Realizing low-level electrical leakage conductance of PVC based dielectric composites containing amorphous carbon spheres

Carbon nanotubes (CNTs) are used to prepare polymer composites with a high dielectric constant. However, a high leakage conductance is undesirable. Herein, amorphous carbon spheres were used to replace single-walled CNTs (SWCNTs) to fabricate polyvinyl chloride (PVC) composites. Two sets of composite films, marked with PVC/SWCNT and PVC/carbon sphere, were prepared. Dielectric, conductive and breakdown traits of composites were determined. PVC/carbon sphere composites display more advantageous properties than PVC/SWCNT composites. Unlike SWCNTs, carbon spheres exhibit a mild interface polarization with PVC and no percolation, resulting in balanced electric properties of composites including a rationally increased dielectric constant, greatly reduced dielectric loss and significantly improved breakdown strength. The optimal PVC composite with 12 wt% carbon spheres has a dielectric constant of ~ 186, dielectric loss of ~ 0.19 at 100 Hz, and breakdown strength of ~ 333 MV m⁻¹. This work boosts a large-scale fabrication of outstanding composites used in modern capacitors.