Wood-plastic composites (WPCs) were made from isotactic polypropylene and 10 wood species (8 hardwoods and 2 softwoods). Water sorption and durability of the composites were evaluated. WPCs made with eastern redcedar and Osage orange had low moisture sorption characteristics, lower levels of fungal decay, and increased resistance to mold compared with composites made from other species. The color of the composites was initially quite different, reflecting the differences in color of the various wood species, but after outdoor exposure, the samples were similar in appearance. Metals in contact with WPCs corroded during accelerated exposure and the corrosion of galvanized steel was greatest when in contact with WPCs made from southern pine and black walnut. WPCs made from hickory, sweet gum, black cherry, and red oak corroded ordinary steel more than composites containing other species. These results demonstrate that the inherent characteristics of the wood filler can affect the properties of WPCs. The use of durable wood species in WPCs could result in products with improved durability performance
