Study on the Mechanical Properties and Creep Behaviour of Carbon Fiber Nano-Composites
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Study on the Mechanical Properties and Creep Behaviour of Carbon Fiber NanoComposites Yi-Luen LI1, Wei-Jen Chen1, Chin-Lung Chiang2, Ming-Chuen Yip1,* 1
Department of Power Mechanical Engineering, National Tsing-Hua University, Hsin-Chu
30043, Taiwan, R.O.C. 2
Department of Safety, Health and Environmental Engineering, Hung-Kuang University,
Taichung, 433, Taiwan, R.O.C. ABSTRACT The surface modification of carbon nanotubes ΰ CNTs α has been recently observed to influence the distribution of CNTs in epoxy resin and the mechanical properties and electrical conductivities of these CNTs. Accordingly, the treatment of CNTs with organic acids to oxidize them generates functional groups on the surface of CNTs. This investigation studies the consequent enhancement of the mechanical properties and electrical conductivities of CNTs. The influence of adding various proportions of CNTs to the epoxy resin on the mechanical properties and electrical conductivities of the composites thus formed is investigated, and the strength of the material is tested at different temperatures. Moreover, the creep behavior of carbon fiber ΰCFα/epoxy resin thermosetting composites was tested and analyzed at different temperatures and stresses. The creep exhibits only two stages- primary creep and steady-state creep. The effects of creep stress, creep time, and humidity on the creep of composites that contain various proportion of CNTs were investigated at various temperatures. Creep strain is believed to increase with applied stress, creep time, humidity, and temperature. It also increases as hardness decrease. The test results also indicate that mechanical strength and electrical conductivity increase with the amount of CNTs added to the composites. Different coefficients of expansion of the matrix, fiber and CNTs, are such that overexpansion of the matrix at high temperature results in cracking in it. An SEM image of the fracture surface reveals debonding and the pulling out of longitudinal fibers because of poor interfacial bonding between fiber and matrix, which reduce overall strength. INTRODUCTION The incorporation of nanoparticles or nanotubes into the matrix of fiber-reinforced composites has been extensively investigated in recent years [1]. The creep deformation of engineering materials at elevated temperatures has received significant attention for many years [2-5]. This investigation studies the surface modification of CNTs, and the mechanical strength [6,7] and electrical conductivity of thermosetting composites with various proportions (0.25, 0.5, 0.75 wt%) of CNTs [8,9], The creep behavior of thermosetting composites is tested under various conditions of temperature, load and humidity [10-11]. The results of testing are adopted to investigate the mechanical strength, electrical conductivity and creep behavior.
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EXPERIMENTAL Materials and Experimental Procedure The MWCNTs that were used for reinforcement in this study were supplied by Desun Mamo Co. Ltd. A MWCNT / epoxy resin prepreg laminate was formed by hot pressing. E
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