Percolation threshold and scattering power law of gelatin gels.

Gelation of gelatin was broadly studied by experimental and theoretical methods. Power laws observed on the gel point-mainly obtained by dynamic light scattering (DLS)-are considered to be the signature of some special dynamic phenomena ascribed to the appearance of a percolation cluster. We present here experimental (DLS and rheometric measurements) and Monte Carlo simulation studies showing that the percolation threshold and DLS power-law decay occur on different times. We ascribe the percolation point to the time where the scattering medium mode diverges. This mode is sensitive to the clusters' growth and diverges when the system attains the percolation threshold. The power-law behavior is obtained only in the postpercolation regime.