In recent years, intensive researches have been stimulated to explore the promising prospect for carbon nanotubes (CNTs) in the fabrication of novel polymer sensor composites. In this study, the fabrication and properties of a flexible and stretchable composite elastomer fabricated from direct-spun carbon nanotube fiber (yarns) were presented, and the novel CNT fiber/polydimethylsiloxane (PDMS) elastic conductive composite shows the reversible two-stage conductivity owing to its unique structure of CNTs fabricated by the floating catalyst chemical vapor deposition (FCCVD). As the strain increased from 0% to 10% (Stage I), stretching the oriented CNT fiber/PDMS elastic conductive composite induces a constant decrease in the conductive pathways and contact areas between CNTs depending on the stretching distance. However, this composite elastomer will retain almost stable electrical resistance while being stretched by over 10% (Stage II). Furthermore, the composite shows very little variation in resistance under 187 stretching–releasing cycles up to a pre-strain level of 6%, indicating the outstanding stability and repeatability in performance as stretchable conductors. The microstructure, reversible two-stage conductive properties and mechanism were also discussed.

中文翻译：

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一种具有可逆两级电导率的新型定向CNT纤维/PDMS弹性导电复合材料

近年来，人们进行了深入的研究，以探索碳纳米管（CNT）在制造新型聚合物传感器复合材料中的广阔前景。在这项研究中，介绍了由直纺碳纳米管纤维（纱线）制成的柔性可拉伸复合弹性体的制备和性能，新型 CNT 纤维/聚二甲基硅氧烷（PDMS）弹性导电复合材料显示出可逆的两级导电性。通过浮动催化剂化学气相沉积（FCCVD）制造的碳纳米管的独特结构。随着应变从 0% 增加到 10%（阶段 I），拉伸取向的 CNT 纤维/PDMS 弹性导电复合材料会导致 CNT 之间的导电路径和接触面积不断减小，具体取决于拉伸距离。然而，这种复合弹性体将保持几乎稳定的电阻，同时拉伸超过 10%（第二阶段）。此外，该复合材料在 187 次拉伸-释放循环（高达 6% 的预应变水平）下表现出非常小的电阻变化，表明作为可拉伸导体的性能具有出色的稳定性和可重复性。还讨论了微观结构、可逆两阶段导电性能和机理。