Expanded Polypropylene in Bike Helmets
Expanded polypropylene is another type of lining used in some makes of bike helmets. It is stronger yet, it is less common that expanded polystyrene. The difference is the impactability of the foam liner. Unlike expanded polystyrene. expanded polypropylene will not crack under pressure and if you suffer an impact when wearing your helmet, not only will the foam absorb the shock, it will not crack the liner. Expanded polypropylene will be able to retain it's original shape and form and continue to protect your head so you can actually expect longer service from a bike helmet that is lined with expanded polypropylene instead of expanded polystyrene.