Abstract
Poly p-phenylene-3, 4'-oxydibenzoate) (I), poly (p-phenylene-3, 4'-carbonyldibenzoate) (II) and random copolymers of I and II were prepared by melt polymerization and their thermal properties were studied by differential scanning calorimetry (DSC). All these polyarylates were crystalline and the melting temperatures of copolymers monotonously increased with increasing the content of II. DSC data suggested that these copolymers were isomorphous. The polymer-II and the copolymers containing more than 50 mole% II component were found to form optically anisotropic melts. The melt-spun and hot-drawn polymer-I and the as-spun polymer-II were heat-treated under vacuum for several hours in order to improve the mechanical properties of fibers. The following tensile properties were observed for the fiber from the polymer-I; tenacity (T)=9.7g/d, elongation(E)=2.7% and initial modulus (Mi)=364g/d, and for the polymer-II; T=10.6g/d, E=1.6% and Mi=671g/d, respectively. Fiber identity periods of polymers I and II and copolymer I/II (30/70) were estimated to be ca. 17.1Å from X-ray diffraction data. This indicated that the molecular chain fully extended along the fiber axis.
