Polyaniline is one of the most promising conducting polymers for gas sensing applications due to its relatively high stability and n or p type doping capability. However, the conventionally doped polyaniline still exhibits relatively high resistivity, which causes difficulty in gas sensing measurement. In this work, the effect of carbon nanotube (CNT) dispersion on CO gas sensing characteristics of polyaniline gas sensor is studied. The carbon nanotube was synthesized by Chemical Vapor Deposition (CVD) using acetylene and argon gases at 600 degrees C. The Maleic acid doped Emeradine based polyaniline was synthesized by chemical polymerization of aniline. CNT was then added and dispersed in the solution by ultrasonication and deposited on to interdigitated AI electrode by solvent casting. The sensors were tested for CO sensing at room temperature with CO concentrations in the range of 100-1000 ppm. It was found that the gas sensing characteristics of polyaniline based gas sensor were considerably improved with the inclusion of CNT in polyaniline. The sensitivity was increased and response/recovery times were reduced by more than the factor of 2. The results, therefore, suggest that the inclusion of CNT in MA-doped polyaniline is a promising method for achieving a conductive polymer gas sensor with good sensitivity, fast response, low-concentration detection and room-operating-temperature capability.
Composite of MWCNT and PMMA was prepared by the mean of in-situ polymerization assisted by sonicated mixing. The prepared composites could exhibit electrical conductivity due to conductive path of entangling MWCNT in the polymeric matrix. With the increasing MWCNT content, the conductive path became more uniform, leading to the lower electrical resistance of the composites. Based on experimental results, the 2.0 wt% of MWCNT to PMMA was considered as the percolation threshold. When the composite was exposed to toluene, the polymer matrix would swell, leading to destruction of conductive path and change of the electrical resistance of the composites. Dependence of the sensor sensitivity upon the MWCNT was experimentally investigated. With the lowest MWCNT content, degree of swelling in the composite matrix became much higher. Therefore, the electrical resistance of the composite with the lowest MWCNT content changed substantially.
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