The properties of two series of thermotropic copolyesters

Abstract

Abstract Two series of copolyesters of sebacic acid, 4,4'-biphenol and a nonmesogenic rigid aromatic diol, bisphenol A (BPA series) or hydroquinone (HQ series), were used to investigate the effect of incorporation of a nonmesogenic rigid unit on their properties. The thermal transitions of these two series of copolyesters were determined by DSC in combination with their observation with a polarized light microscope. Their x-ray diffraction patterns at room temperature were also measured. The influences of these two nonmesogenic comonomers on the transition temperatures were found to be considerably different and were characterized by phase diagrams. The presence of the bisphenol A unit greatly destroyed the liquid crystalline behavior of the copolyesters due to the bending structure of bisphenol A unit. The presence of the hydroquinone unit destroyed the liquid crystalline behavior to a lesser extent. The x-ray diffraction data of the copolyesters at room temperature could be correlated with the total tra...