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  • Physics  (2,547)
  • Wiley-Blackwell  (2,547)
  • 1970-1974  (2,547)
  • 1
    Electronic Resource
    Electronic Resource
    Investigation of mechanism of initiation of polymerization of cyclic acetals by protic and aprotic acids (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 1-5 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of polymerization of 1,3-dioxolan and degradation of polydioxolan catalyzed by boron trifluoride etherate have been studied in methylene chloride solution. The S-shape kinetic curves is found to be due to the autocatalytic action of the macromolecules formed. Effective participation of macromolecules in the initiation process has been confirmed on the basis of the relationship of the rate constants of boron trifluoride etherate reactions with cyclic monomer and with the polymer chain as well as by the decrease of the induction period on addition of the polymer or its low molecular weight analog, methylal, to the polymerization system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110101
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of graft copolymer on demixing of immiscible polymers in solution (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 41-53 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of graft copolymer on the demixing of solutions of two immiscible homopolymers and critical conditions for emulsion formation were studied. The graft copolymer used in the present work consists of one backbone poly(vinyl acetate) (PVAc) and one branch polystyrene (PS). PVAc and PS of various degrees of polymerization were used as immiscible homopolymers. The common solvent was benzene. When the concentration of homopolymer blend was not sufficiently higher than the critical concentration for demixing of the blend solution, no stable emulsion was formed, even when a considerable amount of graft copolymer was present, and the added graft copolymer merely reduced the demixing rate. However, as the blend concentration was increased, a stable emulsion could readily be obtained by addition of rather small amounts of graft copolymer. The radius of emulsion droplets was inversely proportional to the weight ratio of the graft copolymer to the dispersed component polymer, in accordance with the theoretical prediction. It was concluded that the emulsions were stabilized against coagulation by graft copolymer molecules fixed strongly as a monolayer on the interface of the emulsion.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110104
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  • 3
    Electronic Resource
    Electronic Resource
    Structure of the tetramer of α-methylstyrene (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 89-104 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the tetrameric dianion formed by α-methylstyrene in tetrahydrofuran by reaction with sodium has been examined. Mass spectral, NMR, infrared, and kinetic data all indicate that the structure is rather than the structure which had previously been assumed for this species.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110108
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  • 4
    Electronic Resource
    Electronic Resource
    Ring-opening polymerizations of cyclic olefins (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 163-173 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A ziegler-type catalyst system consisting of tungsten hexachloride and alkyl or aryl tin compounds was found to polymerize cyclopentene and other cyclic olefins through a ring-opening mechanism. This catalyst system also polymerized α-olefins such as ethylene and 1-octene. An attempt was made to copolymerize cyclopentene and ethylene. Other catalyst systems were also employed for ring-opening polymerizations with limited success.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110113
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  • 5
    Electronic Resource
    Electronic Resource
    Estimation of carboxy-terminated polybutadiene functionality distribution via fractionation on silica gel (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 175-189 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Separations of carboxyl-terminated polybutadiene (CTPB) liquid polymer according to functionality have been effected by using stepwise elution from silica gel. Recoveries in the 90-95% range have been achieved by deactivating the silica gel and recycling the unfractionated portion through progressively more active silica gel. Subjection of the fractions obtained from the silica-gel separation to analysis via gel-permeation chromatography and infrared spectroscopy yields not only functionality distribution data, but also provides an estimation of the relationship between molecular weight distribution and functional type. Repetitive analyses indicate a precision of ±7% (or less) of the amount of each functionality type present. An evaluation has been made of the accuracy of the data by fractionating saturated and methyl ester derivatives of CTPB under test conditions different from those employed in fractionating the original polymer. Within the known experimental error of the techniques employed, these studies have confirmed the data generated for CTPB polymer as received. Analytical techniques and interpretation of data are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110114
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  • 6
    Electronic Resource
    Electronic Resource
    Universal calibration in GPC: A new approach for the calculation of molecular weights (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 191-201 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for determining simultaneously the molecular weight of a broad-distribution polymer and the Mark-Houwink coefficients for that polymer type by using only GPC and intrinsic viscosity data. Standardized samples of poly(vinyl chloride), polystyrene, polybutadiene, and an experimental cycloolefin polymer were analyzed by this method. Shear-corrected intrinsic viscosities were used in all cases because of the high molecular weights involved. Molecular weight data for all samples were found to be in good agreement with molecular weight data obtained by membrane osmometry and from other GPC techniques. The proposed technique provides a means for calculating the molecular weight of a single polymer sample through universal calibration of GPC without knowledge of the Mark-Houwink coefficients for that polymer type.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110115
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  • 7
    Electronic Resource
    Electronic Resource
    Chlorinated polyethylene. II. Chlorine distribution on the polymer chains (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 225-231 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nature of substitution in a slurry-phase chlorination of high-density polyethylene was studied using NMR and IR spectroscopy. The ratios of γ (or greater) methylenes were obtained from the NMR at different chlorine levels and compared with the theoretically predicted values based on a statistical treatment for substitution polymers. The results indicted that, unlike chlorosulfonated polyethylene, chlorinated polyethylene shows a hindered-type substitution. Molecular weight of the parent polyethylene, the degree of chlorination and the degree of residual crystallinity of the samples have no bearing on the type of substitution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110118
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  • 8
    Electronic Resource
    Electronic Resource
    Microstructure of polybutadiene catalyzed by alkali metal tert-butoxides and n-butylsodium. II. (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 253-259 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A polybutadiene of high molecular weight was prepared in hydrocarbon solvent by using n-BuNa-tert-BuOM (M = Li, K) as a polymerization initiator. The microstructure of this polymer varied from 35 to 76% of 1,2 content, depending on the type of modifiers. The kinetics of polymerization was not studied, primarily due to the heterogeneous nature of the catalyst. However, other variables, such as the catalyst concentration and temperature, have been studied. The results and mechanistic implications are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110121
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  • 9
    Electronic Resource
    Electronic Resource
    Evidence for and against concentration gradients in polymerizing latex particles (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 241-251 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A single-charge emulsion polymerization involving a monomer which is a good solvent for its polymer is considered. It is shown to be unlikely that within the polymerizing latex particles there are concentration gradients large enough measurably to affect the kinetics of the reaction. The average displacement of monomers due to Brownian motion within the latex particles and in the absence of concentration gradients is calculated. This diffusive mean free path, corresponding to an interval involving less than 1% change in conversion, is shown to be much longer than the radius of the latex particle. Consequently, loci where monomer concentration is perturbed by conversion to polymer are immediately swamped by unreacted monomer. Also, direct experimental evidence exists showing that the monomer concentration in latex particles is about the same when nonpolymerizing latex particles are saturated or during polymerization in the presence of monomer excess. The thermodynamics of saturation swelling preclude the possibility of the existence of large concentration gradients. The arguments that have been advocated in the literature for core-skin separation within polymerizing latex particles were based on conversion data which were thought to be linear with time, while a reexamination indicates that they were not. The observed core-skin separation obtained when butadiene or tritiated styrene were copolymerized with styrene in the presence of a polystyrene homopolymer seed latex has questionable relevance to single-charge homopolymerization. There are reasons to doubt that the distribution of co-monomers within latex particles can be frozen by their conversion to polymers in a two-stage emulsion polymerization.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110120
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetics of donor-acceptor complex polymerization. IV. Limiting yield in the butadiene-acrylonitrile copolymerization (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 275-278 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analysis of the kinetic equation proposed for donor-acceptor systems indicated that the polymer yield at a given time should attain limiting value with increase in rate of initiation. It was essential that the equilibria not be shifted by temperature variation, and the change in rate of initiation was achieved by controlled current passage through the solution. A definite plateau in the yield of polymer was obtained. This was shown not to be due to diffusion control of the rate of initiation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110123
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