Flexure and water sorption properties of wood thermoplastic composites made with polymer blends

Abstract Most WPC extrusion manufacturers utilize single polymer systems, where only one class of polymers is utilized. The concept of utilizing blended polymer systems can potentially provide lowered material costs, while maintaining or improving the composite properties. This cost savings can potentially be obtained in the ability to utilize mixed recycled plastics without the added costs of separation. Composites made of wood flour and binary blends of polypropylene (PP), high density polyethylene (HDPE), and polyvinyl‐chloride (PVC) were extruded and evaluated for their mechanical and physical performance. The WPCs were also exposed to repeated extrusion runs to determine the influence of enhanced melt‐blending of the composite properties. Torque rheometry, flexural, and water sorption tests revealed subtle differences between the blends and single polymer composites. With increasing extrusion runs, the WPCs water diffusion was decreased, whereas the strength and stiffness of the blends and single polymer systems increased or showed no change. These results indicate that polymer blends can be successfully utilized for commercial WPCs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011