,
products could only be made by cutting the rubber from these rough blocks or by dissolving
it in a suitable solvent, such as turpentine, and spreading it onto fabric or some similar
substrate. However, in 1820 Thomas Hancock [4] noted that on heating, rubber became

soft and plastic; also on kneading it in a dough mixer, without solvent, it would become
soft and more easily worked. Accordingly, he designed a machine to enable the rough
lumps and offcuts to be worked together into a soft mass. This could then be pressed
into a heated mould to give a regular and uniform block of rubber, which was much
easier to handle and work with.
From these prepared blocks, sheets of various sizes and thicknesses were cut for many
applications; one of these was for use as pads between the railway lines and the sleepers,
to reduce vibration. More complicated mouldings were also made and textiles were plied
up with thinly cut sheets or coated for solution. One of the best known names in this
latter context was that of Charles Macintosh, who patented many applications e.g., [5]
for proofing fabrics. In 1823 he established a factory in Glasgow and then later moved
to Manchester, building his plant in Cambridge Street, which site is still used for rubber
manufacture and coating.
Many other uses were found for rubber; by 1825, hoses were being built on mandrels,
with reinforcement of two or more plies of fabric, and with wire spiralling for suction
hose. In 1826, rubber insulated cables were use by Baron Schilling, for detonating
explosives in mines; drive belts made from layers of fabric bonded together with rubber
were used by Isambard Kingdom Brunel to drive the machines used in sinking the Thames
Tunnel. Inflatables of many kinds were produced from coated fabrics. Hancock [4] in
collaboration with Macintosh produced air beds and pillows, such as were used by King
George IV on his deathbed. Large floating pontoons, for floating bridges, were produced
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The Application of Textiles in Rubber
and tested to the satisfaction of the Duke of Wellington. Throughout this period,
waterproof cloaks were worn by the passengers on the stagecoaches.
All these products, however, had severe service limitations. They would soften and become
sticky in warm weather or would harden and become brittle in the cold. Much work was
done to overcome these problems and, independently, Charles Goodyear in the USA and
Hancock in England, discovered the effects of sulphur in vulcanising rubber.

This discovery of vulcanisation gave a great boost to the rubber industry. The properties,
and especially the service life, of all the rubber articles were vastly improved and new
outlets and applications were continually being found. In 1845 a Scotsman, Robert
William Thomson, invented the pneumatic tyre [6]. However, this was designed for use
with steam road engines, which were not in favour with the Government of the time, it
was not developed further until the advent of the bicycle and motor car, when it was re-
invented by John Boyd Dunlop [7, 8]. Between these times, the solid tyre sufficed and
indeed was given royal approval, in 1846, by Queen Victoria.
This was all accomplished with supplies of wild rubber. In 1836, the consumption of
rubber in Western Europe was some 65 tonnes per annum. As the industry grew, so did
consumption, reaching 2,250 tonnes in 1853 and 15,600 tonnes by 1887. At this time,
rubber from sources other than the Hevea brasiliensis, such as Ficus elasticus and the
shrub Guyale, was being imported into Europe.
By this time it was obvious that the industry could not survive on wild rubber only. In
1876 the British explorer Sir Henry Wickham collected about 70,000 seeds of Hevea
brasiliensis, and, despite a rigid embargo, smuggled them out of Brazil. The seeds were
successfully germinated in the hothouses of the Royal Botanical Gardens at Kew in
London, and were used to establish plantations first in Ceylon in 1888 and then in other
tropical regions of the eastern hemisphere. During the next decade, plantations were
more widely established in Ceylon and Malaya but significant imports of plantation
rubber into Europe were not made until 1901, by which time the consumption of wild
rubber had increased to 27,000 tonnes per year. The plantations soon proved their worth,
and by 1936 over 1,000,000 tonnes of rubber were being produced annually, generally
within the geographical range of around 1,100 km either side of the Equator.
While the production of rubber and its uses were expanding, so the technology was
developing. It was quite soon found that the addition of certain metal oxides assisted in
vulcanisation. In 1880, while trying to use ammonia to produce sponge rubber, T. Rowley
found that this vastly increased the rate of vulcanisation [9]. Work in this area continued
and in 1906, George Oenslager discovered two much more readily applicable materials,
to accelerate vulcanisation, aniline and thiocarbanilide.

Chapter 1 31/7/01, 11:34 am8
9
Historical Background
Research continued and, in 1912, the use of piperidine was patented [10] to be followed
by the thiuram disulphides, which were also shown, in 1919, to be able to cure rubber
without the addition of sulphur. Then, in 1923, mercaptobenzthiazole, the basis of many
modern accelerators, was discovered.
Meanwhile, chemists were also studying the composition of the rubber itself. It had been
shown to possess the same empirical formula as isoprene and, in 1860, Charles Greville
Williams established that it was in fact a linear polymer of isoprene. By the 1890s, it was
shown that isoprene could change, on standing, into a rubbery solid, albeit with rather
different properties from those of natural rubber itself. This reaction is now known as
polymerisation. The generally poor properties of the spontaneously polymerised isoprene
arise from the lack of steric regularity, a problem only overcome some 60 years later.
The search for a synthetic rubber continued and was spurred on, in the early 20th century,
by the increasing price of natural rubber and then by the First World War. Various dienes
were investigated for their potential for polymerisation. The most promising of these
was dimethyl butadiene and, during the period from 1915 to 1918, Germany was able
to produce some 2,500 tonnes of ‘methyl rubber’ using the sodium polymerisation route
still in use today. These early synthetic rubbers left much to be desired in their overall
properties; the use of carbon black for reinforcement was not known in Germany and
the technology of vulcanisation and the use of protective anti-oxidants were in the very
early stages of development. On account of these shortcomings, research into synthetic
rubbers was largely allowed to drop.
However, Father Julius Nieuwland, of the University of Notre Dame but working for the
DuPont Company, discovered polychloroprene in 1930, which was first marketed under
the trade name of ‘Duprene’ but latterly called ‘Neoprene’. This group of synthetic rubbers,
as they became available during the 1930s, largely changed the attitude of the rubber
industry towards synthetics. The general properties of these rubbers were quite good but
the ageing and properties, such as the resistance to oils and solvents, were very much

better than with the natural rubber.
This gave a further boost to research and in 1935, the chemists of IG Farbenindustrie in
Germany, developed the ‘Buna’ rubbers, the name being derived from butadiene, one of
the common monomers, and Na, the chemical symbol for sodium, used as the catalyst.
The major types developed were the standard Buna rubbers, copolymers of butadiene
with styrene, and the Buna N types, with acrylonitrile as one of the monomers.
A further great impetus was given to research by the advent of the Second World War,
when supplies of natural rubber from the Far East were completely cut off and the US
Government launched a crash programme to develop a viable alternative. This quickly
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The Application of Textiles in Rubber
led to the development of the GR-S rubbers (styrene-butadiene rubber, now known as
SBR) and the rapid establishment of large scale production of these polymers.
In the 1950s work by Natta and Ziegler on catalysation processes led to the discovery of
novel methods for obtaining highly stereo-regular polymers, including the high cis-
polyisoprene, ‘synthetic natural rubber’, which had been sought since the composition
of natural rubber had been established a century before.
Today, there are many synthetic polymers available, ranging from the general purpose
hydrocarbons with properties largely similar to those of natural rubber; to the special
purpose types with excellent resistance to ageing, oils and solvents; to highly sophisticated
(albeit very expensive) polymers with outstanding resistance to the most hostile of
environments, as found in aerospace, marine and oil exploration applications.
1.3 Textile and Rubber Composites
From the very first references to rubber in South America, its use with textiles has been
noted. This is not very surprising, as from the earliest times, one of the major drawbacks
of textiles was their performance under wet conditions; in the dry, they gave excellent
protection and warmth, but in the wet they soon became saturated and, if anything,
made things seem worse. Many treatments were tried over the years to overcome this
deficiency, using coatings of tars, resins and waxes; the most successful of these was the

treatment with natural drying oils, to give the waterproof oilcloths. The main disadvantage
of these was the stiffness and brittleness imparted to the fabrics.
With rubber, many of these disadvantages virtually disappeared, giving a soft, flexible
and waterproof material (at least at normal ambient temperatures). This is essentially
the stage that Macintosh and Hancock started. Macintosh improved the coating
process, with his single and double textures (this latter consisting of two layers of
fabric adhered together with a thin film of rubber) but it was largely Hancock, with
his imaginative approach, who developed a wide range of applications. Apart from
waterproof coats and cloaks for travellers, he produced waterproof bags. Some were
used by Captain Parry on his expedition to the North Pole, who, in his report on the
voyage, refers to saving a bag of cocoa, which fell off an ice-floe during unloading,
but ‘…the bag being made of Macintosh’s waterproof canvas, did not suffer the
slightest injury I know of no material which, with an equal weight, is equally
durable and waterproof’ [11].
Hancock realised the advantages of combining the strength of the textile with the other
properties of rubber. He produced hose by wrapping successive layers of rubber and
Chapter 1 31/7/01, 11:34 am10
11
Historical Background
fabric onto a mandrel. In spite of fierce opposition from the traditional leather hose
makers, he persuaded Barclays Brewery, in London, to completely re-equip with rubber
hose. This quickly proved its worth as, being seamless, leakage, which had always been
a problem with the stitched leather hose, was reduced to negligible levels.
In the same way that bags could be made waterproof, so also could they be made airtight
and a great many applications for inflatable articles were found, covering air cushions
and pillows, air beds and inflatable boats. A development from these, using inflatable
bags, connected with rubber/fabric air hose, was used for lifting sunken ships. The concept
worked well, but in the end, the project failed because of difficulties in attaching the
bags to the object to be lifted.
In the early days, many of these applications foundered simply because of the poor service

life of the raw rubber. Being unvulcanised, the rubber was susceptible to changes in
temperature but the major problem arose from the poor ageing characteristics. As all
these applications relied on only thin layers of rubber, they were very susceptible to
oxidation and the service life was accordingly very short. It is only over the last few
decades, with the development of effective anti-ageing products, that this has satisfactorily
been overcome and many of Hancock’s inventions have been ‘rediscovered’ and proved
to be sound concepts.
Not all the early products were doomed to failure, however. One of the early successes
was in the field of textile machinery. One of the processes in the spinning of cotton is
carding (for more detail of this, see Chapter 2). The carding engine is equipped with
rollers to which are attached a multitude of fine steel wires; originally these wires were
fixed by means of a leather backing, but the variability of the natural product led to
considerable problems in achieving uniformity when these wired leather strips were wound
onto the steel rollers. Hancock solved this problem by producing a backing of textile
laminated with rubber: this enabled a very uniform ‘card clothing’ to be provided, with
significant advantages in consistency and life of the clothing. The advantages of this
material were rapidly recognised and within a few years, the textile/rubber backed clothing
had completely replaced the original leather version on the cotton cards, and in fact is
still used today.
The earlier products were, with the exception of hose, flat composites. The next great
development, however, was the pneumatic tyre. The tyre, developed by Dunlop, was
originally based on a tube strapped to the wheel by means of rubberised fabric, but soon,
the inner tube with a separate outer tyre was evolved. The outer tyre was made from
layers of square woven cotton canvas and rubber, with wire beads to hold it in place on
the rim of the wheel. By 1915, however, the canvas was replaced by cord fabrics. These
gave improved properties and performance to the tyres, but the limiting properties were
Chapter 1 31/7/01, 11:34 am11
12
The Application of Textiles in Rubber
still those of the rubber. At this time, carbon black was starting to be used: this effectively

doubled the life of the tyres, which now lasted up to 4,000 miles. Further improvements
in tyre life were achieved by the introduction of the balloon tyre in 1923: this used a
much larger cross-section tyre, operating at considerably lower pressure (200-300 kPa)
than the earlier narrow section tyres, which required pressures of up to 700 kPa.
These improvements in tyre performance now threw the restrictions on performance back
to the textile component. The answer to this was to employ the relatively new artificial
fibre, rayon, for the reinforcing plies of fabric. But this introduced another problem.
This was the first major use of fibres other than cotton. Up to now there had been no
problem in adhering the rubber to the textile inserts: the techniques of spreading or frictioning
had resulted in good mechanical adhesion, due to the embedding of the fibre ends of the
staple yarns into the rubber. With the continuous filament artificial fibre, there were no
fibre ends to embed. The search to find some system to give adequate adhesion led to the
first adhesive dips. These were originally based on natural latex and casein, but the casein
component was soon replaced with a resorcinol/formaldehyde resin.
When natural rubber had to be replaced with synthetic, this, of course, applied to the
adhesive systems too. The SBR latex behaved similarly to natural and gave adequate
adhesion to rayon, albeit with some loss of building tack. When nylon was introduced, it
was found that these resorcinol/formaldehyde/latex (RFL) dips did not give satisfactory
adhesion. Research led to the development of a terpolymer latex, containing vinyl pyridine
as the third monomer, which gave significantly improved adhesion with nylon and rayon.
With the introduction of polyester, further adhesion problems arose: the standard RFL
systems did not work. The first systems found to give good adhesion to polyester were
based on very active isocyanates from solvent solution, either on their own, to be
subsequently treated with RFL, or in a rubber cement, in which case, no further treatment
was required. Solvent systems not being popular, much effort was devoted to the search
for a satisfactory aqueous based process and this was finally achieved. Then, several
years later, a similar exercise had to be undertaken to find a system suitable for use with
the newly introduced aramid fibres.
Similarly, with each new synthetic polymer introduced, special adhesive systems have
had to be developed in order to obtain the optimum performance from the resultant

textile/rubber composite.
Thus, over the years, the two technologies, those of rubber and of textiles, have developed
side by side. Today, composites are available which satisfy the stringent performance
requirements met under such diverse and hostile environments as those of outer space or
the depths of the sea and at extremes of temperature.
Chapter 1 31/7/01, 11:34 am12
13
Historical Background
References
1. Gonzalo Fernandez d’Ovideo y Valdas, Universal History of the Indies, Volume
V, Madrid, 1536, Chapter 2, 165.
2. Juan de Torquemada, Monarquia Indiana, Madrid, 1615.
3. S. Peal, inventor; GB Patent 1,801, 1796.
4. T. Hancock, The Origin and Progress of the Caoutchouc or India Rubber
Manufacture in England, Longmans and Roberts, London, 1857.
5. C. Macintosh, inventor; BP Patent, 4,804, 1823.
6. R.W. Thomson, inventor; GB Patent 10,990, 1845.
7. J.B. Dunlop, inventor; GB Patent 10,607, 1888.
8. J.B. Dunlop, inventor; GB Patent 4,116, 1889.
9. J. Rowley, inventor; GB Patent 787, 1880.
10. F. Hoffman and K. Gottlob, inventors; Bayer Co., assignee; DT 226,619, 1912.
11. Capt. W.E. Parry, Narrative of an Attempt to Reach the North Pole in Boats,
attached to HMS HECLA, in 1827, London, 1828.
Chapter 1 31/7/01, 11:34 am13
15
2
Production and Properties of Textile Yarns
Introduction
There are five main types of fibres used in the production of reinforcements for rubbers.
Cotton, one of the original reinforcing fibre types, is still in use in many applications, but

is steadily being replaced by man-made fibres. It is worth mentioning there is a difference
between the USA and Europe concerning the term ‘synthetic’. In the USA the term is taken
to mean any fibre which is produced by man, and so rayon is classified as a synthetic yarn.
In Europe, however, the term synthetic is used only when referring to fibres in which the
fibre-forming polymer is not of natural origin. Thus in Europe, rayon, based on naturally
occurring cellulose, is classified as ‘man-made’ or ‘artificial’ but is not considered to be a
‘synthetic’ yarn. Rayon, the first of the successful artificial fibres, is chemically very similar
to cotton, but the various processes by which the yarn is produced introduce certain
differences in properties between the two. The nylons (both nylon 6.6 and nylon 6) were
the first of the truly synthetic fibres to be adopted for use by the rubber industry, and offer
certain advantages over the cellulosic fibres. Polyester, with strength similar to nylon, has
a higher modulus, which renders it more suitable for certain applications. The aramids,
with considerably higher strength and modulus, are the latest reinforcing yarns to be
introduced. The latter are still somewhat limited in their application due mainly to their
relatively high cost, although on a strength/cost basis, they are comparable with steel wire.
Although not strictly textile fibres, glass and steel have found many applications as
reinforcements in elastomers. Their general physical properties are briefly compared with
the true textiles, in order to cover the complete range of materials in use at the present time.
2.1 Production Methods for Textile Fibres
2.1.1 Cotton
Cotton is a natural fibre, consisting of the seed hairs of a range of plant species in the
Mallow family (Genus Gossypium). The plants are grown, mainly as an annual crop, in
many countries around the world between latitudes 40°N and 40°S.
Chapter 2 31/7/01, 11:34 am15
16
The Application of Textiles in Rubber
The seed is usually sown in the spring and by early summer the plants are in flower:
within three days, the flowers fall, leaving the small seed-pod or boll. The boll, containing
the seeds with the cotton fibres attached, grows and in about three months, bursts. At
this stage, the cotton fibres are wet and tightly crushed together, but they rapidly dry out

and form a fluffy ball, ready for picking. This was originally all done by hand, but
machinery is now available to do this work. Average production these days is something
in excess of 600 kg/ha.
On picking, the cotton is still attached to the seeds in the boll and so needs separating.
This is done with a machine called a gin. Essentially, this consists of a steel comb, with
toothed discs running between the teeth of the comb. The disc teeth catch the cotton
fibres and pull them through the comb, but the seeds are too large to pass through and so
are separated. The cotton, known at this stage as lint, is collected, compressed and baled
ready for shipment to the spinning mills. Not all of the cotton is stripped off at this first
pass, so the residue is usually passed through the gin for a second time; on this second
pass, it is only the remaining broken and short fibres that are removed and these, known
as linters, are used mainly for stuffing upholstery or as a source of cellulose for industrial
uses, such as the production of rayon.
After baling, the cotton is sent to the Cotton Exchanges in various parts of the world, for
sale to the spinners. At this stage, it is necessary to grade the cotton. This grading takes
into account many properties of the fibres, such as general appearance, cleanliness,
maturity, etc., but the main characteristic is the staple length, that is the average length
of the individual fibres. Broadly speaking, the cotton falls into four main types, known
as Sea Island, Egyptian, American Upland and Indian. These designations originally
indicated the areas where the cotton has been grown, but they have now become more of
a type classification rather than an indication of origin, as is shown in Table 2.1.
sepytnottocfonoitacifissalclareneG1.2elbaT
noitangiseDegnaRhtgneLerbiF
)mm(
snoitacilppArojaM
dnalsIaeS06–04snrayytilauqhgiheniF
naitpygE05–03snrayenifotmuidemytilauqdooG
dnalpUnaciremA04–02dnalarenegrof,snrayesraocotmuideM
snoitacilppalairtsudni
naidnI03–01scirbafpaehc;seniwtdnasnrayesraoC

Chapter 2 31/7/01, 11:34 am16
17
Production and Properties of Textile Yarns
At the spinning mill the cotton goes through various processes to convert it from the
rough compressed bales to a strong coherent and uniform yarn. The various stages are as
follows:
(1) Bale Breaking: the bales are opened and slabs pulled off and fed into the breaking
machine, in which the lumps are subjected to the action of contrarotating rollers,
fitted with steel spikes. These pull tufts of the cotton off the compressed mass, and
these then pass over various screens, to remove some of the impurities present, such
as twigs, leaves and sand.
As cottons of different grades and from different sources are usually blended together,
in order to obtain the desired properties in the final yarn, the blending normally
starts at this stage, by feeding slabs from different bales consecutively.
After bale breaking, the cotton, still in fair-sized lumps, passes to the next stage.
(2) Opening and Cleaning: the lumps of cotton from the breaker pass through fluted
steel rollers to a beating section, where rotary bladed cylinders beat the lumps, reduce
the size of the tufts and at the same time remove still more of the contaminants,
which fall through the bottom mesh of the machine.
At the output end of the opener, the sheet of loose randomly laid fibres is fed through
nip rollers and wound up into a lap, for feeding to the next stage. By this point, the
cotton has changed from a hard compressed bale to a soft fibre web, similar to
‘cotton wool’.
(3) Carding: a diagram of a cotton card is shown in Figure 2.1. The cotton, in the form
of the lap from the opener, passes through a feed nip and is presented to the ‘taker-
in’, which consists of a roller covered with ‘card clothing’. Card clothing comprises a
heavy backing made from rubberised fabric, through which angled steel wires pass,
as shown in Figure 2.1 (a) ; the angle and length of these wires are of great importance
as they control the efficiency and performance of the card.
As the lap approaches the taker-in, the wires take hold of the fibres; as the roller has

a much higher surface speed than the lap feed, the web of cotton becomes considerably
attenuated. This web of fibres passes round the taker-in until it reaches the main
cylinder, also covered with card clothing, with the wires angled in the same relative
direction. As the main cylinder is moving faster than the taker-in, the condition as
shown in Figure 2.1 (b)(i) applies and the fibres are stripped from the taker-in, being
completely transferred to the main cylinder and becoming still more attenuated. As
the fibres are carried round the main cylinder, they reach the point where they meet
the ‘flats’, also covered with clothing. These are moving more slowly than the cylinder,
Chapter 2 31/7/01, 11:34 am17
18
The Application of Textiles in Rubber
but in the same direction and with the wires angled in the opposite direction, as in
Figure 2.1(b)(ii). A carding action occurs; the fibres are divided between the two
surfaces and thereby the tufts are teased out more fully still, until ultimately, all
agglomerations of fibres are broken down, giving a web of largely unentangled fibres.
As the flats are carried round, they are cleaned so that clear surfaces are continuously
presented to the cylinder. The fibre web continues round the cylinder until it meets
the ‘doffer’, which rotates faster than the cylinder and strips the web off; the web is
then in turn stripped from this by the ‘doffer comb’, from whence it passes over
guide rollers and a funnel shaped guide, which reduces its width to about 25 mm, in
which form it is coiled into a large can for passing to the next stage. In this form, the
continuous ‘rope’ of cotton is called a ‘roving’.
(4) Drafting: the drafting stage in the spinning process performs three essential functions.
The first of these is the parallelisation of the individual fibres, which up to now have
been laid in a more or less random manner. Secondly, it enables further blending of
the different fibre types to take place. Thirdly, it can thin down the rovings to a much
finer form, with a slight twist inserted, to give sufficient strength for the final spinning.
Figure 2.1 Cotton carding
Flats
LAP

IN
Feed
nip
Taker-
in
Main
cylinde r
Doffer
Comb
ROVING
OUT
(a) CARD CLOTHING
Wires
Textile/
rubber
ba cking
(b) CARDING ACTIONS
Positio n Motion Actio n
(i)
(ii)
stripping
carding
Chapter 2 31/7/01, 11:34 am18