Multi-walled carbon nanotube (MWNT) films were prepared on interdigital electrodes by air-brush technique, and their sensing properties to dimethyl methylphosphonate (DMMP) were studied. The MWNT films were observed by scanning electron microscope. The capacitive response to different concentrations of DMMP vapor was investigated at room temperature. The results showed that the capacitance and loss tangent of the air-brush MWNT sensor both decreased rapidly in varying concentrations ranging from 2.4 to 12 ppm. The sensitivity of capacitance was higher than that of the loss tangent at all the concentrations of DMMP vapors. The sensor exhibited high sensitivity and fast response for DMMP vapor detection.
In this paper, four different series of polymer solutions were presented to study the effects of solution properties on the
morphology and diameters of nanofibers, including the polyethersulfone (PES) dissolving in N, N-dimethylformamide,
polyvinylpyrrolidone (PVP) in ethanol, poly(acrylic acid) (PAA) in water and poly(vinylidene fluoride) (PVDF) in N, Ndimethyl
acetamide. These solutions revealed different conditions of the formation of beads, the spatial structures and the
diameter of fibers. The PVDF nanofibers had plenty of small beads on the fibers, while the other three were uniform
fibers without beads. The nanofibers of PES, PVP and PVDF showed good three dimensional structures except the PAA
fibrous membranes. The change of fiber diameters of PVDF was much larger than that of PVP.
This paper described a procedure based on electrospinning for generating nanofibers with controllable diameters and
morphology. When an acetone and N,N-dimethylacetamide (DMAc) mixture solvent containing poly(vinylidene
fluoride) (PVDF) was injected through a needle under a strong electric field, nanofibers made of PVDF formed as a
result of electrostatic jetting. To control the diameter and morphology of PVDF nanofibers, the solution properties and
process parameters were investigated, such as polymer concentration, the ratio of the mixture solvent, feeding rate,
applied electric field, and needle-to-collector distance. The fabricated fibers were 30-8000 nm in diameter. The increase
in the polymer concentration caused an increase in the fiber diameter. However, the increase in the feeding rate and
applied electric field decreased the fiber diameter. Variation in the needle-to-collector distance did not result in
significant changes in the fiber diameter. The ratio of the solvent also had a very significant impact on electrospinning.
The diameter and morphology of the PVDF nanofibers were characterized by optical microscope and scanning electron
microscope (SEM).
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