Interlaminar properties of carbon fibre/epoxy laminates produced through a semi-curing process

The performance of semi-cured laminate interfaces with degrees of cure ranging from 0.3 to 0.9 was explored in Mode I and II, and compared to a baseline laminate produced through a single infusion and cure. The results showed that if the initially semi-cured element is kept to a degree of cure below the gel point prior to integration with the rest of the structure, average Mode I properties are retained to within 10 % of the baseline. At degrees of semi-cure above the gel point, a 33 % reduction in Mode I was measured, however, plasma pre-treatment mitigated this reduction to only 11 %. In Mode II, interlaminar properties are fully retained. Over the wide range of semi-cure studied, both resin flow and chemical cross-linking were observed, with the latter viewed as being more important when seeking to retain interfacial properties. The semi-curing process is considered a viable manufacturing method to produce composite laminates by resin infusion.