Structure-property relationships in polyethylene blends: the effect of morphology on electrical breakdown strength

Blends of linear and branched polyethylene were prepared covering the composition range 1-20% linear polyethylene, and three thermal treatments were subsequently chosen to produce a range of different morphologies. Isothermal crystallization at 124 degrees C gives rise to compact linear inclusions within a matrix of branched polyethylene, isothermal crystallization at 115 degrees C produces an open, banded spherulitic morphology and, finally, quenching leads to a continuous spherulitic texture. Ramp testing was then employed to investigate the effect of morphology on electrical strength. It was found that the electrical strength of the blend depends primarily on the morphology and that, by optimizing thermal treatment and linear polyethylene content, substantial improvements in properties can be obtained.