Diffusion of the Solvent and Forming Process of Fiber in the Wet Spinning of Acrylonitrile Copolymer.

Abstract

The dope, which consisted of Acrylonitrile (AN)-Methylacrylate (MA) copolymer (AN/MA=90/10wt%, Mw=15.9×104) dissolved in 58wt% aqueous NaSCN, was casted into film and coagulated with a dilute aqueous NaSCN solution. Diffusion of solvent (NaSCN) was measured under various coagulation conditions. During coagulation the diffusion coefficient D of NaSCN in proto film increased with the coagulation temperature but decreased with the NaSCN concentration of coagulant and polymer concentration of the dope. The coagulation became fast with the increase of diffusion of solvent and concomitantly the microstructure of gel became rough. The apparent activation energy was 5.2kcal/mol. Using the diffusion coefficient obtained above, the time necessary to complete the coagulation throughout wet spun fiber was estimated, which gave satisfactory coincidence with observation of fiber obtained by the two stepwise wet spinning process.