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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 115 (1983), S. 183-196 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Charakterisierung von zwei Resolen, die mit Methanol in Gegenwart von Säure verethert wurden, wird zum ersten Male beschrieben. Die Harze wurden in Trimethylsilylderivate übergeführt, und die einzelnen Komponenten mittels Kapillargaschromatogrphie getrennt. Die Strukturen wurden anhand von Modellsubstanzen mittels Massenspektroskopie identifiziert. Die ursprünglichen Resole wurden auf gleiche Weise analysiert.
    Notes: The characterisation of two resols which had been etherified with methanol under acidic conditions is described for the first time. The resins were converted into trimethylsilyl derivatives and the individual components were separated by means of capillary gas chromatography. Structural assignments were made using mass spectrometry measurements and with the aid of model compounds. The precursor resols have also been analysed by the same technique.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1553-1570 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The wedge interferometer technique was used to measure the diffusion coefficients for concentrated solutions of polystyrene. A wide range of molecular weights, all monodisperse except for one, and 14 solvents were studied. Reproducibility of the data was demonstrated in the concentrated region, and good agreement with the sparse literature was observed. The experimental results are discussed and analyzed in terms of current knowledge and theories. In the concentrated region, the solvent type plays a significant role in determining the diffusion coefficient. Its effect cannot be explained simply in terms of hydrodynamics nor the molecular structure of the solvent. In cyclohexanone the diffusion coefficient was found to increase with polymer molecular weight up to 100,000 and to become independent thereafter.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 2023-2051 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fibers made from poly(ethylene terephthalate) (PET) are characterized by a hydrophobic surface with low reactivity. Modifications of the PET surface to render a higher degree of hydrophilicity and reactivity are therefore common. The modification often involves a surface layer of only a few nanometers thickness. The relatively low fraction of the modified surface layer and the fact that it is generally an organic modification on a thin curved organic substrate presents difficulties in surface analyses. Surface characterization is, however, of high importance in the evaluation of the degree and durability of a given surface modification. The paper will discuss the possibilities and the limits of using wettability studies according to the Wilhelmy method to evaluate the degree of surface modification and its permanence. Comparison between internal and external reflection Fourier-transform infrared spectroscopy will be made. The use of electron spectroscopy for chemical analysis, secondary ion mass spectrometry, laser microprobe mass analysis, and microprobe molecular optics laser examiner will be illustrated. Data will be presented from studies of model yarns and films coated with D-417 dip.
    Additional Material: 23 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 485-500 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The equilibrium and kinetics of gas sorption by a silicone rubber filled with highly adsorptive molecular sieves was studied. Sorption in this system is by two mechanisms: gas is simply dissolved in the polymer matrix according to Henry's law, while it is adsorbed by the dispersed sieve phase in accordance with a Langmuir's isotherm. The latter effectively immobilizes the gas molecules preventing their further diffusion. All equilibrium parameters were determined experimentally. Immobilization greatly affects sorption kinetics and renders conventional analyses invalid. A theory to account for this process was adapted from a previous analysis by Vieth and Sladek which assumes that the kinetics of adsorption is very fast compared to diffusion. For this situation the kinetics always assume a Fickean form. The experimental data agreed very well with the predictions of this theory in a comparison where all parameters were defined by independent experiments. It was found that a single effective diffusion coefficient describes sorption kinetics, steady-state permeation, and time-lag results once the effects of immobilization are properly accounted for.
    Additional Material: 10 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 267-274 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Carboxylgruppen Können in vernetztes Polystyrol über einen Zweistufenprozeß durch 2-Chlorbenzoylierung und Aufspaltung des Reaktionsproduktes mit einer Mischung von Kalium-tert-butoxid und Wasser eingeführt werden. Den Umsatz kann man durch die Gewichtsänderung des Harzes und durch Chloranalyse leicht abschätzen. Carboxylgruppen können auch durch Benzoylierung eingeführt werden. Das bereits beschriebene Verfahren, um Carboxylgruppen einzuführen, indem man vernetztes Polystyrol chlormethyliert, das erhaltene Produkt zu einem Formylharz oxidiert und dieses Produkt zu einem Carboxylharz weiteroxidiert, kann durch die Verwendung von Peressigsäure in Methansulfonsäure als Oxidationsmittel im letzten Schritt verbessert werden.
    Notes: Carboxyl groups can be introduced into crosslinked polystyrene by a two step process involving 2-chlorobenzoylation and cleavage of the product using a mixture of potassium tert-butoxide and water. The reaction yields can be estimated easily by the change in weight of the resin and by chlorine analysis. Carboxyl groups can also be introduced via benzoylation. The previously described method of introducing carboxyl groups, in which crosslinked polystyrene is chloromethylated and the product oxidized to a formyl resin, which is then oxidized to a carboxyl resin, can be improved by using peracetic acid in methanesulphonic acid as the oxidant in the last step.
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1793-1804 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A review is presented of the general features of amide bond formation by prior capture of the amine-bearing peptide fragment. Capture by formation of a bond to the N-terminal nitrogen is shown in eight model systems to result in slow intramolecular acyl transfer, accompanied by anomalously large Gly/Ala and Gly/Val rate ratios. Two examples are given of rapid intramolecular acyl transfer via rings of 9 and 12 members. The transfer efficiency as estimated by the effective molarity of reactive amine at the acyl carbon in the latter case is 18M. Capture at the thiol function of an N-terminal cysteine residue is shown to be feasible in mercurithio and disulfide systems. In the latter case, effective concentrations of 3M and intramolecular transfer half-times of 10 min are demonstrated.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A careful solvent-exchange procedure followed by liquid-phase reaction of ethyleneimine with cellulose film in a nonpolar solvent provides an effective method of uniformly aminoethylating cellulose. The protonated aminoethyl groups on the cellulose can then ionically bind heparin, a blood anticoagulant. Heparinized aminoethylated cellulose tubing at low levels of aminoethylation (ca. 0.2-0.3% nitrogen) exhibited excellent antithrombogenic properties as well as excellent mechanical strength properties. The in vitro tests demonstrated indefinitely long whole-blood clotting times with normal thrombin times. In the in vivo experiments, the heparinized aminoethylated cellulose tubing provided extended patency when implanted intravascularly in the regions of low blood flow rate (infra renal inferior vena cava of dogs). A principal use of this film is in the artificial kidney.
    Additional Material: 5 Ill.
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