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Cyclic oligomers of butylene terephthalate (CBT™)† represent a new chemical route to semi-crystalline thermoplastic polybutylene terephthalate (PBT). The oligomers of interest melt completely at about 150°C to produce a low viscosity fluid that is ideal for wetting and dispersing fibrous fillers and reinforcements thereby enabling the development of composites that were previously not possible when working with high viscosity commercial PBT. Introduction of catalyst to undiluted molten cyclic oligomer leads to rapid ring opening polymerization and the formation of high molecular weight thermoplastic PBT without the generation of volatile organic compounds. The polymer resulting from this polymerization will be hereby referred to as pCBT. Treatment of cyclic oligomers in this fashion results in pCBT thermoplastic resin with a high melting point (230°C) and physical performance similar to that of other commercially available PBT resins.

Syndiotactic Polystyrene (SPS) is a new semi-crystalline polymer under development by Dow Plastics. The material is completely different from conventional styrenics in structure, physical properties and synthetic method, and represents the basis for an entirely new family of materials based on crystalline polystyrene. SPS has a melting point of 270°C (520°F) combined with excellent resistance to moisture and automotive fluids. Additionally, SPS products exhibit exceptional electrical performance and competitive toughness and stiffness. A wide range of products have been formulated for specific applications including impact-modified and glass-reinforced grades. This paper was designed to discuss the performance attributes of SPS as they relate to use of this material in automotive, interconnect systems where a combination of heat resistance, chemical resistance, dimensional stability and enhanced processability are required.