Simultaneous Increase in Dielectric Breakdown Strength and Thermal Conductivity of Oriented UHMWPE Containing Diamond Nanoparticles

In modern electronics and devices, the miniaturization, higher power, and higher frequency trends have led to an increase in heat generation, which has become a significant limiting factor. Polymer dielectrics with high thermal conductivity are highly desired to prevent thermal breakdown caused by accumulated heat, hence extending service life and reducing device size. Much effort has been devoted to enhancing the heat conduction of polymer dielectrics for the sake of efficient heat dissipation. The most common strategy is to introduce thermally conductive and electrically insulating fillers. However, the very high filler contents needed to achieve significant values of thermal conductivity typically impair other properties, especially dielectric breakdown strength. Herein, we demonstrate that it is possible to tackle this problem by the unique combination of high thermal conductivity (27 W·m–1·K–1) and high breakdown strength (627 MV·m–1) exhibited by oriented ultra-high-molecular-polyethylene nanocomposite films containing a small amount of nanodiamonds (0.5 wt % NDs). The influence of high thermal conductivity on reducing operating temperature is explored and quantified through finite element simulation. We demonstrated that a significant reduction in equilibrium temperature (>15 K) in a wound film capacitor can be obtained with our polymer dielectric films, with thermal conductivities in the region of 20 W·m–1·K–1, while maintaining other properties like breakdown strength without compromise.