The thickening effect of cellulose ether depends on: the degree of polymerization of cellulose ether, solution concentration, shear rate, temperature and other conditions. The gelling property of the solution is unique to alkyl cellulose and its modified derivatives. The gelation properties are related to the degree of substitution, solution concentration and additives.
For hydroxyalkyl modified derivatives, the gel properties are also related to the modification degree of hydroxyalkyl. For MC and HPMC with low solution concentration and low viscosity, 10%-15% concentration solution can be prepared. Medium viscosity MC and HPMC can prepare 5%-10% solution while high viscosity MC and HPMC can only prepare 2%-3% solution. Usually, the viscosity classification of cellulose ether is also graded by 1%-2% solution.
High-molecular-weight cellulose ether has high thickening efficiency, and polymers with different molecular weights have different viscosities in the same concentration solution. The target viscosity can only be achieved by adding a large amount of low molecular weight cellulose ether. Its viscosity has little dependence on shear rate. To achieve the target viscosity with high viscosity, less dosage is required, and the viscosity depends on the thickening efficiency.
Therefore, to achieve a certain consistency, a certain amount of cellulose ether (concentration of the solution) and solution viscosity must be guaranteed. The gel temperature of the solution also decreases linearly with the increase of the concentration of the solution. And gels at room temperature after reaching a certain concentration. The gelling concentration of HPMC is relatively high at room temperature.
Comprehensive Analysis of Thickening and Thixotropy of Cellulose Ether(2)