航空密封材料热解特性研究

Study on pyrolysis characteristics of aerospace sealing material

采用热重-差热分析仪研究DAPCO 2200、3M-AC-380两种密封材料在氮气氛围、不同升温速率条件下的热解特性规律。结果表明:在氮气氛围下,DAPCO 2200密封胶、3M-AC-380密封胶的热解均有2个阶段,热解过程中二者的初始温度相差较大;终止温度均随升温速率的提高向高温方向移动;热解速率、质量损失速率随着升温速率的提高而增大。热解动力学分析表明,在热解反应开始阶段表观活化能相对较小,热解速度相对较快;随着转化率的升高,表观活化能变大,材料热解速度降低。采用Kissinger法、Flynn-Wall-Ozawa法计算表观活化能,DAPCO 2200密封胶表观活化能平均值分别为109.08kJ/mol、144.88kJ/mol,3M-AC-380密封胶表观活化能平均值分别为99.43kJ/mol,81.71kJ/mol。DAPCO 2200密封胶2个阶段的初始分解温度、最终分解温度以及最大质量损失速率温度均高于3M-AC-380密封胶,表明DAPCO 2200密封胶的热稳定性较好。

The pyrolysis characteristics of DAPCO 2200 and 3M-AC-380 sealing material were studied by thermogravimetric-differential thermal analysis under different heating rates in a nitrogen atmosphere.The results showed that the pyrolysis of DAPCO 2200 sealant and 3M-AC-380 sealant had two stages in a nitrogen atmosphere,and the initial temperatures of DAPCO 2200 sealant and 3M-AC-380 sealant were quite different during the pyrolysis process.With the increase of heating rate,the termination temperatures moved towards high temperature.The pyrolysis rate and mass loss rate increased with the increase of heating rate.The pyrolysis kinetics analysis revealed that the apparent activation energy was relatively small and the pyrolysis rate was relatively fast in the initial stage of the pyrolysis reaction.With the increase of conversion rate,the apparent activation energy increased and the pyrolysis rate decreased.Using the Kissinger method and Flynn-Wall-Ozawa method to calculate the apparent activation energy,the average values for DAPCO 2200 sealant were 109.08kJ/mol and 144.88kJ/mol,respectively,and the average values for 3M-AC-380 sealant were 99.43kJ/mol and 81.71kJ/mol,respectively.The initial decomposition temperature,final decomposition temperature and maximum mass loss rate temperature of the two stages of DAPCO 2200 sealant were higher than 3M-AC-380 sealant,indicating that the thermal stability of DAPCO 2200 sealant was better.