Dispersive Evaluation and Self-Sensing of Single Carbon Fiber/CNT-Epoxy Composites using Electro-Micromechanical Techniq
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1075-J05-04
Dispersive Evaluation and Self-Sensing of Single Carbon Fiber/CNT-Epoxy Composites using Electro-Micromechanical Techniques Joung-Man Park1,2, Jung-Hoon Jang1, Zuojia Wang1, Pyung-Gee Kim1, Woo-Il Lee3, Jong-Kyoo Park4, and Lawrence K. DeVries2 1 School of Nano and Advanced Materials Engineering, Gyeongsang National University, 900 Gajwa-Dong, Jinju, 660-701, Korea, Republic of 2 Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, 84112 3 School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-742, Korea, Republic of 4 4-R&D Center, Agency for Defense Development, Daejeon, 305-600, Korea, Republic of
ABSTRACT Self-sensing and interfacial evaluation were investigated with different dispersion solvents for single carbon fiber/carbon nanotube (CNT)-epoxy composites by electromicromechanical technique and acoustic emission (AE) under loading/subsequent unloading. Optimized dispersion procedure was set up to obtain improved mechanical and electrical properties. Apparent modulus and electrical contact resistivity for CNTepoxy composites were correlated with different dispersion solvents for CNT. CNTepoxy composites using good dispersion solvent showed higher apparent modulus because of better stress transferring effect due to relatively uniform dispersion of CNT in epoxy and enhanced interfacial adhesion between CNT and epoxy matrix. However, good solvent showed high apparent modulus but low thermodynamic work of adhesion, Wa for single carbon microfiber/CNT-epoxy composite. It is because hydrophobic high advanced contact angle was shown in good solvent, which can not be compatible with carbon microfiber well. Damage sensing was also detected simultaneously by AE combined with electrical resistance measurement. Electrical resistivity increased stepwise with progressing fiber fracture due to the maintaining numerous electrical contact by CNT.
INTRODUCTION Since carbon nanotube (CNT) was discovered in 1991 by Iijima [1], many scientists studied CNT because inherent mechanical properties and several potential functional advantages. Carbon nanocomposites filled with CNT have high stiffness, strength and good electrical conductivity at relatively low concentration of reinforcing CNT materials [2]. Carbon nanocomposites with electrical conductivity can be applied to electrostactic discharge (ESD) and electromagnetic interference (EMI) protection especially applicable for aircraft parts [3]. Electrical and mechanical properties of CNT reinforced polymer composites depend on many factors such as inherent aspect ratio, fiber shape and content etc [4]. Efficient exploitation of CNT properties to improve the materials performance is generally related to the degree of dispersion, impregnation with matrix and the interfacial adhesion [5]. The degree of dispersion is one of very important parameter
and difficult to control in preparing nanocomposites. Experimentally-observed percolation threshold concentration is known to be strongly dependent on the aspect ratio
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