Enhanced breakdown strength and restrained dielectric loss of polypropylene/maleic anhydride grafted polypropylene/core-shell ZrO₂@SiO₂ nanocomposites

To simoutinusly achieve improved breakdown strength (BDS) and suppressed dielectric loss, a modified ternary nanocomposite composed of polypropylene (PP), maleic anhydride-grafted PP and core-shell structure SiO₂@ZrO₂ nanoparticles is proposed. By tailoring the thickness of SiO₂ shell from 3 to 11 nm and the nanofillers content from 0.5 to 5 wt%, the particles disparsion is improved and meanwhile both the deep trap density and the interaction force between molecules are enhanced. In consequence, the restricted transportation of electrons along molecule chains as well as between chains together raise the DC BDS, that the BDS of optimum sample film reaches 430.8 kV/mm, 23% higher than neat PP. Besides, the ternary nanocomposites with SiO₂@ZrO₂ less than 3 wt% maintain the tanδ below 0.3% at a broad frequency ranging from 0.1 Hz to 100 kHz, which is an extremely low level same as neat PP.