Polymers in Sport and Leisure

Polymers in Sport and Leisure
polyolefin units with a number of ‘spikes’ forming
the surface, and polyvinyl chloride or nylon filament
brushes held in a metal channel. The latter appeared
to give better performance.
2.6 Playgrounds
Traditional children’s playgrounds were asphalt or
hard, compressed turf essentially bare of grass.
Concern over injuries has led to the installation of a
very large number of safety surfaces based on bound
crumb or shred rubber, similar in concept to the
synthetic turf shock pad.
The surface can be cast in-situ or constructed of
preformed tiles. Generally, the level of impact
absorption required is greater than for shock pads or
athletics tracks. The top surface needs to be suitably
wear resistant but not to the level of a track and usually
spikes are banned. To obtain the necessary absorption
capability to protect against falls from heights as great
as 3 m needs a relatively thick surface, but rather more
deformability can be tolerated than for sports surfaces.
For cast in-situ systems, the level of impact absorption
can be increased by using two layers, the lower one
having a particularly open structure. For preformed tiles
a so-called engineered construction improves impact
absorption by having a webbed structure on the
underside which buckles under impact. As for sports
surfaces, a dynamic base can lower costs and improve
impact absorption.
Less common is the use of a needlepunch or synthetic
turf carpet over a shock pad and/or a dynamic base.
2.7 Ground Conditioning
An alternative to replacing natural turf with synthetic
is to use polymers to improve the performance,
particularly the durability, of the natural material. In
this way the traditional characteristics and appearance
are retained. The basic concept is to introduce a
reinforcing structure and is particularly applicable to
high wear areas such as goal mouths.
Polypropylene needlepunch material has been used
with the grass seed sown below it and the open structure
of the needlepunch filled with soil. Although under very
heavy wear the grass may be worn away, play can
continue on the needlepunch and the root structure is
retained for the grass to regrow. Geotextile ‘netting’ is
also used for this purpose and is sometimes seen in car
parks (396). Another approach is to incorporate rubber
crumb or shred into the top few centimetres of soil.
Crumb can also be used as a top dressing where it is
claimed to protect the grass root system and reduce
compaction (299).
Where sports grounds have to be built on land with
adverse soil conditions, needlepunch membrane is used
as a filter to protect the drainage course from infiltration
of the sub-soil. This is similar to its use in dynamic
bases for synthetic surfaces.
Problems with natural turf include water logging and
freezing. Drainage systems are a significant outlet
for unplasticised polyvinyl chloride pipe and a
heating system using polyethylene piping has been
described (54).
3 Clothing
Special clothing is either necessary or is desirable for
all sports and it is not surprising that large amounts
of synthetic fibres are consumed. As a generality,
sports clothing is technically not dissimilar to normal
clothing but there is, for example, a particular need
for breathable fabrics in activities such as walking
and climbing.
A particular requirement in some sports is for
protective clothing, where foams are frequently used.
An example is protective jackets for equestrian use
which are now mandatory in several branches of riding
activity. The degree of protection is compromised by
the restrictions of what is too uncomfortable to wear
and during the 1990s there was competition amongst
suppliers to improve impact absorption without
increased thickness.
Shin guards and similar items are another example.
An effective design has a foam interior with a rigid
moulded plastic shell. Gloves are produced from a
variety of materials for a range of particular
applications. Some include padding or a latex non
slip surface.
A different example is the fire resistant Nomex fabric
used in underwear, balaclavas, gloves, boots and race
suits for motorsports. A combination of Kevlar,
silicone gel and closed-cell foam has been used in
knee pads for mechanics and Kevlar heat sleeves can
protect them when working on hot engines.
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