Polymers for going higher, faster, stronger

Plastics in freestyle

Although evolutions in materials, and more particularly polymers, play a decisive role in breaking records in motor sports, they are just as decisive for sportsmen and women who use their muscles to exceed their limits. Of course, the ever-improving knowledge of the human body plays a role in terms of knowing in which hundredths of a second to give the impulse to get out of a starting block, but the human body, like any living organism, has its limits. Without the help of increasingly efficient equipment, many records would not have been broken. On the flip side, athletes sometimes have to modify their technique to adapt to their new equipment. This is the case for skiers, for example, who had to revise their turning technique with the advent of parabolic skis in the 1990s. 
This "constraint" is not relevant to the practitioners of speed skiing, an alpine skiing discipline which consists of going straight down as fast as possible in order to beat a record.

Perfectly waterproof and able to slide through the air, vinyl is the perfect material for designing speed skiing suits.

The most recent record for both women and men is held by Italians: 247 km/h in the first case and 255 km/h in the second. Since 1932, the official date of the first world record, the speed reached by skiers has almost doubled. And we owe those records to evolutions in the equipment used! Similarly to Formula 1, the international regulations, based on the principle that the heavier you are, the faster you go, impose a maximum weight on the equipment (helmet, boots, skis, etc.) in order to guarantee the safety of the skiers.

Thus, the skis must not exceed 15 kg with the bindings. Although the core is still made of wood or metal, it is encapsulated in a sandwich of polyamide or fibre-reinforced epoxy composite. These materials are both light enough and, above all, rigid enough to prevent the ski from vibrating, which could be fatal at these speeds.

However, it is undoubtedly on the base, the part of the ski in contact with the snow, that the most research has been done. On modern skis, it is made of polyethylene, a polymer that promotes gliding. It is not smooth but covered in almost imperceptible grooves. These micro-grooves create a cushion of air that heats up under the effect of friction and melts the snow sufficiently to transform it into water. This improves the glide because, contrary to popular belief, a ski glides better on a thin film of water than on ice.

To gain the few tenths of a kilometre per hour needed to improve the record, the skier must also improve his aerodynamics. The only solution is a suit made of vinyl and latex. The suit is watertight and promotes better air flow around the body. Made to measure, it is enhanced with fins made of polycarbonate or carbon, very rigid materials that do not deform at high speeds. Of course, these champions are also equipped with a helmet designed to split the air which, for the same reasons, is made of hand-moulded fibreglass and Kevlar fibres coated with epoxy resin.

Polymers have a need for speed There are many records to be broken in the world of cycling, but the most prestigious is certainly the hour record, which consists in covering the longest distance in only one hour. It was attempted for the first time in 1893 by Frenchman Henri Desgrange who covered 35.3 km. Since 2019, it has been held by Belgian Victor Campenaerts, who covered 55 km, i.e. 20 more. His performance is not only down to preparation. In 130 years, we have moved from steel bicycles to racing machines made entirely of composite materials.

It is impossible to beat the hour record on a bicycle without resorting to a specific machine. Carbon and resin share the limelight once again!

These bicycles are tested in a wind tunnel, and are a far-cry from ordinary city bikes. The frame is not an assembly of tubes but is made up of two carbon and resin half-shells that have been glued together. The wheels are profiled: the rear one is lenticular and the front one has only three wide spokes, resembling an aeroplane propeller. Of course, they are also made of composite materials. Only the chain, sprocket and crank-set are made of metal. As for the tyres, the part in contact with the road is made of natural rubber, but the carcass is made of polyester, a polymer that undergoes very little deformation and is very light. In short, it is a machine designed solely to break a record on the track and is virtually unusable on the road.

Cold shower for plastics

The first swimming suits appeared at the end of the 1990s. They were a real revolution! In barely a decade, they have broken several hundred world records. They work by gliding over the water and thus improve the swimmer's hydrodynamics. Initially made of silicone or polyamide and elastane, they were custom-made and of course only intended for the great champions with Olympic potential who were under contract with the manufacturers. This privilege was tolerated until the Beijing Olympic Games in 2008. During this Olympiad, the Speedo brand did very well by offering a new model of suit mainly made of resolutely innovative polyurethane. Designed in collaboration with NASA and the Australian Institute of Sport, the suit helped swimmers break records. Only two months after its release, 35 of the 37 world records had been broken! Inspired by shark skins, the suit reduced drag by 5%, in particular because the profiled polyurethane panels help to keep the swimmer horizontal. In addition, it was no longer sewn, but glued to avoid unnecessary friction. As the suit’s competitive advantage became obvious, it was banned by the International Swimming Federation in 2009. Going forward, it will be very difficult to beat the records achieved during that period.

The high-performance polyurethane suits have broken many records. Deemed to constitute an unfair advantage, they were subsequently banned by the International Federation.

Despite many attempts, pole-vaulters have remained faithful to the fibreglass/polymer resin composite.

A flea’s jump for polymers Advances in equipment, whether ergonomic or material-related, are a determining factor in breaking records. We have discussed this subject in detail in some of our previous features Plastics in the starting blocks and Golden Ball for plastics. The materials used by sportsmen and women discussed in those features all have one thing in common: they are constantly evolving.

To this end, they rely in particular on the formidable performance-enhancing properties of polymers: tennis racket frames in epoxy carbon and hybrid polyester together with Kevlar fibre strings for services at over 260 km/h, a range of different polymers to make running shoes more comfortable and dynamic enabling the wearer to run the marathon in less than 2 hours and 2 minutes, and more.
There are many other examples of the increased performance offered by polymers, but there is still one discipline where a record is occasionally broken despite the equipment not having evolved much or having remained the same for a long time. That discipline is pole vaulting. The poles were initially made of bamboo, which was subsequently replaced with metal. In the 1980s, the fibreglass/polymer resin duo made its appearance. Records were broken left and right, and it was in 1985 that pole-vaulter Sergey Bubka became the first person to vault over the 6-metre bar. Today, the world record is 6.18 m for men and 5.06 m for women. Although the progress made may seem small, in this discipline every centimetre gained is a real feat.

Can we thank the carbon/polymer resin duo for this performance? The answer is no. Despite many attempts, it quickly became clear that the carbon poles, although lighter, were also more fragile and tended to break. Athletes and manufacturers alike naturally preferred to keep using fibreglass. They refined the manufacturing process by precisely dosing the amount of material to be put in one place or another. They also learned to adjust champions’ poles to fit their morphology and technique.

Finally, climbing so high is one thing, but falling back down without injury is quite another. Here again, polymers have a knack for protection since such jumps would be impossible without mats and landing blocks to safely catch a pole-vaulter falling from the equivalent of nearly two floors. The appearance of blocks made of expanded polypropylene foam and/or polyurethane foam has made things much easier and has contributed in no small part to each new broken record. They are rarely if ever given their due recognition, and we would like to change that here.