Abstract
Random copolyarylates containing about 80 mole% ρ-benzoate were synthesized by melt polymerization, using 4, 4′-diacetoxydiphenyl, 3, 4′- or 4, 4′-oxydibenzoic acid (mp or pp) and isoor terephthalic acid as comonomers. They formed optically anisotropic melts without thermal decomposition. The enthalpies of fusion (ΔH) estimated by DSC measurement showed higher values for the copolymers containing either mp or pp as a sole dibasic acid component and decreased with increasing the content of iso- or terephthalic acid in the copolymers. These copolymers were melt-spun and heat-treated under vacuum for several hours to yield high-strength and high-modulus fibers (tenacity 15_??_25g/d, initial modulus 500_??_800g/d). Tenacities of these fibers retained at elevated temperatures were not necessarily related to ΔH of the copolymers and fairly inferior to that of Kevlar®, but their flex fatigue endurances were somewhat superior.
