用DMA研究环氧预浸料的等温固化过程

Dynamic mechanical analysis of isothermal curing of epoxy prepreg

采用动态力学分析法(DMA)对648环氧预浸料的等温固化过程进行了表征分析。以储能模量E′的相对增长率作为动态力学性能增长的指标,研究了不同恒温温度下E′的增长规律,并用Hsich非平衡热力学涨落理论、Avrami方程和等转变率3种方法研究了预浸料的等温固化动力学。结果表明:648环氧预浸料等温固化过程中E′的增长分为高温和低温2种增长模式,低温下包含一个高温下没有的模量增长的过渡阶段,该阶段与测试频率具有明显的相关性。Hsich非平衡热力学涨落理论、Avrami方程可以对648环氧预浸料等温固化过程储能模量的相对变化进行分段描述。对活化能的计算结果表明,不同温度范围内恒温储能模量增长过程中活化能的数值及其变化趋势不同。

Dynamic mechanical analysis（DMA） is an important method to study the cure process of prepregs.It was used to investigate the isothermal curing of the 648 epoxy prepreg.Based on the relative conversion definition of the increase in storage modulus E′,the evolution of E′ at different isothermal temperatures was studied.It was found that the increase of E′ during isothermal cure process at high temperatures is different from the one at low temperatures.The low temperature conversion curve includes a transitional stage which was not observed in the high temperature curves,and this transitional stage is found to be strongly frequency-dependent.Hsich＇s non-equilibrium thermodynamic fluctuation theory and Avrami equation are fitted to the conversion curves of E′,and can describe the evolution of E′ by two separate stages.The value and evolution of activation energy calculated by Avrami equation and the isoconversional methods are different in different temperature regions.