On morphology, molecular composition and breakdown behaviour in semi-crystalline polymers

The short-term dielectric breakdown behaviour of a number of model polymer systems has been investigated. For polyethylene blends, it is found that the addition of linear polyethylene and the imposed thermal history of the blend have, jointly, resulted in a significant improvement in properties. The effect of anti-oxidants and DCP on the breakdown behaviour of LDPE and XLPE is discussed; these have a negligible effect. Finally, for a clarified propylene/ethylene copolymer, it is found that crystallization conditions have a significant effect on electrical strength although the effect of the clarifying additive alone is less certain.