Polymer-Single Wall Carbon Nanotube Composites for Potential Spacecraft Applications
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Polymer-Single Wall Carbon Nanotube Composites for Potential Spacecraft Applications Cheol Park1, Zoubeida Ounaies1, Kent A. Watson1, Kristin Pawlowski, Sharon E. Lowther, John W. Connell, Emilie J. Siochi, Joycelyn S. Harrison, and Terry L. St. Clair Advanced Materials and Processing Branch, NASA Langley Research Center, 1ICASE MS-226, Hampton VA 23681-2199 ABSTRACT Polymer-single wall carbon nanotube (SWNT) composite films were prepared and characterized as part of an effort to develop polymeric materials with improved combinations of properties for potential use on future spacecraft. Next generation spacecraft will require ultralightweight materials that possess specific and unique combinations of properties such as radiation and atomic oxygen resistance, low solar absorptivity, high thermal emissitivity, electrical conductivity, tear resistance, ability to be folded and seamed, and good mechanical properties. The objective of this work is to incorporate sufficient electrical conductivity into space durable polyimides to mitigate static charge build-up. The challenge is to obtain this level of conductivity (10-8 S/cm) without degrading other properties of importance, particularly optical transparency. Several different approaches were attempted to fully disperse the SWNTs into the polymer matrix. These included high shear mixing, sonication, and synthesizing the polymers in the presence of pre-dispersed SWNTs. Acceptable levels of conductivity were obtained at loading levels less than one tenth weight percent SWNT without significantly sacrificing optical properties. Characterization of the nanocomposite films and the effect of SWNT concentration and dispersion on the conductivity, solar absorptivity, thermal emissivity, mechanical and thermal properties were discussed. Fibers and non-woven porous mats of SWNT reinforced polymer nanocomposite were produced using electrospinning.
INTRODUCTION This study proposes an approach to design a durable, ultra-lightweight structure using single wall carbon nanotubes in a polymer matrix that possess a unique combination of properties required for long-term performance in aerospace applications. These novel nanocomposites will be designed to provide the following features; ultra-lightweight, chemical stability, high thermal and electrical conductivity, low permeability, hydrolytic oxidation resistance, radiation resistance, atomic oxygen resistance, low solar absorption, high emissivity, low coefficient of thermal expansion, and mechanical durability. Carbon nanotubes have attracted tremendous attention since their discovery [1] due to their unique electronic and mechanical properties [2]. These superb intrinsic properties are most likely to be expected in SWNT, rather than in MWNT because of its flawless structure and low density (1.33–1.40 g/cm3). There is a great deal of interest in aerospace and electronics applications involving high temperature polymers (e.g. polyimides), and significant benefits in strength and electrical properties are expected from SWNT reinforcemen
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