Micrographs of the fracture of vinyl ester composites cured by microwaves: Pilot study

Short bar method of fracture toughness measurement was used to perform tests to find out the difference in fracture toughness between microwave cured vinyl ester particulate composites and those cured under ambient conditions [1-3]. The results show that the difference in the fracture toughness is minimal [5]. This paper presents the analysis of the fracture of the samples using a Scanning Electron Microscope (SEM). The fracture toughness of vinyl ester composites varies slightly after undergoing microwave treatment; it varies with different microwave power level and duration of exposure. The microscopic results show some important features such as brittle behavior, elongation of the fracture surface. The sample with lower fracture toughness is found to have more bubbles in the composite than those samples with higher fracture toughness. Therefore, the microwave power level and exposure time appear to correlate with the fracture toughness values obtained.