Material property characterization of 3D printed polypropylene wood plastic composites

Wood flour (WF) at 10 wt.% and 20 wt.% loadings was used as a reinforcing filler to enhance the applicability of polypropylene (PP) for 3D printing. After performing printability tests of PP wood plastic composites (WPCs), the mechanical properties of both injection-molded and 3D-printed PP WPC specimens were explored. Test specimens were prepared from 3D printed hexagons for analyzing the mechanical properties. Adding WF to neat PP increased the storage modulus and the glass transition temperature while decreasing the degree of crystallinity and the coefficient of thermal expansion, while enhancing the printability of neat PP. The tensile strength, tensile modulus of elasticity, flexural strength, and flexural modulus of elasticity of injection-molded neat PP improved by up to 21%, 59%, 30%, and 56%, respectively, with 20 wt.% WF. However, the impact strength of injection-molded neat PP decreased by 85%, with 20 wt.% WF. After 3D printing, the tensile strength and tensile modulus of elasticity of printed neat PP increased by up to 84% and 60%, respectively, with 20 wt.% WF. The flexural strength and flexural modulus of elasticity of neat printed PP remained unchanged compared to those of PP filled with 20 wt.% WF, while the impact strength decreased by 87%. Highlights WF was used as a reinforcement in polypropylene designed for 3D printing A pilot-scale, pellet-fed 3D printer was used to print hollow hexagons, and then test specimens were fabricated from these hexagons for mechanical properties The tensile and flexural properties of 3D printed neat polypropylene improved, while the impact strength decreased after adding 20 wt.% WF to the neat PP.