In this contribution, a novel technique to accurately sense the thermal aging of the epoxy alumina nano-composites employing complex electric modulus is proposed. To sense the thermal ageing of epoxy nano-composites accurately, knowledge of relaxation behavior is necessary. However, relaxation behavior cannot be understood completely due to electrode polarization and charge transport effects at high temperatures and at low frequencies. To overcome this problem, electric modulus which is defined as the inverse of the complex permittivity, is being proposed in this study to analyze the aging behavior of the epoxy alumina nano-composites quantitatively. For this purpose, three epoxy resin samples mixed with alumina (Al ₂ O ₃ ) nano-fillers with different filler concentrations were prepared and thermal aging of the same samples was done for 100 hours, 200 hours, 300 hours and 400 hours, respectively. For each sample, the complex dielectric modulus ( $M^{\ast }$ ( $\omega $ )) was computed using frequency domain spectroscopy measurement to observe their frequency dependent relaxation behaviors. The variation of the real ( $M^{\prime }$ ( $\omega $ )) and imaginary ( $M^{\prime \prime }$ ( $\omega $ )) part of ( $M^{\ast }$ ( $\omega $ )) over the frequency range from 1 mHz to 10 kHz was further fitted using Cole-Cole (C-C) model. From the nature of variation of $M^{\prime \prime }$ ( $\omega $ ) spectrum and the fitting parameters of the C-C model, two characteristic parameters were extracted to quantitatively describe the thermal aging of the epoxy nano-composite samples. Investigations revealed that the extracted parameters can be accurately used to sense the aging condition of the epoxy nano-composites.

中文翻译：

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使用电模量检测环氧氧化铝纳米复合材料的热老化

在此贡献中，提出了一种新技术，该技术可利用复数电子模量准确地感测环氧氧化铝纳米复合材料的热老化。为了准确地检测环氧纳米复合材料的热老化，需要了解松弛行为。但是，由于高温和低频下的电极极化和电荷传输效应，不能完全理解松弛行为。为了克服这个问题，在这项研究中提出了被定义为复介电常数的倒数的电模量，以定量分析环氧氧化铝纳米复合材料的老化行为。为此，将三个环氧树脂样品与氧化铝（Al ₂ O ₃ ）制备了具有不同填料浓度的纳米填料，并对相同样品进行了100个小时，200个小时，300个小时和400个小时的热老化。对于每个样品，复介电模量（ $ M ^ {\ ast} $ （ $ \ omega $ ））是使用频域光谱测量法计算的，以观察其频率相关的弛豫行为。实数（ $ M ^ {\ prime} $ （ $ \ omega $ ））和虚构的（ $ M ^ {\ prime \ prime} $ （ $ \ omega $ ）） 部分 （ $ M ^ {\ ast} $ （ $ \ omega $ ））使用Cole-Cole（CC）模型进一步拟合了从1 mHz到10 kHz的频率范围。从变化的本质 $ M ^ {\ prime \ prime} $ （ $ \ omega $ ）光谱和CC模型的拟合参数，提取了两个特征参数以定量描述环氧纳米复合材料样品的热老化。研究表明，提取的参数可以准确地用于检测环氧纳米复合材料的老化条件。