Study On Preservative Penetration Of Bamboo And Its Influencing Factors

As shortage of wood resource,people attach great importance to the rich bamboo resources in China.As the bamboo is easy to cause insects,mildew and decay,resulting in its strength,appearance and other performance is reduced,the scope of application is limited,so it must be protected with preservative.In the process of protection of bamboo,the permeability of bamboo determines the effect of the advantages of pharmaceutical treatment.Therefore,the dynamic process and influencing factors of liquid infiltration in bamboo are worthy of further study.In this paper,based on the previous study on the penetration of bamboo wood,with Moso bamboo(Phyllostachys edulis)as the research object,using the developed pressurized immersion injection equipment,three main factors affecting the permeability of bamboo,physical and chemical properties of penetrating fluid,structure and properties of bamboo and treatment processing parameters were studied.The process and mechanism of permeation,distribution and retention of dyes and preservatives in bamboo were analyzed to provide theoretical basis for the development of bamboo treatment technology for different types of preservatives.The specific research and conclusions are as follows:Effect of solvents properties on atmospheric permeability of bamboo under atmospheric pressure was reached.Methyl,ethyl,isopropanol,butanol,formamide,dimethyl formamide,dimethylacetamide,normal hexane and xylene were used to investigate the effect of different physical properties of solvents on permeability at atmospheric pressure and temperature(NPT)of bamboo strip.By calculating the amount of solvent permeation and the swelling index of bamboo volume on the surface of bamboo,the infiltration of different kinds of liquid in bamboo were measured.The research result shows that the volumetric permeability amount of the solvent used in the experiment reached the maximum after atmospheric pressure infiltration for 240 h.In the first 48 h,the penetration rate was the fastest and the permeability amount could be achieved 70%-80% of the whole volumetric permeability amount.The volumetric permeability amount at 240 h of all the solvent was in the following order: DMAC> DMF> methanol> water> formamide> ethanol> n-hexane> xylene> isopropanol> butanol.The molar permeability amount was in following order: water > methanol> formamide > DMF > DMAC > ethanol > isopropanol > n-hexane > butanol > xylene.The molar permeation amount of the solvent decreases with the number of molecules of carbon atoms rising and increase with the as the polarity of solvent increasing.The volumetric permeability of the alcohol in the bamboo had close linearity correlation in the reciprocal of the viscosity,and the fitting coefficient was above 0.96.The flow of the alcohol solvents in the bamboo is consistent with the viscous flow or linear laminar flow.There was a significant positive correlation between the swelling index of bamboo volume and the volumetric permeability amount of solvent in bamboo.The build-up of the solvent in the bamboo depends on the volume of the solvent rather than its molecular weight.The swelling index of bamboo volume is proportional to the polarity(dielectric constant or dipole moment)of the different kinds of solvent.Effect of bamboo properties and pressure on the permeability of bamboo under pressure was reached.In order to study the effect of bamboo properties on the penetration,distribution and diffusion of liquid in bamboo strip under pressure,the self-designed pressurized equipment was used for one-way pressure impregnation of bamboo with different densities and the dye was used to track the infiltration path to analyze the influence factor for the distribution and diffusion of the liquid in the bamboo.Researches show that the density of bamboo as a single factor on the penetration of liquids and dyes in bamboo has no fixed pattern.With the increasing of pressure,the infiltration time of the dye in the bamboo is drastically reduced and the infiltration velocity increased.The relationship between the pressure and the infiltration velocity are in accordance with the Poiseuille Formula.When the pressure is 0.2-0.4 MPa,the dye is obviously trapped in the bamboo and the liquid at the exit end is near colorless.During dye infiltration,the decline rate of the number of dyeing vascular bundle in the inner surface was more than it in the outer surface of bamboo.The longitudinal pressure permeability of Moso bamboo is better than that of populus ussuriensis and Larix kaempferi.The bamboo was subjected to pressurized impregnation using copper azole in the factory treatment conditions.The penetration rate of copper azole in vascular bundles was less than 100 %.The vascular bundle penetration rate of 80% or so bamboo strip,bamboo split and bamboo tube are more than 80 %.Factors affecting penetration and interception of preservatives in bamboo were reached.To explore the penetration process of preservatives in bamboo and its influencing factors,bamboo strips were impregnated with copper sulfate solution(CuSO4)at different pressures and different concentrations,and the samples of bamboo were selected for the determination of copper ion content.The results shows that the length of the specimen,the concentration of CuSO4 and the pressure had a significant effect on the copper content in different positions;The effect of pressure on the decrease in copper content from the pressure end to 50 cm was significant;the length of the test sample and the concentration of the solution had a significant effect on the copper content of each position and the decrease from pressure end to exit end.With the increase of CuSO4 concentration,the copper content in each position increased.From Position 1 to Position 4,the copper content was conforming to the exponential decline.