Experimental study on mechanical properties of material extrusion additive manufactured parts from recycled glass fibre-reinforced polypropylene composite

This paper presents an optimised material extrusion (MEX) 3D printing method with feedstock produced from glass fibre reinforced polypropylene (GFRPP) composite waste and investigates the effect of glass fibre weight fraction (0%, 15%, 30%, 40%) on the printability and mechanical properties of filaments and printed specimens. GFRPP feedstock filaments were fabricated by optimising the filament extrusion process parameters. The highest ultimate tensile strength (112 MPa) was obtained in a filament with 40% fibre weight content. In addition, repeated recycling of filament was shown to reduce the fibre aspect ratio and enhance the filament quality. It was shown that the increase in glass fibre content from 0% to 40% improved the ultimate tensile strength of MEX 3D printed specimens from 14.7 MPa to 23.4 MPa as well as the flexural strength of MEX 3D printed samples from 11.68 MPa to 66.55MPa. The increase in fibre weight content from 30% to 40% had a minimal effect (+1%) on the ultimate tensile strength of the printed samples. In addition, the 40% filaments exhibited a more brittle behaviour, rendering them less suitable for MEX 3D printing than 30% GFRPP. The results showed that waste industrial GFRPP material can be effectively enhanced and converted to short fibre reinforced material extrusion filament feedstock for the printing of components as a circular economy demonstrator.