The transition zone for gelatin gels as measured by high-frequency rheology

The high-frequency (100 Hz-200 kHz) linear viscoelastic behaviour of gelatin in the transition zone was investigated. During the early stages of ageing, the dynamic shear modulus for a 4 wt% gelatin gel at the gel point at 25 degrees C was found to vary according to a power law G' proportional to G " proportional to omega(n), with n approximate to 0.75. Within the framework of a recent model by Groot et al. [J. Chem. Phys., 104, 9202 (1996)], this value is consistent with a result derived earlier from large deformation rheology, suggesting that the network bonds in a gelatin gel are more stretched than an ideally swollen polymer chain. However, ageing effects observed in large deformation experiments are not observed for the small deformation high-frequency data.