Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 6

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  36.20.-r
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

SANS Study of Poly(ethylene glycol) Solutions in D_2O

100%
Lancz G., Avdeev M., Petrenko V., Garamus V., Koneracká M., Kopčanský P.
Acta Physica Polonica A
|
2010
|
vol. 118
|
issue 5
980-982
EN
Poly(ethylene glycol) is used for coating of colloidal particles and other surfaces for gaining biocompatibility. Particularly, it can be introduced into magnetic fluids. The aim of the current study was to reveal the structural characteristics of poly(ethylene glycol) in neat D_2O using small-angle neutron scattering technique. Solutions of poly(ethylene glycol) (at temperature of 37°C) with different molecular weights in an interval of 400-20000 were investigated. It is concluded that at low concentrations (less than 2% of mass fraction) poly(ethylene glycol) molecules behave as Gaussian coils.
2
Content available remote

Effect of Uniaxial Stretching on Structural Properties of Poly(3-Alkylthiophenes)

100%
Łużny W., Zagórska M.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 3
491-500
EN
The influence of uniaxial stretching on the molecular structure of poly(3-alkylthiophenes) was studied with the use of X-ray diffraction. Three poly(3-alkylthiophenes), namely these containing n-hexyl, n-octyl and n-decyl groups, were investigated. The samples were oriented by stretching and the diffraction patterns for two geometries of scattering were obtained for undoped samples. The comparison of experimental diffraction data for unoriented and oriented samples, gives information about the role of the side chains in the changes of molecular conformation induced by stretching of the polymer sample. The main conclusion of our work is that the process of orientation induces similar phenomena in all samples studied, but the structural and conformation changes depend on the side chain length: the shorter the alkyl substituent, the easier the straightening of the main polymer chain. The authors suggest that uniaxial stretching of poly(3-alkylthiophenes) changes the degree of main chain planarity. This effect can influence the π-conjugation in polymer system, which may have great importance for any future application of poly(3-alkylthiophenes).
3
Content available remote

Braids for Pretzel Knots

80%
Suffczyński M.
Acta Physica Polonica A
|
2000
|
vol. 98
|
issue 6
663-671
EN
The words of braid closures for the pretzel knots, in particular the twist knots relevant to molecular supercoils in biochemistry, are recorded in a standardized form, which enables one to see the regular pattern of the words, and thus to write the braid words representing pretzel knots for general values of the crossing number.
4
Content available remote

Spectroscopic Study of the Dimerization Process οf Iron Protoporphyrin IX

80%
Dziedzic-Kocurek K., Byrne H., Świderski A., Stanek J.
Acta Physica Polonica A
|
2009
|
vol. 115
|
issue 2
552-555
EN
The commercial protoporphyrin IX, iron-ferriprotoporphyrin IX-chloride and synthesized iron porphyrin μ-oxo-dimers were examined by UV/vis absorption and fluorescence, Fourier transformed infrared spectroscopy, resonance Raman, X-ray absorption, Mössbauer spectroscopy and SQUID. The evidence of Fe-O-Fe antiferromagnetic coupling concluded from SQUID and Mössbauer in the case of samples containing dimerized forms confirmed the presence of the oxo-bridges. In this paper the results of UV/vis, fluorescence, Fourier transform infrared FTIR and Raman spectroscopies are reported and discussed. The study is based on the comparison of the free-base protoporphyrin IX, Fe-PPIX-Cl and the synthesized dimerized specimen. The vibrational modes in two energy regions i.e. 330-650 cm^{-1} and 750-900 cm^{-1}, reportedly characteristic of the existence of Fe-O-Fe bridges, are discussed. A significant photoluminescence emission, strongly Stokes shifted from the Soret band, absent in the protoporphyrin IX and the iron-ferriprotoporphyrin IX-chloride, is observed. The strong Stokes shift and the mismatch of the excitation spectrum to the Soret band suggest that is does not have origin in the de-excitation of the porphyrin moiety and that it could have origin in an Fe-O-Fe charge transfer state.
5
Publication available in full text mode
Content available

Spectroscopic Studies of Poly(ε-Caprolactone)/Sodium Montmorillonite Nanocomposites

61%
Krzaczkowska J., Fojud Z., Kozak M., Jurga S.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 1
187-196
EN
Polymer-layered silicate nanocomposites belong to a new class of hybrid materials consisting of organic-synthetic polymer matrix and inorganic filler-layered structure clay minerals. The paper presents the results of FTIR, NMR, and SAXS studies of poly(ε-caprolactone)/sodium montmorillonite nanocomposites. We observed a correlation between the concentration of poly(ε-caprolactone) in nanocomposite samples and structural changes both of the clay mineral and the intercalated polymer. Stiffening of the clay structure appears as a result of poly(ε-caprolactone) intercalation into a clay structure. ^{27}Al NMR studies indicated in nanocomposites two non-equivalent sites of aluminium ions, i.e. in octahedral and tetrahedral coordination, whereas in the montmorillonite clay structure the aluminium ions are located in the interlayer space too. We found also that the temperatures of structural changes and softening process of poly(ε-caprolactone) chains in the nanocomposites depend on the concentration of poly(ε-caprolactone).
6
Content available remote

Structural Identification of Polymer Nanocomposites

51%
Bilewicz M., Labisz K., Tański T., Konieczny J., Górniak M.
Acta Physica Polonica A
|
2014
|
vol. 126
|
issue 4
895-901
EN
Composites and nanocomposites as commercially used engineering materials with continuous development, are important for rising market and industry needs. Significant role is played by polymers, whose consumption increases every year, thanks to low cost of production, economical processing and broad scope of material composition possibilities, including nanomaterials and basing on them nanocomposites. Nanocomposites, using power of nanotechnology, may improve physical, chemical and mechanical properties, comparing to composites. Investigation of structure and properties of such materials is necessary to obtain knowledge about phenomena at micro and nanoscale and gives opportunity to design and control structure, because the properties of any material depend on its matter. Polymer matrix nanocomposites are interesting and very promising class of polymer composites. Investigation of structure development due to different heat treatment and under different processing condition of injection molded specimens of polypropylene and montmorillonite composition has been performed. Dispersion of nanoreinforcement, in the shape of 2:1 layer silicates, was observed under transmission and scanning electron microscope. Application of advanced technology of multiplication of oriented layer mostly reinforcing and orienting micro and nanoparticles along polymeric specimen, allowed to obtain several layers and significantly reinforced material. Light microscope has been used for observation layered zone, visible just in polarization mode.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.