Polybutylene terephthalate (PBT) is a polyester made by polycondensation of terephthalic acid and 1,4-butanediol, an important thermoplastic polyester, and one of the five major engineering plastics. PBT is a milky white, semi-transparent to opaque, semi-crystalline thermoplastic polyester with high heat resistance. It is not resistant to strong acids or bases, can withstand organic solvents, is flammable, and decomposes at high temperatures. PBT is widely used in automotive, machinery, precision instrument components, electronic appliances, textiles, and other fields. Most PBT resins are processed into compounds for use, modified with various additives, and blended with other resins to achieve excellent heat resistance, flame retardancy, electrical insulation, and good processing properties.