The Kinetics of Gelation of Some Accelerated Acid Anhydride Cured Epoxy Resins

The gelation kinetics of two epoxy resin systems (difunctional and tetrafunctional) cured with acid anhydrides was determined as function of time, temperature, and accelerator concentration by means of viscosity and gel time measurements. The activation energies for the initial viscosity and for the gelation process were calculated using an Arrhenius type equation. A simple reciprocal relationship between the gel time, determined by Tecam gel timer, and the gelation rate that was independent of temperature and acclerator (at low accelerator levels) was established. Equiviscosity curves were plotted by computer over the viscosity range of 102 to 105 centipoises and gelation time up to several thousand hours.