Peptization of Aluminum Soap Gel. I

In order to elucidate fundamental problems regarding preparations using aluminum soap, macrorheological examinations were made on the peptization of aluminum distearate-Nujol gel in concentrations used in preparations. Dependence of shear thixotropy on the concentration of various additives was examined by the improved McMichael viscosimeter and the result indicated that peptization decreased B coefficient of thixotropic breakdown with time. From the mode of this variation, this peptization was classified specifically into one kind of unpeptization type and three kinds of peptization type. At the same time, the same classification was derived from variation in equilibrium plastic viscosity. The optimal peptization concentration was at equimolar ratio of Al (OH) (OOCC17H35)2 and the equilibrium plastic viscosity markedly decreased at that concentration to show the minimum value. Compounds which act as a peptizer are those having free hydroxyl, carboxyl, or amino group, and they showed characteristic peptization type. The peptizer of hydroxyl system caused spinability in the gel and then a marked viscoelasticity, such as the Weissenberg effect. The foregoing phenomena were considered to be due to interaction between macromolecular micelle of aluminum stearate and peptizer compound, resulting in the severing or rearrangement of the micelle and destruction of gel in a network.