Resistance of Flat-Pressed Wood-Plastic Composites to Fungal Decay: Effects of Wood Flour Content, Density, and Manufacturing Technology

Use of wood-based materials in exterior application is inherently at risk of degradation caused by fungal decay. This risk also holds for wood-plastic composites (WPCs), whether they are extruded into rod-shaped elements or flat-pressed to large-dimensioned panels. In this study, to show the potential of WPC panels in exterior applications, fungal decay was studied by investigating mass loss in an agar-block test using Gloeophyllum trabeum (Gt), Coniophora puteana (Cp), and Pleurotus ostreatus (Po) as test fungi. Characterization of WPC panel durability was performed in comparison with solid wood samples by calculating the decay susceptibility index (DSI). Moreover, durability of WPC panels from laboratory (single-daylight press) and industrial (continuous double-belt press) manufacturing were compared with commercial extruded WPC decking planks. Experiments showed that the wood particles in flat-pressed panels were well protected against fungal decay by the polymeric matrix. The fungal-induced mass loss depended on panel density and wood flour content. Using DSI as an evaluation tool, WPC panels were found to be more durable than wood samples used as reference materials (DSI < 100)

Properties of Flat-Pressed Wood Plastic Composites Containing Fire Retardants

This study investigated physical, mechanical, and fire properties of the flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) [5 or 15% by weight (wt)] at 50 wt % of the wood flour (WF). The WPC panels were made from dry-blended WF, polypropylene (PP) with maleic anhydride-grafted PP (2 wt %), and FR powder formulations using a conventional flat-pressing process under laboratory conditions. The water resistance and strength values of the WPC panels were negatively affected by increasing the FR content as compared to the WPC panels without FR. The WPC panels incorporated with zinc borate (ZB) gave an overall best performance in both water resistance and strength values followed by the panels containing magnesium hydroxide (MH) and ammonium polyphosphate (APP). For these three FR's, the best fire resistance as measured in the cone calorimeter was obtained with the 15 wt % APP treatment and then followed by 15 wt % ZB, or 15 wt % MH formulations. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3201-3210, 201