ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Polymer and Materials Science  (239)
  • Project report/description
  • 1980-1984  (241)
  • 1982  (241)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 381-398 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Numerous hypotheses exist to explain observed blood-materials interactions. It is the purpose of this article to test two popular hypotheses, namely, the minimum interfacial free energy hypothesis and the optimum polar/apolar ratio hypothesis. Methacrylate polymers and copolymers were characterized using the captive bubble underwater contact angle method; bulk water content was determined by gravimetric methods; streaming potential measurements were made; and surface roughness and possible particulate contamination were evaluated by reflected light microscopy. In vitro blood tests include whole blood clotting time measurements on polymer-coated tubes; centrifugal force platelet adhesion on polymer-coated coverslips; and a measure of the partial thromboplastin time, Russell's viper venom time (Stypven time), and the prothrombin time of native whole blood exposed to polymer-coated microscope slides. Results suggest that platelet adhesion correlates in the opposite direction of whole blood clotting time and partial thromboplastin time, emphasizing the need for a multiparameter approach to blood-materials testing. Based on these tests the minimum interfacial free energy hypothesis is not supported. In fact, the data suggest the opposite to be true. It is apparent that platelet adhesion can be a misleading indicator of blood compatibility. Neither hypotheses can explain the apparent conflict between the platelet adhesion data and the coagulation time data.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 2265-2277 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Human fibrinogen was treated with thrombin in the presence of fibrinoligase (Factor XIIIa) and calcium ion at pH 8.5, ionic strength 0.45, and the ensuing polymerization was interrupted at various time intervals (t) both before and after the clotting time (tc) by solubilization with a solution of sodium dodecylsulfate and urea. Aliquots of the solubilized protein were subjected to gel electrophoresis on polyacrylamide gels after disulfide reduction by dithiothreitol and on agarose gels without reduction. The degree of γ-γ ligation was determined from the former and the size distribution of ligated oligomers, for degree of polymerization x from 1 to 10, from the latter. In some experiments, thrombin was inhibited, after partial polymerization, by p-nitrophenyl-p′-guanidinobenzoate. From these, it was concluded that for thrombin concentration ≤0.013 units/mL and fibrinoligase ≥30 mg/L, oligomer assembly is rapid compared with peptide A release and ligation is rapid compared with assembly. Under these conditions, the theory of the first paper of this series describes rather well the time dependences of the degree of γ-γ ligation, the weight fractions of monomer and small oligomers, and the number- and weight-average degrees of polymerization after solubilization of the staggered overlapped assemblies, each of which splits to give two strands of end-to-end ligated oligomers. The theory assumes that the second A peptide is released by thrombin more rapidly than the first by a factor q, which, from the experimental data, is determined to be 16. The subsequent assembly into staggered overlapped oligomers follows the statistics of linear polycondesation taking into account the presence of both difunctional and monofunctional combining units. For higher thrombin or lower fibrinoligase concentrations, ligation fails to keep pace with oligomer assembly, and the size distributions after solubilization show a higher proportion of very small and a lower proportion of larger ligated oligomers, owing to separation of the staggered overlapped assemblies into smaller fragments.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 3591-3595 
    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: Oligomers are potentially useful as well characterized models for studying the chemical and physical properties of their long chain homologues. These model compounds are often available only as mixtures which must be separated. This separation may be accomplished using chromatographic techniques, i.e., GPC. Polydispersity (Mw/Mn) is often used as a criteria for the extent to which separation has been achieved. Values of polydispersity of 1.01-1.03 are considered indicative of very narrow fractions in the high polymer area. A purpose of this paper is to show that such low values of polydispersity are misleading when applied to oligomers containing 2-20 repeat units. Further, the existence of a single “sharp” melting endotherm is not necessarily proof that one has separated out a single molecular weight component. An intimate mixture of different molecular weight oligomers can give a single narrow endotherm.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 33 (1982), S. 155-163 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Triphenylmethanfarben als Korrosionsinhibitoren für Aluminium-Kupfer-Legierungen in SalzsäureDie Inhibierung der Korrosion von Aluminium B 26 S in Salzsäure durch Triphenylmethan-, Anthrachinon- und Acridinfarben wurde unter Berücksichtigung von Säurekonzentration, Inhibitordosierung, Versuchsdauer und Temperatur untersucht. Im allgemeinen nimmt bei konstanter Säurekonzentration der Hemmwert von Malachitgrün, Methylviolett 6 B and „light green“ mit der Inhibitorkonzentration zu, während der von Fuchsinbase und Kristallviolett mit zunchmender lnhibitorkonzcntration geringer wird. Bei konstanter Inhibitorkonzentration nimmt andererseits die Wirksamkeit aller untersuchten Verbindungen (mit Ausnahme von Methylviolett 6 B und Acridinorange) mit steigender Säurekonzentration zu. Der Hemmwert aller untersuchten Verbindungen steigt im Temperaturbereich 20-50°C mit der Temperatur, während kein Einfluß der Versuchsdauer zu erkennen ist. Bei einer lnhibitorkonzentration von 0,1% in 0,5 M Salzsäure nimmt der Hemmwert in der folgenden Reihe zu: Fuchsinsäure (32%) 〈 Acridinorange 〈 Fuchsinbase (39%) 〈 Alizarinrot S (46%) 〈 Methylviolett 6 B (50%) 〈 Malachitgrun (64%) 〈 Kristallviolett (70%) 〈 „light green“ (80%).Die Wirkung der Inhibitoren scheint durch Absorption nach einer Langmuir-Adsorptionsisotherme bedingt zu sein. Das wird durch die Korrosionspotentiale bestätigt; allerdings dürfte bei galvanostatischer Polarisation die Kathode bevorzugt polarisiert werden.
    Notes: The inhibition of the corrosion of B 26 S aluminium in HCl solutions by triphenylmethane, anthraquinoid and acridine dyes has been studied in relation to the concentration of acid and inhibitor, duration of immersion and temperature. In general, at constant acid concentration, the inhibiting efficiency of malachite green, methyl violet 6 B and light green increases, whereas that of fuchsine base and crystal violet decreases as the inhibitor concentration increases. At constant inhibitor concentration the efficiency of all the compounds except methyl violet 6 B and acridine orange increases with increasing acid concentration. The inhibitive efficiency of all the compounds increases with temperature in the range 20-50°C, but no dependence can be recognized on the duration of immersion. At an inhibitor concentration of 0.1% in 0.5 M HCl the efficiency increases in the order: fuchsine acid (32%) 〈 acridine orange ≤ fuchsine base (39%) 〈 alizarin red S (46%) 〈 methyl violet 6 B (50%) 〈 malachite green (64%) 〈 crystal violet (70%) 〈 light green (80%).The inhibitors appear to function through adsorption following the Langmuir adsorption isotherm. From the corrosion potentials the inhibitors appear to function through general adsorption but under galvanostatic polarisation conditions, the cathode appears to be preferentially polarised.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 105 (1982), S. 83-90 
    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: 2-Hydroxypropylmethacrylat wurde mit Ethylacrylat und n-Butylacrylat in Masse bei Temperaturen zwischen 60 und 100°C copolymerisiert unter Verwendung von Benzoylperoxid als Initiator. Die Zusammensetzung der Copolymeren wurde durch Hydroxylgruppenbestimmung analysiert; die Copolymerisationsparameter wurden nach der Kelen-Tüdös-Methode berechnet. Die Arrheniusparameter wurden abgeleitet, und die Grenzviskositäten und das thermische Verhalten der Copolymeren wurden ebenfalls untersucht.
    Notes: 2-Hydroxypropyl methacrylate has been copolymerized with ethyl acrylate and n-butyl acrylate in bulk at temperatures between 60 and 100°C using benzoyl peroxide as initiator. The compositions of copolymers have been analyzed by hydroxyl determination; the reactivity ratios have been calculated by Kelen-Tüdös method. Arrhenius parameters have been derived. The intrinsic viscosities and the thermal behaviours of the copolymers were also studied.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 2351-2360 
    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 mechanical properties of binary blends of high-density polyethylene and polypropylene are quite good compared to those for blends of some other immiscible pairs. The property relationships observed depend strongly on the process used to fabricate the blends as shown by comparisons of specimens made by injection and compression molding with widely varied cooling rates in the latter. Strength and modulus may show additive behavior or have positive or negative deviations, depending on the process conditions; however, measures of ductility like impact strength or elongation at break always show negative departures from additivity and exhibit minima in some cases. Addition of an appropriate ethylene-propylene elastomer greatly improves the ductility of these blends but with a corresponding decrease in strength and modulus. The presence of weld lines has a serious detrimental effect on mechanical properties of these blends.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1269-1276 
    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: Uncrosslinked cis-trans polybutadiene films were prepared on ultraclean glass microscope slides by uniform dipping. The samples were stored in different environments prior to evaluation of surface oxidation by dynamic contact angle using the Wilhelmy plate method and by X-ray photoelectron spectroscopy (XPS). Storage conditions evaluated were: (1) laboratory air at 20°C and 30% relative humidity; (2) vacuum at 0.1 torr; (3) distilled water equilibrated with air; and (4) degassed distilled water. XPS and contact angle analysis indicate that samples exposed to air undergo significant surface oxidation within 8 h. Exposure of polybutadiene to air-equilibrated water results in slower oxidation. Samples stored in degassed water demonstrated less surface oxidation. Vacuum-stored samples demonstrated the least surface oxidation. Dynamic contact angle measurements demonstrated that receding contact angles are more sensitive to changes in surface oxidation than are advancing contact angles, as expected. Changes in surface wetting characteristics are readily observed after only 1 h in laboratory air, although XPS analysis does not show evidence of oxidation within 4 h of air storage.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 4861-4866 
    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: Studies on polymerization of styrene by the heterogeneous catalyst system Cu2Cl2 + AlEt3 are reported. Kinetic studies carried out at an optimum catalyst composition [Al]/[Cu] = 0.8 and aging time of 4 h give a value of 55 kJ/mol for the activation energy. The rate law can be presented as R = K [cat] [mon]2. A radical mechanism is proposed on the basis of the effect of hydroquinone and ESR spectra. The mechanism of polymerization with this catalyst system is different than that of CuCl2 + AlEt2X (X = Br, Cl), which was reported earlier.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 104 (1982), S. 145-161 
    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: The determination of internal double bonds in PVC by oxidative chain scission with ozone in tetrachloroethane (TCE)-solution at -20°C can be quickly and easily performed measuring directly the intrinsic viscosities of samples during the reaction. Using a series of PVC-standards, the evaluation of the Mark-Houwink constants for TCE as solvent resulted in K = 0.027 [cm3/g] and α = 0.75. 1H-NMR-spectroscopic studies of the ozonolysis of model compounds as oleic acid and low molecular PVC fractions provided some information on the mechanism of the ozonolytic scission under the applied reaction conditions.
    Notes: Die Bestimmung der internen Doppelbindungen in PVC ist durch oxidative Spaltung mit Ozon in Tetrachlorethan (TCE)-Lösung bei - 20°C schnell und einfach möglich, indem die Grenzviskositäten der vor und während der Ozonolyse entnommenen Proben direkt im Reaktionsmedium ermittelt werden. Die zur Berechnung der Molekulargewichte benötigten und mit einer Reihe von PVC-Eichsubstanzen für TCE ermittelten Konstanten der Viskositäts-Molekulargewichts-Beziehung sind K = 0,027 [cm3/g] und α = 0,75. Durch 1H-NMR-spektroskopische Untersuchung von Modellverbindungen wie Ölsäure und niedermolekularen Anteilen aus PVC konnte ein Einblick in den Mechanismus der ozonolytischen Spaltung unter den ausgearbeiteten Reaktionsbedingungen erhalten werden.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 11-16 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The poly(tetra peptide), H- (L·Val1-L·Pro2-Gly3-Gly4)n-L·Val-OMe, which is a recurring sequence in tropoelastin the precursor protein of the elastic fiber, has been irradiation crosslinked to produce an elastomeric material with limited strength. When a material such as a Dacron fabric is impregnated by the coacervate phase of the poly(tetra peptide) prior to irradiation crosslinking at 50 Mrad, the crosslinked product exhibits stress-strain curves with good elastomeric properties and high strength. In addition to the stress-strain curves, the material is characterized by scanning electron microscopy.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...