Wood plastic composites (WPCs) have many applications as structural and non-structural materials. Adding wood flour to polymer will not only improve its mechanical properties, compared to net polymer, but also will lead to products with moldability characteristics. As the outdoor application of Wood Plastic Composites (WPCs) becomes more widespread, the resistance of these products against weathering, particularly ultraviolet (UV) light, and biodegradation becomes more of concern. In present study, composites from bagasse and high density polyethylene, with and without pigments, have been made through extrusion and gone through accelerated weathering for 1440h, then weathered and non-weathered samples were exposed to fungal and termite resistance tests. The chemical and surface qualities of samples were studied by means of ATR-FTIR spectroscopy, colorimetric, contact angle and roughness tests after weathering. After fungal and termite resistance tests, color changes and weight loss were observed. The results have indicated that using bagasse as filler can relatively reduce the discoloration of weathered samples. Moreover adding pigments into WPCs can reduce effects of weathering by reducing surface oxidation. However, it cannot affect the biodegradation after weathering. Despite of high resistance of samples against biological attack, weathering can enhance the termites and fungal attack on the surface and can cause surface quality loss.
