SHEAR EFFECTS DURING THE GELATION OF AQUEOUS GELATIN

Measurements of the viscosity of aqueous solutions of gelatin at a wid e range of shear rates during and after gelation are presented. Althou gh the viscosity is shear rate dependent, experiments in which the she ar rate was changed during gelation show a shear rate history independ ence. This implies that shear does not disrupt intermolecular junction s between the gelatin molecules; i.e., the bond probability p is not a function of the shear rate gamma. Thus the viscosity is a function of p and gamma, i.e., eta = eta(p, gamma), with the important distinctio n that p and gamma act independently to determine the state of the sys tem.