To date, most of the research performed on foamed WPCs are experimental and to some extent analytical. Bledzki and Faruk suggested that exothermic chemical blowing agents were more effective in lowering the density and enhancing the tensile strength than the endothermic ones and their mixture. Endothermic foaming agent was reported to have reduced the surface roughness by nearly 70%. Matuana et al. found that the cellular morphologies of the foamed PVC/wood-fiber composites were a strong function of the content of plasticizer and the surface treatment of wood-fiber as well as the gas saturation and foaming conditions. Blair indicated that when the cell size was increased, the compressive and tensile strength of plastic foams decreased.