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2015
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vol. 70
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issue 1
EN
Wettability of poly(tetrafluoroethylene) (PTFE) by aqueous solutions of binary mixtures composed of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) with polyoxyethylene (23) lauryl ether (Brij 35) was considered on the basis of the measured values of contact angle and surface tension. It was shown that the value of the critical surface tension of PTFE surface wetting at the studied system (23.5 mN/m), does not depend on the concentration and composition of the binary mixtures of studied surfactants in water, and it was higer than the surface tension of PTFE (20.2 mN/m). The best wettability of polytetrafluoroethylene (PTFE) by studied aqueous solutions of binary surfactants mixtures occurs at the mixtures concentration corresponding to the critical micelle concentration of their solutions.
EN
Methyl methacrylate - butyl acrylate - methacrylic acid copolymer and butyl methacrylate - methacrylic acid amide copolymer of a different segmental structure were stabilised with non-ionic and anionic surfactants. Gel chromatography, viscosimetry, tensiometry, conductometry and sedimentation methods were applied to define the properties of the synthesized copolymers, surfactants in water solutions and water dispersions. The types and the properties of the phases being in a state of sedimentation balance were also determined. The obtained experimental data were interpreted and justified by using the copolymer and surfactants properties. The existing correlations were pointed out. The obtained results show that the stability of a disperse system considerably depends on the structure of the copolymer. The MMA/BA/MAA copolymer has monomeric units of elastic butyl acrylate. Segments containing these monomeric units adsorb surfactants much better and form more stable water disperse systems. However, the MBA/AMAA copolymer with the polarity of amide group of methacrylamide makes disperse systems less stable.
EN
Polyethylene terephthalate (PET) foils have been exposed to oxygen plasma and its afterglow in order to reveal compositional and structural modifications of the surface layer. Oxygen plasma was created by electrode-less RF discharge in a glass chamber so the O-atom density was close to 1022 m-3 although the density of charged particles was only about 1 × 1016 m-3. Long-living reactive particles created in plasma were leaked into the afterglow chamber using a two-stage rotary pump of pumping speed 4.4 × 10-3 m3 s-1. The density of O-atoms in the afterglow as measured with a catalytic probe was 3 × 1021 m-3, while the density of reactive oxygen molecules was estimated theoretically. The functionalization was accomplished even after a brief exposure to either plasma or afterglow since all samples were saturated with oxygen-rich functional groups as revealed by XPS. The water contact angle measurements, however, showed that only plasma treatment allowed for super-hydrophilicity, explained by rich surface morphology as detected by AFM. The differences in morphological properties between plasma and afterglow treated samples were explained by different interaction mechanisms between low and high energy particles impinging the polymer surface.
4
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Multilayer coatings for flexible high-barrier materials

88%
EN
A multilayer, flexible, and transparent high-barrier system based on flexible plastic foils, polyethyleneterephthalate (PET) and ethylene-tetrafluoroethylene-copolymer (ETFE), combined with vacuum-deposited, inorganic SiOx layers and hybrid ORMOCER® varnish layers were prepared in different orders on a semiproduction level. Barrier properties of prepared systems, as water vapour transmission (WVTR) and oxygen transmission (OTR), were measured and studied in connection with surface energy, surface topography, and water vapour adsorption properties. Correlations among layers sequence, barrier properties, and other parameters are presented, including some basic principles of permeation of substances through multilayer barrier systems. A combination of several inorganic and hybrid varnish layers is necessary to achieve the technological demands from a barrier standpoint. It is easier to suppress the oxygen transport than the water transport, due to the additional active penetration of water through hydrogen bonds and silanol creations at oxide interfaces, capillary condensation, and swelling with high internal pressure, leading to new defects.
EN
In this review, the research devoted to synthesising chitosan apatites, their biologically active properties, and their application in medical practice is analysed. The data are from articles published between 2001 and 2022 on the formation of calcium- and phosphorus-containing chitosan composites and the mechanism of their interaction
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