1. Polyurethanes for medical useTanja Pivec, Majda Sfiligoj-Smole, Petra Gašparič, Karin Stana-Kleinschek, 2017, pregledni znanstveni članek Opis: Polyurethanes are synthetic copolymers containing urethane linkages in their complex chemical structure. They consist of three monomers: a diisocyanate, a polyol and a chain extender, which enables the synthesis of an endless number of polyurethanes with different physicochemical and mechanical properties. The physicochemical properties of various polyurethanes are largely dependent on the conformation of polyols, which may contain two or more different polyols, stabilisers, catalysts, liquids or solid additives and, in the case of foams, foaming agents. Depending on the structure of the polyols, i.e. the length of the chain, structure of the units (aliphatic or aromatic), ester or ether groups, or functionalisation by hydroxyl groups, polyurethanes may be flexible or rigid, and therefore suitable for various applications. In addition to the physical and chemical structure of polyurethanes, this review paper specifically addresses their use in medicine, particularly in wound dressings, tissue engineering scaffolds and drug delivery with nanoparticles and nanocapsules, and provides guidelines for the development of new biodegradable polyurethane materials.
Ključne besede: segmented polyurethanes, chemical structure, reactants, medical applications
Objavljeno v DKUM: 03.10.2017; Ogledov: 1768; Prenosov: 552
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2. The crystal and molecular structures of two reaction products of geminal dicyano oxirane with thiohydantoine (compound I) and thioxobenzoxazole (compound II)Ivan Leban, Alenka Majcen Le Marechal, Albert Robert, 1993, izvirni znanstveni članek Opis: The crystal and molecular structures of two reaction products of geminal dicyano oxiranes with thiohydantoione and thioxobenzoxazole have been determinated from ▫$Mo-K_\alpha$▫ X-ray diffraction data. The two reaction products were: 2H-2-(p-tolyl)-imidazol[1,2-b]thiazole-3,6-dione (compound I) and Z-3-benzoxazole-3-phenyl-2-oxo-2-propanenitrile (compound II) with the following crystal data at 293(1) K: Compound I, ▫$C_{12}H_{10}N_2O_2S$▫, monoclinic ▫$P2_1/c$▫, a=15057(3), b=5.200(3), c=14.724(4) Å, ▫$\beta=104.24(3)°$▫, Z=4; final R and ▫$R_w$▫ values were 0.034 and 0.049 for1647 observed reflexions. Compound II, ▫$C_{16}H{10}N_2O_2$▫, monoclinic, ▫$P2_1/n$▫, a=14.396(3), b=4.326(1), c=21.335(4) Å, ▫$\beta-107.79(1)°$▫, Z=4;final R and ▫$R_w$▫ values 0.040 and 0.053 for 1516 observed reflections.
Ključne besede: organic chemistry, crystal structure, chemical reactions, oxiranes, coordination compounds, structural chemistry
Objavljeno v DKUM: 05.07.2017; Ogledov: 1572; Prenosov: 118
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3. The influence of structural properties on the dye diffusion and dyeability of PA 6 fibresSimona Strnad, Slava Jeler, Karin Stana-Kleinschek, Tatjana Kreže, 2003, izvirni znanstveni članek Opis: The relationships were investigated between the structural and dyeing properties of different structurally modified PA 6 fibers. PA 6 monofilament yarn samples were applied having different crystalline degrees and different content of alpha, respectively gamma crystalline modification. The diffusion coefficients of two different acid dyes were determined together with the content of dyestuff absorbed (under specific conditions) by fiber samples. In order to estimate colorimetry method from the viewpoint of polymer structural change detection, the colors of the dyed PA 6 samples were determined (L*, a*,b*, C*, h coordinates) and the color differences (L*, a*, b*, C*, H*, E*) were calculated between untreated standard and structurally modified samples. The dyeability of PA 6 fibers depended mainly on the way in which crystallinity had been achieved, i.e. on the materialćs history. Different crystalline modifications caused different sorption properties and fiber dyeability. Smaller increases (app 20%) of crystallinity degree caused a decrease in diffusion coefficients. Contrary to expectations, the significant increase of crystallinity degree (app 50%) had an influence on the increase ofdyeability, presumably owing to the formation of larger empty spaces in the structure. The results achieved by colorimetry were in good correlation with dye absorption measurements. The colorimetry of dyed fiber samples was sensitive enough to detect even small differences in the quantities of absorbed dyestuff.
Ključne besede: textiles, PA 6 fibres, dyeing, dyeability, fibre structure, crystallinity, chemical modification
Objavljeno v DKUM: 01.06.2012; Ogledov: 2331; Prenosov: 36
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