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  • 1
    Digitale Medien
    Digitale Medien
    Kinetic aspects of the copolymerization of tetrahydrofuran with alkylene oxides (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 3547-3554 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cationic (BF3) copolymerizations and terpolymerizations of 1,2-butylene oxide (BO), propylene oxide (PO), and tetrahydrofuran (THF), have been carried out at 0°C in ethylene dichloride under dry inert conditions. Reactivity ratios of THF-BO, THF-PO and BO-PO systems have been determined with the use successively of 1,2-propanediol and 1,2,3-propanetriol (glycerine) as cocatalysts. Terpolymer compositions established experimentally compare well with those predicted by calculations with the reactivity rations determined in the binary systems. With the triol as cocatalyst, the existence of a ternary azeotrope was confirmed. Its composition is: M1(THF) = 0.125; M2(BO) = 0.205; and M2(PO) = 0.670.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1971.150091212
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  • 2
    Digitale Medien
    Digitale Medien
    Anionic polymerization of 1,2-butylene oxide (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 10 (1972), S. 1353-1362 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Anionic polymerizations of 1,2-butylene oxide were carried out in vacuum-sealed dilatometers in the range of 30-60°C. Potassium terbutoxide and dimsyl sodium were used as initiators; dimethyl sulfoxide (DMSO) and mixtures of DMSO with tetrahydrofuran were solvents. The polymer products were analyzed by gel permeation chromatography and infrared spectroscopy. The object of the investigation was to obtain information on the mechanism of the reaction and to elucidate some of its kinetic aspects. It has been shown that the polymerizations occur by two different processes, depending on the choice of experimental conditions. One of the processes involves free ions and ion-pairs, the other, ion-pairs alone. In the first case, where dimethyl sulfoxide is used as solvent, the order of the reaction with respect to the initiator concentration far exceeds unity (∼1.8), while in the second case, involving mixed solvents, the order of the reaction, for all practical purposes, is one.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1972.150100507
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  • 3
    Digitale Medien
    Digitale Medien
    Copolymerization of tetrahydrofuran with propylene oxide. III. 1,2,3-propanetriol as cocatalyst (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 10 (1972), S. 399-412 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The cationic copolymerization of tetrahydrofuran with propylene oxide was investigated with the use of boron trifluoride etherate, 1,2,3-propanetriol, and ethylene chloride as catalyst, cocatalyst, and solvent, respectively. The reactions were carried out in the liquid phase under a blanket of dry nitrogen at atmospheric pressure and in the temperature range from -10° to +20°C. Comonomer consumption was followed by vapor-phase chromatography, while the products were analyzed by gel-permeation chromatography, nuclear magnetic resonance, vapor-pressure osmometry, and chemical endgroup analysis (phthalation). The investigation was directed towards the elucidation of the influence of the initial cocatalyst content, the initial mole fraction of the comonomer, and the temperature of reaction, on the kinetics of the reaction (rates of disappearance of comonomers, reactivity ratios, comonomer conversions and product yields) and on the characteristics of the products formed (composition, molecular weight, and primary and secondary hydroxyl content). An attempt is made to interpret the results reported in the paper.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1972.150100207
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  • 4
    Digitale Medien
    Digitale Medien
    Anionic polymerization of propylene oxide (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 10 (1972), S. 3089-3102 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The anionic polymerization of propylene oxide with the use of potassium tert-butoxide and naphthalene sodium as initiator and dimethylsulfoxide, tetrahydrofuran and mixtures of both as solvent was investigated. The reactions were carried out in vacuum-sealed dilatometers over the temperature range 20-60°C. The products were analyzed by gelpermeation chromatography and infrared spectroscopy. The object of the investigation was to obtain information on the mechanism of the reaction and elucidate some of its kinetic aspects. It is shown that the polymerization occurs by two different processes depending on the experimental conditions: one involving free ions and ion-pairs, the other, ion-pairs alone. In the first case, where DMSO was used as solvent, the order of the reaction with respect to the initiator is greater than unity (∼1.7), while in the second case, involving the mixture of DMSO and THF and ion-pairs alone, the reaction order is only one. Transfer to monomer is believed to take place only in the strongly dissociating DMSO medium, where free ions are present.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1972.170101025
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