Effects of carbon nanotubes geometrical configurations and concentrations on mechanical, thermal and dielectric properties of nanocomposites
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In the recent years research has been focused on improving the properties of the polymeric resins. The use of nanomaterial inclusions as reinforcement for better properties has been a key chapter in the field of polymeric composite materials. Carbon Nanotubes (CNTs) and other nanomaterial inclusions can provide considerable improvement to the properties of polymer composites. In this research, the Multiwall Carbon nanotube (MWCNTs) and Carbon NanoHeliCoils (CNHCs) were used as nano-inclusions in the epoxy resin. The CNHCs and MWCNTs were dispersed in a resin using a solvent and later heated and stirred continuously until the solvent was evaporated. Next, the hardener was added to the mixture and cured in room temperature that was later followed by post curing in an oven for optimum properties. Different weight ratios of CNHCs and MWCNTs were used to fabricate nanocomposite panels. The goal in this research was to find out the optimum values of weight ratios for improvement of mechanical properties of the nanocomposites as well as to study the relationship between the weight percentage of nanoreinforcements used to improve the thermal and dielectric properties of the nanocomposites. Test samples were prepared with different weight ratios of nanoreinforcement for tensile testing, Single Edge Notch Bending (SNEB), hardness testing, dielectric constant and thermal conductivity testing, according to ASTM standards. It was observed that the CNHCs and MWCNTs reinforcements perform the best for mechanical properties improvements at 0.05% and 0.1% loading respectively. However both Dielectric constant and Thermal Conductivity of the nanocomposites were improved as the CNTs concentration was increased, regardless of their geometrical configurations. In addition, scanning electron microscopy and high-resolution optical microscopy was used to characterize the fractured surfaces and investigate the failure modes of test samples.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering