This study examines the effects of pressure, temperature, and treatment time on supercritical fluid impregnation of such composites as plywood, particleboard, flakeboard, and medium-density fiber-board. Carbon dioxide with methanol as a cosolvent was used as the supercritical fluid, with tebuconazole as the biocide. Biocide distribution, as measured by extraction and analysis, generally increased with pressure, temperature, and treatment time, although the retentions sometimes decreased at the highest pressure tested (4500 psig). In general, biocide retentions were far above those required for fungal protection, and the distribution was more uniform than that found with conventional pressure treatments. The results suggest that supercritical fluid impregnation represents a simple method for impregnating composites with biocides without the permanent damage typical of other treatment systems
