Compressive behaviors of 3D printed polypropylene-based composites at low and high strain rates

3D-printed composites have promising potential for applications as structural or functional parts in different engineering fields. However, due to the presence of pores and weak interface interactions, 3D-printed parts have weaker mechanical performance than traditional processed ones. In recent years, polypropylene (PP) emerged as a new 3D printing material with enormous potential. In this work, two PP-based composites (PP/EPR(ethylene-propylene-rubber) and PP/EPDM(ethylene-propylene-diene-monomer)/talc) were chosen to study the effects of extrusion temperature and layer thickness on the quasi-static and dynamic behavior of 3D-printed PP-based composites. The results obtained in this study indicated that the processing induced voids have a significant impact on the mechanical properties of printed specimens as they could cause stress concentration and trigger crack propagation. A smaller layer thickness and a moderate printing temperature could reduce pore size and porosity in the printed parts and consequently increase their mechanical properties. Compared to the response under quasi-static loading, the apparent strength and modulus for both materials under dynamic compression were much higher. Under impact loading, polypropylene-based composites exhibited different rupture characteristics caused by the different reinforcement.