Papers by Keyword: Carbon Nanotube Network

Abstract: The sensing properties of pristine and hexamethylene diamine (HDA)-treated multiwall carbon nanotube networks (MWCNT-Ns) to selected primary, secondary (sec-) and tertiary (ter-) alcohols were examined by resistance measurements. It was seen that sensor responses, S (%), of MWCNT (HDA)-N to these alcohols were much higher than those of the pristine network. An increase in the S (%) values per mm Hg of both networks was observed from propanol to butanol, when their values from primary alcohols to sec-/tert-ones decreased due to the change in the interaction area of these alcohols with the MWCNT-Ns.

Abstract: The effect of oxidation of multi-walled carbon nanotubes by KMnO₄ on the electrical resistance of a nanotube network/polyurethane composite subjected to bending has been studied. In this respect, the main achievement is a multiple increase of gauge factor for the evaluating electromechanical properties of the composite after nanotube oxidation with KMnO₄. It indicates favorable properties of the composite for its use as a high-deformation strain-sensing element.

Abstract: A highly deformable composite composed of a network of electrically-conductive entangled carbon nanotubes embedded in elastic polyurethane for sensing tensile deformation by changes in strain has been prepared. The testing has shown that the composite can be extended as by much as 400 % during which the electrical resistance increases more than 270 times. The high strain sensing can be attributed to the network cracking upon extension. To understand the cracking mechanism and explain the resistance change, the structural changes of networks made of pristine carbon nanotubes (as well as functionalized multi-walled) were examined. The microscopic observation of crack formation and resistance change of the networks correlates well with the amount of cracking.

Abstract: Multi-walled carbon nanotubes networks (MWCNTs) were used as a layer for organic vapor detection. The sensor detects volatile organic compounds (VOC). The gas sensing by MWCNTs is measured by means of macroscopic electrical resistance. The selected solvents had different polarities and volume fractions of saturated vapors. The electrical resistance of MWCNTs increases when exposed to organic solvent vapors, and a reversible reaction is observed when the MWCNT is removed from the vapors. The MWCNTs were modified by means of plasma treatment. For modifications RF plasma in O₂ at 50 Pa and an afterglow configuration were used. The modified MWCNTs show an increase in sensitivity caused by creating carboxylic groups on the surface of the carbon nanotubes. It leads, for example, to enhancement of the sensitivity from usual 30 % for heptane at RT to more than 200% after plasma treatment in O₂ for 10s.

Abstract: Multiwall carbon nanotubes (MWCNT) network “Buckypaper” was made by the vacuum filtration method of MWCNT aqueous suspension. The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure nanotubes to various organic solvent vapors (tetrahydrofuran, methyl ethyl ketone, and ethanol) has been investigated by resistance measurements. The results demonstrate that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the sample is removed from the vapors. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor detection.

Abstract: Multiwall carbon nanotubes (MWCNT) network “Buckypaper” was made by the vacuum filtration method of MWCNT aqueous suspension. The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure nanotubes to various organic solvent vapors (tetrahydrofuran, methyl ethyl ketone, and ethanol) has been investigated by resistance measurements. The results demonstrate that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the sample is removed from the vapors. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor detection.

Abstract: Two kinds of Multiwall carbon nanotubes (MWCNT) networks “Buckypaper” were made by the vacuum filtration method of MWCNT aqueous suspension. The first one was prepared from pure CNT and the second from its oxidized form by acidic KMnO4 as oxidizing agent. The CNT oxidation increase content of oxygen bonded to the surface of CNT decreasing their hydrophobic character. The sensitivity of MWCNT networks to two kind of organic solvent vapors (ethanol and hepane) has been investigated by resistance measurements. The solvents had different polarities given by Hansen solubility parameters and nearly the same volume fractions of saturated vapors at the condition of experiment. CNT oxidation significantly increases the sensitivity of CNT resistive sensor to vapors of ethanol and decrease response to heptane vapors. The present paper demonstrates the effective way how to add proper selectivity for organic vapor detection.