PREPARATION AND CHARACTERIZATIONS OF THERMOTROPIC COPOLYESTERS OF P-HYDROXYBENZOIC ACID, SEBACIC ACID, AND HYDROQUINONE

A series of copolyesters of p-hydroxybenzoic acid (HBA), sebacic acid and hydroquinone were prepared by melt polycondensation of p-acetoxybe nzoic acid, sebacic acid and p-phenylene diacetate. The copolyesters w ere characterized by IR, NMR, DSC, polarized microscopy, and X-ray dif fraction. It was found that the copolyesters exhibited liquid crystall inity when the HBA content was 25-67 mol %. The copolyesters with an H BA content of 25-43 mol % showed a nematic phase and a biphasic range, and the isotropization temperature increased as the HBA content incre ased. The copolyesters with an HBA content of 54-67 mol % showed a nem atic phase up to above 400 degrees C. The liquid crystalline order inc reased as the HBA content increased due to the increase of the average length of the rigid moieties. (C) 1995 John Wiley and Sons, Inc.