Concentration Dependence of Mechanical Properties of Gelatin near the Sol-Gel Transition Point

Abstract

The concentration dependence of mechanical properties for gelatin near the sol-gel transition point was analyzed by the scaling law derived from the percolation theory, and compared with the results previously obtained for polyacrylamide. The critical concentration at the sol-gel transition point, φ_g, was estimated from the concentration (φ) vs. the reciprocal of viscosity (η) plots by extrapolating 1/η to zero. The critical exponent for sol viscosity, s, was estimated from the slope of a log(φ_g-φ) vs. log η plot. The critical exponent s was about 1.1, being larger than the value predicted by the percolation theory assuming the superconductor model. The critical exponent for gel elasticity, t, was estimated from the slope of a log(φ-φ_g) vs. log G' plot, where G' is the dynamic shear modulus at a frequency of 2 Hz. The critical exponent t was about 2, being similar to the value predicted by the percolation theory.