Wood—plastic composites (WPCs) were made from isotactic polypropylene and extracted and unextracted flours of one of four different wood species. WPCs made with extracted wood flour had lower mechanical properties than unextracted WPCs with the exception of pine WPCs. For all of the species except pine, WPCs made with extracted wood flours showed higher moisture sorption and thickness swelling characteristics. Higher levels of fungal decay were observed for the WPCs made with extracted wood, except for the pine WPCs, in which there was lower fungal decay from brown rot in the extracted wood samples. These results demonstrate that wood extractives affect the mechanical properties, water sorption, and fungal decay resistance of WPCs
