EFFECT OF INJECTED SPACE CHARGES ON BREAKDOWN STRENGTH IN LDPE FILMS.

The authors have compared the measured breakdown strengths of two lightly doped polyethylene (LDPE) specimens: one pretreated in water saturated air (H-S), and the other vacuum-dried (D-S). They have observed the space-charge resulting from the presence of water molecules in the region of the breakdown. The recovery time of space charges observed at 25 degree C in H-S is shorter than tha in D-S. The effect of water molecules on the prestressing of polymers was to assist electron injection, while their effect on charged polymers was to make trapped carriers more free.