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  • 1
    Electronic Resource
    Electronic Resource
    Effect of alkalies on suspension polymerization of vinyl acetate monomer, properties of poly(vinyl acetate) beads and poly(vinyl alcohols) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 707-713 
    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: The use of weak alkalies such as sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3) and their 1 : 1 molar mixture, and strong alkalies such as sodium hydroxide (NaOH) and sodium methoxide (NaOMe) as pH controllers in suspension polymerization of vinyl acetate monomer (VAM) has shown to have diverse effects on the yield of resulting poly(vinyl acetate) (PVAC) beads. Carbon dioxide as such or the carbonate seems to influence the yield. Further, these alkalies have a deep-seated effect not only on properties like viscosity, stereoregularity, glass transition temperature (Tg), and swelling coefficient (Q) of the PVAC beads but also on those of poly(vinyl alcohol) (PVA) obtained by alcoholysis of PVAC beads. The PVAC beads obtained using Na2CO3 showed higher viscosity, higher swelling coefficient (Q), and the PVA derived from these beads had higher Q, higher syndiotacticity/isotacticity ratio, and lower Tg.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460417
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of Senecio Alkaloids by thermospray liquid chromatography/mass spectrometry (1990)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1990), S. 1-12 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of Senecio alkaloid and alkaloid N-oxide standards has been analyzed using positive and negative ion thermospray liquid chromatography/mass spectrometry (LC/MS) with an ammonium acetate-containing mobile phase. On-line separations of pyrrolizidine alkaloids from extracts of Senecio jacobaea (tansy ragwort) and Senecio vulgaris (common groundsel) were done using an ammonium hydroxide-containing mobile phase. All of the alkaloids known to be present in the extracts were detected by ammonium hydroxide thermospray LC/MS, as well as many other components which may be as-yet-unidentified alkaloids.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200190102
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  • 3
    Electronic Resource
    Electronic Resource
    Improvement in properties of poly(vinyl acetate): Emulsion with dibasic acids (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 2675-2684 
    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: We report an attempt to graft cis (maleic and citraconic) and trans (e.g., fumaric and mesaconic) unsaturated dibasic acids onto poly(vinyl acetate) in emulsion system, in the presence of an initiator and a small quantity of vinyl acetate. The resulting emulsions showed better adhesiveness, higher shear strength, and varied viscosity, and yielded relatively translucent films with faster drying properties. Grafting in the case of these acids was poor, but the cis acids were better grafted than the trans acids. Furthermore, saturated acids (e.g., oxalic and succinic acid) and an inorganic acid (boric acid) were only physically incorporated in the poly(vinyl acetate) emulsion (PVAc emulsion); the resulting product also showed similar improvement in the end properties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070310823
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  • 4
    Electronic Resource
    Electronic Resource
    Synthese von Oligobutadienen durch radikalische Substanzpolymerisation (1983)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 637-639 
    Details
    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: Telechelic butadiene oligomers were prepared by bulk polymerization with nitril- and xanthogenate terminal groups and average molecular weight 〈 5000 g/mol. 2.2'-Azo-bis-iso-butyronitril (AIBN) and xanthogenate disulfides being used as initiator and chain transfer agents, respectively. The average molecular weight and the nitril functionalities of the oligomers were decreased and the xanthogenate functionality was increased by the application of chain transfering agents. Synthesis and characterization of the oligomers are described.
    Notes: Telechele Butadienoligomere werden in Substanzpolymerisation mit Nitril- und Xanthogenatendgruppen unter Verwendung von 2,2'-Azo-bis-isobutyronitril (AIBN) als Initiator und Dialkylxanthogendisulfiden als Kettenüberträger hergestellt. Die relativen mittleren Molmassen liegen unter 5000 g/mol. Die mittlere Molmasse und die Nitrilfunktionalität der Oligomere sinken, die Xanthogenatfunktionalität steigt bei Einsatz von Kettenüberträgern. Die Synthese und Charakterisierung der Präpolymere werden beschrieben.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1983.010341008
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  • 5
    Electronic Resource
    Electronic Resource
    Bestimmung der Übertragungskonstanten von Di-alkyl-xanthogen-disulfiden bei der radikalischen Substanzpolymerisation von Butadien (1984)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 35 (1984), S. 58-60 
    Details
    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: According to MAYO and SMITH, the chain transfer constants of dialkyl xanthogendisulfides with different alkyl substituents were investigated in the bulk polymerization of butadiene. Contrarily to emulsion polymerization, the chain transfer constants are independent of the alkyl groups. By ESR measurements no difference in the stability of the radicals was found. The values of retardation of polymerization rate were compared with those of emulsion polymerization.
    Notes: Die Übertragungskonstanten nach MAYO und nach SMITH für Di-alkyl-xanthogendisulfide mit unterschiedlichen Alkylsubstituenten bei der Substanzpolymerisation von Butadien wurden bestimmt. Im Gegensatz zur Emulsionspolymerisation wurde gefunden, daß die Übertragungskonstanten unabhängig vom Alkylgruppenrest sind. ESR-Messungen zeigten ebenfalls keine Unterschiede in der Radikalstabilität. Die Retardierung der Polymerisationsgeschwindigkeit wurde mit Werten aus der Emulsionspolymerisation verglichen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1984.010350113
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  • 6
    Electronic Resource
    Electronic Resource
    The [C5H8]+· radical cation: Structural studies by energy-resolved mass spectrometry (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 727-732 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Control of the degree of collisional excitation of an ion can be achieved by varying the collision energy or the number of collisions. The former experiment yields a series of daughter spectra which is analogous to a breakdown curve and which serves to characterize the ion undergoing collisionally activated dissociation (CAD). Recognition of differences in the spectra between isomeric ions is facilitated if the curves obtained from the energy-resolved data are considered in pairs and their differences are plotted. This procedure serves to demonstrate that ionized 1,3- and 1,4-pentadiene are structurally distinct, even though they are not distinguishable in conventional CAD. 2-Pentyne and 3-octyne give [C5H8]+· fragment ions which are closely related to the 1,3- and 1,4-pentadiene structures, respectively. Any particular ion can be characterized by another form of difference spectrum: one comparing data at two collision pressures each taken over a range of collision energies. This procedure yields conclusions regarding ion structure which match those reached from the energy-resolved experiments.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210201206
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of matrix effect correction and direct intensity-concentration relationship methods for major element analysis of geological materials by X-ray fluorescence spectrometry (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 16 (1987), S. 87-94 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Forty international geochemical reference samples were used to test two methods for data processing of intensity values and to obtain major element concentrations by XRF spectrometry. It was found that the direct intensity - concentration relationship method gives better results than the more commonly employed matrix correction technique. The major differences show up in MgO, Na2O and Al2O3. The method is precise to about ±1% and accurate to ±6% or better for most elements of geological interest.
    Additional Material: 13 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300160209
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  • 8
    Electronic Resource
    Electronic Resource
    Stability and Polymerization of uranyl-catechol chelates (1968)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 38 (1968), S. 280-288 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interaction of uranyl ions with catechol has been investigated by the potentiometric and spectrophotometric techniques. Potentiometric titrations of uranyl nitrate with caustic potash in presence of catechol exhibited a sharp inflexion at 2⅔ moles of alkali der mole of the metal ion. At the initial stages of the titration, the reaction was shown to proceed as: \documentclass{article}\pagestyle{empty}\begin{document}$$ \rm{UO}_2^{2 + } + \rm{C}_6 \rm{H}_4 \left({\rm{OH}} \right)_2 \rightleftharpoons \rm{UO}_2 \rm{C}_6 \rm{H}_4 \rm{O}_2 + 2\rm{H}^ + . $$\end{document} The equilibrium constant of the reaction was found to be 2.88 · 10-7 giving a value of 3.87·1014 for the formation constant of the chelate. Equilibrium constant of the reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$ \rm{2UO}_2^{2 + } + 2\rm{H}_2 \rm{A} \rightleftharpoons \left({\rm{UO}_2 \rm{A}_2 } \right)_{\rm2} + 4\rm{H}^ + . $$\end{document} has been found to be 1.00·10-10. The binuclear chelate species have been found to polymerize further through hydrolytic reactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19680380507
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