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1

Optical, Structural, and Electrical Properties of Aromatic Triphenylamine-Based Poly(azomethine)s in Thin Layers

100%

Palewicz M., Iwan A., Sikora A., Doskocz J., Strek W., Sek D., Mazurek B.

Acta Physica Polonica A

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2012

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vol. 121

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issue 2

439-444

EN

Spectroscopic and photophysical properties of the poly(azomethine)s with triphenylamine moieties were investigated by UV-vis, X-ray diffraction and atomic force microscopy methods. Current-voltage measurements were performed on ITO/polymer/Alq_3/Al, ITO/PEDOT/polymer:MWCNT/Al and ITO/polymer:MWCNT/Al devices. Multiwall carbon nanotubes were blended with polymer in the ratio 1:1. The lowest optical band gap value at 2.33 eV was detected. Moreover, an absorption coefficient α was calculated from transmission and reflectivity measurements. In this paper, we presented photophysical and structural properties of the poly(azomethine)s in solid state of great interest for the emerging field of molecular electronics and for their uses as active layers in (opto)electronic devices such as solar cells.

2

Dielectric Study of Pure Polymer and Mixed Monomer-Polymer Single Crystals of pTS Diacetylene: a Comparison with Neutron Scattering Results

100%

Longevile S., Even J., Bertault M., Kołodziej H. A., Sworakowski J.

Acta Physica Polonica A

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1995

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vol. 88

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issue 2

359-367

EN

Temperature and frequency dependences of the electric permittivity in mixed monomer-polymer single crystals of the diacetylene pTS (2,4-hexadiynylene bis(p-toluenesulphonate)) are reported. The dependences were determined in the temperature range 100-250 K, and in the frequency range 100 Hz - 1 MHz. Two types of single crystals were studied: nearly-fully polymerized ones, and those containing ca. 20% of polymer in the monomer matrix. The dynamics is characterized by a high-frequency response (v ≫ 3 GHz) which corresponds to the soft mode analysed previously by the Raman and neutron inelastic scatterings. At low frequencies (v ≤ 1 kHz), another component is observed, its dielectric intensity peaking around the transition temperature in the fully polymerized crystals. The results are consistent with the results obtained from NMR and neutron scattering experiments.

3

Adsorption of Benzene on 4H-SiC (0001) Surface: First Principles Calculations

100%

Tokár K., Majewski J.

Acta Physica Polonica A

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2012

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vol. 122

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issue 6

1049-1051

EN

We study adsorption of the benzene molecule on the Si terminated (0001) surface of 4H-SiC by performing first principles calculations in the framework of density functional theory. We find out that chemical reaction leading to the chemisorption of benzene on the surface has endothermic character. The adsorbed benzene molecule is bounded to two surface Si atoms and it does not lose its integrity, however, it undergoes strong deformations and causes distortion of the substrate. We analyze also changes in the electronic structure caused by benzene adsorption.

4

Dielectric Relaxation in Cellulose and its Derivatives

100%

Rachocki A., Markiewicz E., Tritt-Goc J.

Acta Physica Polonica A

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2005

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vol. 108

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issue 1

137-145

EN

The relaxation processes in cellulose, methyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose were studied by dielectric spectroscopy. The dielectric spectra for these polysaccharides were measured in the frequency range from 100 Hz to 1 MHz and in the temperature range from 100 to 450 K. The dielectric relaxation data for cellulose, methyl cellulose, hydroxypropylmethyl cellulose were described by Arrhenius and Eyring equations and interpreted as due to a local motion of chain segments via the glucosidic linkages, so-calledβ-relaxation. The same relaxation process was also determined for the hydroxypropyl cellulose polymer in the temperature range of 240-270 K. At higher temperature in hydroxypropyl cellulose another relaxation mechanism occurs due to the reorientation of the side chain built of a few hydroxypropylene groups. The activation parameters of the observed dielectric relaxation processes were determined.

5

Characterization of Structure and Self-Diffusion of Elastomers by NMR Method

100%

Kulagina T., Karnaukh G., Smirnov L.

Acta Physica Polonica A

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2015

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vol. 127

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issue 4

1128-1132

EN

In this work the theory of free induction decay in linear and cross-linked flexible polymers with a various average length of a polymeric chain in a wide temperature is represented. It is shown the change of topological structure of linear polymers with increasing of mean molecular weight M_{w}, and at M_{w}>10⁵ the physical network of entanglements starts being formed. The correlation function of molecular motion which is applied to calculation of diffusion attenuation of spin echo is received. The general approach to calculation of signals of diffusion attenuation spin echo and its application for determination of coefficient of self-diffusion in elastomers with various topological structures is offered. It allowed explanation observed experimentally anomalous diffusion.

6

Effect of Thermal Annealing on the Sensitivity of Makrofol-DE Polycarbonate

100%

Kahraman A., Poffijn A., Kaynak G.

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vol. 125

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issue 2

271-274

EN

Solid state nuclear track detectors have been applied in different studies including nuclear physics, particle physics, archaeology etc. Makrofol, a particular group of thermoplastic polymers, is used for radon detection. High background track numbers in the foils cause big uncertainties for places where the radon concentrations are quite low. Therefore, it is of great importance to lower the background track signal as much as possible, without reducing the sensitivity of the foils. The present study reports track density and sensitivity of Makrofol-DE after thermal annealing. The unexposed foils were heated at temperatures ranging from 110C to 140C for 10 min with the aim of observing changes in the number of background tracks. As a result a reduction in the background track density was observed. In order to observe the change in the sensitivity, pre-heated and unheated foils were exposed to alpha radiation in a radon chamber. At the temperatures of 110, 120, and 130°C, the track density in the heated and unheated exposed foils is quite similar. An increase was observed in the track density in heated exposed foils at 140C.

7

Studies of Fast Electron Irradiated Ferroelectric Poly(Vinylidene Fluoride)

88%

Goslar J., Hilczer B., Smogór H.

Acta Physica Polonica A

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2005

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vol. 108

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issue 1

89-94

EN

Radiation-induced functionalization of ferroelectric poly(vinylidene fluoride) was studied by ESR spectroscopy. The samples were irradiated in the high vacuum of a Van de Graaff accelerator with 1.0 MeV and 1.5 MeV electrons at room temperature and the decay of free radicals was studied after transferring the samples into the air. The samples exhibit a multicomponent ESR spectrum that can be decomposed into: a large asymmetric signal in the centre related to peroxy radicals, a quintet with hyperfine splitting A_F = 4.3 mT centred at g = 2.004, assigned to the in-chain radical (-CF_2-CH-CF_2-), and a triplet due to an end-chain (-CH_2) radical with A_H = 1.6 mT and g = 2.009.

Refine search results

Optical, Structural, and Electrical Properties of Aromatic Triphenylamine-Based Poly(azomethine)s in Thin Layers

Dielectric Study of Pure Polymer and Mixed Monomer-Polymer Single Crystals of pTS Diacetylene: a Comparison with Neutron Scattering Results

Adsorption of Benzene on 4H-SiC (0001) Surface: First Principles Calculations

Dielectric Relaxation in Cellulose and its Derivatives

Characterization of Structure and Self-Diffusion of Elastomers by NMR Method

Effect of Thermal Annealing on the Sensitivity of Makrofol-DE Polycarbonate

Studies of Fast Electron Irradiated Ferroelectric Poly(Vinylidene Fluoride)