Retention of Silafluofen in Wood-Based Composites After Supercritical Carbon Dioxide Impregnation‪.‬

Abstract The retention of silafluofen in wood-based composites treated using supercritical carbon dioxide (SC-C[O.sub.2]) as a carrier was determined chemically. Specimens of five commercially available structural-use wood-based composites (medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strandboard) were treated with 4 g of silafluofen dissolved in 20 ml ethanol under nine SC-C[O.sub.2] treatment conditions: temperatures of 35[degrees], 45[degrees], and 55[degrees]C and pressures of 7.85, 9.81, and 11.77 MPa. The middle length of each silafluofen-treated composite was cut, divided into face and core sections, and separately milled for chemical analyses. Laboratory tests to determine the termiticidal efficacy of silafluofen using sugi (Cryptomeria japonica D. Don) blocks prepared by vacuum-soak impregnation supported the notion that a sufficient amount of silafluofen was transported into the wood-based composite under these treatment conditions to protect them against termite attack.