硼酚醛/硅橡胶基绝热材料热解动力学研究

Pyrolysis kinetics of insulation materials based on boron phenolic resin/silicone rubber

  • 摘要: 为研究硼酚醛/硅橡胶基绝热材料的热解行为,减小反应特征参数和机制函数的求解误差,针对氩气气氛下的热重测试结果进行了分析。分别利用Starink法、Flynn-Wall-Ozawa法、Friedman-Reich-Levi法对绝热材料热解反应的活化能进行了求解,分析了不同方法的计算误差来源及其对反应机制函数的影响,综合Coats-Redfern法和双等双步法确定了热解反应的机制函数并计算了动力学补偿方程。结果表明:硼酚醛/硅橡胶基绝热材料热解反应只有一个失重段,于750 K左右开始,900 K左右结束;三种方法计算得到的活化能分别为151.63 kJ·mol−1、156.47 kJ·mol−1、160.01 kJ·mol−1,不同方法求解结果基本一致,但在计算过程中,微小的活化能求解差异同样会影响后续反应机制函数的确定。综合不同热分析方法求解结果确定氩气气氛下绝热材料的热解反应机制为随机成核和随后生长(n=2),动力学补偿方程为lnA=0.17Ea-5.58。硼酚醛的加入会导致热解曲线前段(小于800 K)失重,引起热解动力学求解结果与实验结果偏差。

     

    Abstract: To investigate the pyrolysis behavior of insulation materials based on boron phenolic resin/silicone rubber and minimize errors in determining reaction characteristic parameters and mechanism functions, an analysis of the TG results under argon atmosphere was conducted. The activation energy of the pyrolysis reaction in the insulation material was determined using Starink method, Flynn-Wall-Ozawa method, and Friedman-Reich-Levi method, respectively. The sources of calculation errors for each method and their impact on the reaction mechanism functions were examined. By combining Coats-Redfern method with a double equal double step approach, the mechanism function of the pyrolysis reaction was established and a kinetic compensation equation was calculated. The results indicate that the pyrolysis of phenolic resin/silicone rubber-based insulation material exhibits a single weight loss stage, commencing at approximately 750 K and concluding around 900 K. The activation energies determined through three distinct methodologies are calculated as 151.63 kJ·mol−1, 156.47 kJ·mol−1, and 160.01 kJ·mol−1 respectively. Overall, the outcomes obtained from different approaches demonstrate consistency; however, slight variations in the calculation of activation energy may also impact the determination of subsequent reaction mechanism functions. The pyrolysis mechanism of insulation materials in nitrogen atmosphere is determined to follow a nucleation and growth (n=2) process, as revealed through comprehensive analysis using various thermal analysis techniques. The kinetic compensation equation is represented by lnA=0.17Ea-5.58. The introduction of boron phenolic aldehyde induces weight loss during the early stage (below 800K) of the pyrolysis curve, leading to a discrepancy between the calculated pyrolysis kinetics and experimental results.

     

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