Methyl cellulose

Maximum solubility in water is at the degree of substitution: 1.64-1.92. Soluble in alkaline solutions at lower degree of substitution, at higher degree of substitution the polymer is soluble in polar organic solvents. At low concentrations the polymer show thixotrophic behavior [1]. Below the gel point, the polymer exhibit pseudoplastic behavior [2]. When heated a solution of methyl cellulose gel, and melts again on cooling [3]. The mechanism is believed to be an improved hydration of the polymer on heating, thus weakening the structural integrity of the solvent [3]. Gelation does not occur in methyl celluloses with homogenous methylation. The gelling is enhanced with the formation of di- and tri-methylation, and it is the methylated regions that form the junction zones [3].

The viscosity is proportional to the concentration and is limited primarily by the hydration limits at higher concentrations. The viscousity is stable at pH 3-11. The viscousity of the polymer decreases with increasing temperature to a certain point, after which the viscousity increases sharply. This is dependent on the degree of substitution [1].