Preparation And Performance Of Bamboo Laminated Lumber Treated With Flame Retardant

Bamboo has the advantages of fast growth, high yield and high strength performace and so on, which has gradually become hot research topic in the field of materials science in recent years. Bamboo contains much cellulose, hemicellulose, and lignin, as well as wood belongs to flammable materials, which could cause a fire safety problems. Therefore, bamboo laminated lumber made with bamboo strips as the basic unit must be treated by reasonable flame retardant processing, to meet relevant standards, which would make it to gain market recognition.In this paper, moso bamboo(Phyllostachys edulis) was used as raw material, The most efficient of flame retardant is composed of phosphorus-nitrogen and boric acid-borax mixture in certain proportion, flame retardant treatment process was optimized by single factor experiment to manufacture a variety types of flame retardant bamboo laminated lumber, the physical and mechanical properties, combustion performance and flame retardant mechanism were studied, and the decay resistance and mold resistance of flame retardant bamboo laminated lumber were tested. The objective of this study is to provide the theory basis for the actual production of bamboo laminated lumber, and expand the application range of bamboo.The main results are as follows:(1) The best flame retardant was screened by the method of burning heavy residue, MAP with SBX mixed in a proportion of 7:3 has the best burn resistant behavior, which showed a certain composite flame retardant effect.(2) The flame retardant impregnation process was optimized through single factor experiment, the best technology of flame retardant processing bamboo is as follows: the degree of vacuum is 0.08 MPa, the vacuum time is 30 min, the pressurized pressure is 1.0 MPa, the pressurized time is 2 h.(3) With the increase of the retention, the mechanical strength of flame retardant bamboo laminated lumber decreased, the average MOR declined by 3.5%~13.42%, the average MOE decreased 5.21%~13.30%; The shear strength of flame retardant bamboo laminated lumber made with PF and MUF was between 10~12 MPa, which fell slightly compared with the untreated one; The delamination of bamboo laminated lumber was good, the surface wettability fell slightly.(4) The combustion performance of flame retardant bamboo laminated lumber was analyzed by CONE, results showed that, The flame retardant property of bamboo laminated lumber with the retention of 89.72 kg·m-3 can achieve B standard of GB8624-2006, bamboo laminated lumber with the retention of 74.32 kg·m-3 is also up to the B standard of GB8624-2006, bamboo laminated lumber with the retention of 59.34 kg·m-3 can only achieve C standard of GB8624-2006; The combustion performance of flame retardant bamboo laminated lumber made by MUF acquilt better than the one made by PF; Bamboo laminated lumber made of the thinner bamboo strips has a poorer flame retardant performance,becaues of excess glue line; As bamboo laminated lumber board thickness increases, the appearing time of the second heat release peak was delayed, the amount of heat release has a certain increase; Composite flame retardant has a good performance of flame retardant property and smoke suppression performance as well as the commercial flame retardant, which could significantly promote bamboo into carbon, reduce the rate of thermal decomposition and the release of toxic gas.(5) The decay resistance performance of bamboo laminated lumber with flame retardant has been somewhat improved, the one with retention of more than 74.32kg·m-3 can reach the strong corrosion level; The mold resistance of bamboo laminated lumber with flame retardant has certain prevention function to the mold, as the retention rise,the effect of mold resistance increased. The one with retention of 89.72kg·m-3 works best, whose effect of mold resistance achieved 98.60%. the inhibition performance of botryodiplodia theobromea is not very ideal, the best control effect was only 30%.(6)The flame retardant mechanism of bamboo laminated lumber treated with composite flame retardant were studied and discussed by thermogravimetric analyzer, environmental scanning electron microscope, X-ray diffractometer. The result shows that the thermal degradation process of flame retardant bamboo changed, the initial degradation temperature was been moved up, carbon residue rate increased significantly; Flame retardant was mainly injected into the bamboo cell cavity, and which has a good filling characteristicscan and form a layer of boron trioxide mucus layer on the cell cavity surface after burning; The relative crystalinity of flame retardant bamboo fiber has fallen slightly after flame retardant processing.