Thermal conductivity of polyurethane sheets containing beryllium oxide nanofibers

Polyvinyl alcohol/beryllium sulfate/polyethyleneimine (PVA/BeSO₄/PEI) precursor nanofibers (NFs) was first fabricated to obtain PVA/BeSO₄/PEI electrospun NFs by electrospinning technology, finally manufactured beryllium oxide (BeO) NFs followed by various heat treatment methods. The minimum calcination temperature for pure BeO NFs was 1000 °C, and the minimum specific surface area (5.1 m² g^-1) and pore volumes (0.0128 cm³ g^-1) were at 1300 °C. 46.18% Be and 53.82% O was measured in BeO NFs by X-ray photoelectron spectroscopy. BeO NFs were then impregnated with polyurethane (PU) aqueous solution to make PU/BeO NFs heat-dissipating sheet. This heat-dissipating sheet showed superior thermal conductivity (14.4 W m^-1 K^-1) at 41.4 vol% BeO NFs content. The electrical insulating properties of the heat-dissipating sheet were likewise excellent (1.6 × 10¹² Ω □^-1). In this study, the author attempted to create a thermally conductive but electrically insulating PU/BeO NFs heat-dissipating sheet that could effectively eliminate generated heat from electric equipment.