Shape memory polymer composites by molding aeronautical prepregs with shape memory polymer interlayers

Carbon-fiber-reinforced (CFR) and shape-memory polymer (SMP) composites have been manufactured by molding commercial prepregs used for aeronautical structures. These prepregs typically do not show any shape memory behavior as they consist of CF fabrics impregnated with high performance epoxy resins. In the current study, shape memory (SM) properties have been added by using uncured SMP interlayers during the prepreg lamination, and following co-curing of the laminate layers. A new test has been adopted to quantify SM properties of final CFR-SMP laminates. A full thermo-mechanical cycle is applied to the composite samples during bending and shape fixity, shape recovery and frozen stresses data are extracted. By means of this test, the effect of the number of plies on the SM behavior of composite laminates has been studied. Furthermore, dynamic mechanical analysis and dimensional observations have been carried out to understand the physical phenomena at the basis of the laminate behavior. Results show that manufacturing of CFR-SMP composites is feasible also by using available commercial products, and final laminates are able to combine strength and stiffness of traditional aeronautical composites with the functionality of SMP materials.