Impulse tree in ethylene based copolymers

Electrical tree initiation by impulse voltage was investigated in EVA and EAA with various monomer contents, and LDPE at room temperature and 77 K. EVA and EAA show very close characteristics of impulse tree initiation voltage as a function of crystallinity, which are improved with increasing crystallinity. At high monomer contents no polarity difference was observed. However at low monomer contents, negative tree initiation voltages are higher than positive ones. The characteristics at 77 K is better than those at room temperature.<>