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Effect of Ball Milling and Oxidation on Dispersibility and Dispersion Stability of Multiwalled Carbon Nanotubes in High Viscous Heat Exchange Fluids
Author(s) -
Vishal Chachin,
Raju Chinthalapati Siva Kesava,
Krishna Kanala Raghava,
Raman Ravishankar,
Rao Bojja Ramachandra,
Kanaparthi Ramesh
Publication year - 2020
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201904413
Subject(s) - materials science , carbon nanotube , raman spectroscopy , nanofluid , chemical engineering , ball mill , thermal stability , dispersion (optics) , agglomerate , composite material , dispersion stability , surface modification , sonication , nanotechnology , nanoparticle , polymer , physics , engineering , optics
Multiwalled carbon nanotubes (MWCNTs) tend to agglomerate resulting in poor dispersion in most of the common solvents due to possessing long tubular structure, high Vander Waal force of attractions and poor interfacial interactions with the surrounding matrix. To improve the dispersion stability, MWCNT, were subjected to ball milling with 300 rpm for 1 h to reduce the length of the MWCNT to improve the functional groups to the MWCNT wall during chemical functionalization. MWCNTs were subjected to thermal oxidation in air at different temperatures before acid treatment to remove the amorphous carbon from MWCNT. Morphology studies of MWCNTs nanofluids were carried out by using a SEM and TEM methods to characterize the surface deformity of MWCNT structure and extent of defect formation, respectively. FT IR and XRD methods were used for the identification of different functional groups and crystalline nature of pristine, ball milled and oxidized MWCNT, respectively. Raman spectroscopy was applied to measure the relative intensities (I D /I G ) to estimate the defect ratios. Preparation of nanofluid by dispersing high defect ratio MWCNTs with a concentration of 100 ppm in the base fluid by the ultra‐sonication method. Nanofluids dispersion stability and cycle stability were studied by using UV‐Visible spectroscopy and MWCNTs treated with combined ball milling and oxidation method have exhibited high stability and high dispersibility.