Examining the use of oxide particles to enhance the sensitivity of polymer\carbon black nanocomposite gas sensors (original) (raw)
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The effect of surfactants on the properties of poly(vinyl acetate) (PVAc)/carbon black (CB) composite gas sensors was examined. Percolation curves of the composites with and without surfactant were prepared. The percolation curves of surfactant treated composites showed that the resistivity of the composite was increased due to better dispersion of the CB and also the prevention of the CB from reagglomerating after shear mixing. TEM images were used to investigate the effect of adding surfactant to the composites. These images confirmed that the surfactants significantly improved the level of dispersion of CB in the composites and prevented reagglomeration of the CB. The response (DR/R%) was increased by addition of surfactants and implies that increased dispersion increases response to methanol vapour.
Sensors Journal, …, 2002
The performance of polymer carbon-black composite chemical vapor sensors as a function of underlying electrode size and geometry has been studied. The sensor performance parameters investigated were sensor response magnitude to a toluene analyte (100, 500, and 1000 ppm), fundamental sensor noise in the presence of air, and two concentrations of toluene (100 and 500 ppm), and signal-to-noise ratio (100 and 500 ppm). An array of sensors with 42 different circular electrode configurations were designed, fabricated, and tested where electrode gap was varied from 10 to 500 m and the diameter of the sensors was varied from 30 to 2000 m. Each array of electrodes was coated with an approximately 1-m-thick layer of conducting polymer carbon-black composite with an insulating poly(alkylacrylate) polymer. The response magnitude, fundamental noise, and signal-to-noise ratio of each sensor was measured and compared to electrode geometry, such as electrode gap, aspect ratio, and overall size. No significant dependence of sensor response magnitude and noise to electrode configuration has been observed to be larger than the variation from sensor to sensor. However, the signal-to-noise ratio tended to decrease for sensors with the smallest scales.
Sensors and Actuators B: Chemical, 2011
Poly(vinyl alcohol) was modified by esterification to prepare poly(vinyl alcohol) copolymers. The degree of esterification on poly(vinyl alcohol) was elucidated by FTIR, 1 H NMR, and elemental analysis. The obtained products were poly(vinyl benzoate)-co-poly(vinyl alcohol) (B-PVA) and poly(vinyl p-toluoate)co-poly(vinyl alcohol) (P-PVA). The chemical vapor sensors were fabricated by the mixtures of polymer and carbon black in dimethyl sulfoxide and their subsequent preparation as thin films onto the interdigited electrodes by the application of the spin-coating technique. The chemical vapor sensing properties of the sensors were examined with various solvents, such as hexane, toluene, methanol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, acetonitrile, dimethyl sulfoxide, and water. The experimental results indicated that modifying the chemical structure of PVA results in the decreased polarity of the obtained products. The composites of modified PVA consequently responded well to low polarity solvents, such as THF or ethyl acetate.
PROPERTIES OF caRbOn-black cOmPOSITE vaPOuR dETEcTORS baSEd On mulTIFuncTIOnal POlymERS
Journal of the Balkan Tribological Association
in this work the electrical properties of vapour detectors, formed from composites of conductive carbon-black and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. the new composites are tailored to produce increased sensitivity towards specific classes of analyte vapours. resonant frequency shift of a Quartz crystal Microbalance (QcM) and dc resistance measurements have been also performed simultaneously on polymercarbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVc) with di(2-ethylhexyl)phthalate (doP), a traditional low-molecular weight plasticiser, is used as representative of the behaviour of a traditional composite vapour detector.
Properties of Multifunctional Polymers–Carbon Black Composite Vapor detectors
In this work the electrical properties of vapor detectors, formed from composites of conductive carbonblack and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. The new composites are tailored to produce increased sensitivity toward specific classes of analyte vapors. Resonant frequency shift of a Quartz Crystal Microbalance (QCM) and dc resistance measurements have been also performed simultaneously on polymer-carbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVC) with di(2-ethylhexyl)phthalate (DOP), a traditional low molecular weight plasticizer, is used as a representative of the behaviour of a traditional composite vapor detector. These new detectors showed an enhanced sensitivity upon exposure to acetic acid and amines vapors; the performances of our systems are 10 3 times higher than those of a traditional composite vapor detector. Moreover the extent of such responses is beyond that expected by mass uptake upon exposure to the same vapors and cannot be attributed solely to differences in polymer/gas partition coefficients. In this respect, several different chemical factors determine the dc electrical response of this system: in our opinion changes in polymer conformation during the adsorption process also play a significant role. The effects of the temperature on the electric resistance of the vapor detectors have also been studied. These materials showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the T g of the composites.
Polymer Journal, 1999
Poly(ethylene glycol) (PEG) having different molecular weight was successfully grafted onto carbon black surface by direct condensation of terminal hydroxyl groups of PEG with carboxyl groups on the surface using N,N'dicyclohexylcarbodiimide as a condensing agent. The electric resistance of a composite prepared from PEG and PEGgrafted carbon black drastically increased to 10 3-10 4 times of initial resistance in humidity and vapor of methanol, and ethanol, which are good solvent of PEG, and returned immediately to initial resistance when it was transferred in dry air. But the change of electric resistance of the composite was hardly observed in hexane and toluene vapor, which are poor solvent of PEG. The logarithm of electric resistance is linearly proportional to relative humidity. The sensitivity of electric resistance decreased with increasing molecular weight of PEG. In addition, the electric resistance of the composite from PEG-grafted carbon black lost the responsibility against solvent vapor above melting point of PEG. By crosslinking of the composite from PEG-grafted carbon black with triisocyanate, the responsibility against solvent vapor disappeared completely. These results indicated that the crystalline structure of PEG plays an important role on the responsibility of electric resistance of PEG-grafted carbon blacks against humidity and alcohol vapor.
Properties of multifunctional polymers – carbon black composite vapor
Publishing House of Lviv Polytechnic National University, 2011
In this work the electrical properties of vapor detectors, formed from composites of conductive carbonblack and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. The new composites are tailored to produce increased sensitivity toward specific classes of analyte vapors. Resonant frequency shift of a Quartz Crystal Microbalance (QCM) and dc resistance measurements have been also performed simultaneously on polymer-carbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVC) with di(2-ethylhexyl)phthalate (DOP), a traditional low molecular weight plasticizer, is used as a representative of the behaviour of a traditional composite vapor detector. These new detectors showed an enhanced sensitivity upon exposure to acetic acid and amines vapors; the performances of our systems are 10 3 times higher than those of a traditional composite vapor detector. Moreover the extent of such responses is beyond that expected by mass uptake upon exposure to the same vapors and cannot be attributed solely to differences in polymer/gas partition coefficients. In this respect, several different chemical factors determine the dc electrical response of this system: in our opinion changes in polymer conformation during the adsorption process also play a significant role. The effects of the temperature on the electric resistance of the vapor detectors have also been studied. These materials showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the T g of the composites.
Conductive Polymer-Composite Sensor for Gas Detection
Conductive polymers with carbon black filler were prepared for gas sensor application utilising ultrasonic mixing. The composite sensors were exposed to different types of gases and the resulting changes in the resistivity were recorded. The effects of ultrasonic mixing and sensitivity of the composite sensor to various organic gases were examined.
On the fabrication process of polymer-composites based sensors
The results of investigations of the effects of two organic solvents of preparation, tetrahydrofuran (THF) and 1,1,1,3,3,3 Hexafluoro-2-propanol (HFIP), and of three different electrical geometry of devices on drop-coated poly (methyl-methacrylate)/ carbon black (PMMA/CB) composites gas sensors are presented. Using HFIP solvent, it is possible to obtain a good dispersion of the CB filler in the polymeric matrix but the thermodynamic responses of devices to acetone and ethanol vapours are independent from their morphology and from the geometry of devices. The highest sensor responses are to acetone vapor. This behavior could be probably attributed to the higher chemical affinity of less polar molecule as acetone towards PMMA. The filler dispersions, the current-voltage (I/V) characteristics and the stability of devices in the time were also studied and discussed.
Gas sensing properties of conductive polymer nanocomposites
Nanocomposites consisted of carbon nanotubes (CNT) dispersed in various polymer matrices were prepared for the investigation of their sensing properties. The results from morphology study and electrical/dielectric characterization showed good dispersion of the filler with low percolation threshold. The response to water and ethanol vapour, at different concentration, was also studied showing better response for the more hydrophilic polymers and those with glass transition temperature below room temperature.