Chemical modification of multiwalled carbon nanotube with the liquid phase method

Abstract

In this study, multiwalled carbon nanotubes (MWNTs) were purified by using chemical method with different proportion of nitric acid and sulfuric acid liquid phase mixture. Carboxyl groups and other functional groups could be modified on the MWNTs surface. However, oxidation can damage the structure of carbon atoms on the surface of the carbon nanotube. Furthermore, the characteristic properties of MWNTs specimens were demonstrated by Raman spectrograph and Fourier transform infrared spectrum. The thermal properties and morphology of MWNTs were checked by Thermogravimetric analysis and Scanning electron microscope.

Piezoresistive properties of CNT reinforced cementitious composites

“…Test results in this study indicate that the functionalisation of CNT with carboxyl has beneficial effects on piezoresistive response of the composite because the dispersion of CNT is improved when it is functionalised with carboxyl. 18,19 It appears that CNTs effectively fill the pores in the cement matrix, which helps electrons to exchange between CNTs when compressive loadings are applied. Test results also suggest that higher levels of moisture in the composites degenerate the piezoresistive sensitivity.…”

“…18 The dispersion of CNTs in an aqueous solution produces the governing effects in developing the mechanical properties of CNT reinforced cementitious composites. 18,19 While a number of studies applied chemical admixtures such as surfactants and ultrasonication to achieve effective dispersion of CNT in aqueous solutions, this study applied only ultrasonication to the aqueous solution. This approach was chosen because the surfactants could adhere to the surface of CNTs, which would result in a change in piezoresistive properties in the composites.…”

“…In order to create functionalised nanotubes with carboxyl, MWCNTs were treated with a mixed solution of H 2 SO 4 and HNO 3 (3 : 2 ratio) for 72 h. 18,19 After the acid treatment, MWCNTs were neutralised using pure water and sampled after filtering and drying the solutions. CNTs have a strong tendency to cohere with each other due to van der Waals force.…”

Preparation and Applicability of Vinyl Alcohol Group Containing Polymer/MWNT Nanocomposite Using a Simple Saponification Method

“…To improve dispersion, several techniques have been attempted, including the use of surfactants, sonication, and other mixing methods. Recent work has demonstrated superior dispersion of MWNTs in polymers by functionalization of the nanotubes to compatibilize them with solvents and the matrix polymers [Chiu and Chang, 2007;Wu et. al., 2006;Balasubramanian and Burghard, 2005;.…”

“…Such accessibility of the catalyst to reactants is important for rapid and efficient reactions. Carboxyl groups and other functional groups could be modified on the MWNT surface [Chiu and Chang, 2007].…”