In the mix: The effect of wood composition on the 3D printability and mechanical performance of wood-plastic composites

Abstract

The material composition of 3D printed elements has enormous influence on the qualities of the final product – it is decisive in determining the mechanical performance, aesthetic appearance and sustainability of a product and as a result, on its marketability and the range of possible applications. This paper presents how sawdust, a by-product of the forest industry, can be valorised as a component of Wood-Plastic Composite (WPC) to manufacture 3D printed elements that are semi-green and suitable for architectural applications. Specifically, the study investigates two common types of Australian hardwood, Red Gum and Grey Box, and the effects that the variation of the wood compositions have on the mechanical properties of 3D printed WPCs in terms of wood species, particle size and shape distributions, and the wood to plastic ratio in the composite. WPC filaments were extruded from a mixture of wood flour, Acrylonitrile Butadiene Styrene (ABS) and maleic anhydride. Tensile specimens were 3D printed from the manufactured WPC filaments. The results show that wood particles with rounder shapes and smoother surfaces increase the strength, stiffness and density of 3D printed WPCs due to the better adhesion of these shaped wood particles with the polymer. A higher wood to plastic ratio creates a ‘greener’ product with improved stiffness. The ‘double extrusion’ process, used in this study to homogenise the filament fabricated via extrusion, has a profound effect on enhancing the quality of the WPC filaments for 3D printing.