Study On Preparation And Mechanism Of Bamboo Packaging Materials With Flame Retardant

In this paper,in this paper,the effects of three processes of hydrothermal method,ultrasonic method and freeze-drying method on the permeability of bamboo were discussed.The optimal process conditions were selected by orthogonal experiment.The water absorption curve of the optimum conditions under the three processes was compared.The microscopic morphology of the sample after permeation treatment was observed by SEM.The pore size and its distribution were discussed by mercury intrusion method.Nano-hexagonal boron nitride(nBN),boric acid(B),borax(BX),nanosilica(nSiO2),disodium octaborate(DOC),ammonium polyphosphate(APP)as a flame retardant,utilization the method of physical blending,blending the flame retardant with the water-based coating,and coating the surface of the bamboo laminated material.The combustion performance of the flame retardant coating was analyzed by cone calorimeter from the aspects of heat release,smoke emission and mass loss.The mechanical properties of the coating were analyzed from the aspects of wear resistance and adhesion.The experimental results of three-point bending resistance were analyzed,and the influence of the elastic modulus and bending strength of bamboo laminated timber was analyzed.X-ray diffraction,thermogravimetric analysis and scanning electron microscopy were used to comprehensively analyze the flame retardant mechanism and penetration effect of the flame retardant coating.Through the research in the above chapters,the following conclusions can be drawn:(1)The best experimental process based on the orthogonal method in the penetration test of bamboo laminated timber.The optimal treatment process of the freeze-drying method is to achieve the best penetration effect under the vacuum of 0.5 mbar,the freezing time of 5 h,and drying for 15 h.The water absorption test results of the three processes showed that the permeation effect of the freeze-drying group was 47%higher than that of the control group,and the improvement effect of the hydrothermal group and the ultrasonic group was only increased by 5%and 12%.The results of mercury intrusion analysis showed that the untreated control group had a mercury volume of only 0.4759 mL/g,and the freeze-drying method increased the volume of mercury into about 83%and the porosity by 10%.However,compared with the control group,the volume of mercury in the ultrasound group and the hydrothermal group increased by only 20%and 11%.(2)From the viewpoint of the combustion performance of each test piece,boric acid/borax and nano-silica have a great influence on the flame retardant effect.From the point of heat release rate and total heat release,top coat-nSiO2,top coat-BBX/DOC/nSiO2 and primer-BBX have a beter flame retardant effect.In terms of smoke suppression,the boron-based compound and nano-SiO2 produced a synergistic effect,and the test piece top coat-BBX/DOC/nSiO2 was reduced by 0.8 m2 relative to the untreated sample.In terms of quality loss,the flame retardant coating has a higher carbon content than ordinary waterborne coatings.(3)After freeze-drying,the mechanical properties showed a significant decrease,the static bending strength decreased by 18.4%,the elastic modulus decreased by 18.3%,and the relative crystallinity of bamboo laminated timber decreased by about 3%.Bamboo was proved from the microscopic level.The mechanical properties are indeed related to the crystallinity of bamboo fibers.The infiltrated sample is more likely to form a stable coating after coating,and after the flame retardant treatment,the initial temperature of thermal decomposition of the aqueous coating increases,the combustion process is terminated early,and the final residual carbon ratio can be increased by 20%.