The gelation behavior of chitosan in an alkali/urea aqueous solution was studied by means of rheology, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The sol-gel transition temperature of the chitosan alkaline solution strongly depends on chitosan concentration and heating rate. The equilibrium sol-gel transition temperature, T_c, which was obtained by an extrapolation method based on multiwave oscillation, decreases with increasing chitosan concentration, and could be fitted to a parabolic equation, T_c = −4.1 + 48.0w - 11.5w², where w is the weight fraction of chitosan in the alkaline aqueous solution. At the sol-gel transition point, the relaxation behavior shows a strong dependence on kinetics and the equilibrium critical relaxation exponent n_e decreases as chitosan concentration increases. The FESEM images verified that the chitosan gel is formed as a fibrillar network and the fibrillar network is denser at a higher polymer concentration or a lower heating rate, leading to an irreversibility of the sol-gel transition of chitosan in the alkaline aqueous solution. A schematic diagram has been proposed to describe the change of gel network structure with chitosan concentration.

通过流变学，X射线衍射（XRD）和场发射扫描电子显微镜（FESEM）研究了壳聚糖在碱/脲水溶液中的胶凝行为。壳聚糖碱性溶液的溶胶-凝胶转变温度很大程度上取决于壳聚糖的浓度和加热速率。通过基于多波振荡的外推法获得的平衡溶胶-凝胶转变温度T _c随着壳聚糖浓度的增加而降低，并且可以拟合为抛物线方程，T _c  = -4.1 + 48.0w-11.5w ²，其中w是壳聚糖在碱性水溶液中的重量分数。在溶胶-凝胶转变点，松弛行为表现出对动力学的强烈依赖性，并且平衡临界松弛指数n _e随着壳聚糖浓度的增加而降低。FESEM图像证实，壳聚糖凝胶形成为纤维状网络，且在较高的聚合物浓度或较低的加热速率下，纤维状网络更致密，从而导致了碱性水溶液中壳聚糖的溶胶-凝胶转变不可逆。已经提出了示意图来描述凝胶网络结构随壳聚糖浓度的变化。