Effect of salts on the formation and properties of microcrystalline cellulose and chitosan gels 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Abstract

Abstract The difference in the effect of salts on the formation and properties of gels based on microcrystalline cellulose (MCC) and microcrystalline chitosan (MCCh) was investigated. Bleached sulphate pulp from wood and chitosan obtained from exoskeletons of crustaceans served as raw materials. These were destructed by a thermocatalytic method to the levelling-off degree of polymerisation and then dispersed in solutions of different salts. At a sufficiently high concentration, gels with a liquid crystalline structure were formed. For MCC, the gels are stronger when the dispersion solution contains polyvalent cations, which decrease the negative charge on the cellulose surface caused by the carboxyl groups present there. As a result, the mutual repulsing forces between the cellulose particles decrease and the lattice formed by them becomes stronger. For MCCh, strong gels with a great viscosity are formed when the dispersion solution contains polyvalent anions, which decrease the positive charge on the chitosan surface caused by amine groups. The effect of salts depends also on their concentration in the solution.