Progress 07/23/91 to 03/31/10
Outputs
OUTPUTS: Composite materials treated with tebuconazole using supercritical carbon dioxide continue to be exposed in Hilo Hawaii. Tebuconazole treated oriented strandboard samples have largely failed, but plywood samples continue to perform well after 5 years of exposure. Imidicloprid treated laminated timbers also continue to resist termite attack. As a follow up to previous studies on pressure develop in wood during treatment pressure probes were inserted into southern pine sapwood blocks to assess the rate of pressure change during treatment. As expected, pressure changes were generally very rapid; however, there was a consistent lag in response. The results highlight the need for careful processed control to avoid pressure differentials that exceed the material properties of the wood. Studies on the micro-distribution of biocides delivered into wood using SCF have been largely unsuccessful owing to the inability to resolve chemical elements in the wood. We have explored iodine and chlorine based systems but these are only visible at extremely high loadings that would be well beyond those typically used to protect wood. PARTICIPANTS: Jeffrey Morrell, PI/Professor; Milo Clauson, Senior Faculty Research Assistant; Anders Kjellow, University of Copenhagen (Collaborator); Brad Gething, Penn State University (Collaborator); and Dr. Alan Preston, Viance (Collaborator). TARGET AUDIENCES: Wood treaters, wood-based composite manufacturers PROJECT MODIFICATIONS: Since this project had no funding for personnel or materials, we sought collaborators who wish to use our facilities. We have had two Ph.D. students, one from Denmark and the other from Penn State, using the facilities on a regular basis.
Impacts
This process remains commercially viable in Europe, but the current economic situation in the wood products industry has sharply diminished interest in new treatment methods unless they can be proven to be markedly less costly. SCF treatment does not meet that requirement; however, we do anticipate renewed interest as the housing market improves and manufacturers week improved methods for protecting wood-based composites.
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Composite materials treated with tebuconazole using supercritical carbon dioxide continue to be exposed in Hilo Hawaii. Tebuconazole treated oriented strandboard samples have largely failed, but plywood samples continue to perform well. As a follow up to previous studies, pressure probes were inserted into southern pine sapwood blocks to asses the rate of pressure change during treatment. As expected, pressure changes were generally very rapid; however, there was a consistent lag in response. Further studies are underway to determine if this lag is due to measurement error. Trials to examine micro-distribution of biocides delivered into wood using SCF have been restarted. The University recently acquired a new Energy Dispersive X-ray system which should provide much better spatial resolution of heavy elements in wood. We plan to begin these trials as soon as the scope is on line. PARTICIPANTS: Milo Clauson, Senior Faculty Research Assistant; Anders Kjellow, University of Copenhagen (Collaborator); Brad Gething, Penn State University (Collaborator); and Dr. Alan Preston, Viance (Collaborator) TARGET AUDIENCES: Wood treaters, wood-based composite manufacturers PROJECT MODIFICATIONS: Since this project has no funding for personnel or materials, we will continue to seek collaborators who wish to use our facilities. At present, we have two Ph.D. students, one from Denmark and the other from Penn State, using the facilities on a regular basis.
Impacts
This process remains commercially viable in Europe, but the current economic situation in the wood products industry has sharply diminished interest in new treatment methods unless they can be proven to be markedly less costly. SCF treatment does not meet that requirement; however, we do anticipate renewed interest as the housing market improves and manufacturers seek improved methods for protecting wood-based composites.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The potential for treating wood based materials continues to be assessed. In this past year, we have explored the treatment of glued laminated Douglas-fir timbers with fungicide/insecticides mixtures as well as several other wood based composites with fungicides. The laminated timbers have been exposed to Formosan termite attack along with untreated controls. At the end of 18 months, the untreated controls have been destroyed, while the treated samples continue to remain free from attack. Exposure of similarly treated samples in above ground tests show that SCF treated pine remains free of fungal attack after 24 months of tropical exposure.
PARTICIPANTS: Milo Clauson, Senior Faculty Research Assistant; Anders Kjellow, University of Copenhagen (Collaborator), Brad Gething, Penn State University (Collaborator ), Dr. Alan Preston, Viance (Collaborator).
PROJECT MODIFICATIONS: Based upon the short-term loss of the Danish collaborator due to illness, we will likely modify the project to concentrate on SCF treatment of laminated materials and expect the PSU collaborator to spend several months working in our facility.
Impacts
Discussions have begun with several commercial treatment providers concerning the potential for using these processes. Primary interest has been with composite-based materials, however, recent downturns in the market has slowed this effort. We are also cooperating with researchers at the Penn State University and the University of Copenhagen, Denmark to coordinate research efforts concentrating on understanding the effects of process conditions on micro-distribution of biocide. Our primary interest is to develop methods for assessing biocidal movement in situ. Initial efforts to collaborate with PSU investigators were unsuccessful when we realized we could not obtain the sensitivity required. Further discussions are underway.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
Field evaluations of composites treated with tebuconazole using conventonal and supercritical fluid processes continue to be evaluated at our field site in Hawaii. Plywood panels treated with tebuconazole continue to perform well with no evidence of decay, but some weathering. Untreated control panels have begun to experience substantial decay. Oriented strandboard samples have tended to experience much higher levels of damage even at high tebuconazole loadings. OSB tends to be difficult to protect with conventional wood preservatives, parrticualry under such harsh conditions. These results indicate that OSB protecton will require either higher loadings of this chemcial or the use of more effective systems. The insecticide treated glued laminated timbers also continue to perfrom well in Hawaii, while untreated timbers have begun to experience formosan termite attack. Our modeling work has progressed very slowly due to the departure of the key graduate student earlier
this year. Attempts to use data developed in earlier studies to predict biocide deposition levels initially appeared promisng, however, we could not get the model to converge and the results failed to agree with our actual data. Furhter work will continue in this area.
Impacts
SCF treatment remains an experimental process, but it is also one of the few effective techniques for delivering biocides into finished composite wood products and it has widespread potential for use with the emerging organic wood preservatives. Our research combines process control with an understanding of wood in order to help commercializers of this process develop more effective methods for impregnation.
Publications
- Kang, S.-M., K.L. Levien and J.J. Morrell. 2006. Effect of process variations during supercritical fluid impregnation on cyproconazole retention and distribution in ponderosa pine sapwood. Wood and Fiber Science 38:64-73.
- Kang, S.M., J-B. Ra, K.L. Levien and J.J. Morrell. 2006. Developing diffusion coefficients for SCF impregnation of Douglas-fir heartwood with cyproconazole. J. Wood Chemistry and Technology 26(2):111-124.
- Oberdorfer, G., R.L. Leichti and J.J. Morrell. 2006. Internal pressure development and deformation during supercritical fluid impregnation of selected wood-based materials. Wood and Fiber Science 38:190-205.
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Progress 01/01/05 to 12/31/05
Outputs
We have continued to examine the use of supercritical fluids for treatment of refractory wood species. This year, we have examined the use of SC carbon dioxide for impregnating glued-laminated timbers with an insecticide. The results were mixed. While we were able to achieve full penetration of the material, residual pressure following treatment exceeded the material properties of the wood. As a result, the wood exploded. We assessed additional processing steps to reduce residual pressure, including using temperature to produce deposition instead of pressure release, as well as the use of post-treatment vacuums. These steps allowed us to successfully reduce pressure differentials and treated materials are now under termite exposure in Hawaii. We are developing the methodology to use diffusion coefficients for biocide movement through wood under supercritical conditions. The results should allow us to create a more global model of the process, which would reduce the
iterative trial and error process now being used to identify conditions suitable for treatment of various materials. At present, any change in chemical or wood necessitates extensive trials to develop suitable process conditions. Our data should help alleviate that need, making the process more attractive to potential users. Finally, we continue to evaluate wood treated with biocides using supercritical carbon dioxide and exposed under tropical conditions. Various composite materials continue to perform well, although oriented strandboard has proven the most difficult to protect.
Impacts
SCF treatment remains an experimental process, but it is also one of the few effective techniques for delivering biocides into finished composite wood products and it has widespread potential for use with the emerging organic wood preservatives. Our research combines process control with an understanding of wood in order to help commercializers of this process develop more effective methods for impregnation.
Publications
- Kang, S.-M., K.L. Levien and J.J. Morrell. 2005. Supercritical fluid impregnation of wood and biocides using temperature reduction to induce deposition. Wood Science and Technology 39(5):328-338.
- Morrell, J.J., M.N. Acda and A.R. Zahora. 2005. Performance of oriented strandboard, medium density fiberbord, plywood and particleboard treated with tebuconazole in supercritical carbon dioxide. International Research Group on Wood Protection. Document No. IRG/WP/05-30364. Stockholm, Sweden.
- Schneider, P.F., J.J. Morrell and K.L. Levien. 2005. Internal pressure development during supercritical fluid impregnation of wood. Wood and Fiber Science 37(3):413-423.
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Progress 01/01/04 to 12/31/04
Outputs
We have spent most of the past year consolidating our data and preparing manuscripts for publication. We have submitted five manuscripts related to this process to various journals (two have been accepted thus far). During 2005, we plan to assess biocide movement into wood during SCF impregnation. Understanding the dynamics of biocide movement during this process will help treaters to develop more effective methods for employing this technology. Graduate Students: 1 Ph.D. student.
Impacts
SCF treatment remains an experimental process, but it is also one of the few effective techniques for delivering biocides into finished composite wood products and it has widespread potential for use with the emerging organic wood preservatives. Our research combines process control with an understanding of wood in order to help commercializers of this process develop more effective methods for impregnation.
Publications
- Anderson, M.E., R.J. Leichti and J.J. Morrell. 2004. Cellular and fractural failure after supercritical fluid impregnation of four wood species. International Research Group on Wood Preservation. Document No. IRG/WP/04. Stockholm, Sweden. 13 p.
- Kang, S.-M. and J.J. Morrell. 2004. Potential for using dip/supercritical fluid treatments for wood impregnation. International Research Group on Wood Preservation. Document No. IRG/WP/04-40276. Stockholm, Sweden. 8 p.
- Oberdorfer, G., R.J. Leichti and J.J. Morrell. 2004. Deformation of wood-based material during supercritical fluid carbon dioxide treatment. Wood and Fiber Science 36:511-519.
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Progress 01/01/03 to 12/31/03
Outputs
We have explored the use of initial dipping as a means for delivering biocide to the shell of the wood that can then be solubilized and carried into the wood. This approach was explored in an attempt to overcome the solubility issues associated with our normal treatment approach. In addition, we have explored the effect of diffusion distance on supercritical fluid transport into refractory wood. Our data suggests that the process can be modeled and we are working with a Korean collaborator to further this work.
Impacts
SCF treatment remains an experimental process. The only commercial facility (in Denmark) has been closed for several months due to financial issues, but appears to be close to reopening. Our data will assist those attempting to develop this technology by providing the fundamental background that will limit the need for endless trials to establish treatment parameters.
Publications
- Kang, S.M. and J.J. Morrell. 2003. Supercritical fluid impregnation of Douglas-fir heartwood with cyproconazole using temperature induced deposition. International Research Group on Wood Preservation Document No. IRG/WP/03-40259. Stockholm, Sweden
- Schneider, P.F., K.L. Levien and J.J. Morrell. 2003. Internal pressure measurement techniques and pressure response in wood during treating processes. Wood and Fiber Science 35:282-292.
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Progress 01/01/02 to 12/31/02
Outputs
We have completed our development of modified SCF deposition processes and can now reliably deliver the desired amount of biocide into the wood within 10% of the target value. This is comparable with conventional treatment processes and sharply reduces the potential for excessive use of costly biocides. We are now working to develop better data on flow of biocides into wood during SCF impregnation as a means of predicting treatment. The development of predictive models would reduce the need for costly iterative treatment trials to establish treatment parameters, especially when small changes are made in material flow. Finally, we are evaluating previous data developed using our vessel to better understand the effects of process parameters on treatment results.
Impacts
One SCF treatment facility was opened in Denmark this past year to treat spruce for the window industry. While there remains much to be learned about this process the practical aspects of this treatment strategy are currently being evaluated. The data developed through this project should make it easier for the US industry to adopt this technology without the costly learning curve experienced at the Danish facility.
Publications
- Kang, S.M., A. Unger and J.J. Morrell 2002. Supercriticial fluid extraction of DDT from wood artifacts: Effects on color. p. 313-316 In: Enhancing the Durability of Lumber and Engineering Wood Products, February 11-13, Kissimmee, FL. Forest Products Society, Madison, WI. Publication 7249.
- Morrell, J.J. and P.I. Morris. 2002. Methods for improving preservative penetration into wood: A review. International Research Group on Wood Preservation. Document No. IRG/WP/02-40227. Stockholm, Sweden. 17 p.
- Kang, S.M. 2002. Supercritical fluid impregnation of wood with biocides using temperature reduction. Ph.D. Thesis. Department of Wood Science and Engineering, Oregon State University, Corvallis.
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Progress 01/01/01 to 12/31/01
Outputs
Efforts to develop improved processes for using supercritical fluids (SCF) to impregnate wood based materials are continuing. SCFs were found to readily penetrate a variety of composite materials with little evidence of deformation. The exception was Douglas-fir laminated veneer lumber, which experienced excessive pressure build up and deformation. Studies to develop more uniform methods for biocide deposition have also continued. We can now deliver measured amounts of biocide into the system and produce uniform loadings in both solid pine and oriented strandboard. Prior to this work, retentions routinely varied by factors or 2 or 3 fold. We can now deliver retention within plus or minus 10%. The ability to reproducibly treat wood based materials represents an important aspect of the move to successful development of this process. 1 Ph.D., 1 visiting M.S. student.
Impacts
Supercritical fluid technology has the potential to allow for treatment of virtually all wood based materials with an array of less toxic biocides in a closed loop system. While the technology is relatively new, commercialization efforts are already underway in Europe Successful development would open new markets for wood products that cannot be treated using current technologies.
Publications
- Oberdorfer, G. 2001. Development of internal pressure during supercritical fluid impregnation of wood composites and its effects n material properties. Diplomingenieur, University of Agricultural Sciences, Vienna, Austria (research performed at OSU). 115 pp.
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Progress 01/01/00 to 12/31/00
Outputs
We continue to develop fundamental information on the behavior of supercritical fluids during impregnation of various wood-based materials. This past year, we completed a series of studies on the development of internal pressure in various wood-based composites as well as the effect of pressure on panel deformation. In general, pressure gradients from the surface to the interior of panels were small, except as pressure approached the critical region. Panel deformation often followed similar patterns, suggesting that presence of many voids and flow paths in composites largely limited the development of internal pressure gradients that could lead to permanent changes in panel properties.
Impacts
Developing supercritical fluid treatment technologies will provide the opportunity for complete impregnation of virtually all wood species. This would provide opportunity for value enhancement of a variety of wood species. The process will also allow the treatment of composites. Current treatment technologies are not suitable for composite treatment, reducing potential for these materials.
Publications
- Morrell, J.J. 2000. Processes: How will they change in the new millennium? Proceedings Canadian Wood Preservation Association 20:157-162.
- Morrell, J.J. and K.L. Levien. 2000. Extraction of biologically active substances from wood. p. 221-226 In: Supercritical Fluid Methods and Protocols. Chapter 29. J.R. Williams and A.A. Clifford, eds. Humana Press Inc., Totowa, NJ.
- Morrell, J.J. and K.L. Levien. 2000. The deposition of a biocide in wood-based material. p. 227-234 In: Supercritical Fluid Methods and Protocols. Chapter 30. J.R. Williams and A.A. Clifford, eds. Humana Press, Inc., Totowa, NJ.
- Oberdorfer, G., P.E. Humphrey, R.J. Leichti and J.J. Morrell. 2000. Internal pressure development within oriented strandboard during supercritical fluid impregnation. International Research Group on Wood Preservation Document No. IRG/WP/40175. Stockholm, Sweden. 11 pp.
- Anderson, M.E., R.J. Leichti and J.J. Morrell. 2000. The effects of supercritical CO2 on bending properties of four refractory wood species. Forest Products Journal 50 (11/12):85-93.
- Kim, G.H. and J.J. Morrell. 2000. In-situ measurement of dimensional changes during supercritical fluid impregnation of white spruce lumber. Wood and Fiber Science 32(1):29-36.
- Morrell, J.J. 2000. Above ground issues on aging pole systems. p. 51-57 In: Proceedings, Northeast Utility Pole Conference, October 17-18, Binghamton, NY. Oregon State University, Corvallis.
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Progress 01/01/99 to 12/31/99
Outputs
The effects of supercritical fluid impregnation on pressure development were studied using solid wood and oriented strandboard (OSB). Pressure equilibrated rapidly in OSB, but required several hours to equilibrate in some wood species. These differences sometimes exceeded the material properties of the wood and helped to explain the negative mechanical effects observed with some wood species. Further trials are now underway using laminated veneer lumber and medium density fiberboard. Graduate Students = 2.
Impacts
Developing supercritical fluid treatment technologies will provide the opportunity for complete impregnation of virtually all wood species. This would provide opportunity for value enhancement of a variety of wood species. The process wil also allow the treatment of composites. Current treatment technologies are not suitable for composite treatment, reducing potential markets for these materials.
Publications
- DeBell, J.D., Morrell, J.J. and Gartner, B.L. 1999. Within-stem variation in tropolone content and decay resistance of second-growth western redcedar. Forest Science 45:101-107.
- Garcia, S.M. and Morrell, J.J. 1999. Fungal associates of Buprestis aurlenta in western Oregon. Canadian Journal Forest Research 29:517-520.
- Gezer, E.D., Michael, J.H. and Morrell, J.J. 1999. Effects of glycol on leachability and efficacy of boron wood preservatives. Wood and Fiber Science 31(2):136-142.
- Mankowski, M.E. and Morrell, J.J. 1999. Effect of substrate type and moisture requirements in relation to colony initiation in the carpenter ant species. International Research Group on Wood Preservation, Document No. IRG/WP/99-10320. Stockholm, Sweden. 10 p.
- Morrell, J.J. and Rhatigan, R.G. 1999. Effect of through-boring on flammability of ACZA- and pentachlorophenol-treated Douglas-fir poles: Proceedings American Wood Preservers' Association 95.
- Morrell, J.J. and Freitag, C.M. 1999. Accelerated laboratory testing of preservatives on 13 North America wood species. International Research Group on Wood Preservatives, Document No. IRG/WP/99-30201.
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Progress 01/01/98 to 12/31/98
Outputs
Studies to assess the effects of elevated pressure on mechanical properties and anatomical changes have been completed on four wood species. Spruce was the most sensitive to collapse, followed by western redcedar. Douglas-fir and yellow poplar were fairly resistant to damage, Strength losses closely mirrored collapse. Studies have nearly been completed on the development of internal pressure in various wood species during supercritical fluid impregnation. Further trials are now underway in an attempt to correlate wood permeability with pressure changes. The goal of this work is to use previously developed permeability coefficients to predict suitability for SCF treatment as a means of avoiding extensive treatment trials.
Impacts
(N/A)
Publications
- Acda, M., Morrell, J.J., Silva, A., Levien, K.L. and Karchesy, J. 1998. Using supercritical carbon dioxide for extraction of western juniper and Alaska-cedar. Holzforschung 52:472-474.
- Morrell, J.J. and Levien, K.L. 1998. Supercritical fluid treatment research cooperative first annual report. Forest Research Laboratory, Oregon State Univ., Corvallis, OR. 18 p.
- Sahle-Demessie, E., Levien, K.L. and Morrell, J.J. 1998. Impregnation of porous solids using supercritical CO2. Chemtech 28(3):12-18.
- Sahle-Demessie, E., Yi, J.S., Levien, K.L. and Morrell, J.J. 1997. Supercritical fluid extraction of pentachlorophenol from pressure-treated wood. Separation Science and Technology 32(6):1067- 1085.
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Progress 01/01/97 to 12/31/97
Outputs
Studies to develop a better understanding of the effects of pressure change on the dimensional stability of wood during supercritical fluid impregnation are continuing. In general, species that are sensitive to collapse tend to experience these changes at the start of the treatment process and the shifts are sensitive to the rate of pressure application. Trials to develop data on the rate of internal pressure change during supercritical fluid impregnation have just begun. Pressure equilibration appears to be fairly rapid during the initial stages of pressurization. The rate of pressure change internally is a concern because pressure drops below the critical pressure which results in deposition of the biocide and may slow the overall impregnation process. Further trials are planned.
Impacts
(N/A)
Publications
- ACDA, M., MORRELL, J.J. and LEVIEN, K.L. 1997. Effects of supercritical fluid treatments on physical properties of wood-based composites. Wood and Fiber Science 29(2):121-130.
- ACDA, M.N., MORRELL, J.J. and LEVIEN, K.L. 1997. Effect of process variables on supercritical fluid impregnation of composites with tebuconazole. Wood and Fiber Science 29(3):282-290.
- KIM, G.-H., KUMAR, S., ET AL. 1997. Bending properties of TCMTB-treated southern pine sapwood using supercritical carbon dioxide impregnation process. International Research Group on Wood Presv. Doc. No. IRG/WP/97-40080. Stockholm, Sweden.
- MORRELL, J., LEVIEN, K., SAHLE DEMESSIE, E. and ACDA, M. 1997. Impregnating wood with biocides using supercritical carbon dioxide: Process parameters performance & effects on wood properties. Proc., Amer. Wood Preservers' Assoc. 93:367-384.
- SAHLE DEMESSIE, E., YI, J.S., LEVIEN, K.L. and MORRELL, J.J. 1997. Supercritical fluid extraction of penta chlorophenol from pressure treated wood. Separation Science and Technology 32(6):1067-1085.
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Progress 01/01/96 to 12/30/96
Outputs
Studies to better understand the potential for using supercritical fluids for impregnating wood with biocides are continuing. Treatment trials indicate that Douglas-fir, white spruce, western redcedar, red alder, and white oak were all readily impregnated with tebuconazole using supercritical carbon dioxide plus methanol. Mechanical testing of treated beams revealed that treatment induced no significant negative effects on properties of Douglas-fir, red alder, and white oak. Spruce and cedar samples experienced some collapse. Further trials are underway to develop processes for minimizing this damage. Trials have been completed to use SC-carbon dioxide for extracting juniper oil from western juniper. Extraction was most efficient when methanol was used as a cosolvent. These results suggest that SCF extraction may be a useful method for recovering valuable oils from wood.
Impacts
(N/A)
Publications
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Progress 01/01/95 to 12/30/95
Outputs
Trials to evaluate the ability of supercritical carbon dioxide to serve as a carrier for preservatives for wood impregnation are continuing. Efforts to impregnate a variety of composites have proven highly successful. Particle board, plywood, waferboard, and medium density fiberboard were all completely impregnated with little or no negative effect on panel properties. Trials have also been undertaken to explore extraction of cedar oil from western juniper in place of conventional steam distillation. These trials are continuing as are studies to determine the behavior of binary and ternary mixtures under supercritical conditions. GRADUATE STUDENTS=2 Ph.D.
Impacts
(N/A)
Publications
- SAHLE-DEMESSIE, E., LEVIEN, K.L. and MORRELL, J.J. 1995. Deposition of chemicals in semiporous solids using supercritical fluid carriers. p. 415-428 In: Innov. in Supercritical Fluids. Am.Chem.Soc.:608. Washington, DC.
- VELICHETI, R.K. and MORRELL, J.J. 1995. Media enhancement of bioprotectant capabilities against wood-staining fungi. p. 245-248 In: Proceedings, Wood Preservation in the 90s and Beyond. Forest Products Society, Madison, WI.
- HASSAN, A., LEVIEN, K.L. and MORRELL, J.J. 1995. Phase behavior of binary and ternary mixtures of wood preservatives in supercritical carbon dioxide with co-solvents. In: Innov. in Supercritical Fluids. Am.Chem.Soc.:608. Washington, DC.
- SAHLE-DEMESSIE, E., HASSAN, A., LEVIEN, K.L., KUMAR, S. and MORRELL, J.J. 1995. Supercritical carbon dioxide treatment: Effect on permeability of Douglas-fir heartwood. Wood and Fiber Science 27(3):296-300.
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Progress 01/01/94 to 12/30/94
Outputs
Trials are continuing to better understand the ability of biocides in supercritical fluids to impregnate wood based materials. Fungus cellar trials of small southern pine and white oak stakes treated with biocide in SCF suggest that some biocides may be inappropriate as stand-alone systems for these applications. Trials with alternative systems continue. Efforts are continuing to better understand the behavior of supercritical fluid/biocide mixtures under critical conditions. The results suggest that predictive models can be developed to explain phase behavior. Disclosure of Patent: LEVIEN, K.L., MORRELL, J.J., KUMAR, S. and SAHLE-DEMESSIE, E. Process for removing chemical preservatives from wood using supercritical fluid extraction. U.S. Patent No.: 5,364,475. Washington, DC. Date: November 1994.
Impacts
(N/A)
Publications
- MORRELL, J.J., LEVIEN, K.L., SAHLE-DEMESSIE, E., KUMAR, S. AND BARNES, H.M. 1994. Impregnation of wood poles using supercritical fluid treatment processes. p. 325-337 In: Proc., Intl. Pole and Piling Conf., Ft. Collins, CO.
- MORRELL, J.J. AND LEVIEN, K. 1994. Development of new treatment processes for wood protection. In: Proceedings, Wood Preservation: In the 90's and Beyond. Forest Products Society, Madison, WI.
- SAHLE-DEMESSIE, E., HASAN, A., LEVIEN, K.L., KUMAR, S. AND MORRELL, J.J. 1994. Effect of supercritical carbon dioxide treatment on permeability of Douglas-fir heartwood. Wood and Fiber Science. (In press).
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Progress 01/01/93 to 12/30/93
Outputs
Trials to identify process conditions for supercritical fluid treatment of wood with selected biocides have been completed. The results illustrate the difficulty of obtaining uniform biocide distribution and studies are underway to better understand the behavior of the fluid. Field trials of stakes treated with selected biocides in conventional solvents and supercritical fluids have also been established in Hilo, HA and will be monitored over the coming years. Finally, tests to determine the effects of supercritical fluid treatments on wood mechanical properties have also been completed and indicate that the treatment process has little effect on wood strength.
Impacts
(N/A)
Publications
- KUMAR, S. AND MORRELL, J.J. 1993. Effect of fatty acid removal on treatability of Douglas-fir. Intl Research Group on Wood Preservation. Document No. IRG/WP/93-40008. Stockholm, Sweden.
- SMITH, S.M. AND MORRELL, J.J. 1993. Supercritical fluid treatment: Effects on bending strength of white spruce heartwood. Intl Research Group on Wood Preservation. Document No. IRG/WP/93-20008. Stockholm, Sweden.
- SMITH, S.M., SAHLE-DEMESSIE, E., MORRELL, J.J., LEVIEN, K.L. AND NG, N. 1993. Supercritical fluid (SCF) treatment: Its effect on bending strength and stiffness of ponderosa pine sapwood. Wood and Fiber Science 25(2):119-123.
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Progress 01/01/92 to 12/30/92
Outputs
The development of methods for employing supercritical fluids for wood treatmentare continuing. A variety of biocides have been screened for solubility in selected SCF with co solvents. Solubilities of up to 30 percent by weight have been achieved with some chemicals. Wood treatments indicate that complete penetration of refractory species such as Douglas-fir can be achieved without significant structural damage. Further trials are continuing.
Impacts
(N/A)
Publications
- NO PUBLICATIONS REPORTED THIS PERIOD.
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Progress 08/01/91 to 12/30/91
Outputs
Laboratory screening of potential biocides for use in supercritical fluid treatments has begun and a total of 12 biocides have been screened with a number of solvents. The research is in the very preliminary stages and high pressure vessels are now being constructed for wood treatment trials.
Impacts
(N/A)
Publications
- NO PUBLICATIONS REPORTED THIS PERIOD.
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