PBT is a thermoplastic engineering polymer that is used as an insulator in the electrical and electronics industries. It is a thermoplastic (semi-) crystalline polymer and a type of polyester. PBT is resistant to solvents, shrinks very little during forming, is mechanically strong, heat-resistant up to 150°C (or 200°C with glass-fiber reinforcement) and can be treated with flame retardants to make it noncombustible.