Study On The Dissolution And Spinning Of Cellulose/Chitosan In Ionic Liquids

Ionic liquid is a new kind of green solvent. Study on the dissolution and spinning ofcellulose/chitosan in ionic liquids so as to prepare cellulose/chitosan fiber which contains boththe property of cellulose fiber and chitosan fiber. It could fully utilize the natural resource,increases the sorts of differential textile fiber industrial material in our country, which have animportant theoretic and practical significance.In this thesis, the dissolution of chitosan in four kinds of ionic liquids:1-butyl-3-methylimidazolium acetate([BMIM]Ac),1-ethyl-3-methylimidazoliumacetate([EMIM]Ac),1-butyl-3-methylimidazolium chloride([BMIM]Cl),1-ally-3-methylimidazolium chloride([AMIM]Cl), and the degradation of cellulose in the fourkinds of ionic liquids were studied firstly. Then the rheological property ofcellulose/chitosan/[EMIM]Ac solution were studied carefully, and the cellulose/chitosanblend fiber wre prepared by wet spinning method successfully. The main results of the thesisare as follows:The low molecular weight chitosan could get more than15%(w/w) solution in[EMIM]Ac at100℃. The thermal stability of chitosan regenerated from water and methanolwas increased, while it was decreased from ethanol. The crystal morphology of regeneratedchitosan was changed from α-type to β-type.The degradation of cellulose in [EMIM]Ac is the lowest and in [AMIM]Cl is the highestfor four kinds of ionic liquids. Temperature is the most important factor affecting thedegradation of cellulose in ionic liquids, and propyl gallate can reduce the degradation ofcellulose in ionic liquids. The optimum dissolution condition for cellulose in [EMIM]Ac is:80℃,230r/min, and1hour.The low molecular weight chitosan/[EMIM]Ac solution shows Newtonian fluidcharacteristics when the mass fraction is less than3%, otherwise, it becomes pseudoplasticliquid.The viscosity of cellulose/chitosan/[EMIM]Ac solution decreases with increasing ofchitosan content, and the rheological properties of solution is in line with Cox-Merz rule.There is a cross point of loss modulus(G”) curve and storage modulus(G’) curve, and it shifts to the higher frequency range with increasing of temperature. The zero shear rate viscousactivation energy of solution is about52.1to62.5KJ/mol, calculated from the Cross andArrhenius equation, which is similar to that of cellulose/N-methylmorpholine-N-oxidesolution. However, the structural viscosity index of the solution is smaller than that ofcellulose/[EMIM]Ac solution. All these means that the cellulose/chitosan/[EMIM]Ac solutionhas a potential spinnability.The tenacity of resulted cellulose/chitosan blend fiber from spinning experiments were2～4dtex, and the breaking tenacity were2.6～3.3cN/dtex, which shows the betterproperties than that of viscose staple fiber. The surface and cross-sectional of blend fiber arehomogeneity.