In situ interlaminar shear behavior of carbon fibers reinforced polymer composites exposed to severe thermal aggressions: PPS versus epoxy laminates

Abstract

This study investigates the influence of a combined thermal heat flux and a flexural loading on the interlaminar shear behavior of quasi-isotropic carbon fibers reinforced PPS and Epoxy laminates. Regardless the intensity of the heat flux (ranging from 20 to 50 kW/m2), the maximum surface temperature is higher than the onset of thermal decomposition [Formula: see text] in C/Epoxy laminates ([Formula: see text]) whereas the thermal decomposition is reached only for 40-50 kW/m2 heat fluxes in C/PPS laminates ([Formula: see text]). A mechanical bench was specifically designed to study the interlaminar shear behavior of polymer-based laminates during the thermal aggression (imposed by a cone calorimeter). In C/PPS laminates, with respect to the reference values (as received state), the flexural modulus and the apparent ILSS (under 50 kW/m2) decreases by about 80%. In C/Epoxy laminates, with respect to the reference values (as received or virgin state), the flexural modulus and the apparent ILSS (under 50 kW/m2) decreases by about 20% and 50%, respectively. In carbon fiber-reinforced polymer materials, the matrix state is crucial for preserving the cohesion of the fibers network and the bonding of the plies together, a role that seems compromised in C/Epoxy and C/PPS laminates under high heat flux conditions, once the pyrolysis of the matrix has severely degraded the interlaminar properties of the material.