Rheology of Chitosan Solutions in 1-Ethyl-3-Methylimidazolium Acetate

The ionic liquid of 1-ethyl-3-methylimidazolium acetate ［EMIM］Ac is a good solvent for chitosan. Static and dynamic rheological properties of chitosan［EMIM］Ac solutions were investigated by a Hake MARSⅢ rotational rheometer. Results of static rheological properties show that the low molecular weight chitosan［EMIM］Ac solution is Newtonian flow fluid when the mass fraction is less than 3%, otherwise, it becomes pseudoplastic liquid. The shear viscosity and structural viscosity index decrease with the increasing of temperature. The viscosity of solution increases with the increasing of molecular mass of chitosan at the same concentration. The viscous activation energy at constant shear rate decrease with the increasing of shear rate. The results of dynamic rheological properties show that the storage modulus and loss modulus of the solution decrease with the increasing of temperature. There is a crossing point between the loss modulus curve and storage curve, and it moves to the high frequency area as the temperature increases.