Size‐Dependent Electrical and Thermal Properties of Onion‐Like Carbons/Polyurethane Composites

Results of dielectric/electrical studies of onion‐like carbon (OLC)/polyurethane composite films in very broad frequency (20 Hz–3 THz) and temperature (26–300 K) ranges are presented. We show that the percolation threshold in these composites strictly depends on OLC aggregate size and is lower for composites having smaller OLC aggregates. The electrical conductivity in the composites is mainly due to electron tunneling between OLC clusters and quasi‐one‐dimensional hopping inside the clusters. The thermal diffusivity increases with OLC concentration and, as for electrical conductivity, is the highest for composites having the smallest OLC aggregates. POLYM. COMPOS., 39:E1834–E1840, 2018. © 2018 Society of Plastics Engineers