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Sports
Shoes and Clothing
Sports
shoes and clothing need to be strong, light and comfortable. For the uppers
of sports shoes, which now weigh half what they did in the 1960s, polyurethane
and nylon are often used, sometimes
bonded to natural leather.
The soles of footwear like football boots and tennis shoes need to be
rigid but flexible, and resistant to abrasion, so a thermoplastic elastomer
such as polyether-block-amide
(PEBA) is used. The toes are given impact resistance with polyaramid
(e.g. "Kevlar"). Inner soles require a flexible foam such as
EVA (ethyl vinyl acetate) to absorb
shock.
Sports
clothing has to resist tear and abrasion and be permeable to water vapour,
so nylon and polyesters
are used. PTFE can be woven into
fabrics to help them repel rain whilst remaining "breathable".
Elastomeric fibres allow frequent stretching of fabrics during sporting
action, with no loss of spring.
Athletics
For
track athletes, the quality of the running shoe is vital. To give flexibility,
ethyl vinyl acetate (EVA), as well
as rubber, is used in sections
of the sole. Polyurethane
and polyaramid provide tough
and durable outer materials. Spikes and studs can be in nylon.
The various components of the shoe have to hold together under demanding
conditions, so reliable synthetic adhesives
are essential. Equipment for field events such as high-jump, javelin and
pole-vault needs to be tough and lightweight, so nylon,
glass-reinforced polyester
and epoxy resins are used,
as well as other plastics. Clothes kits rely on acrylic,
polyester and elastomeric
as well as natural fibres, and are given their bright colours as a result
of synthetic dyestuffs.
Football
Originally
footballs were made of leather
with a rubber bladder, and it
became very heavy to kick in wet weather. Modern balls are usually made
of a leather substitute such as polyurethane,
which is lighter, absorbs less moisture in wet conditions, and can be
made with a cover in a combination of white and attractive colours. Children's
play footballs are often made in PVC.
Football boots use a range of polymers, including polyurethanes,
nylon for sole parts and studs
and EVA flexible foam for inners.
Attractive colours are provided by pigments.
Shirts and socks are in hard-wearing polyester fibre coloured with synthetic
organic dyestuffs. Shin-guards
are moulded in polypropylene with EVA
foam to absorb impact. Goal nets and corner flags need to be made in tough,
weatherproof material such as nylon
or polypropylene.
Golf
The
humble golf ball has had a remarkable evolution, with wood, boiled feather
inners and leather cases all being used in the distant past. The modern
ball is made of a mixture of natural and synthetic materials: a hard rubber
core is wrapped with fine rubber strands and covered with a casing of
balata or gutta-percha,
obtained from natural latex. Polyurethanes
or neoprene are now used as
alternatives for the casing. Golf club shafts have evolved from wood to
tubular steel to reinforced polymer systems, especially glass-fibre
with polyester, or polyaramid
or carbon-fibre ("graphite")
with epoxy resin. The head
of the club is usually steel, titanium
or a laminated composite.
Motor
Racing
Great
strides have been made in designing racing cars and equipment to protect
the driver without losing the speed and thrills that the sport provides.
Every Formula One driver is now protected by a strong, rigid survival
cell built using tough carbon
fibre and polyaramid
in an epoxy resin matrix.
Around the survival cell, items such as the nose cone and side and rear
panels are built using synthetic foam to absorb impact forces. The driver's
gloves are woven in polyaramid
fibre, for fire-resistance as well as strength. Motor racing and rallying
provide fierce testing grounds for other strong, lightweight automotive
components such as polyethersulphones used in electrical connectors to
withstand high temperatures, glass-reinforced nylon
for intake manifolds and polycarbonate
for headlamp material.
Swimming
Modern
swimming costumes are the result of advances in fibre technology. Non-absorbent
microfibres of polyester
or polyethylene are coated
with PTFE to repel water and reduce
drag. Elastomeric fibres
(such as "Lycra") are used for their excellent stretch-and-return
properties. Goggles are of clear and tough acrylic
or polycarbonate, with
the straps of silicone or
synthetic rubber, which is also
used for headwear. Buoyancy aids employ flexible synthetic foam such as
EVA, inside a PVC
casing. Flippers are in a thermoplastic elastomer such as polyether-block-amide.
In the pool, lane dividers may use polyester
ropes, with moulded polyethylene
or polypropylene floats,
while addition of a small amount of chlorine
is the commonest way of ensuring that the water remains germ-free.
Tennis
Great
tennis players of the past such as Rod Laver and Maria Bueno used rackets
made of wood. Now, with new materials, rackets can be made stronger yet
lighter. Epoxy resin reinforced
with carbon fibre ("graphite")
is a favourite material; glass-reinforced polyester
and titanium are also used.
Strings, traditionally of beef gut, are now of strong synthetic fibres
such as nylon. The balls are
of hollow synthetic rubber,
inflated to high pressure, covered with felt and sealed by means of welded
seams. Hard courts are of specially formulated concrete or asphalt, often
covered with a rubberised layer to soften the surface. Nets are of weather-resistant
synthetic material such as nylon
or polyester.
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