分子筛矿化木的制备及其阻燃性能

Preparation and flame retardancy of molecular sieve mineralized wood

木材固有的易燃性限制了其在建筑、装饰等方面的应用,利用无机物对木材进行矿化处理是一种生态友好的阻燃处理方法。在常温下调配LTA分子筛前驱体,通过真空加压浸渍法处理东北青杨(Populus cathayana),干燥后制得分子筛矿化木。利用扫描电镜、X射线衍射、傅里叶变换红外光谱等手段表征了矿化木的形貌和化学结构,并利用极限氧指数仪、热重分析仪和锥形量热仪考察了矿化木的热稳定性和阻燃抑烟性能。结果表明:LTA分子筛呈三维花状沉积在木材细胞腔中;矿化木的极限氧指数(LOI)从未处理材的26.1%提高到52.9%,阻燃性能得到极大提升;矿化木的热解速率较未处理材明显降低,残炭量大幅增加至33.46%,热稳定性提高;矿化木具有优异的阻燃性能,且抑烟效果较好,矿化木的第1热释放峰值(HRR_(pk1))和第2热释放峰值(HRR_(pk2))较未处理材分别降低了52.31%和59.87%,总热释放量(THR)降低了32.20%;平均有效燃烧热(av-EHC)降低,质量损失(MLR)减缓,可燃性挥发物的释放量减少;总烟释放量(TSP)和一氧化碳产量(COP)比未处理材分别降低了45.35%和53.85%。矿化木的阻燃机理是木材内的分子筛可起到阻隔作用,减少热量和氧气进入木材,延长矿化木的点燃时间;同时分子筛含有Lewis酸性可催化木材中的纤维素在较低温度下脱水碳化,减少可燃性气体的释放,促进生成更多、更稳定的炭层;连续稳定的炭层能减少热量和氧气传递,从而降低燃烧过程中的质量损失,减少热量和烟气释放。

The application of poplar is limited by its high flammability,and the flame-retardant treatment of wood can address its flammability issues to a certain extent,and effectively extend its applications.Mineralization of wood with inorganic substances is an eco-friendly flame-retardant treatment method,which meets the current requirements of environmental protection and sustainable development of materials.LTA molecular sieve precursor was allocated at room temperature,Populus cathayana was impregnation-treated under a vacuum pressure,and the molecular sieve mineralized wood was prepared after drying.The morphology and chemical structure of the mineralized wood were characterized by the scanning electron microscope,X-ray diffraction and Fourier transform infrared spectroscopy,and the flame retardant and smoke suppression properties of the molecular sieve mineralized wood were investigated by the limiting oxygen index and cone calorimeter.The results showed that the LTA molecular sieve deposited in wood cell cavity in three-dimensional flower shape.Compared with the untreated wood,the limiting oxygen index(LOI)of the mineralized wood increased from 26.1%to 52.9%,and the flame retardant performance was greatly improved.The pyrolysis rate of the mineralized wood was significantly lower than that of the untreated wood,the amount of carbon residue increased significantly to 33.46%,and the thermal stability was improved,showing that the mineralized wood had excellent flame retardancy and good smoke suppression influence.Compared with the untreated wood,the first heat release peak(HRR_(pk1))and the second heat release peak(HRR_(pk2))of the mineralized wood were reduced by 52.31%and 59.87%,respectively,and the total heat release(THR)was reduced by 32.20%.The average effective heat of combustion(av-EHC)decreased,the mass loss rate(MLR)slowed down,and the release of combustible volatiles decreased.The total smoke production(TSP)and CO production(COP)decreased by 45.35%and 53.85%,respectively,compared with those of the untreated wood.The flame retardant mechanism of the mineralized wood is that the molecular sieve in wood can play a blocking role,reducing heat and oxygen from entering wood and prolonging the ignition time of the mineralized wood.At the same time,the Lewis acidity of molecular sieve can catalyze the dehydration and carbonization of cellulose in wood at a low temperature,reduce the release of combustible gas and promote the generation of more and more stable carbon layers.As a result,a stable carbon layer can reduce heat and oxygen transfer,reducing the mass loss and smoke emission in the combustion process.