Development of Deterioration Diagnostic Technique of Polymer Electric Insulating Materials Using the Dielectric Measurements with Surface Depth Resolution

研究者们一直在研究利用具有表面深度分辨率的介电测量来发展聚合物电绝缘材料的劣化诊断技术。将交流高场施加到聚合物材料（如硅橡胶）上的叉指电极上，可以检测在水的吸收和解吸期间介电性质的变化、ATH填料的量和填料的处理。结果表明：（1）采用叉指电极法测量样品表面的介电常数，可以检测样品的介电损耗和电容量的变化。介电特性的评价深度与电极指的间隔成比例。因此，不直接接触样品表面的介电性质是可测量的。（2）AC商用频率的高场应用可以测量所施加的场的每一个周期的介电性质，然而，低场应用只能在高频（kHz和更高）下检测聚合物状态的变化。（3）测量试样表面粗糙度可以确定材料中ATH填料的含量，但不能检测试样在脱附过程中表面粗糙度的变化。（4）通过对样品表面疏水状况的图像分析，可以较好地评价材料的疏水状况。（5）当测量温度改变时，疏水水平的温度依赖性改变。随着样品温度的升高，疏水性增加。表面亲水性越强，HC值的变化越大。（6）综合以上测定结果，可以更准确地评价高分子材料的降解情况。

The investigator has been studying the development of deterioration diagnostic technique of polymer electric insulating materials using the dielectric measurements with surface depth resolution. Application of AC high field to the inter-digital electrodes on the polymeric materials, such as silicone rubber, can detect the change in dielectric property during the absorption and de-sorption of water, the amount of ATH filler and the treatment of fillers. Changes in weight, hydrophobicity and surface roughness of the samples are also measured to compare the degradation condition of the specimens.The results are summarized as follows :(1)Dielectric measurement using inter-digital electrodes on a sample surface can detect the change in dielectric loss and capacity of the specimen. The evaluation depth of the dielectric property is proportional to the interval of the electrode fingers. Therefore, dielectric property without direct contact to the sample surface is measurable.(2)High field application of AC commercial frequency can measure the dielectric property for every one cycle of the applied field, however, low field application can detect the changes of polymer condition only at high frequencies(kHz and higher).(3)The measurement of the surface roughness of the samples can define the amount of ATH filler of the materials, however, the change in surface roughness during the de-sorption of water of the samples can not detect.(4)Image analysis of the hydrophobic condition of the sample surface can evaluate the condition of the materials, successfully.(5)Temperature dependence of the hydrophobic level is changed when the measurement temperature is changed. Increasing the sample temperature, hydrophobic level is increased. The changes in HC value are larger when the surface is more hydrophiric.(6)Combination of all above measurement results can evaluate the degradation condition of the polymer materials more accurately.