Properties of an industrial extruded HDPE-WPC: The effect of the size distribution of wood flour particles

This work aims understanding the influence of the size distribution of wood flour particles on the physical and mechanical properties of an extruded wood plastic composite (WPC). A industrial-scaled process has been tested for both the wood flour production and the composite forming. Three size distributions of wood flour have been produced from the same batch of wood chips. The analyses of the particle size and form for the three wood flours were carried out by sieve column and by image analysis, revealing the limits of sieving in the case of particles with a high aspect ratio. The present study investigates the influence of the wood flour size distribution on the tensile and flexural behavior of WPC. The Charpy impact behavior of HDPE-WPC is also studied. In addition to the industrial process, the originality of this work lies in relating the microstructure to the mechanical performances of the extruded WPC; especially the orientation of the wood particles that differs according to the size distribution of the wood flour used. In general, mechanical performances of composites are improved by adding large particles. However, in the transverse direction to the extrusion, fine wood flour allows better performances.