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In the past two decades, many studies on piezoelectric nanofibers (NFs) prepared from poly(vinylidene fluoride) (PVDF) and its copolymers, including single NFs, randomly oriented nonwoven mats, and aligned NFs, have been reported. However, studies on the relationships between the PVDF NF diameter, the orientation of the β-phase crystals inside NFs, and the piezoelectric properties of the NFs are still limited. In this study, the effect of the fiber diameter on the internal molecular packing/orientation and piezoelectric properties of aligned PVDF NF thin films was investigated. Herein, piezoelectric thin films composed of densely packed, uniaxially aligned, PVDF NFs with diameters ranging from 228 to 1315 nm were prepared by means of electrospinning with a rotating collector and successive hot-pressing and poling. The effect of the diameters of PVDF NFs on their internal structures, as well as the piezoelectric properties of the thin films, was investigated. All prepared NFs mainly contained β-phase crystals with a similar total crystallinity. The orientation of the β-phase crystals inside the NFs increased with an increase in the fiber diameter, resulting in an improved transverse piezoelectric coefficient (d31) for the thin films. The output voltage of the prepared thin films reached a maximum of 2.7 V at 104 Hz. [ABSTRACT FROM AUTHOR]

The synthesis and applications of semiconducting nanostructures such as zinc oxide (ZnO) nanowires and tungsten disulfide (W[S.sub.2]) nanotubes is reported. The findings from the studies could be used to fabricate the transistors/phototransistors and photovoltaic (PV) energy conversion cells.

An explanation of the transport mechanism of 1-butene and propylene through dry AgNO(sub 3)-doped PSM membranes is detailed. This is achieved by multilayer diffusion together with the swelling of the surrounding polymer pendant side chains by the sorbed alkene molecules.

Research into the sorption mechanism of 1-butene in dry silver salt-doped perfluorosulfonate membranes and the anion effect on the sigma-pi complexation of Ag+/1-butene is presented. The interaction energy and the limiting heat had almost the same tendency.

The current-voltage curves of a composite bipolar membrane (CBM) were experimentally measured for the various mole fractions of methanol-water, ethanol-water and n-propanol-water mixed solution systems using 0.1 mol/L LiCl as electrolyte for each solution system. Results showed that a CBM has the characteristics of a bipolar membrane. The current-voltage curves showed that the maximum local effective value of a CBM resistance will increase with an increase in the mole fraction of alcohol. This is attributable to the weaker dissociative ability of alcohol as compared to water.

A measurement of the membrane potentials across cation- and anion-exchange membranes for five LiBr-various solvent systems found good agreement between theoretical predictions and experimental data. The solvents used were water, dimethyl sulfoxide, ethylene glycol, methanol and n-propanol. The Donnan equilibrium and the Nernst-Planck equation of ion flux were the basis of analysis of experimental data, with the effect of ion pairing of the electrolyte in the external solution taken into account.

Research was conducted to examine the effect of proton on potassium ion in countertransport across fine porous charged membranes. Proton and potassium ions countertransport across perfluorocarbon-type and hydrocarbon-type cation-exchange membranes was also investigated. Experimental results on the K-101 membrane agreed with theoretical predictions. However, experimental results on the Nafion membrane did not agree with theoretical predictions.