The dielectric permittivity of synthetic rubber polymers, nitrile butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM), with both frequency and temperature variations, was thoroughly investigated by dielectric relaxation spectroscopy (DRS). The spectrum versus frequency of DRS was analyzed with the semiempirical Havriliak–Negami formula and conductivity contribution by employing the newly developed “dispersion analyzer” analysis program. The main dielectric relaxations called the α- and β-processes, associated with the cooperative motion of chains in polymers, were discovered in the low-temperature region. In the high-temperature region, we found Maxwell–Wagner–Sillars (MWS) relaxation associated with polymer interfacing and normal-mode (α’) relaxation responsible for end-to-end dipole vector motion. The activation energies of schematic molecular chains responsible for the relaxation processes were obtained with the information about its motional mode. The glass transition temperature and dipole moment for the side group were also determined and compared with those from previous studies. In the EPDM specimen, the peaks of α- and β-relaxation merged at high temperature and were separated with decreasing temperature. The first observations of both merging and splitting were consistent with the results on the temperature dependency of the relaxation strength. Both contour mapping and three-dimensional plots for the two rubbers provide visual information for the distribution and mapping of relaxation.

中文翻译：

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合成橡胶聚合物中的介电弛豫谱：丁腈橡胶和乙烯丙烯二烯单体

通过介电弛豫光谱法（DRS）对合成橡胶聚合物，丁腈橡胶（NBR）和乙丙二烯单体（EPDM）的介电常数以及频率和温度变化进行了彻底研究。DRS的频谱与频率之间的关系采用半经验Havriliak–Negami公式进行了分析，并采用了新开发的“色散分析仪”分析程序对电导率的影响进行了分析。在低温区发现了称为α-和β-过程的主要介电弛豫，与聚合物链的协同运动有关。在高温区域，我们发现麦克斯韦-瓦格纳-西勒斯（MWS）弛豫与聚合物界面和正常模式（α'）弛豫负责端到端偶极子矢量运动。通过有关其运动模式的信息获得负责松弛过程的示意分子链的活化能。还确定了侧基的玻璃化转变温度和偶极矩，并将其与先前研究的结果进行了比较。在EPDM样品中，α-和β-松弛峰在高温下合并，并随着温度降低而分离。合并和分裂的第一个观察结果与弛豫强度的温度依赖性结果一致。两种橡胶的轮廓映射和三维图均提供了松弛分布和映射的可视信息。