Gelation of an epoxy resin and percolation theory

Abstract The percolation theory has been applied to the isothermal hardening of the TGDDM‐DDS system (tetraglycidyldiaminodiphenyl‐methane‐diaminodiphenylsulfone). At each temperature, the variations of viscosity as a function of the extent of reaction are well described by a percolation law. The variations of the critical threshold and of the percolation parameter with temperature may be explained by a modification of the reaction mechanism. The percolation threshold is in agreement with the gel point defined on the experimental curves of the logarithm of loss modulus as a function of time log G″ = f(t).