Characterization of simulated low earth orbit space environment effects on acid-spun carbon nanotube yarns

Abstract

The purpose of this study is to quantify the detrimental effects of atomic oxygen and ultraviolet (UV) C radiation on the mechanical properties, electrical conductivity, and piezoresistive effect of acid-spun carbon nanotube (CNT) yarns. Monotonic tensile tests with in-situ electrical resistance measurements were performed on pristine and exposed yarns to determine the effects of the atomic oxygen and UVC exposures on the yarn’s material properties. Both type of exposures were performed under vacuum to simulate space environment conditions. The CNT yarns’ mechanical properties did not change significantly after being exposed to UV radiation, but were significantly degraded by the atomic oxygen exposure. The electrical conductivity of the yarn was not significantly affected by either exposure. The piezoresistive effect did not significantly change due to atomic oxygen exposure, but was significantly enhanced as a result of the UV exposure. Scanning electron microscopy revealed significant erosion due to atomic oxygen exposure, but the UV exposure did not significantly change the appearance of the yarn’s external surface. Raman spectroscopy showed that both exposure types induced significant structural disorder in the surface level CNTs. Focused ion beam milling of a UVC exposed yarn revealed that the depth of the induced disorder was very shallow. Keywords: Carbon nanotube yarn, Mechanical properties, Conductivity, Ultraviolet radiation, Raman spectroscopy