Novel Miscible Polycarbonate/Copolyester Blends Having Optical-Grade Clarity and Their Upper Critical Solution Temperature Type Phase Behavior

摘要

Bisphenol-A polycarbonate (PC) is increasingly used as a homopolymer since it combines optical-grade clarity with toughness, rigidity, and high heat deflection temperature. However, drawbacks of PC such as poor resistance to solvent stress cracking and poor processability caused by its high melt viscosity often deterred its applications. Since one may achieve useful combinations of the advantages of each polymer into single product by blending, numerous studies related to the PC blends have been performed. Among these, PC blends with polyesters have been investigated extensively to overcome drawbacks of PC. From early investigations related to the PC blends with aliphatic polyester, it was concluded that miscibility occurred when the methylene content of polyester is approximately between two and seven methylene segments per ester group. Among these miscible blends, PC blends with polyester containing alicyclic structure are using commercially as optical grade. Even though miscible PC blends with semi-aromatic polyesters such as poly(1,4-dimethyl cyclohexane terephthalate) (PCT) and polyester based on 1,4-cyclohexanedimethanol/ terephthalic acid/iso terephthalic acid (PCDT) are miscible at processing temperature, it can not be used as optical grades because of the crystalline of PCT or PCDT.