Study On Modification Technology Of Superhydrophobic Rubberwood

Rubberwood,as the residual by-product after cutting latex from economic tree species,has the advantages of light color,beautiful texture,low density,good processing performance and coating performance.It has poor dimensional stability and biological durability,however,due to its strong hydrophilic and hygroscopicity.At present,the main method of wood anti-mildew and anti-corrosion is to add chemicals to kill invading wood microorganisms by using the toxicity of chemicals,but toxic chemicals also cause serious environmental pollution.In order to reduce the environmental burden,hydrophobic modification was taken as the starting point in the paper.Polystyrene(PS)was used as the skeleton material to build superhydrophobic coating on the surface of rubberwood.Combining with simple moisture-proof pretreatment,meanwhile,to prepare high-efficiency water-proof rubber wood.The effect of the corresponding processing parameters on the modification effect was studied.After that,the anti-mildew and anti-corrosion properties were tested.The results are as follows:(1)To explore the best technology of two super hydrophobic modification systems for PS/ethanol and PS/SiO₂,the best solution concentration of PS on rubber wood surface was determined to be 10%(w/v)firstly.The effect of ethanol content(5%,10%,15%,20%,25%),SiO₂ emulsion concentration(0%,0.4%,0.8%,0.8%,0.8%,0.8%)and secondary impregnation time(1s,5S,10s,30s,60s)on the properties of rubber wood hydrophobic film were studied.The results showed that the properties of the first modification system reached the peak when PS/CH₂Cl₂ solution concentration and ethanol content were 10%(w/v)and10%(v/v)separately,and the water contact angle(WCA)rubberwood was increased to 132.7°.The second system peaked when SiO₂/acetone emulsion concentration and secondary impregnation time were 1.6%(w/v)and 5s respectively,and the WCA of rubberwood was increased to 155.6°.(2)In view of the hygroscopicity problem of superhydrophobic modified rubber wood,two methods of physical(high temperature heat treatment)and chemical modification were used to pretreat the rubberwood.The treatment temperature(185?,200?,215?,230?),treatment time(1.5h,3h,4.5h),types of reagents(acetic anhydride,furfuryl alcohol,maleic anhydride)and impregnation time(1h,2h,3h,4h)were studied.It was found that the weight gain rate of the heated rubberwood optimum process was decreased by 46.29%when treatment temperature and time were 230?and 4.5h separately.The optimal process of chemical modification was to select furfuryl alcohol as the reagent,and the soaking time was4h.Under this condition,the moisture absorption and weight gain rate of modified specimen was reduced by 25.03%.(3)Modified woods after the first and second stages of experimental treatment were tested for anti-mildew.Specimen treated with IPBC was added,meanwhile,as the second control group to evaluate the effects of anti-hygroscopicity and superhydrophobic modification on the microbial resistance of Thai rubberwood.The test results show that the optimum treatment conditions for mildew and corrosion prevention were 230?and 4.5h treatment rubberwood with superhydrophobic coating.The area of mould infection was reduced by 38.57%,the infection value was improved from grade 4 to grade 3.The loss rates of erosion quality of white rot fungi and brown rot fungi were reduced by 79.60%and 76.07%respectively.These data indicated that the superhydrophobic interface was helpful to inhibit the growth and diffusion of microorganisms,but could not sterilize them.It has a certain time limit for wood protection.In this paper,a kind of modified rubber wood with highly effective hydrophobic and moisture-proof effect was prepared.At the same time,it has been proved that the modified specimen has certain anti-mildew and anti-corrosion properties,which was conducive to prolonging the reserve and service life of Thai rubberwood.In addition,it avoids the use of toxic reagents,reduces the pollution in the production process and has high economic and social benefits.