以修正WLF方程研究压力作用下丁腈橡胶的阻尼性能

时温等效原理表明固定频率下温度越高,模量越低,而相同温度下频率越低,模量越低,即升高温度与降低频率具有同等效应。根据这一规律,可将聚合物的力学性能随温度的变化转化为这些性能随频率的变化,从而可通过不同温度下的力学性能测试数据,换算成宽频率范围内的材料力学性能表现。为了研究压力作用下橡胶阻尼性能的基本变化规律,通过自由体积理论推导出加压后的修正WLF方程,采用动态热机械分析实验,测试得到丁腈橡胶在不同温度下的损耗因子tanδ对频率ω的曲线,根据计算得到不同压力下的测试温度至室温的平移因子,便可做出加压后的丁腈橡胶的损耗因子-频率谱的主拟合曲线,其曲线的频率跨度达10个数量级以上。结果表明,丁腈橡胶的tanδ测试段在高于参考温度以后出现,而随着压力的增加,玻璃化温度相应升高,峰值往高频移动达1.5个数量级。此结果为研究压力作用下橡胶材料阻尼性能的定量变化提供了理论依据。

Study on the Damping Properties of Nitrile Rubber under Pressure by Modified WLF Equation

According to time-temperature superposition, it is shown that at certain frequency, the higher temperature the lower modulus. At a certain temperature, the lower frequency the lower modulus, which indicates that elevated temperature and reduced frequency has the equivalent effects. Based on this, the mechanical properties of rubber materials at wide frequency can be obtained by the data in different temperatures. For studying the basic theory of the damping properties of rubber, a modified Williams-Lendel-Ferry (WLF) equation under pressure has been proposed in this work. According to the loss factor tan δ from DMTA experiments, the shift factors under different pressures might be calculated. Then, the mast curve of loss factor versus frequency could be plotted, in which the range of frequency spanned about ten orders of magnitude. The result showed that the peak of tan δ appeared below the reference temperature. With the increasing pressure, the glass transition temperature moved towards higher frequency, and enhenced by 1.5 orders of magnitude. This method offered the theoretical basis to quantitatively characterize the damping properties of rubber materials.