Procedure effect on the physical and mechanical properties of the extruded wood plastic composites

This article investigates the effect of raw material preparation on the mechanical and physical properties in wood‐plastic composite (WPC) production. Four possible procedures in material preparation to obtain a determined level of wood content are: (i) to use and feed raw materials in the same ratio of the desired composition (single stage), (ii) to use the batch of granules of the same composition (two‐stage), (iii) to add wood to the batch of granules having a lower wood content, (iv) to add polymer to the batch of granules having a higher wood content. The main question then is that, while it is economically attractive to use granules of a fixed wood content in all productions, whether there are noticeable differences in final properties of the products. The examined compositions were 50, 60, and 70 wt% of wood content which are considered as highly filled WPCs and mainly used in the WPC markets. Thus, 12 sets of WPC profiles were manufactured and the processing conditions (temperature, pressure, and outlet velocity) recorded. The flexural properties, impact strength, density, and water uptake were measured. Results revealed that in the production of WPCs with 50 and 70 wt% of wood content, using the WPC granules with the same composition yields better physical and mechanical properties. However, for producing WPC with 60 wt% of wood content, using WPC granules with 70 wt% of wood and adding appropriate amount of polymer exhibit better results. POLYM. COMPOS. 34:1349–1356, 2013. © 2013 Society of Plastics Engineers