Addition of poly (ethylene-co-acid-methacrylic) (EMAA) as a self-repair agent in carbon-epoxy composites
Composites, carbon-epoxy, self-healing, poly(ethylene-co-methacrylic acid).
Self-healing techniques in epoxy resins have been developed to improve the life-span and reduce costs associated with repairs of these materials during service. The addition of thermoplastics into the thermoset matrix producing mendable resins appears as a promising self-healing technique. In this study, poly(ethylene-co-methacrylic acid) (EMAA) was added to carbon fiber-epoxy composites to produce a self-healing system. Specimens with different percentages of thermoplastic were manufactured and interlaminar shear strength test (ILSS), dynamic mechanical analysis (DMA), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and field-emission gun scanning electron microcopy (FEG-SEM) were employed in order to evaluate the effect of the addition of the thermoplastic to the composite and its behavior before and after a healing cycle. The healed samples had similar mechanical properties to the properties presented by the samples before healing. However, for higher percentages of EMAA, there was a reduction of these properties, besides a reduction of Young’s modulus and Tg, in relation to the values presented by the unmodified composite. SEM images confirmed the strong adhesion between EMAA and epoxy resin, producing an adhesive layer that prevented the formation of delamination in the mid-plane of the laminate.