Largely enhanced energy density of polypropylene based nanocomposites via synergistic hybrid fillers and high shear extrusion assisted dispersion

The energy density of a film capacitor is proportional to the square of the breakdown strength (BDS) of the material. However, polymer composites' BDS is usually compromised by the filler's agglomeration, thus resulting in very limited increase in the energy density. In this work, we adopted a high-shear extrusion technique to improve filler's dispersion. A synergistic effect between montmorillonite (oMMT) and boron nitride (BN) on BDS of polypropylene was observed, particularly for samples prepared by high shear extrusion. As a result, the energy density of PP can be improved from 2.98 J/cm(3) to as high as 5.14 J/cm(3) while energy discharged efficiency barely changed. In addition, we have also demonstrated that PP/oMMT/BN ternary composites prepared by high shear extrusion show much improved mechanical properties. This work offers a scalable fabrication of PP based nanocomposites with superior energy density that could be easily achieved by using hybrid fillers and high shear extrusion.