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

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=0.17E_a－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.