一种80℃固化环氧树脂体系的非等温固化动力学

摘要

采用非等温DSC研究了80℃固化环氧树脂体系LTCEP的非等温固化行为.采用Gaussian-Lorentzian加和模型对DSC曲线进行分峰处理,采用Flynn-Wall-Ozawa法确定不同阶段反应的活化能随转化率的变化情况.然后采用Málek方法研究不同阶段反应的非等温固化动力学,得到树脂体系总的反应速率方程并预测树脂体系在不同温度下的固化行为.最后采用拉伸测试表征了LTCEP体系的力学性能.非等温DSC结果表明该树脂体系的DSC曲线可用三个独立的放热峰进行叠加来拟合;三个阶段反应活化能随转化率的变化均不明显,其活化能平均值分别为85.98、84.85和87.16 kJ/mol;~esták-Berggren模型可很好地描述该树脂体系在不同阶段的固化行为.预测LTCEP在150℃下3 min、140℃下5.5 min即可达到90％转化率.拉伸测试结果表明LTCEP经80℃固化后拉伸强度和断裂伸长率分别为(51.34±11.78) MPa和(1.23±0.34)％,125℃后处理对拉伸性能影响不大.%DSC was used to study the non-isothermal curing kinetics of an 80℃ curing epoxy resin system(LTCEP),and the sum model coupling the Gaussian distribution and the Lorentzian distribution was used to simulate the DSC peaks.Afterwards the variation of activation energy versus conversion and the non-isothermal curing kinetics for each stage of the curing reaction were studied by the Flynn-Wall-Ozawa method and a model-fitting Málek approach,respectively.The overall reaction rate was obtained according to the peak fit results and then the isothermal curing behaviors at different temperatures were predicted.Finally,tensile experiment is performed to investigate the tensile properties of LTCEP.The peak fit analysis indicated that each DSC curve could be well simulated by using three GaussianLorentzian components.Afterwards the non-isothermal kinetics investigation revealed that the variation of activation energy versus conversion for each stage of the curing reaction changed insignificantly and the curing rates of each stage could be well described by the (S)esták-Berggren model.Moreover,it is predicted from the overall reaction rate that the conversion of LTCEP would be up to 90％ when this resin system was cured at 150℃ for 3 min or 140℃ for 5.5 min.The tensile test at room temperature showed that the tensile strength and the elongation at break of LCTEP cured at 80℃ for 8 h are respectively 51.34±11.78 MPa and 1.23％±0.34％,and the tensile properties did not change significantly after the post treatment on the samples at 125℃.