Thermoresistive Characterization of Monofilament Composites Based on Carbon Nanotube Yarns

Abstract

The effect of embedding a single carbon nanotube yarn (CNTY) in epoxy resins with different curing temperatures and the effect of a thermal program is addressed by studying the thermoresistive response of CNTY/epoxy resin monofilament composites. Heating-cooling ramps ranging from room temperature (RT~25 °C) to 110 °C are applied to CNTY/epoxy resin composites. CNTY embedded in epoxy resins curing at room temperature (RT) and high temperature (HT, 130 °C) showed a negative dependence of electrical resistance with temperature during the heating-cooling program. The average temperature coefficient of resistance during the heating process found for epoxy resin monofilament composites using HT curing was -7.1x10-4 (±0.16x10-4) °C-1. For epoxy resin monofilament composites cured at RT the temperature coefficient of resistance was -5.26x10-4 (0.10x10-4) °C-1. This small difference may be attributed to an increased density of the polymer chains of the epoxy resin curing at HT, as well as to the level of infiltration of the viscous resin within the external bundles of the CNTY. At the end of the heating process, the fractional change in electrical resistance of the CNTY monofilament composites containing the epoxy resin curing at HT and RT were -8.3 % and -4.7 %, respectively, indicating a higher thermoresistive sensitivity for the epoxy resin curing at HT.