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• 1. [Article] Effect of process variations during supercritical fluid impregnation on cyproconazole retention and distribution in ponderosa pine sapwood

  The effect of process variations under supercritical conditions on cyproconazole retention and distribution in ponderosa pine sapwood boards was assessed. While pressure and temperature appeared to affect ...

  Citation × Citation Citation Abstract Copy Title: Effect of process variations during supercritical fluid impregnation on cyproconazole retention and distribution in ponderosa pine sapwood Author: Levien, Keith L., Morrell, Jeffrey J., Kang, Sung-Mo The effect of process variations under supercritical conditions on cyproconazole retention and distribution in ponderosa pine sapwood boards was assessed. While pressure and temperature appeared to affect biocide solubility to some extent, the overall results suggested that biocide movement into wood was influenced more by diffusion than bulk flow. Biocide distribution also varied along the specimen length and within the treatment vessel illustrating the importance of mixing and the need to ensure that adequate levels of biocide are available in the supercritical fluid. The role of fluid phase changes near the critical region on final biocide distribution in the wood is also discussed. Title: Effect of process variations during supercritical fluid impregnation on cyproconazole retention and distribution in ponderosa pine sapwood Author: Levien, Keith L., Morrell, Jeffrey J., Kang, Sung-Mo The effect of process variations under supercritical conditions on cyproconazole retention and distribution in ponderosa pine sapwood boards was assessed. While pressure and temperature appeared to affect biocide solubility to some extent, the overall results suggested that biocide movement into wood was influenced more by diffusion than bulk flow. Biocide distribution also varied along the specimen length and within the treatment vessel illustrating the importance of mixing and the need to ensure that adequate levels of biocide are available in the supercritical fluid. The role of fluid phase changes near the critical region on final biocide distribution in the wood is also discussed. Close

• 2. [Article] Internal pressure measurement techniques and pressure response in wood during treating processes

  The development of pressure inside wood during preservative impregnation was studied using Douglas-fir heartwood and ponderosa pine sapwood. Pressure sensors mounted on sample holders provided the most ...

  Citation × Citation Citation Abstract Copy Title: Internal pressure measurement techniques and pressure response in wood during treating processes Author: Levien, Keith L., Morrell, Jeffrey J., Schneider, Philip F. The development of pressure inside wood during preservative impregnation was studied using Douglas-fir heartwood and ponderosa pine sapwood. Pressure sensors mounted on sample holders provided the most reliable measurements. As expected, pressure equilibrated most rapidly with air as the treatment medium and ponderosa pine as the test species. Pressure changes were relatively slow in Douglas-fir heartwood, suggesting that process conditions involving relatively rapid changes in pressure conditions will have little effect on fluid penetration away from the wood surface. Title: Internal pressure measurement techniques and pressure response in wood during treating processes Author: Levien, Keith L., Morrell, Jeffrey J., Schneider, Philip F. The development of pressure inside wood during preservative impregnation was studied using Douglas-fir heartwood and ponderosa pine sapwood. Pressure sensors mounted on sample holders provided the most reliable measurements. As expected, pressure equilibrated most rapidly with air as the treatment medium and ponderosa pine as the test species. Pressure changes were relatively slow in Douglas-fir heartwood, suggesting that process conditions involving relatively rapid changes in pressure conditions will have little effect on fluid penetration away from the wood surface. Close

• 3. [Article] Supercritical carbon dioxide treatment: Effect on permeability of Douglas-fir heartwood

  The effect of supercritical fluid treatment on superficial gas permeability of Douglas-fir was investigated by using carbon dioxide either alone or amended with methanol. Permeability increased in a majority ...

  Citation × Citation Citation Abstract Copy Title: Supercritical carbon dioxide treatment: Effect on permeability of Douglas-fir heartwood Author: Hassan, Ali, Levien, Keith L., Morrell, Jeffrey J., Kumar, Satish, Demessie, Endalkachew Sahle The effect of supercritical fluid treatment on superficial gas permeability of Douglas-fir was investigated by using carbon dioxide either alone or amended with methanol. Permeability increased in a majority of samples, although nearly one-third of the specimens declined in permeability. Improvements in permeability appeared to be unrelated to variations in temperature, pressure, or the presence of a cosolvent, suggesting that the conditions were uniformly suitable for extractive solubilization. Decreased permeability may reflect redeposition of solubilized extractives to positions where they again diminish permeability as conditions drop out of the critical range, a possibility that will be studied further. Title: Supercritical carbon dioxide treatment: Effect on permeability of Douglas-fir heartwood Author: Hassan, Ali, Levien, Keith L., Morrell, Jeffrey J., Kumar, Satish, Demessie, Endalkachew Sahle The effect of supercritical fluid treatment on superficial gas permeability of Douglas-fir was investigated by using carbon dioxide either alone or amended with methanol. Permeability increased in a majority of samples, although nearly one-third of the specimens declined in permeability. Improvements in permeability appeared to be unrelated to variations in temperature, pressure, or the presence of a cosolvent, suggesting that the conditions were uniformly suitable for extractive solubilization. Decreased permeability may reflect redeposition of solubilized extractives to positions where they again diminish permeability as conditions drop out of the critical range, a possibility that will be studied further. Close

• 4. [Article] Supercritical fluid (SCF) treatment: Its effect on bending strength and stiffness of ponderosa pine sapwood

  Adverse effects on mechanical properties from using a supercritical fluid (SCF) to increase preservative penetration of refractory woods were evaluated by treating small ponderosa pine sapwood specimens ...

  Citation × Citation Citation Abstract Copy Title: Supercritical fluid (SCF) treatment: Its effect on bending strength and stiffness of ponderosa pine sapwood Author: Levien, Keith L., Morrell, Jeffrey J., Smith, Susan M., Ng, Harry, Demessie, E. Sahle Adverse effects on mechanical properties from using a supercritical fluid (SCF) to increase preservative penetration of refractory woods were evaluated by treating small ponderosa pine sapwood specimens with supercritical carbon dioxide at 64 combinations of temperatures (35 to 80 C), pressure (1,000 to 4,000 psig), and time (0.5 to 2 h). Thereafter, the treated and identical untreated specimens were equilibrated to constant moisture content and tested for bending strength and stiffness. The SCF-treated and untreated specimens were not significantly different in modulus of rupture (MOR) or modulus of elasticity (MOE). Temperature, pressure, and time had no significant effect on MOR; there were interacting effects of these variables on MOE, although these interactions had no meaningful patterns. Title: Supercritical fluid (SCF) treatment: Its effect on bending strength and stiffness of ponderosa pine sapwood Author: Levien, Keith L., Morrell, Jeffrey J., Smith, Susan M., Ng, Harry, Demessie, E. Sahle Adverse effects on mechanical properties from using a supercritical fluid (SCF) to increase preservative penetration of refractory woods were evaluated by treating small ponderosa pine sapwood specimens with supercritical carbon dioxide at 64 combinations of temperatures (35 to 80 C), pressure (1,000 to 4,000 psig), and time (0.5 to 2 h). Thereafter, the treated and identical untreated specimens were equilibrated to constant moisture content and tested for bending strength and stiffness. The SCF-treated and untreated specimens were not significantly different in modulus of rupture (MOR) or modulus of elasticity (MOE). Temperature, pressure, and time had no significant effect on MOR; there were interacting effects of these variables on MOE, although these interactions had no meaningful patterns. Close

• 5. [Article] Effects of supercritical fluid treatments on physical properties of wood-based composites

  The effects of supercritical fluid (SCF) impregnation on physical properties of composites were investigated at various pressures, temperatures, and treatment times with carbon dioxide as the fluid and ...

  Citation × Citation Citation Abstract Copy Title: Effects of supercritical fluid treatments on physical properties of wood-based composites Author: Levien, Keith L., Acda, Menandro N., Morrell, Jeffrey J. The effects of supercritical fluid (SCF) impregnation on physical properties of composites were investigated at various pressures, temperatures, and treatment times with carbon dioxide as the fluid and tebuconazole as a biocide. In general, within the ranges tested, SCF treatment had no negative effects on modulus of rupture (MOR), modulus of elasticity (MOE), or dimensional stability of particleboard, flakeboard, or medium-density fiberboard; in some instances, SCF treatment appeared to be associated with slight property improvements in some panel types. Shear tests of plywood suggested a similar lack of treatment effect. Results indicate that, despite the elevated pressure employed during the process, SCF impregnation does not adversely affect the mechanical properties of various wood-based composites. Title: Effects of supercritical fluid treatments on physical properties of wood-based composites Author: Levien, Keith L., Acda, Menandro N., Morrell, Jeffrey J. The effects of supercritical fluid (SCF) impregnation on physical properties of composites were investigated at various pressures, temperatures, and treatment times with carbon dioxide as the fluid and tebuconazole as a biocide. In general, within the ranges tested, SCF treatment had no negative effects on modulus of rupture (MOR), modulus of elasticity (MOE), or dimensional stability of particleboard, flakeboard, or medium-density fiberboard; in some instances, SCF treatment appeared to be associated with slight property improvements in some panel types. Shear tests of plywood suggested a similar lack of treatment effect. Results indicate that, despite the elevated pressure employed during the process, SCF impregnation does not adversely affect the mechanical properties of various wood-based composites. Close

• 6. [Article] Effect of process variables on supercritical fluid impregnation of composites with tebuconazole

  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 fiberboard. ...

  Citation × Citation Citation Abstract Copy Title: Effect of process variables on supercritical fluid impregnation of composites with tebuconazole Author: Levien, Keith L., Acda, Menandro N., Morrell, Jeffrey J. 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 fiberboard. 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. Title: Effect of process variables on supercritical fluid impregnation of composites with tebuconazole Author: Levien, Keith L., Acda, Menandro N., Morrell, Jeffrey J. 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 fiberboard. 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. Close