Abstract
Wood-Plastic Composites(WPC)with the woodflour contents from 26.5% to 55.8% were prepared using an industrial scale extruder, and their water resistances were evaluated. The moisture infiltration rate of the WPC was lower compared with solid wood. It required six to 20months for WPC specimens to reach a constant mass soaking in water. Changes of mass and dimension in WPC were increased with increasing woodflour content, and the water-resistance rose remarkably at specimens having woodflour content less than 30%. The increase in mass continued even after one year test period under high humidity condition(90%RH). In a boiling test, only16hours were needed to reach the same mass increase as that of six-month water soaking test. The anisotropic dimensional change was seen at the swelling of WPC by tests of water soaking, high humidity condition and boiling.
Although the initial water resistance of WPC is very high, moisture infiltrates gradually during long-term exposure, and it may be possible for the moisture content to reach a level where decay could occur near the surface at the WPC.
