Characterization of weathered wood-plastic composite surfaces using FTIR spectroscopy, contact angle, and XPS

Much of the current growth of wood-plastic composites (WPCs) is due to increased penetration into the decking market; therefore it has become imperative to understand the durability of WPCs in outdoor applications. In this study, wood flour filled high-density polyethylene (HDPE) composites were manufactured through either injection molding or extrusion. A set of extruded composites were also planed to remove the extruded surface. Composites were weathered in a xenon-arc weathering apparatus. Scanning electron microscopy (SEM) was used to characterize the morphology of the composite surface. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy was useful in showing the loss of wood particles from the surface after weathering. Contact angle was higher for the extruded and planed composites compared with the injection molded composites, and was shown using X-ray photoelectron spectroscopy (XPS) to be due to lubricant used as a processing aid.