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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 405-414 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In both thermal emulsion polymerization of styrene in the temperature range 60-80 °C, and peroxodisulfate-initiated polymerization at 60 °C, weight-average to number-average molecular-weight ratios (M̄w/M̄n) approach 1,5 when potassium octadecanoate is used as emulsifier. A low activation energy for thermal initiation (≈66,0 kJ/mol) was deduced which may indicate a catalytic effect of the emulsifier during the thermal initiation process. Participation of the emulsifier is probably attributed to a transfer of one of two monomer radicals, produced thermally, to the emulsifier, with subsequent desorption to the aqueous phase, leaving one radical in the polymerization locus.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 0021-9304
    Keywords: growth hormone ; biphasic calcium phosphate ; monocyte ; lipopolysaccharides ; cell degradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study investigated the effects of human growth hormone (hGH) on the monocyte/macrophage lineage, the first cell population involved in degradation of calcium phosphate ceramic after in vivo implantation. Monocytes isolated from human blood were cultured on biphasic calcium pellets (200 mg) for 8 days in the presence of lipopolysaccharides (LPS, 0.5 μg/mL), hGH (10 and 50 ng/mL), or an association of LPS with hGH (10 and 50 ng/mL). Unlike LPS, hGH significantly decreased (about 25%) the total number of lacunae formed by monocytes. However, hGH induced the formation of lacunae with a greater surface area (about a 90% increase) as compared to the control. Finally, intense upmodulation (about a 250% increase) of lacuna surface area was observed in the presence of both soluble factors, suggesting that hGH and LPS act synergistically. In view of the development of a drug delivery system for hGH bone release, this study shows that hGH not only stimulates bone cells implicated in the synthesis of the extracellular matrix but also those involved in the early degradation of calcium phosphate biomaterial. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 79-85, 1998.
    Additional Material: 4 Ill.
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  • 3
    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
    Additional Material: 5 Ill.
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  • 4
    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: Nylon 6 fibers were annealed in air at 160°C for periods ranging from 1 to 10 h. Their spectral reflectance values were measured. Color parameters, including luminance factor, dominant wavelength, purity, and the color difference between annealed nylon 6 fiber samples and unheated ones were calculated. The observed variations in the colors of samples were assumed due to the thermal and oxidation degradations. The behavior of the color parameters with heating duration was compared with the general kinetic curve of thermooxidative degradation of polymers and the match between them is discussed. The color difference ΔE values is recommended for monitoring the thermooxidative degradation of nylon 6 fibers. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 40 (1996), S. 307-313 
    ISSN: 0959-8103
    Keywords: swelling ; seed ; electrolyte ; particle size ; rate of polymerisation ; coalescence ; styrene ; 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 effects of adding inorganic electrolyte (below the critical coagulation concentration) have been investigated in two systems for the emulsion polymerisation of styrene. In one system, potassium chloride, at different concentrations, was added at the end of interval I, using three different ionic emulsifiers: potassium octadecanoate which has a low critical micelle concentration (CMC), potassium dodecanoate and sodium dodecyl sulphate (SDS), which have moderately high CMC. A significant increase in the rate of polymerisation was observed in all cases even at the higher levels of electrolyte at which the rate is reduced if the electrolyte is added from the onset of polymerisation. In the second system, the effects of adding sodium chloride, in concentrations up to 0.2M, on the seeded emulsion polymerisation of styrene have been followed. A significant increase in the rate was observed as electrolyte level was increased, with no significant change in particle size. Saturation swelling measurements indicated a slight increase in monomer concentration inside the particles as electrolyte concentration was increased. Evaluation of the average number of free radicals per particle, n¯, by a steady state approach indicates an increase in the value of n¯ as electrolyte level is increased. The value of n¯ is below 0.5 but approaches this value at the highest electrolyte concentration. The increased surface area of the particles may account for this effect by increasing the capture efficiency of the radicals by the particles.
    Additional Material: 5 Ill.
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  • 6
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Einige Kondensationsprodukte von p-Phenylendiaminen mit verschiedenen organischen Säuren wurden synthetisiert. Der Einfluß von γ-Bestrahlung auf PMMA-Filme, die mit drei Proben dieser Amine dotiert wurden, wird mittels UV-Spektroskopie untersucht. Es wurde eine Zunahme der Intensität der Absorptionsbanden mit steigender Bestrahlungsdosis registriert. Die Verwendung der dotierten PMMA-Filme in der Dosimetrie wird vorgeschlagen.
    Notes: Some p-phenylene diamine condensation products with different organic acids were synthesized. The effect of γ-irradiation on PMMA films doped with three samples of these amines was investigated by ultraviolet spectroscopy. A change in the intensity of absorption bands with increasing irradiation dose was recorded. The use of PMMA films doped with this type of amines as dosimeter is suggested.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 708-710 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die durch Cerionen initiierte Pfropfung von Methylmethacrylat auf Stärke wurde untersucht, wobei die nicht absorbierten Cerionen entweder im Substrat blieben oder entfernt wurden. Der Pfropfgrad, die Molekülmasse der gepfropften Ketten und die Anzahl der Pfropfungen wurden in Abhängigkeit von der Konzentration der Cerionen bestimmt. Auf Basis der erhaltenen Ergebnisse wird der Mechanismus der Pfropfreaktion diskutiert.
    Notes: Methyl methacrylate was grafted onto starch by the ceric ion method with and without removing of the unabsorbed ceric ions. Graft level, molecular weight of the grafted chains, and number of the grafted chains were measured in dependence on ceric ion concentration. On base of the results the mechanism of the grafting reaction is discussed.
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Substanzcopolymerisation von Methylmethacrylat und Chromacrylat wurden neue halbleitende Copolymere erhalten. Das chemische Reaktionsschema wird diskutiert. Dichte und Harte der Proben nehmen mit steigendem Chromgehalt ab. Im Infrarotspektrum wurde eine Verbreiterung der Carbonylbande bei 1 710 cm-1 beobachtet, was auf eine mogliche Koordination der C=O-Gruppe mit Chromionen hinweist. Die elektrische Leitfahigkeit der Proben nimmt mit steigendem Chromacrylatgehalt zu. Der Einfluß einer γ-Bestrahlung auf die elektrische Leitfahigkeit der Copolymere wurde untersucht.
    Notes: New semiconducting copolymers were prepared by bulk copolymerization of methyl methacrylate with chromium acrylate. The pattern of the chemical reactions is discussed. The density and hardness of the samples decrease with increase of the chromium content. I n the infrared spectrum broadening of the carbonyl band a t 1710 cm-l is observed, which indicates the possibility of coordination of the C=O group with the chromium ion. The electrical conductivity of the samples increases with increase of chromium acrylate content. The effect of y-irradiation on the electrical conductivity of the copolymers was studied.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 16 (1992), S. 159-167 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An investigation has been carried out of the limiting oxygen index (LOI) test. A review of the literature shows that, although there is abundant information on the test, it is not clear that its results correlate well with those of any other test, or indeed with those of real fires. Theoretical considerations indicate that the test could be improved by using it with bottom ignition rather than with the standard top ignition. A number of materials were tested in the cone calorimeter and in the LOI, and various correlations were attempted. In general, correlations between some of the cone calorimeter properties measured and the inverse of the LOI made sense. These correlations were not, however, sufficiently sensitive, even when investigating small effects on a single base polymer system, to justify using the LOI as a proxy for the cone in any way. The LOI is likely to continue to be used extensively. This work suggests that quality control and, possibly, mechanistic or other flame-retardant additive studies, are its only applications where the results can be justified.
    Additional Material: 9 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 126-128 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Verfahren zur Pfropfcopolymerisation von Acrylnitril auf gebleichte Holocellulose, wobei die nicht adsorbierten Cerionen aus dem Polymerisationssystem entfernt werden, wird beschrieben. Mit dieser Methode werden höhere Pfropfgrade und höhere Pfropfausbeuten erreicht als bei der kontinuierlichen Initiierung.
    Notes: The graft copolymerization of acrylonitrile onto bleached holocellulose using an initiation procedure in which the unadsorbed ceric ions are removed from the polymerization system is reported. With this method higher graft levels and higher efficiency of grafting is achieved than with the continuous initiation method.
    Additional Material: 3 Ill.
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