Influence of morphology on electrical breakdown strength for polypropylene

To elucidate the mechanism of electrical breakdown for an insulating polymer, the authors investigated the correlation of impulse breakdown behavior and morphological structure for polyolefins. Since polypropylene (PP) has a morphology which can easily be observed under a microscope with polarized light, the behavior of this polymer was studied. The morphological structure of PP was controlled by the following methods: (1) incorporation of a variety of additives or polymers having different molecular weights, (2) addition of a nucleating agent, and (3) control of crystallizing temperature and period. As a result of a series of experiments, it was confirmed that the impulse breakdown property of PP was closely related to its morphology, and these methods were effective in improving the impulse breakdown property of polyolefins by changing the morphology