1. Polybutylene terephthalate (PBT) is a thermoplastic engineering polymer that is used as an insulator in the electrical and electronics industries.

2. It is a thermoplastic 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-fibre reinforcement) and can be treated with flame retardants to make it noncombustible.

3. It was developed by Britain's Imperial Chemical Industries (ICI).

4. PBT is closely related to other thermoplastic polyesters.

5. Compared to PET (polyethylene terephthalate), PBT has slightly lower strength and rigidity, slightly better impact resistance, and a slightly lower glass transition temperature.

6. PBTs are sensitive to hot water above 60 °C (140 °F). PBT needs UV protection if used outdoors, most of the grades are flammable, although additives can be used to improve both UV and flammability properties.