Polymers in Sport and Leisure

Polymers in Sport and Leisure
5 Athletics and Gymnastics
The major uses of polymers in athletics are for surfaces
and clothing, which have been discussed in Sections 2
and 3. Polymers have had enormous impact on the
sports in both these areas.
Another product which has had a major effect on
performances is the carbon fibre vaulting pole. The rules
covering vaulting poles are unusual in that they can be
made of any material and be of any length and diameter.
Indeed, it is necessary that the pole is individually
matched to the speed and mass of the vaulter. The poles
are hollow with varying thickness along the length and
top class poles are prebent. An analysis of the stresses
and design principles has been given by Burgess (161).
Polymeric foams are used extensively in mats for high
jumping and pole vaulting, gymnastics and martial arts.
They vary in thickness and foam density to suit the
particular application from 750 mm for a pole vault
landing area to 20 mm for an elementary exercise mat.
The foam is most commonly polyether or reconstituted
polyurethane but thinner mats sometimes use
polyethylene or ethylene vinyl acetate. The prime
objective of the mats is to provide impact absorption
but their resilience and stiffness is also important.
Particularly in sports such as judo, a large deflection
hampering movement could be more dangerous than
the effect of falling. Composite construction using
layers of different density can be used to obtain the
desired characteristics. The mats are typically covered
in polyvinyl chloride coated nylon and have a non-slip
rubber base. Mats are potentially a significant fire
hazard and in the UK are subject to stringent
flammability requirements which means that foams
must be of a fire retarded grade.
6 Winter Sports
Skiing was once something of a minority interest but
with increased leisure and cheap flights it has developed
into a mass sport. Winter sports have continued to grow
in popularity and represent a very large market for
sports goods. With this boom came increased
development of the equipment and polymers now have
a major position. In fact it is not an overstatement to
say that winter sports depend on plastics.
Wooden skis were unresponsive, absorbed water, were
heavy and were not very durable. Plastics have allowed
skiing techniques to improve, made the putting on and
taking off of skis easier, improved safety and comfort,
and reduced costs. Encasing a wood core in glass fibre
reinforced polyester was the first change followed by
the development of polyurethane foam cores. Quite
rapidly skis became a sophisticated construction made
up of many components which can include honeycomb
cores, advanced composites and a sliding layer of
graphite impregnated polyethylene.
The degree of effort put into development is illustrated
by French manufacturer Rossignol which has been
devoting over 3% of turnover to new product
development for 4 decades and has 200 employees
working in research (8). The introduction of modern
materials and construction techniques has been
accompanied by quite radical changes in the dimensions
and shape of skis. Shorter skis with noses at both ends
are said to provide something of a bridge between
conventional skiing and snowboarding and to be
extremely versatile. Generally, skis have become shorter
with the middle being markedly more narrow than the
ends. A wide range of polymers are used in ski and
snowboard construction including rubber as an interface,
glass reinforced epoxy structural components,
polyurethane or thermoset cellular core materials,
aramid, carbon and graphite fibres, polyethylene soles
and injected thermoplastic protective parts. Snowboards
have a similar type of composite structure.
As skiing became a mass sport it quickly became
apparent that leather boots were inadequate. As has so
often been the case with the introduction of polymers
the first step was replacing part of the product, an
injection-moulded thermoplastic sole in this case.
However, the first all-plastic boot appeared as early as
1967. A ski boot has to be extremely tough and retain
its properties at low temperatures. Polyurethane meets
these demands with different hardnesses being suitable
for different parts of the boot but other polymers are
now incorporated.
The binding which attaches the boot to the ski is a vital
component as it has the seemingly impossible task of
holding the boot securely throughout the stresses of
skiing but releases it when stresses reach a danger point.
Here too, plastics have replaced aluminium with several
materials having been used, notably fibre reinforced
nylon. One design uses Hytrel for the straps and hiback,
nylon for the base and acetal for the buckles (146).
To complete the plastics domination, top-of-the-range ski
pole tubes are made from hybrid fibre reinforced materials.
Apart from skis and snowboards, polymers are prime
candidates for use in the various sledges, toboggans
and other snow vehicles. One example reported
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