The Effect of Semi-Curing on Infused Laminate Interfacial Properties

Post cure joining operations and complex preform integration prior to resin infusion processes are two issues facing advanced composite manufacturing. A multistage cure process known as “Semi-curing” has the potential to remove post cure joining operations, inspect for quality as value is added to composite parts, and reduce the complexity of integrated structures. Semi-curing is a process whereby elements of an integrated structure are infused and semi/partially cured prior to integration into preforms comprising the remainder of the structure. Semi-cured laminates with elements initially cured to varying initial degrees of cure were manufactured and tested in mode I and mode II. Mode I testing showed interfacial properties to be broadly unaffected by the degree of cure of the semi cured element up to the gel point, only deteriorating thereafter, whereas in mode II, interfacial properties were retained at all degrees of cure. These results demonstrate the usefulness of the Semi-curing approach up until gelation.