In contrast to crosslinking thermosets, whose cure reaction cannot be reversed, thermoplastics harden when cooled but retain their plasticity; that is, they will remelt and can be reshaped by reheating them above their processing temperature. Less-expensive thermoplastic matrices offer lower processing temperatures but also have limited use temperatures. They draw from the menu of both engineered and commodity plastics, such as polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA or nylon) and polypropylene (PP). High-volume commercial products, such as athletic footwear, orthotics and medical prostheses, benefit from the toughness and moisture resistance of these resins, as do automotive air intake manifolds and other underhood parts. They are increasingly being used in high-performance applications in aerospace and other fields.
