Helmets in sport products are made of polypropylene on the inside and plastic on the outside, and many products are bicycle helmets. This is the most common helmet used for speed skating and recreational roller skating. Safety is ensured by absorbing energy through the deformation and fragmentation of polypropylene.
Polypropylene is divided into two types: primary foaming and secondary foaming. Polypropylene with primary foaming can not see small ball-like bubbles. It is high density, high hardness and high price. It is only used for high-end helmets. Secondary foamed polypropylene is the foam that is usually used for shockproof packaging of electrical appliances. You can see small ball-like bubbles. It is low density, low hardness and low price. It is used in various helmets. Of course, the secondary expanded polypropylene used for helmets is a high-end product in the same product.
High-end and one-foam polypropylene helmets are usually slimmer and have many holes opened to ensure ventilation. Secondary foamed polypropylene high-end helmets are usually thicker and have fewer openings due to low material strength. Some low-end helmets have outer shells formed of thin plastic and taped to the inner polypropylene. These helmets are basically single-use and will shatter upon impact. The instruction manual of many products states that it is strictly forbidden to continue to use the helmet regardless of whether there are visible cracks and damages on the helmet after an impact.
1. Polypropylene lining
It is mostly used in extreme roller skating and FSK projects. Sports product helmets are mainly used to prevent collision with hard objects and protect the head.
2. Hard plastic shell made of engineering plastic plus hard sponge lining
It is mostly used in ice hockey and single-row roller skating. It is mainly used to prevent collision with hard objects and protect the head from the impact of ice hockey. Many helmets can be fitted with plexiglass or welded wire mesh.
3. Helmet with jaw protection
Basically a glass fiber or carbon fiber shell with an EPS lining, some varieties are made of pure EPS, and the part of the lower jaw protection can be removed. Roller skating uses this type of helmet. It is basically the same as the helmet for mountain bike downhill, and some people use motorcycle helmets directly.
4. Aerodynamic helmet
Basically a glass fiber or carbon fiber shell paste, the surface is very smooth, some with EPS lining. The shape is very unique, with large goggles in the front covering half of the face. The rear part of the water sport helmets is very long, and the part where the neck meets the back is rectified when sliding to reduce air resistance, so it is called aerodynamic helmet. This is the equipment of road cyclists, and some people use it in short-distance races of 300 meters, with limited effect. Many helmets have delicate resizing devices that are helpful for wearing the helmet, which is still necessary.