【摘要】Rheological characteristics of cellulose solutions in N-methylmorpholine-N-oxide were studied at 90-120 degrees C in a wide range of compositions. The viscosity of solutions with concentrations c < 0.....全部展开
【摘要】Rheological characteristics of cellulose solutions in N-methylmorpholine-N-oxide were studied at 90-120 degrees C in a wide range of compositions. The viscosity of solutions with concentrations c < 0.18 wt. fract. obeys the laws characteristic of the solutions of flexible-chain polymers. It is shown that cellulose farms in solution a network of intermolecular contacts with a density much higher than that known in the solutions of flexible-chain polymers. This, together with increased rigidity of the cellulose backbone, leads to higher values of the modulus of elasticity. The cellulose solutions studied exhibited considerable broadening of the spectrum of relaxation times with increasing concentration. Cellulose solutions with c > 0.18 wt. fractions showed a considerable increase in the degree of structurization, which led to anomalous increase in the relaxation times, and the values of viscosity, activation energy for the viscous flow, and elastic moduli.收起