Space charge formation related to the morphology of polymers

Thermally stimulated current measurements were carried out on polypropylene sheet samples to get information about temperature-dependent space-charge formation. The relaxation peak at crystallite melting temperature is related to the separation of stored charge carriers from helix molecules in the crystalline region. The method of thermally stimulated infrared spectroscopy reveals that space charge decay at lower temperatures is connected to the relaxation of helices embedded in the amorphous regions. Observing the growth of electrical trees confirms the fact that charge carriers attach mainly to interfaces of the spherulites (amorphous regions), causing a preferred direction for electrical breakdown.<
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