The Improvement On Permeability Of Wood And Redimental Substance Distribution Using Supercritical Carbon Dioxide

Wood function modification has been one of the most active research subjects in the field of wood science. .The supercritical fluids technology as one of the new technologies which being applied on the wood science would greatly attention to wood scientists in recently years. In this paper, wood and wood-based composites were modified by supercritical fluids which have low viscosity, a high diffusion coefficient and good thermal properties.The permeability of mason pine and Sassafrastzumn treated with ethanol methanol or benzne-ethanol using. Supercritical CO₂ were measured with rising-water volume displacement method. The results indicated that the permeability of woods were improved by using supercritical CO₂ treatment. The co-solvent was propitious to the permeability improvement of wood. The permeability of Chinese fir , mason pine and sassafrastzumu were increased when treatment press increased from 10MPa to 35MPa using SCF-CO₂ treatment with benzene-ethanol as co-solvent. It was complex that the effects of the permeability improvement of wood on treatment temperature and treatment time. The extractives of wood solubilized and bordered pits destroy in tracheids were observed under a optics microscope scanning electron microscope after the woods were treated by SCF-CO₂ using benzene-ethanol as co-solvent.The study was performed on the effects of the techniques of SCF-CO₂ impregnation with tebuconazole or IPBC using methanol as con-solvent on biocide average retentions and distribution. The quantities of tebuconazole or IPBC were measured by HPLC. The results indicated that biocide retentions and outer-to-inner ratios generally increased with pressure. The best treatment temperature was from 40℃ to 50℃, treatment time from 30 min to 60 min .The decay resistance , the physics and mechanics, dimensional stability and leachability research of wood and wood-based composites treated by SCF-CO₂ impregnation show that the samples decay resistance were to I levels, SCF-CO₂ impregnation appeared to be associated with slight properties decrease in MOE or MOR and SCF-CO₂ impregnation didn't adversely affect the dimensional stability and leachability of various wood and wood-based composites .Systematic research of the tebuconazole or IPBC distribution in the wood were carried out by optics microscope ESEM-EDAX and FTIR. The results show that it was adsorption action making the tebuconazole or IPBC on the cell wall and wood retained very porous structure. FTIR analysis showed that no chemical function generated in the course of reaction between wood and tebuconazole or IPBC.