Effect of coagulation temperature on the properties of poly(acrylonitrile-itaconic acid) fibers in wet spinning

A dimethyl sulfoxide (DMSO)-water system was used as the coagulation bath in the wet-spun process for poly(acrylonitrile-itaconic acid) fibers. The coagulation bath concentration of DMSO was kept constant at 65%, and the jet stretch ratio was 1. The coagulation bath temperature was varied from 40 to 70 degrees C. The properties of the fibers so obtained were investigated. The diffusion coefficient of solvent was calculated and the concentration profiles of solvent in a moving filament were computed by using a MOL (method of lines) method. The nascent fibers coagulated at 50 degrees C obtained a circular symmetrical cross section with high density and strength. The diffusion coefficients of solvent (DMSO) increase with the bath temperature increase. Simulation results show that the noncircular cross section form was the response of the rapid diffusion rate and the loose structure in the core of nascent fibers was caused by the overmuch remained solvent.