LAUSR

Carbon nanotube yarns (CNTYs) are hierarchical fibers with outstanding electrical properties, and understating the temperature‐dependence of their electrical resistance (thermoresistivity) is essential for sensing applications and development of self‐sensing polymer composites. The cyclic thermoresistive response of individual CNTYs and the effect of embedding the yarn into a polymer are experimentally investigated herein. The effect of confining the CNTY by a thermosetting polymer is addressed by studying the thermoresistive response of CNTY/vinyl ester single‐fiber composites. Heating–cooling cycles ranging from 25 (room temperature [RT]) to 100 °C and 25 to −30 °C are applied to individual CNTYs and to CNTYs embedded into a vinyl ester polymer, while their electrical resistance is simultaneously recorded. Both the CNTY and its single‐fiber composite show a negative dependence of electrical resistance with temperature. For both temperature ranges (above and below RT), the average temperature coefficient of resistance found for individual CNTYs is ≈−9.5 × 10−4 K−1, and its magnitude decreases about ≈30% when the yarn is embedded into the vinyl ester polymer. The hysteresis rendered by the different heating and cooling pathways is small for individual CNTYs, and largely increases when the CNTY is embedded into the polymer.