Comparison of rheological properties of kraft and microcrystalline cellulose dissolved in lithium chloride/N,N-dimethylacetamide

Rheological properties of microcrystalline and kraft cellulose dissolved in lithium chloride/N,N-dimethylacetamide solutions were characterized using an advanced rheometer. First, the effect of LiCl on the viscosity of DMAc (8%) at various temperatures was evaluated. Then the shear rheology of cellulose/DMAc/LiCl solutions was studied in a range of concentrations (0.25–2 wt%) and temperatures (25–80 °C). The solutions of kraft cellulose/LiCl/DMAc behave as non-Newtonian liquids and its viscosity is dependent on the shear rate. The Newtonian flow was recorded for the microcrystalline cellulose/LiCl/DMAc solutions. The viscosity values of these solutions were analyzed in detail for viscosity-concentration and viscosity-temperature. The viscosity of the solutions increased with the increase in solution concentration. The heightening of the solution temperature reduced the viscosity of the solutions. The activation energy of the dissolved kraft cellulose was calculated from the Arrhenius approximation within a concentration range of 0.25–2 wt%, and then compared with that of the microcrystalline cellulose.