Effect of wood species on the mechanical and thermal properties of wood-plastic composites

Abstract

The effect of wood species on the mechanical and thermal properties of wood-plastic composites (WPCs) was explored. Various wood species, including cherry, sweet gum, hickory, yellow poplar, Osage orange, walnut, eastern red cedar, pine, maple, and red oak, were compounded with virgin isotactic polypropylene in a 50 : 50 weight ratio and injection-molded. The tensile strength of WPCs made with cedar and hickory was higher than that of WPCs made with maple, oak, and Osage orange. The tensile modulus of WPCs made with gum and walnut was higher than that of oak WPCs. The tan δ peak temperatures and peak values from dynamic mechanical analysis indicated that pine and hickory WPCs had higher amorphous or void contents than walnut and cherry WPCs. The induction time during isothermal crystallization suggested that red cedar, cherry, and gum WPCs had higher nucleation density than walnut, pine, and oak WPCs. Dynamic mechanical properties of the WPCs appeared to be related to the crystallization behavior of the wood flour, which depends on the surface roughness. Although there were statistically significant differences in mechanical properties among the species, the differences were small, implying that wood flours from many species can be used successfully as raw materials for WPCs. © 2009 Wiley Periodicals, Inc.