Advancing aircraft repair patch prepregs: enhancing composite performance through resin type, cure cycle, and nanomaterial innovations

This study investigates the effect of resin type, degree of cure and nanomaterial type in the aircraft repair patch prepregs for an improved patch performance. For this purpose, a new cure cycle has been developed for one type of resin, and two cure cycles have been implemented for 90% and over 95% cure degrees. Toughening agents were included in the other resin type. For an enhanced nano-integration in the four-component hot-melt epoxy at the industrial production line, a hybrid nano-integration method has been introduced. One- and two-dimensional nanomaterials (MWCNT, thermally exfoliated graphene oxide) have been utilized, DSC tests together with three-point bending tests are performed on nanocomposite specimens. Carbon fiber prepregs are produced from these two types of resin groups and CFRP panels are manufactured in the autoclave, later their specimens being subjected to short beam strength tests. CFRP panels produced from nano-integrated resin materials show a clear improvement in the stiffness values in both nanomaterial types. It was observed that CNTs enhance the ILSS of CFRPs in a more pronounced way (10%) than the case of toughened epoxy, while TEGO flakes lead to a higher increase in the strain at break (12.9%). Consequently, it can be stated that the choice of patch resin matrix requires a careful assessment of the cure cycle, additives, and nanomaterial type for the tailored performance of the composite structure.