Are usually required to have good energy absorption and impact resistance, and the core material is also required to be light in weight.     this makes polypropylene foam an alternative to polyurethane foam in the field of automotive energy absorption and cushioning.     In addition to its light weight, polypropylene foam is more advantageous than polyethylene and polystyrene foam in areas where higher operating temperatures are required, such as sun visors, instrument insulating panels and areas where temperatures tend to rise between doors, due to its higher heat resistance.