Synthesis and thermal characterization of poly(1,3‐phenyl octanoate)

Poly(1,3-phenyl octanoate) (polyHPOA) was prepared by melt and solution polycondensation methods from 8-(3-hydroxyphenyl)octanoic acid (HPOA), a novel monomer useful as a chain disrupter in liquid crystalline copolyesters. The melt polycondensation technique gave a polyester of higher inherent viscosity (0.80 dL/g in p-chlorophenol) than that (0.75 and 0.56 dL/g, respectively, for the Ogata method and thionyl chloride/pyridine method in the same solvent) of solution techniques. The solubility of the polyesters was limited to strongly acidic and polar solvents. The polyester was characterized by elemental analysis, IR spectroscopy, WAXD, TGA, isothermal TGA and DTA. x-ray diffraction pattern of the polyesters indicated that it is amorphous in nature. TGA of the polyesters gave a thermal stability of 470 degrees C in nitrogen atmosphere at 50% decomposition. The available thermal data suggest that the polyester undergoes thermal decomposition by a pyrolytic cleavage involving the ester linkage with the formation of ketene and phenol ended groups as intermediates. (C) 1996 John Wiley & Sons, Inc.