A series of wood fiber reinforced PVC composites were prepared. Three different types of mixture were formed under the same conditions: (1) PVC alone, (2) 30 phr of untreated wood fiber/PVC composites, and (3) 30 phr of silane treated wood fiber/PVC composites. Sorption experiments were carried out on these composites through the dissolution of CO/sub 2/ in the composites. Then, the gas-saturated composites were microcellular foamed. The effects of the wood fiber and coupling agent (silane) on the mechanical properties of the microcellular foamed composites were investigated.