Diffusion Dynamics of Ionic Liquids During the Coagulation of Solution Spinning for Acrylic Fibers

摘要

The coagulation dynamics of acrylic polymer (PAN) with 1-butyl-3-methylimidazolium chloride [BMIM]CI as solvent for PAN and H2O as nonsolvent was investigated in detail.On the basis of Fick's second law of diffusion,a mass-transfer model of [BMIMJCI from concentrated PAN/[BMIM]CI solution was established as verified with the experimental data.The established model has a good fit with the experimental data and the diffusion coefficient D of [BMIM]CI was calculated according to the model.The diffusion coefficient D decreased a little when the concentration of solution increased.As increasing the coagulation bath concentration,the diffusion coefficient D initially increased and then decreased,reaching a maximum of 5 wt% in the coagulation bath.The diffusion coefficient D decreased with the coagulation bath temperature.From the diffusion coefficient and the structure of the coagulated filament,it can be concluded that the diffusion rate of [BMIM]CI from PAN concentrate solutions is relatively slow,which is prospective to prepare uniform-structure fibers.