Gelation of aqueous gelatin solutions. II. Rheology of the sol-gel transition

Abstract

We have studied the rheological behaviour of aqueous gelatin solutions during the gelation process at several temperatures. The linear viscoelastic regim was investigated by dynamical measurements in the frequency range 0.01 Hz to 1.5 Hz, using a Weissenberg rheogoniometer. The relation between the shear moduli and the helix amount at several temperatures puts into evidence that this structural parameter pilots the gelation process. Analysing the rheological data, we propose a method of deriving the gel point, which could be used for other systems. Finally we show that gelatin gelation can be interpreted within the framework proposed by de Gennes and Stauffer of the percolation theory. The exponents for the static viscosity and the relaxed shear modulus are in agreement with the 3d predictions.