Determination of the Diffusion Coefficient of H2O in Polyacrylonitrile Fiber Formation

Abstract

An H2O/dimethyl sulphoxide (DMSO) mixture was used as the coagulation bath of a wet-spun process. The diffusion coefficient of H2O in the protofibers prepared by acrylonitrile homopolymers was determined. It was found that the diffusion coefficient of H2O in the protofibers prepared by homopolymers synthesized by solution polymerization was highest compared with those of homopolymers synthesized by H2O/DMSO mixture suspension polymerization and aqueous suspension polymerization. With an increase of polyacrylonitrile concentration in the dope, the diffusion coefficient of H2O decreased continuously. The diffusion coefficient of H2O increased along with the bath temperature, but the changes of diffusion coefficient values were less prominent as the temperature went beyond 60 ○C. When the DMSO concentration in the coagulation bath was 55%, the value of the diffusion coefficient of H2O was minimal. The diffusion coefficient of H2O increased with increasing jet stretch minus ratio. When the protofiber radius was increased, there was a corresponding increase of the diffusion coefficient of H2O.