Investigação da capacidade de autorreparo de agente termoplástico em compósito carbono-epóxi

Abstract

Polymer matrix composites (PMCs) present an exponential growth in structural applications due to its distinct advantages such as high stiffness, strength, and low weight. Still, PMCs are susceptible to damage and degradation during service and environmental exposure. Repairing these structures may be costly and timeconsuming, for this reason alternative and promising approaches like adding thermoplastic agents to thermoset matrices emerged to extend PMCs service life. The aim of this study is to investigate poly (ethylene-co-acrylic acid) (EAA) as a self-healing agent in carbon/epoxy composites, where damage is introduced in the material by interlaminar shear strength (ILSS). Composite plates of carbon prepregs laminates were manufactured with hot press mold. Samples containing 10%wt of self-healing agent in the middle plan and prepreg only plates were compared. Thermal and mechanical analysis was employed in order to investigate self-healing capability by comparing properties before and after healing cycles. Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Dynamic mechanical analysis (DMA) results showed thermal stability of thermoplastic at working temperatures and slight changes in composite glass transition temperature (Tg) and stiffness with the addition of selfhealing agent. The addition of thermoplastic to the composite material also showed an 8% higher recovery of the interlaminar shear strength compared to the unmodified composite Interlaminar shear strength (ILSS). Fourier-transform infrared (FTIR) spectra indicate good interaction between thermoplastic and epoxy resin. Through the Scanning electron microscopy (SEM) images, it was verified: good adhesion between thermoplastic and epoxy resin, a possible plasticisation effect due to the presence of thermoplastic, and the different healing mechanisms occurring. All results obtained support the self-healing ability of the studied system.