Diffusion dynamics of 1-Butyl-3-methylimidazolium chloride from cellulose filament during coagulation process

The diffusion dynamics of 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl) during coagulation process of cellulose filaments with H2O as non-solvent were investigated in detail. The diffusion coefficients of [BMIM]Cl was calculated based on the Fick’s second law of diffusion according to the experimental data. Several factors which affect the coagulation process including polymer concentration, concentration and temperature of coagulation bath were discussed respectively. It is found that the diffusion rate of [BMIM]Cl decreased with the increasing polymer content in the spinning solutions and the initial concentration of [BMIM]Cl in the coagulation bath, while the diffusion coefficients increased largely with the coagulation temperature becoming higher. The diffusion coefficients of [BMIM]Cl is relatively lower, in contrast with the conventional solvent in the solution spinning process, which is coordinate with the result of polyacrylonitrile [BMIM]Cl system by Zhang et al. (Polym Eng Sci 48(1):184–190, 2008). Compared with the diffusion process of N-methylmorpholine-N-oxide (NMMO) from cellulose filament, the diffusion coefficients of [BMIM]Cl is lower, which suggested a stronger coagulation and washing conditions should be taken to produce regenerated cellulose fiber with [BMIM]Cl as solvent.