Study On Smoke Suppression Effect Of Flame Retardant On Poplar And Mechanism Exploration

In order to explore the flame retardant technology, obtain good flame retardant effect especially smoke suppression effect and improve disadvantages such as high hygroscopicity and poor anti erosion performance of inorganic flame retardant, nitrogen-phosphorus flame retardant was used to impregnate Poplar with different treatment method. Fire retardant effect was evaluated through a variety of measurements. Different concentrations of nitrogen-phosphorus-boron flame retardant agent were added with different proportion of MH/ATH(Mg(OH)2/A1(OH)3) by ultrasonic impregnation treatment after microwave heating. Flame retardant properties were analyzed. Nano SiO2sol was impregnated on the crude material and fire retardant wood with the same ultrasonic method and the improved effect of silica sol on Poplar was studied. The results were showed as follows:There were significant differences between different treatment methods. The application of microwave heating time of1.5min at microwave power of850W and ultrasonic immersion30min at40℃with an ultrasonic power of500W was better for impreganation of poplar at the ratio of liquid to solid was10:1. Drug loading of sapwood and heartwood was up to94kg/m3and76kg/m3, while impregnation depth was respectively10.0mm and9.7mm when treated with15%nitrogen-phosphorus flame retardant liquid. Good flame retardant property was observed with oxygen index of treated Poplar up to68.4%and66.8%.When nitrogen-phosphorus-boron flame retardant was blended with MH/ATH, SDR of all samples was far less than75.20%NP+10%MH/ATH and25%NP+10%MH/ATH treated Poplar had good effect of smoke suppression. The cone calorimeter test showed that, with the radiation intensity of50kW/m, heat release rate, total heat release, average effective heat of combustion and average mass loss rate of20%NP+10%MH/ATH and25%NP+10%MH/ATH could be significantly reduced and the mass loss rate was decreased by60%as well as charcoal yield increased. Analysis of environmental scanning electron microscope indicated that structure of char after burning was denser after blended flame retardant treatment and surface of char was covered by molten layer, which showed that ATH and MH decomposed and formed expansion layer in combustion. Catalytic char forming effect of nitrogen-phosphorus-boron flame retardant had synergistic flame retardant effect with MH/ATH.In order to improve higher moisture absorption and worse anti-loss performance of nitrogen-phosphorus flame retardant agent and compound flame retardant, nano silica sol was used in this study with method of ultrasonic impregnation. It was found the SiO2sol could significantly improve the properties of flame retardant Poplar. Moisture absorption rate was decreased to1.15%and LRV reached as high as98%TG-DTG thermal analysis indicated char yield of blended flame retardant treatment samples significantly increased to35.5%. Fire retardance of Poplar was significantly improved by the blended flame retardant. Catalytic dehydration and catalytic carbon effect of nitrogen-phosphorus-boron flame retardant had good cooperative effect with the oxygen barrier and smoke suppression effect of the expansion oxide decomposition of MH/ATH. Catalytic charring effect of ATH combined with SiO? was better than that of MH.FTIR showed that small absorption in800cm-1wave number was CH2-Si-CH2stretching vibration in silica sol specimens, the1050-1060cm-1absorption peak was Si-O-C bond, the1100cm-1absorption peak was Si-O-Si bond. These confirmed nano silica particles and composite wood had effective chemical combination.