The interlaminar fracture behaviour of unidirectional carbon/epoxy composites has been studied under flexural loading by using end-notched flexure (ENF) specimens. GIIc Values were calculated as total fracture toughness energy at the maximum load sustained by the materials as the delamination extended. The results showed that high temperature moulding systems (XHTM45) have the highest GIIc values well above 1000 J/m2. For medium temperature systems (MTM) GIIc have also increased significantly after post cure. For compression strength after impact (CSAI), the behaviour to a certain extent is related to that found for GIIc tests. Comparison of the GIIc values with CSAI also indicated a relationship between two test results. SEM Micrographs revealed their excellent delamination resistance as good crack stoppers with the evidence of strong fibre/matrix interface. Dynamic mechanical analysis (DMA) indicated the increased Tg and modulus retention of the LTM and MTM prepregs after post curing at elevated temperatures. The failure mechanisms seem to be different for different tough matrix materials and appear to be strongly dependent on the cure and post-curing conditions. This is particularly noticeable for curing at 135°C and 80°C. of medium and low temperature moulding systems.
|Iranian Polymer Journal (IPJ)
|Published - 2003
- FRACTURE TOUGHNESS, CARBON/EPOXY COMPOSITE, DELAMINATION, COMPRESSION AFTER IMPACT, END-NOTCHED FLEXURE (ENF) TEST, UNIDIRECTIONAL FIBRE LAMINATE