Fracture Toughness of Vinyl Ester Composites Cured by Microwave Irradiation: Preliminary Results

The shrinkage of vinyl ester particulate composites has been reduced by curing the resins under microwave conditions. The reduction in the shrinkage of the resins by microwaves will make the manufacture of large vinyl ester composite items possible. The impact strength of the vinyl ester composite components cured under microwave was reduced only by 1% when tested by drop weight impact tests. The aim of this study is to investigate the difference in fracture toughness between microwave-cured vinyl ester particulate composites and those cured under ambient conditions. Short bar method of fracture toughness measurement was used to perform the tests. The results show that the difference in the fracture toughness is minimal between the ambient condition-cured and the microwave-cured samples, provided the power level and duration of microwave irradiation are properly and optimally selected.