FIBER SPINNING FROM THE NEMATIC MELT .1. COPOLYESTER OF POLY(ETHYLENE-TEREPHTHALATE) AND PARA-OXYBENZOATE

The copolyester of poly(ethylene terephthalate) with 60 mol % p-oxybenzoate units was spun with various capillaries using a constant shear rate at the wall. Variables examined were the length-to-diameter ratio of the capillary, the spin draw ratio, and the spinning temperature. Fibers spun at 260 degree C showed improved homogeneity of orientation through the cross section, better crystallite orientation, and higher initial moduli as was increased. The optimum spinning conditions may depend upon whether most of the orientation is introduced by shear in the capillary, or by a high spin draw ratio.