Kinetic studies of curing process and gelation of high performance thermosets based on ternary systems of benzoxazine, epoxy and phenolic resins

High performance ternary systems based on benzoxazine, epoxy novolac, and phenolic resins have been developed. The curing kinetics based on dynamic DSC results of this ternary system shows n-th order kinetics with an overall reaction order of 1.5 using modified Friedman approach. The apparent activation energy for the curing process of the resin is about I I I kJ/mol whereas that of the gelation process shows the value of about 75 kJ/mol. A choice of a resin used for the study provides maximum Tg of about 220 degreesC in its fully cured specimen comparing with other ternary mixture compositions. Tg-conversion relationship of this ternary system can be well-predicted using DiBenedetto equation. The use of phenolic-catalyzed benzoxazine resin as a curing agent for the epoxy novolac resin not only helps reduce the viscosity, thus improves processability, of the resulting resin mixture, but also provides a system with better thermal and mechanical integrity with high flexibility in resin/curing agent mixing ratios. The system has a potential use as high performance electronic packaging molding compounds or highly filled systems.