Rheological study of the isothermal reticulation of an epoxy resin

The complex modulus of shearing G * = G' + jG ″ was measured during the isothermal hardening of several epoxy resins. The gelation induces a slowing down of the rate of growth of viscous modulus ν ″ = d (log G ″)/ dt between two zones where this rate is constant. This slowing down of growth rate varies with the temperature and is null for T = T C gel : ν ″ 2 − ν ″ 1 = K (1/ T C gel −1/ T ). We have shown that the two phenomena of gelation and vitrification stay perfectly distinct at all temperatures and in particular at T C gel . So the decrease of the rate ν ″ associated with gelation disappears at this temperature without the vitrification being responsible.