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  • 1
    Electronic Resource
    Electronic Resource
    Methylzinc or methylcadmium-N,N,N-trimethyl- propylenediaminedithiocarbamates: Precursors for zinc or cadmium sulfide. The X-ray crystal structure of methylcadmiumtrimethylpropylene- diaminedithiocarbamate benzene solvateElectron Microscopy Unit for microscopy. We thank the SERC for a grant to P. O'B., and Mr. Keith Pell of the QMW (1993)
    Weinheim : Wiley-Blackwell
    Advanced Materials 5 (1993), S. 653-654 
    Details
    ISSN: 0935-9648
    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: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19930050913
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  • 2
    Electronic Resource
    Electronic Resource
    Influence de la température sur i'écoulement des polymères. Correlation pratique et mathématique de i'énergie d'activation de i'écoulement pour le polyéthylène basse-densité, polyéthylène haute-densité, polystyrène et d'autres polyoléfines (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 173 (1989), S. 1-13 
    Details
    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 behaviour of materials has been studied in molten state. Measurements were made by a capillary viscometer. We have tried to link the values of activation energy at constant shear rate and a constant shear stress with the values of melt flow.The values of melt flow obtained according to the mathematical approach do not coincide with the values obtained experimentally. The activation energy of LDPE is superior to that of HDPE on account of the free volume of LDPE which is greater.
    Notes: Nous avons étudié les propriétés rhéologiques des matériaux à l'état fondu au moyen d'un viscosimètre à capillaire.Nous avons essayé de relier les valeurs des énergies d'activation, à vitesse et tension de cisaillement constantes, avec les valeurs de l'indice d'écoulement.Les valeurs de l'indice d'écoulement obtenues selon l'approche mathématique ne coincident pas avec les valeurs obtenues expérimentalement. L'énergie d'activation de LDPE est supérieure à celle du HDPE en raison du volume libre de LDPE qui est plus grand.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051730101
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  • 3
    Electronic Resource
    Electronic Resource
    Copolymerisation of ethylene and vinyl acetate under high pressure with a peroxide/triethylaluminium system (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 87-95 
    Details
    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: In der vorliegenden Arbeit wurde die Wirksamkeit eines Zusatzes von Triethylaluminium zu dem in der industriellen Praxis für die Initiierung der Copolymerisation von Ethylen mit Vinylacetat häufig verwendeten tert-Butylperpivalat untersucht. Dazu wurden Polymerisationsversuche in einer kontinuierlich betriebenen Laboranlage bei 1900 bar und 150°C durchgeführt. Es wurden Vinylacetatkonzentrationen im Eduktstrom bis zu 36 Gew.-% eingesetzt. Die Konzentration des organischen Peroxides betrug 50 mol ppm, die des Triethylaluminiums wurde im Bereich von 0 bis 75 mol ppm variiert.Die beobachteten Effekte, nämlich eine Erhöhung des Umsatzes und eine Verringerung des Peroxidbedarfs, waren stärker als bei der Homopolymerisation von Ethy-len. Dies wird auf die zusätzliche Steigerung der Reaktionsgeschwindigkeit des Kettenwachstums neben dem erhöhten Radikalangebot zurückgeführt.Die Eigenschaften der erhaltenen Copolymeren werden durch das Triethylaluminium nur moderat verändert. Neben einer Abnahme der Dichte und einer Zunahme des Schmelzpunkts wurde eine Verringerung der Polydispersität beobachtet.
    Notes: The present study was carried out to examine the effectiveness of an addition of triethylaluminium to tert-butyl perpivalate which is frequently used in industrial applications for initiating the copolymerisation of ethylene with vinyl acetate. For this purpose, polymerisation tests were carried out in the laboratory on a continuous basis at 1900 bar and 150°C. Vinyl acetate was added in concentrations of up to 36 wt.-% in the feed to the reactor. The organic peroxide concentration was 50 mole ppm; the concentration of organoaluminium alkyl was varied within the range of 0-75 mole ppm.The effects observed, namely an increase in the conversion and a decrease in the peroxide consumption were more marked than with the homopolymerisation of ethylene. This is attributable to the increased rate of chain growth in addition to the increased amount of radicals available.The properties of the copolymers obtained are changed only moderately by aluminium alkyl. Apart from a decrease in density and an increase in the melting point, a decrease in the polydispersity was observed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052380108
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  • 4
    Electronic Resource
    Electronic Resource
    Oligomers of a polyester network (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 815-827 
    Details
    ISSN: 0887-624X
    Keywords: polyester network ; glycerol ; succinic acid ; oligomers ; network microstructure ; 13C-NMR spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oligomers of glycerol and succinic acid have been prepared by three different methods and characterised by solution 13C-NMR spectroscopy at 125.8 MHz. The first series of five oligomers was prepared by reacting glycerol with succinic anhydride; only one acid function of each succinic acid residue formed an ester by this means. They were readily distinguished as the shifts of their glycerol residues were dispersed over 16 ppm, and their shifts provided a guide to the assignment of shifts in the more elaborate oligomers. The second set of oligomers was prepared by treating glycerol with a small quantity of succinic acid, ester links being promoted by means of the reagent dicyclohexylcarbodiimide (DCCDI). When we used 2 mol of DCCDI/mol of acid in the presence of an excess of glycerol, no free acid functions remained, and a new set of oligomers was obtained. Furthermore, within this set the proportion of ring molecules was enhanced by repeating the reaction under much more dilute conditions. In this way the shifts of two ring oligomers were recognized in the spectrum. A different set of oligomers again was obtained when the esterification was performed with 1 mol of DCCDI/mol of succininic acid. After the first generation of oligomers had been identified in the mixtures produced by these three experiments, the reactions continued to produce larger oligomers with new fine structure features in the spectra. Glycerol trisuccinate was prepared in a pure form and heated in a vacuum to eliminate succinic acid groups and allow the formation of oligomers with two and three branch points. The structures successively produced by this reaction were readily recognized. In all we were able to recognize the formation of component structures in at least 17 different oligomers. The shifts of the carbons of the glycerol residues are sensitive to the substitution pattern at that residue, to whether the succinic acid residue to which they are linked has reacted a second time, and in some cases the methine shift is sensitive to how the succinic acid residue attached to a neighboring methylene carbon has reacted. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320503
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  • 5
    Electronic Resource
    Electronic Resource
    Langmuir-blodgett films of stilbazole complexes of iridium(I) and rhodium(I) (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 243-251 
    Details
    ISSN: 1057-9257
    Keywords: Langmuir-Blodgett film ; Stilbazole ; Metal complex Iridium ; Rhodium Pyroelectricity ; Alternate layer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Complexes of 4-alkoxystilbazoles with iridium and rhodium form stable Langmuir layers at the air-water interface even when the alkoxy chain is relatively short (C5-C12). The surface pressure-area isotherms indicate that condensed molecular monolayers are obtained. The area per molecule of each compound in its monolayer form is typically 0.60 nm2, which agrees well with the cross-sectional area of the [Ir(CO)2CI] or [Rh(CO)2CI] head group predicated using molecular models. This suggests that the molecules are oriented with the metal moiety close to the water surface and their alkoxystilbazole ‘rod’ protruding from the plane of the water surface. Such floating monolayers have been transferred on to solid substrates such as glass, aluminium (AI2O3/AI/Glass) and silicon (SiO2/Si) at relatively high speed (10 mm min -1) to form Y-type LB assemblies. The UV-Visible absorption properties of these materials in solution and LB film form have been studied. LB films of these complexes yield bathochromically shifted spectra relative to the LB film spectrum of the uncomplexed stilbazole. Additionally, these spectra are often broader and hypsochromically shifted relative to their corresponding solution spectra as a result of the close molecular packing within the LB film and the associated dipole-dipole interactions.The electrically polar nature of the molecules described in this paper suggest that they may be suitable candidates for new pyroelectric materials. Thus the pyroelectric coefficient (the rate of change of electric polarisation with respect to temperature) has been measured for a polar multilayer LB film containing an iridium complex. A pyroelectric coefficient of 3.5 μCm-2K-1 (at 30 °C) has been measured, which is one of the highest reported valued for an LB film. Additionally, a low dielectric loss of around 0.01 has been found over the frequency range 50 Hz-1 kHz, indicating that such LB films may be usfeul materials for pyroelectric sensors.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040403
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  • 6
    Electronic Resource
    Electronic Resource
    Silicon contamination of substrates in fluorocarbon plasmas produced in glass reactors (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 1419-1429 
    Details
    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: Extensive research has been carried out in recent years using fluorocarbon plasmas for modification and depositions on polymer substrates. In some cases anomalous results have been obtained that are not explainable based on conventional fluorine chemistry. In this investigation pure polypropylene films were exposed to carbon tetrafluoride plasmas in a Pyrex glass reactor. At short reaction times (less than 1 min) significant amount of silicon was detected by ESCA on the surface of the films. Analysis of liquid nitrogen trapped fluorocarbon plasma gases and molecular fragments indicated high concentrations of silicon and carbon containing species, the former indicative of ablation and etching reactions of the glass reactor walls. The production of a relatively high quantity of fluorosilicon derivatives was explained by the greater affinity of silicon for fluorine than for carbon, with the tendency to readily form SiF4. These fluorosilicon radical and ionic species generated under cold plasma conditions can easily react with polymeric substrates causing unexpected surface modifications. In addition Si-F bonds could be readily hydrolyzed to SiOH islands on the surface of the substrate to impart anomalous characteristics. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070521008
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  • 7
    Electronic Resource
    Electronic Resource
    Aqueous ring-opening metathesis polymerisation of 7-oxanorbornene derivatives with oxygen-containing functionalities (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 1273-1288 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A number of 7-oxanorbornene derivatives with hydroxymethyl, methoxymethyl and acetoxymethyl functionalities were synthesised and investigated as monomers in ring-opening metathesis polymerisation (ROMP) catalysed by commercial ruthenium trichloride in aqueous ethanolic solvents. Comparison was made with related polymerisations of 7-oxanorbornene derivatives with anhydride, methoxymethyl and carboxylic acid functionalities. The structures of the polymers were investigated by 1H and 13C NMR and their molar masses and molar mass distributions by gel-permeation chromatography.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021950413
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