Space charge distribution and crystalline structure in low density polyethylene (LDPE) blended with high density polyethylene (HDPE)

The space charge distribution in polyethylene blends under direct current electrical field was measured by a pulsed electro-acoustic method. It was found that blending LDPE with 0.5 wt% HDPE decreased the amount of accumulated space charges and improved their distribution. Small-angle light scattering and differential scanning calorimetry showed that crystallization of LDPE/HDPE started at higher temperature than virgin LDPE, and the sizes of LDPE/HDPE spherulites were smaller than that of LDPE. HDPE plays a role on nucleation during the crystallization process. Crystalline form was investigated by wide-angle X-ray diffraction and the results indicate that the crystal form did not change after blending. The reduction of space charges in the blended sample can be explained as the result of the dissipation of charges through boundary regions of smaller spherulites. (C) 2004 Society of Chemical Industry.