Epoxy networks modified by unsaturated oligoesters and acrylates or methacrylates

We have studied the formation of networks on the basis of an epoxy resin ca lled ED-20, the same resin modified with tert -butylhydroperoxide (called E D-20P), unsaturated oligoesters and polyethylenepolyamine in the presence o f acrylates and methacrylates at 20 degrees C, 100 degrees C and 130 degree s C. The gel-fraction contents in the blends and the pendulum damping hardn ess of films made from the blends have been determined. The progress of gel ation has been related to the composition, time and crosslinking temperatur e. The presence of peroxide groups enhances the extent of gelation. When th ose groups are present, acrylates and methacrylates provide still higher va lues of the ultimate gel fractions, acting as diluents ( lowering viscosity of the initial blends) and simultaneously as crosslinking agents. The pedu lum damping hardness tests for organic films performed as a function of tim e provide results parallel to those obtained by the gel fraction determinat ion via Soxhlett extraction with acetone. Thus, both methods can be used to pursue the progress of gelation.