The present study investigates the dispersion stability, viscosity, shear stress, and thermal conductivity of multi-walled carbon nanotubes in the presence of Gum Arabic (MWCNT-GA) as well as functionalized MWCNT with cysteine (MWCNT-Cys) and silver (MWCNT-Ag). In order to realize good dispersibility and high thermal enhancement, MWCNT were first functionalized by cysteine and then silver ions covalently attached with thiol group in cysteine. This efficient technique using a combination of functional silver and cysteine based on MWCNT was developed to enhance the thermal conductivity of MWCNT suspension. At every sequential step of modification, chemical functionalization was investigated by Fourier transform infrared and Raman spectroscopy. Transmission electron microscope imaging was confirmed distribution of silver nanoparticles on MWCNT surface. Viscosity, shear stress and thermal conductivity behavior of MWCNT-GA/water, MWCNT-Cys and MWCNT-Ag/water suspensions were studied in various temperature and weight concentration. To enhanced thermal conductivity, the results suggest the covalent functionalization by Ag is more effective than non-covalent functionalization.

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