Enhancing heat dissipation in polyurethane sheets through the incorporation of freeze‐dried aluminum nitride nanofiber

Abstract

AbstractInspired by a three‐dimensional (3D) structure, we demonstrate 3D aluminum nitride (AlN) nanofibers fabricated by a freeze‐drying technique using polyvinyl alcohol (PVA)/boehmite precursor nanofibers. After applying hot pressing, a series of PVA/boehmite precursor nanofibers were prepared with varying PVA‐to‐boehmite ratios (30/70 wt%, 50/50 wt%, and 70/30 wt%). Our findings reveal that the thermal conductivity of the AlN composite nanofibers is significantly affected by the relative proportions of PVA and boehmite, where the ratio of PVA should be more significant than that of boehmite. We produced AlN nanofibers at a lower temperature (1500°C) than the theoretical formation temperature of AlN (1664°C). The minimum specific surface area and pore volumes were 8.39 m2/g and 0.0166 cm3/g, respectively, at 1500°C. X‐ray photoelectron spectroscopy spectra measured 38.27% aluminum and 23.55% nitrogen in AlN nanofibers. The aligned AlN nanofibers mat was impregnated with polyurethane (PU), which showed good thermal conductivity in the planar (4.1–13.6 W/(m·K)) and thickness (1.5–4.9 W/(m·K)) directions at 18–56 vol% AlN nanofibers content. The heat‐dissipating sheet also showed superior electrical insulating (1.2 × 1012 Ω/cm2) properties. In this study, the author sought to develop a heat‐spreading material made of thermally conductive, but electrically insulating PU/AlN nanofibers that could efficiently dissipate heat from electric devices.