These resins are polymers derived from hydrocarbon molecules that possess one or more alkenyl (or olefinic) groups. The term polyolefin typically is applied to polymers derived from ethylene, propylene, and other alpha-olefins, isobutylene, cyclic olefins, and butadiene and other diolefins.
Polyolefin homopolymers are made from ethylene, propylene, butylene, and methyl pentene. Other olefin monomers such as pentene and hexene are used to make copolymers.
Resilience and energy-absorption properties of these products are exceptional compared with those of conventional polystyrene foams. Polymers available as moldable beads include polyethylene, polypropylene, and a polyethylene/polystyrene copolymer alloy.