Process for making para-aramid fibers having high tenacity and modulus by microwave annealing

摘要

A process is disclosed for heating never-dried para-aramid fibers containing 20 to 200 wt % water, based on dry polymer weight to form a fiber having a modulus of greater than 800 gpd while retaining a high tenacity. The fibers are heated in one or more microwave resonant cavity applicators to a temperature of 250° C. to 425° C. and preferably 270° C. to 310° C. while under a tension of 0.2 to 10 grams per denier. The preferred para-aramid is poly(p-phenylene terephthalamide). Fibers having a density of less than 1.43 g/cc can be made; and fibers having moduli greater than 1100 gpd can be made.