Polybutylene terephthalate polycondensation

Polybutylene terephthalate (PBTP, PBT, and polytetramethylene terephthalate) n. A member of the polyalkylene terephthalate family, similar to polyethylene terephthalate in that it is derived from a polycondensate of terephthalic acid, but with butanediol rather than glycol. PBTP can be modified easily to overcome its relatively low-operating-temperature limit, making it equivalent to plastics used in... 

Semi- Copolymer Polybutylene terephthalate (PBT) Polycondensation of terephthalic acid with 2,3-butanediol... 

Polyalkylene Terephthalate Any of a family of thermoplastic polyesters that are polycondensates derived from terephthalic acid, whose diol components may be any within a wide range. The principal members of the family are Polyethylene Terephthalate and Polybutylene Terephthalate. 

When polyesters are processed, thermal degradation is caused by ester bond cleavage here, polyethylene terephthalate is more stable than polybutylene ter-ephthalate. Ester cleavage is influenced to various degrees by different trans-esterification and polycondensation catalysts. This is less significant in the thermai degradation of polybutylene terephthalate compared to polyethylene terephthalate. 

Polybutylene terephthalate (PBT) is a semi-crystalline saturated polyester, which has been produced since 1942. PBT is made by the polycondensation of terephthalic acid or dimethyl terephthalate with 1,4-butanediol in the presence of a catalyst. Terephthalic acid, dimethyl terephthalate and 1,4-butanediol are derived from petrochemicals such as xylene and acetylene. The polymer is noted for high stiffness and strength, high resistance to heat, low water absorption and high dimensional stability. It has moderate chemical resistance and low resistance to strong acids and bases. 

Aliphatic-aromatic polyesters are formed by the polycondensation of aliphatic diols and a mix of aliphatic and aromatic dicarboxylic acids. Commercially available polyesters obtained by modification of PBT (polybutylene terephthalate) with aliphatic dicarboxylic acids are listed below. 

Polybutylene terphthalate (PBT) is a semicrystalline thermoplastic polyester considered as a medium performance engineering polymer. It is produced industrially in a two-step batch or continuous process. The first step involves the transesterification of dimethyl terephthalate (DMT) with 1,4-butanediol (BDO) to produce hydrobutyl terephtlate (bis-HBT) at a temperature of 200 C. The second step consists to the polycondensation of bis-HBT at 250 C to yield PBT. It exhibits both excellent electrical properties and chemical resistance. When reinforced with glass fibers, it has improved stiffness and mechanical strength. Typical uses include connectors, capacitors and cable enclosures. PBT is also used in hot appliances such as iron and kettles. 

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