Post-curing effect on the mode I fracture toughness of the glass/epoxy laminates

The mechanical properties of polymer matrix composites are a function of their curing and post-curing temperatures. This research has experimentally investigated the effect of post-curing temperature on the mode I fracture toughness of glass/epoxy composites. For this purpose, double cantilever beam (DCB) specimens are fabricated using the wet lay-up assisted with vacuum bagging technique and post-cured under three different curing processes. The mode I fracture tests are carried out in two categories. The post-curing temperature remains constant for the first group of specimens while tests are conducted at three different elevated temperatures. In the second group of specimens, tests are performed at a constant temperature to evaluate the influence of three post-curing processes on the outcomes. The test results showed that increasing the post-curing temperature led to an upward trend in initiation and propagation fracture toughness. Additionally, the results indicated that as the test temperature increased, regardless of the curing process, both initiation and propagation fracture toughness also increased. Room temperature test results show that the post-curing process at 80 degrees C increased initiation and propagation fracture toughness by 20% and 15%, respectively, while the post-curing process at 100 degrees C improved these by 40% and 22%.