Polymers in Sports Equipment

The optimum design of sports equipment requires the application of a number of disciplines, from anatomy to materials science, for enhanced performance, to make the equipment as user-friendly as possible and to avoid injury. In designing sports equipment, the various characteristics of materials must be considered including strength, ductility, density, fatigue resistance, toughness, modulus (damping) and cost. If we want a material that features the highest possible stiffness for the least possible weight, we would select low density materials with the highest specific stiffness.

Spandex Sports Equipment

Spandex (or Lycra®) is an interesting stretchy elastic artificial fibre. It is used to make sports clothing including wetsuits, and with other fibres to make comfortable clothing with a snug fit, that helps to support muscles. Its structure has a stretchy section that makes it soft and rubbery, and a rigid section (containing substituted benzene rings and urea, –NHCONH–, functional groups) that makes it tougher than rubber. Different chains can form hydrogen bonds (C=O IIIIIIII H–N) to one another that align the rigid segments in different chains in the fibres. Spandex is lightweight but doesn’t get damaged by sunlight, sweat or detergents – all of which can make other materials wear out.

Composites in Sports Equipment

To meet the requirements of sports equipment, the materials of choice often consist of a mixture of material types, typically metals, ceramics, polymers, and composite concepts. Composite materials are made from two or more materials with different chemical and physical properties, that when combined, produce a material with characteristics different from those of the individual components. For example, carbon-fibre-reinforced composites are superior to metals in imparting high forces to a ball. To reduce the vibration upon impact, racket handles are constructed of multiple carbon-fibre-reinforced layers wrapped around a soft inner core, which is often an injected polyurethane foam or honeycomb construction. A polyurethane is formed, for example, by reacting a diisocyanate with a diol.

.

In the Paralympics, some sprinters have made use of prosthetic devices featuring carbon-graphite feet bolted to carbon-composite sockets, that provide the right balance of stiffness and flex at a substantially reduced weight compared to conventional materials such as wood. The arrangement acts like a springboard, with the runner punching the track with each step forward, catapulting the athlete more efficiently than if they were running on two human feet. In the 2018 Winter Paralympics, a new prosthetic leg, called the Ottobock ProCarve, was designed with a powerful pneumatic spring and a large air-filled cylinder at the ankle joint which acts as a shock absorber, and is perfect for tough sports like snowboarding.

Ethics of Emerging Materials in Sports Equipment

So, amazing improvements have been made in those sports where equipment is critical. However, the use of advanced materials in sports equipment presents some ethical questions. We can clearly enhance behaviour by allowing the use of advanced materials, but where should the line be drawn, or should there be no restrictions? Can we ensure that athletes are competing and not the advanced materials? Also, should we allow competition at the highest level to be only affordable to the elite because of the high cost of modern equipment?

What do you think?