Expanded Polypropylene (EPP) < back
Though it looks identical to crushable EPS foam, expanded polypropylene (EPP) is a more resilient crushable foam, which is to say that it slowly regains its shape following an impact and retains some of its protective quality. For that reason, EPP can be integrated into helmets designed to help protect users from multiple impacts. It has seen use, for example, in skateboarding helmets. EPP is most commonly used in the automobile industry, where it can be found into products such as bumper bars, sun visors, roof pillars, armrests and headrests.
Though EPP could be an attractive liner material for certain cycling enthusiasts, this particular type of foam generally isn’t utilized for cycling helmets. The reason? EPP offers slightly less impact attenuation for a given thickness than EPS foam, which means that more EPP foam must be employed to provide the same level of energy management. The end result would be a heavier and thicker helmet—both traits are “hard sells” in the cycling, snow sports and motorcycle markets.< back