Study On Properties Of Poplar Veneer Treated By Nitrogen-phosphorus-boron Fire Retardant

In this paper,dicyandiamide/phosphoric acid and boric acid/ammonium bicarbonate were used to prepare DP fire retardant and B fire retardant respectively.Poplar veneers treated by DP and B fire retardants were treated by using vacuum-pressure processes.According to difference of fire retardants and times of impregnation,four different kinds of fire-retardant poplar veneers were obtained,to study the optimum impregnation process and the changes on physical properties and ignition-proof properties.The varieties of poplar veneers' functional groups,relative crystallinity and the influence on thermal decomposition process were characterized by Fourier Transform Infrared Spectroscopy(FTIR),X Ray Diffraction(XRD),Thermogravimetry(TG)and mechanical testing machine,as well as the flame retardancy of poplar plywood,residues of combustion and the effects on bonding strength.FTIR results showed: DP,B,DPBA and DPBB fire-retardant poplar veneers all appeared the characterized absorption peak of Guanylurea phosphate's carbonyl at wave number 1600cm-1.The impregnation of boric acid significantly influenced the absorption peaks at wave number 3419cm-1,1421cm-1.Relative crystallinity of fire-retardant poplar veneers: DPBB>DP>untreated>B>DPBA.TG results showed: The maximun weight loss rate of four kinds of fire-retardant poplar veneers showed before untreated poplar veneers,accelerating the mass loss of wood.Compared to untreated poplar veneers,char yield of poplar veneers treated by DP,B fire retardants were greatly improved.Flame retardant synergistic effect consist between Guanylurea phosphate and boric acid.The drug loading capacity of DP,DPBA and DPBB fire-retardant poplar veneers were 132.38kg/m3?105.23kg/m3?126.83kg/m3 and 150.29kg/m3 respectively.With the increasing of time,hygroscopicity of DP fire-retardant poplar veneers had been below of that untreated.However,hygroscopicity of B,DPBA,DPBB fire-retardant poplar veneers were more than of that untreated,still keeping at a low level.The oxygen index(OI)of DP,B,DPBA and DPBB fire-retardant poplar veneers were 60.8%?50.7%?90.6%?86.6% respectively,much lager than of that untreated poplar veneers(23.3%),significantly improving fire retardant property of poplar.CONE results showed:Heat release rate,total heat release,effective heat combustion and total smoke product,CO2 releasing rate of four kinds of fire-retardant poplar plywood were significantly decreased,and in the meanwhile char yield and time to ignition increased.The efficiency of flame retardant and smoke suppression were effective.On the basis of Japanese standard of fire retardant,DPBA and DPBB fire-retardant poplar plywood could achieve the level of secondary non-combustible material.XRD of residue of combution results showed: After combution,DP,B fire-retardant poplar plywood and untreated poplar plywood were all been thermal decomposition,with formation of char.For DPBA,DPBB fire-retardant poplar plywood's residue of combution,a small sbsorption peak was appeared in at 25oin XRD.The bonding strength of poplar plywood treated by DP and B fire retardants were decreased.Content of boric acid was more,the type ?bonding strength of poplar plywood treated by DP and B fire retardants was weaker.