Elastic properties at the sol-gel transition

We study the elasticity behaviour at the sol-gel transition with a percolation dynamic model via computer simulations on a square lattice. From the fluctuations in the center-of-mass motion of the percolating cluster we determine the critical behaviour of the macroscopic elastic constant of the gel phase, growing above the gel point with a critical exponent mu similar or equal to 2.7 +/- 0.1. We also study time autocorrelation functions and find that the relaxation times diverge, as the percolation threshold is approached from below, with a critical exponent s similar or equal to 1.9 +/- 0.1.