Plastics, safety up in your face

Road safety is as much about the safety of pedestrians and two-wheelers, cyclists and motorcyclists, as it is about the occupants of vehicles. Although the advances in this area are less spectacular, they are nonetheless worthy of praise here, since polymers also play an essential role.

From motorbikes to bicycles, the airbag is becoming more widespread

The widespread use of airbags is only two decades old, but the technology of these inflating cushions is now used in many places. They can be found in the jackets and trousers of motorcyclists, in the vests of extreme skiers and recently even on motorbikes and bicycle helmets.
While the technology is essentially the same, as is the material (polyamide), the innovation lies mainly in the shape that the airbag will take once inflated.

Regarding motorbikes, Japanese Honda set the ball rolling in 2006 by equipping the powerful Gold Wing tourer with the very first airbag. This was located in the tank and triggered in the event of a frontal impact to prevent the rider from going over the handlebars or getting stuck in them. This was not enough to protect it in the quite frequent case of a side impact. This is one of the reasons why equipment manufacturers are designing polyamide airbags in the form of sleeveless waistcoats, which are worn over the jacket.

Japan’s Honda is the first manufacturer to equip one of its motorbikes with an integrated airbag.

They are connected to the motorbike by a string that strikes the airbag gas cylinder in the event of ejection, or fitted with a sensor that can detect an impact. This is the same principle that has been used for decades in sailors’ life jackets. (see our article)

However, things are set to change again thanks to Honda, which in early 2023 filed a series of patents for a new type of motorbike airbag. Once again, the manufacturer has chosen to install it directly on the bike. In reality, as in cars, it is not one but several airbags. The first would deploy from the back of the seat and wrap around the rider’s torso. The second would be located between the legs and would deploy behind the back. Once inflated, the airbags would detach from the motorbike and remain wrapped around the rider, protecting the body in the event of a slip, but more importantly, in the event of an impact with an oncoming vehicle, for example. Also, Italy’s Piaggio and Sweden’s Autoliv, the world leader in airbag systems for cars, recently joined forces to develop an airbag for two wheels. Mounted directly on the chassis, first of scooters and then of motorbikes, it would deploy in a few milliseconds.

Cyclists are also entitled to their own airbag, as there is a special model for them. Recently marketed by the Swedish company Hövding, it comes in the form of a neck brace. Equipped with various sensors, it deploys in 1/10th of a second around the cyclist’s head in the event of a fall. Although it replaces the helmet, and is less restrictive, it is more expensive and remains a single-use item.

According to the Swedish manufacturer of the Hövding airbag for cyclists, it protects eight times better than a helmet. This innovation has been awarded the French Road Safety Prize

Helmets: plastics come out of their shells

Helmets are now an essential safety feature for all users of two-wheelers, whether motorised or not. The biker’s helmet is well known, with the shell (the outer part) usually being made of polycarbonate, a strong material that is injection moulded. Higher-end models can be made of fibreglass and epoxy resin. The final product is based on a composite of carbon and aramid fibres and an epoxy resin. The advantage is twofold: it is an ultra-protective helmet and very light, which makes it less tiring for the neck.
The shock-absorbing interior is made of expanded polystyrene or polyester foam and is covered with a synthetic fibre fabric such as polyamide or polyester for easy cleaning.

Jet, full-face, modular… all motorbike helmets are based on the same design: a polycarbonate shell or even an ultra-resistant composite polymer material and foamed plastics to absorb impacts.

While all approved helmets provide effective protection, the difference between the higher and lower ranges lies in the details, such as the number of vents to allow air to circulate more freely or the quality of the visors, which are usually made of polycarbonate and can be treated with an anti-fog coating, which in turn contributes to safety.

The helmet can even be made smart. Kosmos Smart Helmets, a French start-up, recently launched the first smart helmet. This incorporates a brake light made up of LEDs, mini plastic bulbs that consume little energy and are very light. It is reminiscent of the third brake light in cars. Even better, the helmet is linked to the rider’s smartphone and is able to send an emergency message in the event of a serious impact.
The next generation of motorbike helmets may well include an airbag. Redundant design? This is not certain, because the Italian helmet manufacturer Airoh and the Swedish Autoliv, both of whom initiated this project, have shown that the airbag is a perfect complement to the helmet to reduce the risk of serious head injuries in the event of an accident. The airbag would be placed at the top of the helmet and would deploy in a ring. This helmet of the future is still under development, but some bikers are already waiting for it… 

Although simpler, bicycle helmets are not to be taken lightly — even though lightness is most often sought after! Their shells are usually made of PVC or polycarbonate, sometimes ABS. Polystyrene in its expanded or foamed form also dominates the interior. A lightweight polymer with very good absorption capabilities. For models made of polystyrene foam, an additional reinforcement is required. This can be made of polyamide, Kevlar or even Kevlar-reinforced aramid. Whatever its shape, polystyrene absorbs serious impacts by deforming. This deformation, linked to the packing of the material, is essential because it reduces the rebound effect and thus protects the skull. Unfortunately, polystyrene never returns to its original shape and, once compressed, it loses its effectiveness. For this reason, it is strongly recommended to change your helmet after a serious impact.

The principle of the bicycle helmet is the same as that of the motorbike helmet, although the design is generally simpler.

 With the development of sustainable mobility, the number of cyclists is growing rapidly and is pushing helmet manufacturers to constantly innovate. Thus, the small MIPS logo (Multi-Directional Impact Protection System) can be seen on some top-of-the-range models. This technology is inspired by spinal fluid, which prevents the brain from hitting the skull in the event of an impact causing brain damage. In fact, this system consists of an additional polycarbonate cap placed inside the helmet. This is not pressed against the shell but is connected to it by small elastomer rods, creating a small air cushion. In the event of an impact, the cap and shell will slide a few millimetres on top of each other, allowing the rotational forces to dissipate better and preventing the brain from coming into contact with the cranium.

The accessory is becoming essential!

These are the accessories that most often help to protect pedestrians, cyclists and motorcyclists in the event of an accident. The list is long, almost as long as the list of the polymers that make them up. For example, motorcycle jackets can be fitted with shoulder pads, elbow pads, back plates, etc. made of polyurethane, polyethylene or even carbon fibre. They protect the joints and prevent burns from slipping. Clothing and gloves are also made of Cordura®, a polyamide that is particularly resistant to abrasion.

Including thousands of glass microbeads in a polyester jacket makes it visible at night up to 300 metres. This jacket developed by Urban Circus and Continental is a guarantee of safety for many cyclists

The prize for innovation goes to the Urban Circus brand, which has developed an all-polyester jacket with water-repellent treatment and thousands of light-reflecting glass microbeads in collaboration with Continental, the tyre manufacturer. The designers claim that it would be detectable at night up to 300 metres away, compared to 50 metres for a traditional white garment. The addition of fluorescent inserts also improves daytime visibility.

The motorbike jacket manufacturer Raylier preferred to use LEDs to improve the visibility of bikers, integrated in the front and back, around the chest. The driver operates them by pressing a button on the forearm and chooses whether to have them light up continuously or flash. The jacket also has a deceleration sensor that will quickly flash the LEDs in case of emergency braking.

Finally, let’s also mention this initiative by a French construction company which, at first glance, might make you smile. The latter designed a life-size human figure representing a worker. Cut out of a PVC sheet, it is placed near a construction site whose intention is to slow down motorists. For psychoanalysts, this is the perfect illustration of the cognitive approach. Tests have shown that the sight of the silhouette was more effective in slowing down drivers than the traditional “cautionary construction site” sign. This shows that in the field of road safety, even the simplest ideas have their place when it comes to saving lives.