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.
Statistical modeling of the dip-spin coating process to describe colloidal PTFE dispersion coating on the external surface of a small diameter hollow tube was developed by using 2 4 factorial design with a center point to predict the coating thickness in a range of 4-10 m. The coating parameters included viscosity, withdrawal rate, spin speed, and immersion time. The adequacy of the predicted model was verified by coefficients of determination and lack-of-fit test. Model accuracy was verified by comparing predicted values with experimental results. The significant interaction effects on the coating thickness were three-way interaction among withdrawal rate, spin speed, and immersion time and two-way interactions between viscosity and withdrawal rate, viscosity and spin speed, and viscosity and immersion time. Cube plot for coating thickness reveals a trend of increasing coating thickness towards high levels of viscosity, withdrawal rate, and immersion time and lower level of spin speed.
Effects of azodicarbonamide (ADC) and vulcanization method, that is, hot air (HA) and infrared (IR), on acrylonitrile–butadiene rubber/polyvinyl chloride (NBR/PVC) foam properties were investigated. Results reveal that ADC content had no significant influence on the onset of vulcanization. The cure pattern of the compounds was dependent on ADC content. Foam density was reduced, whereas water absorption and compression set were increased with increasing ADC content. Regardless of the vulcanization method, the blowing agent utilization efficiency was increased slightly, whereas the thermal conductivity was decreased with increasing ADC content up to 50 phr and then leveled off. At any given ADC content, the vulcanization method had no significant effects on both foam density and porosity. Compared with HA vulcanization method, IR vulcanization method gave slightly lower thermal conductivity but greater values of water absorption and compression set. Foam structure was used to explain the results.
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