Dissolving And Spinning Of Cellulose In Ionic Liquids

As a species of highly promising green solvent in recent years, ionic liquids have opened up a new research area of cellulose solvent systems. 1-N-Butyl-3-methylimidazolium chloride ([BMIM]C1) was selected as the solvent for the dissolution and spinning of cellulose.First, the dissolution experiments were carried out in the blender with vacuum system. Several factors which influence the dissolution process including cellulose concentration, time and temperature were discussed respectively. The relationship of dissolution time and torque moment was introduced to establish the direct criteria for continuous dissolution. In addition, the influences of dissolution conditions on cellulose degradation were studied according to the variation of degradations of polymerization. Degradation occurred simultaneously in the dissolution and mainly in the initial dissolution process. However, the degradation degree could be controlled by the dissolution dynamic conditions, which was helpful to develop the continuous technology for the clean process of cellulose fibres.The diffusion dynamics of [BMIM]C1 during coagulation process of cellulose fiber with H₂O as nonsolvent was investigated. Based on the diffusion dynamics model, the diffusion rate of [BMIM]C1 from concentrated cellulose filament during coagulation was simulated. The results had a good fit with the experimental data. Several factors which affect the coagulation process including polymer concentration, concentration and temperature of coagulation bath were discussed respectively.The dry-wet spinning experiments were conducted with [BMIM]C1 as solvent and water as non-solvent so that the cellulose fiber with uniform surface was obtained. With the draw ratio increases, the orientation, crystallinity and breaking tenacity increase at first and then decrease while these properties are at the maximum with the draw ratio of 3.2. The crystalline orientation of the cellulose fiber is 0.83 with the draw ratio of 3.2 and the crystallinity is 57.2%. The tensile strength is 1.73cN/dtex and the elongation at break is 7.41%.