STUDIES ON CO[POLY(ETHYLENE TEREPHTHALATE-P-OXYBENZOATE)] THERMOTROPIC COPOLYESTER (III) - MORPHOLOGICAL OBSERVATION BY POLARIZING MICROSCOPY

A series of co[poly(ethylene terephthalate-p-oxybenzoate)] thermotropic copolyesters with various compositions were prepared by the copolymerization of either poly (ethylene terephthalate) (PET) polymer or its oligomer as moiety (I) and p-acetoxybenzoic acid as moiety (II). A detailed description of the crystalline morphology of copolyesters with different compositions as well as under different preparation temperatures is discussed by using a polarized optical micrograph. It is found that the p-oxybenzoate (POB)/PET copolyesters with the POB moiety content above 60 mol % were shown to be highly anisotropic. It is also believed that the copolyester made from the PET oligomer (OET) as moiety (II) has shorter repeating units than that of the copolyester made from PET polymer (PET) in the main-chain structure. The solid-state polymerization may cause the randomization of two units due to a transesterification reaction that is examined by NMR spectroscopy analysis. Using the micrographs with different compositions, parallels between before and after the solid-state polymerization are contrasted. (C) 1993 John Wiley & Sons, Inc.