Research On Performances Of Densified Bamboo By Impregnation And Fumigation

Under the background of increasing shortage of timber resources and increasing price,the existence of bamboo as a substitute is of great value.China is the country with the richest bamboo resources in the world,known as the "Bamboo Kingdom",especially the production of bamboo is the most.However,how to solve the problems of bamboo shrinkage and swelling deformation,bio-erosion,flammability and other issues has become an urgent problem to be solved.It is an effective method to solve the above problems by impregnation and fumigation.The effects of melamine formaldehyde(MF)resin,sodium silicate and ammonium polyphosphate(APP)on the strength,flame retardancy,abrasion resistance and hardness of bamboo were studied.By impregnation to enhance the strength properties of bamboo.The results of orthogonal experiment show that the three factors affect the strength: concentration > time >temperature.The optimized treatment method is time 2h,concentration 10% and temperature80 ℃.The strength is the highest at this time,but it is not significantly improved.The intensity of the drying after impregnation is increased.At the appropriate temperature(80℃),appropriate time(2h),more MF resin penetrated into the bamboo at the appropriate concentration(10%),and the maximum strength is up to 143.22 MPa.After the MF resin modified,various water has different effects on the compressive strength.The comparison test shows that the unmodified bamboo has the tendency to decrease with the increase of moisture content,and the maximum strength is 98.41 MPa when the moisture content is 5%.After the modification,the strength showed a decreasing trend withthe increase of moisture content,and the highest strength is at full dry.The fumigation method is used to densify the bamboo material.The optimum processing technology of bamboo was modified: time 6h,concentration 10% and temperature80 C.The concentration is greatest for strength,followed by time,and the effect of temperature on modified bamboo is minimal.Under the optimal treatment conditions,the bamboo has the highest strength after modification.Compared different flame-retardants(sodium silicate,APP)effect on the properties of bamboo flame retardant.The maximum flame-retarding time is 48.73s(sodium silicate)and129.50s(APP).Sodium silicate is better for flame retardant of bamboo.With the increase of temperature,the internal moisture gradually escapes and reaches stability.At this time,the porosity of bamboo will tend to be stable as the moisture evaporation increases to a certain extent.After impregnated with melamine formaldehyde resin,the porosity decreases and the thickening effect is better.The rate of dry shrinkage and swelling after modification is longitudinal < radial <chordwise.The longitudinal change rate of bamboo is the largest when the concentration is0.3%,but has little effect on the longitudinal.The pretreatment method has a great influence on the radial and chordwise(full dry shrinkage)change rate.The comparison test shows that the wear rate of and after fumigation is 0.88%(sodium silicate)and 1.13%(APP),the wear rate of impregnated is 1.11%(sodium silicate),APP is 1.28%,and the bamboo with sodium silicate makes it more beneficial to the wear resistance of bamboo.The hardness of modified bamboo by fumigation is better than that by impregnation.The hardness of bamboo after fumigation is 93.77 s for sodium silicate and85.03 s for APP;the time for impregnation with sodium silicate is 82.57 s and the APP is74.20 s.The solidified sodium silicate has played a catalytic role in bamboo hardness.The application of impregnating and fumigation method is more widely used,which can provide some reference for the study of the properties of modified bamboo.