Rheological behaviors of cellulose/[BMIM]Cl solutions varied with the dissolving process

Cellulose/1-butyl-3-methylimidazolium chloride ([BMIM] Cl) solutions were prepared with different dissolving process including static state, mechanical stirring and kneading. Rheological measurements were employed to investigate the effect of dissolving process on the rheological behavior. It is found that the solutions prepared by static state showed the largest zero shear viscosity and relaxation time. From temperature sweep profiles, the temperature dependence of viscoelasticity on the three solutions followed the gel transition phenomenon with the characteristics of physical gels proposed by Winter et al. Further investigation showed that dissolving process had effects on the gel transition temperature. Solutions prepared by static state showed the highest gel transition temperature, whilst those prepared by kneading had the lowest. This indicates significant differences occurring in the structuralization of solutions prepared by different dissolving process. The SEM images of films regenerated from kneading solution exhibited a dense and homogeneous morphology while films prepared by static-state dissolving process were loose with coarse aggregation, which is consist with the deduce from the rheological results.