Use of compatible blends to fabricate carbon black composite vapor detectors (original) (raw)
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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.
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.
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.
Progress in Solid State Chemistry, 2005
This paper investigates the use of NiO particles to enhance the vapour sensing properties of polyethylene adipate (PEA)\carbon black (CB) composite materials. Four PEA\CB suspensions were prepared with 0, 10, 20 and 30 w/w% NiO, respectively. Hypermer PS3 surfactant was shear mixed into each of the suspensions for 300 s to achieve a homogenous dispersion and to prevent reagglommeration of both the CB and NiO particles. A 0.1 ml drop of each composite was deposited between Cu electrodes on a printed circuit board (PCB) substrate using a microlitre syringe. The samples were allowed to dry for 24 h in an oven at 333 K to remove any remaining solvent. After preparation, the sensors were exposed to propanol and butanol at concentrations ranging from 0 to 25 000 ppm in steps of 5000 ppm. The response of the PEA\CB sensors improved significantly as the concentration of NiO particles in the material increased and maximum relative differential responses as high as 37% and 92.8% were recorded after exposure to 25 000 ppm propanol and butanol, respectively. This high response can be explained using the FloryeHuggins interaction parameter along with structural changes in the polymer composite caused by the addition of NiO. This paper concludes that NiO particles can be used as a method to increase the sensitivity of existing conducting polymer composite gas sensing materials.
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.
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.
Novel Contamination and Gas Sensor Materials from Amphiphilic Polymer-Grafted Carbon Black
Polymer Journal, 2006
The responses of electric resistance of composites prepared from amphiphilic polymer-grafted carbon blacks to contamination in solution and solvent vapor were investigated. The electric resistance of the composite prepared from poly(N-isopropylacrylamide) (PNIPAM)-grafted carbon black drastically increased when the composite was dipped in n-hexane containing contamination, such as methanol, THF, dioctyl phthalate, and chloroform, and returned to the initial resistance when it was transferred to dry air. The logarithm of the electric resistance of the composite was linearly proportional to chloroform concentration in n-hexane. The electric resistance of the composite drastically increased in organic polar solvent vapor, such as methanol, THF, and chloroform and returned to the initial resistance when it was transferred to dry air. But the response to non-polar solvent vapor, such as n-hexane, was very small. The logarithm of electric resistance of the composite was linearly proportional to humidity. In addition, electric resistance of the composite prepared from poly(diethylacrylamide) (PDEAA)-grafted carbon black also drastically increased when the composite was dipped in n-hexane containing contamination, such as methanol, trichloroethane, THF, chloroform, and benzene, and returned to the initial resistance when it was transferred to dry air. Based on the results, it was found that the composites could be used as a novel contamination sensor in n-hexane and gas sensor.
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.
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.
Modeling carbon black/polymer composite sensors
Sensors and Actuators B: Chemical, 2007
Conductive polymer composite sensors have shown great potential in identifying gaseous analytes. To more thoroughly understand the physical and chemical mechanisms of this type of sensor, a mathematical model was developed by combining two sub-models: a conductivity model and a thermodynamic model, which gives a relationship between the vapor concentration of analyte(s) and the change of the sensor signals. In this work, 64 chemiresistors representing eight different carbon concentrations (8-60 vol% carbon) were constructed by depositing thin films of a carbon-black/polyisobutylene composite onto concentric spiral platinum electrodes on a silicon chip. The responses of the sensors were measured in dry air and at various vapor pressures of toluene and trichloroethylene. Three parameters in the conductivity model were determined by fitting the experimental data. It was shown that by applying this model, the sensor responses can be adequately predicted for given vapor pressures; furthermore the analyte vapor concentrations can be estimated based on the sensor responses. This model will guide the improvement of the design and fabrication of conductive polymer composite sensors for detecting and identifying mixtures of organic vapors.