Isomerization of Diphenyl Polyenes.Part IV. Evidence for Two Luminescent Conformers of 1,4-Diphenyl-1,3-butadiene in Poly(vinyl alcohol) Films

1993 ◽  
Vol 48 (7) ◽  
pp. 759-764 ◽  
Author(s):  
A. Kawski ◽  
B. Kukliński ◽  
A. Kubicki ◽  
G. Piszczek
Keyword(s):  
Polyvinyl Chloride ◽  
Fluorescence Lifetime ◽  
Intensity Distribution ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Light Wavelength ◽  
Lifetime Measurements ◽  
Excitation Light ◽  
Polyvinyl Formal ◽  
Before And After

Abstract Investigations of the effect of the excitation light wavelength on the intensity distribution in the fluorescence band of 1,4-diphenyl-1,3-butadiene (DPB) in poly(vinyl alcohol) films (PVA) at 296 and 87 K for samples before and after heating to 423 K, and fluorescence lifetime measurements have shown that trans-trans and cis-trans conformers are responsible for the emission of fluorescence. The fluorescence properties of the DPB sample in PVA heated to 423 K were found to be similar to those of DBP in polyvinyl chloride and polyvinyl formal at 296 K.

Isomerization of Diphenyl Polyenes. Part V. The Origin of Fluorescence of l,6-Diphenyl-1,3,5-hexatriene in Poly (vinyl alcohol) Films

1993 ◽  
Vol 48 (8-9) ◽  
pp. 861-867 ◽  
Author(s):  
A. Kawski ◽  
A. Kubicki ◽  
B. Kukliński ◽  
G. Piszczek
Keyword(s):  
Intensity Distribution ◽  
Fluorescence Spectra ◽  
Fluorescence Decay ◽  
Fluorescence Band ◽  
Effect Of Temperature ◽  
Poly Vinyl Alcohol ◽  
Excitation Light ◽  
Polyvinyl Formal ◽  
Band Position ◽  
Double Exponential

Abstract The effect of temperature on the absorption and fluorescence spectra of l,6-diphenyl-1,3,5-hexatriene (DPH) was investigated in three different polymer films: polyvinyl chloride) (PVCh), polyvinyl formal) (PVF) and polyvinyl alcohol) (PVA) in the temperature range 296-423 K. Anomalous behaviour of the fluorescence intensity was observed only for DPH in non-heated PVA film. The intensity distribution in the fluorescence band of DPH in both non-heated and heated PVCh and PVF films was found to be independent of the excitation light wavelength, λexc . The behaviour of DPH is similar in the PVA film heated to 423 K. For these samples, single exponential fluorescence decay was observed. The behaviour of non-heated DPH samples in PVA is quite different, the intensity distribution and the fluorescence band position depending strongly on λexc and the fluorescence decay being double exponential. It can be inferred that the fluorescence of DPH in a non-heated PVA sample consists of two components, the first originating from the all-trans conformer and the second from the ground-state s-cis conformer.

scholarly journals Synthesis of poly(vinyl alcohol) — hydroxyapatite composites and characterization of their bioactivity

2013 ◽  
Vol 11 (9) ◽  
pp. 1403-1411 ◽  
Author(s):  
Zuzana Balgová ◽  
Martin Palou ◽  
Jaromír Wasserbauer ◽  
Jana Kozánková
Keyword(s):  
Vinyl Alcohol ◽  
Sol Gel ◽  
Calcium Nitrate ◽  
Weight Percent ◽  
Poly Vinyl Alcohol ◽  
Aqueous Environment ◽  
Calcium Nitrate Tetrahydrate ◽  
In Vitro Bioactivity ◽  
Before And After

AbstractAbstract A series of poly(vinyl alcohol) membranes reinforced with hydroxyapatite in various weight percent — 0%, 10%, 20%, 30%, 40% and 50% were prepared. Hydroxyapatite was prepared by a sol-gel procedure using diammonium hydrogen phosphate and calcium nitrate tetrahydrate as starting materials in an alkaline aqueous environment and then mixed with a solution of poly(vinyl alcohol), which was prepared by dissolving it in water at 85°C. The different mixtures were cast in a mould and evaporated for 7 days at a temperature of 30°C to obtain 1 mm thin membranes. FTIR spectroscopy was used to identify the different functional groups in the composites. The surface morphology was examined using a scanning electron microscope. In vitro bioactivity tests in Simulated Blood Fluid were performed for up to 28 days, especially for the membrane containing 50 wt.% HA. SEM was used to characterise the surface microstructure of biocomposite membranes before and after soaking in SBF. It was observed that the formation of clusters in membranes increases with increasing amount of HA. The clusters are formed due to agglomeration and crystal growth of HA particles during drying of the membranes. The in vitro bioactivity was found to increase with soaking time of biocomposite materials in simulated blood fluid. Graphical abstract

scholarly journals Enhancing High-Frequency Dielectric Properties of Beta-SiC Filled Nanocomposites from Synergy between Percolation and Polarization

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1699 ◽  
Author(s):  
Cheng Peng ◽  
Yefeng Feng ◽  
Jianbing Hu
Keyword(s):  
Electrical Properties ◽  
Polyvinyl Chloride ◽  
High Frequency ◽  
Vinyl Alcohol ◽  
Large Scale ◽  
Breakdown Strength ◽  
Induced Polarization ◽  
Poly Vinyl Alcohol ◽  
Scale Production ◽  
High Permittivity

Promising comprehensive properties, including high permittivity, low dielectric loss, high breakdown strength, low electrical conductivity, and high thermal conductivity, are very hard to simultaneously obtain in high-frequency applicable polymer nanocomposite dielectrics. Instead of traditional electric percolation, in this work, a novel route based on a synergy between electric percolation and induced polarization has been raised to prepare 0–3 type nanocomposites with an enhanced high permittivity (high-k) property and low loss at high frequency. This work aimed at optimizing that synergy to achieve the favorable properties mentioned above in composite dielectrics used at high frequencies such as 1 MHz and 1 GHz. Conductive beta-SiC nanoparticles with a particle size of ~30 nm were employed as filler and both insulating poly(vinyl alcohol) and polyvinyl chloride were employed as polymer matrices to construct two composite systems. Utilizing polyvinyl chloride rather than poly(vinyl alcohol) realizes higher comprehensive electrical properties in composites, ascribed to optimization of that synergy. The optimization was achieved based on a combination of mild induced polarization and polarization-assisted electric percolation. Therefore, this work might open the way for large-scale production of high-frequency applicable composite dielectrics with competitive comprehensive electrical properties.

Polarizer effect and structure of iodinated before and after casting poly(vinyl alcohol) film

2010 ◽  
Vol 120 (1) ◽  
pp. 397-405 ◽  
Author(s):  
Eun Joo Shin ◽  
Won Seok Lyoo ◽  
Yang Hun Lee
Keyword(s):  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Before And After

Effect of Silicon Oxide Size and Reducing Environment on the Photocatalytic Capability of Poly(Vinyl Alcohol)/Chitosan/Silicon Oxide Beads

2014 ◽  
Vol 699 ◽  
pp. 1000-1005
Author(s):  
Syazwan Liyana Sulaiman ◽  
Sufizar Ahmad ◽  
Hariati Taib
Keyword(s):  
Vinyl Alcohol ◽  
Silicon Oxide ◽  
Poly Vinyl Alcohol ◽  
Acidic Environment ◽  
Photocatalytic Process ◽  
Chromium Reduction ◽  
X Ray ◽  
Before And After ◽  
Reducing Environment ◽  
Scanning Electron

The present work assess the capability of silicon oxide (SiO2) nanoparticle and microparticle incorporated in poly (vinyl alcohol)/chitosan/silicon oxide (PVA/CS/SiO2) beads to reduce chromium (Cr) ions of Cr (VI) to Cr (III). PVA/CS/(nanoand micro)-SiO2beads were prepared through a simple drop wise method. The elemental analysis of prepared photocatalytic beads were confirmed by scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and morphology of PVA/CS/SiO2beads before and after Cr ions reduction were observed with SEM. The reduction of chromium (Cr (VI)) ions by both of PVA/CS/(nanoand micro)-SiO2) beads, as evaluated by the reduction duration taken were studied by photocatalytic process in which factors of SiO2powders size and pH of reducing environment were varied. Photocatalytic studies revealed better performance of PVA/CS/nanoSiO2beads in compared to PVA/CS/micro-SiO2beads in Cr (VI) to Cr (III) ions reduction. Reduction Cr (VI) to Cr (III) ions by PVA/CS/nanoSiO2beads occurred in 30 minutes and 50 minutes by PVA/CS/micro-SiO2. Moreover, both PVA/CS/(nanoand micro)-SiO2showed excellent reduction of Cr (VI) ions at lower pH environment. It is thus concluded that both of PVA/CS/(nanoand micro)-SiO2beads are capable for chromium reduction in highly acidic environment in which PVA/CS/nanoSiO2beads showed better performance.

Miscibility of poly(vinyl alcohol)/polyacrylamide blends before and after gamma irradiation

2003 ◽  
Vol 52 (2) ◽  
pp. 225-234 ◽  
Author(s):  
Horia M Nizam El-din ◽  
Abdel Wahab M El-Naggar ◽  
Faten I Ali
Keyword(s):  
Gamma Irradiation ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Before And After

scholarly journals Adsorption of tetracycline from water using glutaraldehyde-crosslinked electrospun nanofibers of chitosan/poly(vinyl alcohol)

2018 ◽  
Vol 77 (5) ◽  
pp. 1324-1335 ◽  
Author(s):  
Aliyeh Yousefi Abdolmaleki ◽  
Hamid Zilouei ◽  
Saied Nouri Khorasani ◽  
Kiomars Zargoosh
Keyword(s):  
Vinyl Alcohol ◽  
Electrospun Nanofibers ◽  
Poly Vinyl Alcohol ◽  
Maximum Adsorption Capacity ◽  
X Ray Diffraction ◽  
Injection Flow ◽  
Before And After ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order

Abstract In this work, the preparation and characterization of glutaraldehyde-crosslinked electrospun nanofibers of chitosan/poly(vinyl alcohol) (GCCPN) as a new adsorbent for tetracycline (TC) is reported. Electrospun nanofibers of chitosan/poly(vinyl alcohol) (PVA) were prepared by employing a 75:25 volumetric ratio of chitosan:PVA, voltage of 30 kV, collection distance of 10 cm, and injection flow rate of 2 mL/h. Then, the nanofibers were crosslinked via applying the glutaraldehyde on them for 3 h at 40 °C. The nanofibers were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction. Uniform beadless nanofibers with minimum diameters of 3–11 and 6–18 nm were obtained before and after crosslinking, respectively. Then the applicability of the synthesized GCCPN for removal of TC from aqueous solutions was investigated. The response surface method was applied to evaluate the influence of pH (6–12), TC concentration (50–250 mg/L) and the adsorbent dose (0.05–0.25 g in 20 mL solution) on the adsorption characteristics of GCCPN. The maximum adsorption capacity was 102 mg/g. The adsorption kinetics was explained most effectively by the pseudo-second-order model. The adsorption data of TC on the GCCPN surface was explained well by the Langmuir isotherm model.

Surface Properties of Poly(vinyl alcohol) with Iron(III)chloride Before and After UV-Irradiation

2010 ◽  
Vol 295 (1) ◽  
pp. 114-118 ◽  
Author(s):  
Jolanta Kowalonek ◽  
Halina Kaczmarek ◽  
Dagmara Bajer
Keyword(s):  
Surface Properties ◽  
Uv Irradiation ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Before And After
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