In this article, a method is proposed for the characterisation of epoxy resin thermal and hygrothermal ageing based on microwave resonator with interdigital-capacitor-shaped defected ground structure (IDCS-DGS), which can realise rapid and simple non-destructive testing of the ageing degree of epoxy resin materials. The resonant frequency of IDCS-DGS was proved to decrease with the increase of dielectric constant of the around material by means of simulation. The breakdown test at high voltage showed the deterioration of epoxy resin after hygrothermal ageing, which is caused by moisture absorption and hydrolysis process. In addition, thermal ageing also caused a decline in the insulation performance of epoxy resin samples. Accelerated oxidation of epoxy resin samples at high temperatures produces polar molecules that increase the dielectric constant of the samples. As for the hygrothermal ageing samples, the entrance of polar water molecules will increase the dielectric constant of epoxy resin, and thus make an effect on the resonant frequency of IDCS-DGS. The tests of transmission performance show that after the hygrothermally aged epoxy resin samples were put on the microwave sensor, the resonant frequency decreased continuously with hygrothermal ageing time, and the deviations of resonant frequency are highly consistent with the weight variation rate of the samples.

中文翻译：

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基于叉指状缺陷接地结构微波谐振腔传输特性的环氧树脂湿热老化表征

本文提出了一种基于叉指电容器状缺陷接地结构微波谐振器(IDCS-DGS)的环氧树脂热湿热老化表征方法，可实现快速、简单的老化无损测试。环氧树脂材料的程度。通过仿真证明IDCS-DGS的谐振频率随着周围材料介电常数的增加而降低。高压击穿试验表明，环氧树脂在湿热老化后发生劣化，这是由于吸湿和水解过程造成的。此外，热老化也导致环氧树脂样品的绝缘性能下降。环氧树脂样品在高温下加速氧化会产生极性分子，从而增加样品的介电常数。对于湿热老化样品，极性水分子的进入会增加环氧树脂的介电常数，从而对IDCS-DGS的谐振频率产生影响。传输性能测试表明，将湿热老化后的环氧树脂样品放在微波传感器上后，谐振频率随着湿热老化时间的延长而不断降低，且谐振频率的偏差与样品的重量变化率高度一致。