Polybutylene terephthalate thermal properties

Japan s Showa Highpolymers, part of the Showa Denko group, and Korea s SK Chemicals both have small plants producing aliphatic (polybutylene succinate) and aliphatic-aromatic (polybutyrate adipate terephthalate) polyesters. Both firms also offer their resins in the USA. Showa s Bionelle products are used in commodity bags, agricultural films, traffic cones, and industrial trays. Some Bionolle grades are modified with diisocyanate chain extenders to improve stiffness and thermal properties. 

Engineering thermoplastic resins (ETP) are those whose set of properties (mechanical, thermal, chemical) allows them to be used in engineering applications. They are more expensive than commodity thermoplastics and generally include polyamides (PA), polycarbonate (PC), linear polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyphenylene ether (PPE) and polyoxymethylene (POM). Specialty resins show more specialized performance, often in terms of a continuous service temperature of 200°C or more and are significantly more expensive than engineering resins. This family include fluoropolymers, liquid crystal polymers (LCP), polyphenylene sulfide (PPS), aromatic polyamides (PARA), polysulfones (P ), polyimides and polyetherimides. 

Another blend, also invented at General Electric, is Xenoy . This is an immiscible blend of polybutylene terephthalate (PBT) and polycarbonate (PC) [5,6]. This blend is immiscible it has separate phases of PBT and of PC. An immiscible blend is characterized by two distinct Tgs and thermal analysis of this blend shows the Tg of PBT and of PC as well as a sharp melting point for the crystalline PBT. The blend also includes an impact modifier. It exhibits the good impact associated with PC and the solvent resistance associated with PBT. Because of these properties, it is suitable for applications such as automotive bumpers requiring high impact and gasoline resistance. 

El Fray and Altstadt [12] used MTA to study the relationship between morphological features of semi-crystalline and multi-block polymeric materials and their thermal properties. Samples of semi-crystalline polybutylene terephthalate and its copolymer were crystallised from the melt showing a spherulitic morphology. The surface of the spherulitic shapes was subjected to L-TA at selected regions of different thermal conductivity (at the centre of the spherulite and at its outer surface). This reveals information, which cannot otherwise be obtained. 

At the beginning of a thermal loading condition, the mechanical properties of polybutylene terephthalate are often influenced by the increase in crystallinity, so that, e.g., impact strength decreases because of the higher degree of crystallization. Subsequently, oxidation will cause property changes. Figure 5.199. 

The promise of large-scale low-cost fermentations from renewable resources, especially corn, has spurred interest in the United States to develop chemical production for large-volume chemicals using bio-based processes. Succinic acid can be converted by hydrogenation to 1,4-butanediol, which has a world market in excess of 500,000 metric tons. Butanediol is used to produce polybutylene terephthalate (PBT) resins that have desirable mechanical and thermal properties and are a high-performance version of polyethylene terephthalate resins (PET). Also, 1,4-butanediol is a precursor of tetrahydrofuran, which can be polymerized to polytetrahydrofuran (PTHF). Gamma butyrolactone (GBL) can also be derived from 1,4-butanediol, and much of GBL is used to manufacture the solvent N-methyl-2-pyrrolidone (Szmant 1989). 

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