1987 Volume 44 Issue 10 Pages 761-770
The effects of initiator type, concentration of initiator and molecular weight of oligomer were studied in the EB curing of bisphenol A diglycidyl ether type epoxy oligomer containing an onium initiator. Cured products of above 95% of gel contents were obtained from liquid oligomers with an onium initiator content of 0.05 mol/kg. For solid oligomers the final levelling-off gel content decreased with increasing molecular weight of the original oligomer. However, unreacted epoxide bonds still remained in the cured system, although the gel content had almost reached its maximum. The post effect of curing was observed the present system. After irradiation, the decay of epoxide bonds continues following first order reaction kinetics and the apparent rate constant is directly proportional to the preirradiation dose. Dynamic mechanical studies show that heat-treatment after room temperature irradiation gives the cured product of higher glass transition temperature and crosslinking density than those of the product cured with tertiary amine at elevated temperature.
