Space charge evolution in polypropylene containing synthetic and natural organoclays

Fully synthetic tetrasilisic mica from Topy Co., Ltd. and Cloisite® 20A powder of Wyoming natural montmorillonite clay from Southern Clay Products were used to manufacture poly-propylene-based nanocomposites with organoclay concentrations of up to 8-wt%. Both types of nanofiller reduce the amount of space charge accumulated under a dc field as compared with the base material without any nanoparticles but their concentrations have to be kept below ∼4-wt% to achieve this effect. For the same particle concentration, nanocomposites containing natural clay, which has significantly smaller aspect ratio of the individual platelets than the synthetic clay, acquire less space charge than the nanocomposites containing fully synthetic clay.