The influence of morphology on the electrical breakdown strength of polypropylene film

The relationship between the microscopic structure morphology and the electrical strength of polypropylene (PP) film used in PP-laminated paper (PPLP) in very high voltage oil-filled cable is studied by several methods including infrared spectrum, X-ray diffraction and dynamic mechanical spectra. It is found that the key to improve the breakdown strength, the tensile strength and the stability in oil for PP film is to increase its structure parameters, namely, its crystallinity, orientation and molecular weight. The interaction between PPLP and liquid dielectric is also studied. It is found that when it is immersed in dodecyl benzene at 100 degrees C, the strength of PP film decreases because the amorphous part dissolves and disorientation occurs.<
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