Effect of Extractives on the Performance Properties of Wood Flour-Polypropylene Composites

In this study, the effects of extractives in wood flour on the physicomechanical properties of wood flour-polypropylene (PP) composites have been investigated. Three different solvents, hot-water (HW), 1% NaOH (AL), and dichloromethane (DM), were used to remove extractives in both poplar and eucalypt wood flour. The obtained results showed that mechanical properties of the composites were moderately enhanced on using extractive-free lignocellulosic materials in both the wood types. A large increase in the strength of eucalyptus flour-PP composites was observed upon the removal of extractives from eucalyptus flour. Unlike the mechanical properties, no improvement in the water absorption and thickness swelling was observed for any type of extracted-free samples. The thermal degradation behavior of the composites showed that in both cases, the degradation temperatures shifted to higher values after removing the extractives. In general, the removal of AL solubles was more effective in its improvement of the physicomechanical properties than the removal of HW and DM extractives. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1563-1567, 2012