Preparation method and application of dielectric test sample

Abstract

The invention provides a preparation method of a dielectric test sample. The method includes the steps of: a) placing isolation columns and a dielectric test sample at a lower electrode to obtain a dielectric test sample placed lower electrode, wherein the dielectric test sample is distributed in a circle with the lower electrode center as the circle center; b) subjecting the dielectric test sample placed lower electrode obtained in step a) to vacuum drying, then performing covering with an upper electrode, and conducting pressing so as to obtain a to-be-tested sample. Compared with the prior art, the sample preparation method provided by the invention can measure the chain relaxation movement of a non-polar polymer material, improve the accuracy of the dielectric test result, and can carry out temperature variation test, even if the test sample temperature exceeds the glass transition temperature or melting point of the to-be-tested sample, testing can still be carried out normally. In addition, the sample preparation method provided by the invention does not introduce new substances, and does not cause pollution to the test sample. Also because of the existence of the isolation columns, the flow of sample is limited, and the sample and the electrodes do not fall off easily.

Description

technical field [0001] The invention relates to the technical field of dielectric testing, in particular to a sample preparation method and application of a dielectric testing sample. Background technique [0002] For many years, non-polar polymer materials have always been a difficult point in dielectric testing. There are no obvious polar groups in the non-polar polymer system, only a very weak dipole along the direction of the molecular chain, because its strength is too weak, it is very easy to be interfered, resulting in undetectable or inaccurate measurement. If the contact between the sample and the electrode is not good, the test result will be inaccurate, and the test result will be smaller than the true value; if the sample contains air or water, the relaxation effect of the sample itself will be covered by the molecular relaxation effect of air or water, and it will not be possible detected. Therefore, such weak interactions cannot be detected by conventional sa...

AI Technical Summary

Problems solved by technology

There are no obvious polar groups in the non-polar polymer system, only a very weak dipole along the direction of the molecular chain, because its strength is too weak, it is very easy to be interfered, resulting in undetectable or inaccurate measurement

If the contact between the sample and the electrode is not good, the test result will be inaccurate, and the test result will be smaller than the true value; if the sample contains air or water, the relaxation effect of the sample itself will be covered by the molecular relaxation effect of air or water, and it will not be possible detected

Therefore, this weak interaction cannot be detected by conventional sample preparation methods

[0003] Poor contact between the sample and the electrode may have two effects on the test: (1) The measured result is too small compared with the real value; the thickness and area parameters of the sample are required in the dielectric test, and the area of ​​the upper electrode is usually used as the area of ​​the sample parameter, but because the sample and the electrode cannot be completely and seamlessly contacted, the volume of the sample participating in the test is smaller than the input value, resulting in a small test result of the sample (mainly referring to the dielectric constant and dielectric loss), which increases the test error

(2) Due to the presence of air in the gap between the sample and the electrode, under certain conditions (appropriate electric field strength), interface effects will occur, and the measured results in this case are wrong

[0006] However, the above-mentioned silver paste method has three disadvantages: (1) in order to ensure the shape of the sample, it can only be dried below the melting point or glass transition temperature, and cannot completely remove air or water molecules; (2) the silver paste can easily penetrate into the sample , resulting in a short circuit of the sample; (3) the silver paste may detach from the sample and become an additional transition layer between the sample and the electrode, which cannot achieve the purpose of increasing contact; (4) the method of applying silver paste is not suitable for variable temperature tests: in variable temperature tests In the process, when the temperature exceeds the melting point or higher than the glass transition temperature, the molecules of the sample can flow and will mix with the silver paste to affect the test

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