Thermal aging influence on the damage mechanisms of fully recycled composite‐reinforced polypropylene/polyethylene blend

The main aim of this work is to study the effect of thermal aging on damage mechanisms of a totally recycled composite. The studied material was elaborated by injection molding from a mixture of both recycled matrix (polypropylene‐polyethylene blend) and reinforcement (short carbon fibers). Damage mechanisms analysis was carried out using scanning electron microscope (in situ three point bending tests performed on specimens taken at different times of oxidation under different temperatures: 120, 130, and 140°C. Damage mechanisms were identified for different material states. It was shown that thermal aging affects the fiber–matrix interfacial zone while good adhesion between the reinforcement and the matrix was observed for the virgin sample. Furthermore, a quantitative analysis was performed at the local scale in a representative zone of the tensile area. Representative local damage indicators were defined. Results display clearly that damage evolutions always begin during the induction period. Thermal aging effect was then analyzed through the comparison of damage thresholds and kinetics for different material states after different times of oxidation. POLYM. COMPOS., 40:3342–3350, 2019. © 2019 Society of Plastics Engineers