Low thermal and high electrical conductivity in hollow glass microspheres covered with carbon nanofiber–polymer composites

To take advantage of both the low density and thermal conductivity of hollow glass microspheres, and the high mechanical and electrical conductivity of carbon-based nanofillers, micro- and nanosized fillers can be combined into a single composite material. Here we prepared composite materials from hollow glass microspheres (HGMs) and from the same microspheres surrounded by carbon nanofibers (CNFs). By adding 10% wt. of HGM-CNFs to a high-temperature resin we can obtain a low density (0.8 g/cm3), low thermally (0.17 W/mK) and high electrically conductive (7±3×10−4S/m) composite. This novel method demonstrates the possibility to achieve an unusual combination of properties such as low thermal and high electrical conductivity which, along with their light weight and thermal stability, makes these materials promising for aerospace applications or thermoelectric devices.