Effect of Ball Milling and Oxidation on Dispersibility and Dispersion Stability of Multiwalled Carbon Nanotubes in High Viscous Heat Exchange Fluids

Abstract

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 (ID/IG) 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.

A Simple Ball Milling and Thermal Oxidation Method for Synthesis of ZnO Nanowires Decorated with Cubic ZnO2 Nanoparticles

“…A clear and intense E 2 (high) peak and a very weak E 1 (LO) peak are particularly evident in the C-Mg sample, indicating that the synthesized ZnO is of greater purity. Moreover, in addition to the sharpest and strongest peak corresponding to E 2 (high), the clear presence of the peaks corresponding to A 1 (TO) and E 1 (TO) can be found, which may be due to the improved crystal quality, a feature that for other growth methods often appears at high temperatures [ 24 ]. Additional peaks (not shown) belonging to the phononic modes E 2 and A 1 (or their combination) have also been found in the region with the highest wave number (900 to 1300 cm −1 ).…”

“…W. Zhang-Wei [ 23 ] obtained Fe-doped ZnO nanowires suitable for flexible planar UV device applications by thermal oxidation at 500 °C. Recently, C. Vishal et al [ 24 ] used ball milling and thermal oxidation for the fabrication of multiwalled carbon nanotubes.…”

“…X.H. Wang et al have synthesized Mg-doped ZnO nanomaterials by chemical vapor deposition by studying the impact of growth temperatures on morphologies, compositions, and optical properties [ 24 ]. Moreover, our process was carried out in a conventional laboratory muffle furnace; it took place in the air and did not use carrier gases, auxiliary substrates, catalyst agents, or other chemicals that may have required costly waste treatments.…”