Studies on certain wood-plastic-composites prepared by gamma irradiation

Wood-plastic-composites have been prepared using locally available soft wood and commercial monomers by vacuum impregnation of monomer in wood and subsequent polymerization by gamma irradiation. The irradiation was performed by means of a⁶⁰Co source of strength 50,000 Ci at 0·2 Mrad/h. The radiation dosage required for maximum conversion of monomer into polymer was less than 2 Mrad except styrene which required a much larger dose of about 10 Mrad. The impregnation efficiency was found to be more for wood with high pore volume. The impregnation efficiency also depended on the ambient pressure: the more the vacuum, the more was the impregnation efficiency. Mechanical strength of the composites was found to be enhanced and water absorption considerably reduced. X-ray diffraction studies showed that the crystallinity of the cellulose did not get affected by the radiation polymerization which suggested that grafting of polymer on to the cell wall took place only in the amorphous regions.