Thermal properties of films and solutions of cellulose sulfate acetate salt forms

Different salt forms of cellulose sulfate acetate with Li⁺, Na⁺, K⁺, and Ca²⁺ as compensating cations were synthesized by ion exchange reaction. Thermogravimetric (TGA) and differential thermal analyses (DTA) of cellulose sulfate acetate samples were performed in the temperature range of 15-300°C. An endothermic effect (85-95°C) due to sample dehydration and an exothermic effect (197-250°C) due to the thermooxidative degradation of cellulose sulfate acetate were detected on TGA and DTG curves for all samples. It was shown that the thermal stability of cellulose sulfate acetate films regularly increases with size and charge of counterions. It was assumed that the amenability of cellulose sulfate acetate salt forms to lyotropic mesomorphism is determined by the structure of water in the close environment of compensating counterions.