Ground-Based Space Radiation Effects Studies on Single-Walled Carbon Nanotube Materials

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Ground-Based Space Radiation Effects Studies on Single-Walled Carbon Nanotube Materials R. Wilkins1, M. X. Pulikkathara2, Valery N. Khabashesku3, E. V. Barrera2, Ranji K. Vaidyanathan4, S. A. Thibeault5 1

NASA Center for Applied Radiation Research and the Department of Electrical Engineering, Prairie View A&M University, Prairie View, TX 77446 USA 2 Department of Mechanical Engineering and Material Science, Rice University, Houston, TX 77005 USA 3 Department of Chemistry and Center for Nanoscale Science and Technology, Rice University, Houston, TX, 77005 USA 4 Advanced Ceramics Research, E. Hemisphere Loop, Tucson, AZ 85706, USA 5 NASA Langley Research Center, Hampton, VA 23681-2199 USA ABSTRACT Materials based on carbon nanotubes hold great promise for a variety of applications relevant to space exploration and the aerospace industry. Materials used for these applications will be subject to hostile environments including increased levels of high-energy particulate radiation. The type, energy range and fluence of the radiation will depend on the environment of the space mission. While it is not feasible to conduct an exhaustive study of the effects of space radiation on the earth’s surface, ground-based experiments can be designed to simulate expected radiation environments using sources representing components of the relevant radiation environments. In this paper we present a compilation of results on materials based on singlewalled carbon nanotubes (SWNT) emphasizing nano-composites with raw (non-functionalized) and with 2-5% functionalized SWNTs in a polyethylene matrix. Materials such as these are promising candidates for multi-functional materials with good structural and radiation shielding characteristics. The radiation sources discussed here are relevant to the upper atmosphere (high energy neutrons), low earth orbit (medium energy protons) and interplanetary space (high energy protons and heavy ions). The samples are characterized before and after radiation with Raman spectroscopy which gives information on the structure of the SWNT and state of sidewall functionalization. Based on results from the SWNT papers (“buckypapers”) and the composites made from functionalized and non-functionalized SWNT, our data indicates that structural integrity and any sidewall functionalization of the SWNT in the nano-composite are radiation tolerant to radiation fluences commensurate with expected exposures on long-term spaceflight. More importantly, we find that the chemistry and material science of the processes used to produce the pristine and functionalized SWNT can affect the radiation characteristics of the nano-composites. INTRODUCTION New materials for structures and instrumentation will help enable human and robotic exploration of the solar system and beyond. In particular, nano-scaled materials have extraordinary properties which may revolutionize many technologies [1,2] including technologies with aerospace applications [3]. Carbon nanotube-based materials that take

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