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  • Polymer and Materials Science  (18)
  • ASTROPHYSICS  (17)
  • Chemical Engineering  (8)
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  • 1
    Electronic Resource
    Electronic Resource
    The influence of molecular weight on the large deformation behavior of SBS triblock copolymer elastomers (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 629-643 
    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: Engineering stress-strain properties were determined for two polystyrene-polybutadiene-polystyrene (SBS) triblock copolymer elastomers, one consisting of blocks of molecular weight 7000/43000/7000 and the other, 16000/85000/17000. In addition, various blends of these two materials were prepared in order to vary the number-average molecular weight of the blocks in a systematic way while maintaining polystyrene content in the range of 25-28 wt %. Samples were solvent cast from benzene or benzene/heptane mixtures and annealed before testing. Ring specimens were extended to rupture at varying strain rates on an Instron tensile tester. Results indicate that number-average molecular weight has a marked influence on stress-strain behavior over the range of molecular weights and testing conditions employed. The observed behavior is consistent with a systematic increase in the proportion of a mixed interfacial region between the pure polystyrene and polybutadiene domain as molecular weight decreases. The interfacial region contributes to mechanical hystersis, rate sensitivity, and toughness in the SBS materials. Scanning electron photomicrographs of fracture surfaces also showed systematic changes with molecular weight.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210305
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  • 2
    Electronic Resource
    Electronic Resource
    Block copolymers of isotactic polypropylene and 1,4-polybutadiene (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 2457-2466 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two block copolymers of isotactic polypropylene and 1,4 polybutadiene were synthesized using techniques involving a transformation from anionic to Ziegler-Natta polymerization mechanisms. The yield of block copolymer was about fifteen percent (weight basis) in both polymerizations, the remainder being unreacted polybutadiene from the first block synthesis. Molecular characterization experiments and model reactions were consistent with a block-like structure for the copolymers; definitive evidence for the proposed molecular structure was obtained through transmission electron microscopy which clearly revealed microphase-separated morphologies characteristic of block copolymers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080241008
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetic modelling and optimization of the trifluoropropylmethylsiloxane polymerization (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 1241-1258 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Use of promoter dimethylsulfoxide (DMSO) in conjunction with initiator normal butyllithium has resulted in rapid and controllable ring-opening polymerization of 1,3,5-tris-(3′,3′,3′-trifluoro-propyl)1,3,5-trimethylcyclotrisiloxane at 40°C; monomer consumption rate can be varied by at least four orders of magnitude depending on the ratio of promoter-to-initiator concentrations. Compared to the sodium counterion also studied here, the lithium initiator slows the backbiting alkyl-reactions which cause degradation of polymer to cyclics containing four or more fluoroal-kylsiloxy units. This previously uninvestigated polymerization methodology offers greater opportunity for capturing high, nonequilibrium polymer yield of this fluoroalkylsiloxane through appropriately timed termination of the reaction. To facilitate this optimization, a kinetic model of the polymerization was developed by solving the isothermal, constant density rate expressions for a two-step, series mechanism. The solution to the coupled system of nonhomogeneous ordinary differential equations is obtained by matrix variation of parameters. The rate constants were determined by appropriate kinetic analysis of the experimental data obtained for polymer and cyclics concentrations as a function of time under various conditions. This results in a quantitative model capable of predicting optimum polymerization time to maximize the yield of poly(3,3,3-trifluoropropylmethylsiloxane) at ca. 85-90%.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270411
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of interaction energy on floc structure (1987)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 33 (1987), S. 1571-1575 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690330920
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  • 5
    Electronic Resource
    Electronic Resource
    Theory and practice of the analytical centrifugation of an active substrate-enzyme complex (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 203-225 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The active enzyme centrifugal-ion (AEC) method presented here permits the hydrodynamic study of active enzyme-substrate(s) complexes in solutions containing micro-gram amounts of the studied enzyme, even if the enzyme preparation is very impure. The AEC method can he used only when the specific enzymatie reaction can be measured directly in a spectrophotometer. The general equations relevant to the method and their solutions are presented in detail. Their use requires some numerical calculations. A practical summary of the AEC method is given, and the precision of the measured values of the sedimentation and diffusion coefficients is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050208
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  • 6
    Electronic Resource
    Electronic Resource
    Gas transport in polybutadiene treated with aqueous bromine (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 403-408 
    Details
    ISSN: 0887-6266
    Keywords: gas permeability ; selectivity ; barrier membranes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Diffusion, solubility, and permebility coefficients were measured for He, Co2, Ar, and CH4 in polybutadiene (PB) and in polybutadiene reacted in the solid state to various extents with aqueous bromine. Analysis of the sorption curves and X-ray emission spectra showed that the bromination created a heterogeneous membrane with an outer brominated skin and an unreacted core. At relatively low extent of bromination, the diffusion and permeability coefficients for CO2, Ar, and CH4 decreased by two orders of magnitude, while the transport coefficients for He were virtually unchanged. The permeability coefficients for CO2, Ar, and CH4 became immeasurably small after about 3% bromination. The ideal separation factor for gas pairs with different molecular size increased with bromination, suggesting applications in gas separation processes. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090310404
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  • 7
    Electronic Resource
    Electronic Resource
    The influence of diblock copolymers on the structure and properties of polybutadiene-polyisoprene blends (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 639-646 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 structure and properties of a ternary polymer system comprised of 1, 4 polybutadiene, cis 1, 4 polyisoprene, and the corresponding 1, 4 polybutadiene/cis 1, 4 polyisoprene diblock copolymer have been investigated. Dynamic mechanical properties were measured as a function of frequency (3.5 to 110 Hz) and temperature (-135 to 40°C). Thermomechanical analysis and transmission electron microscopy provided additional information on the, phase relationships in the various specimens. The blends studied covered the entire triangular composition diagram; both slow solvent evaporation and rapid spin casting techniques were employed in the sample preparation. Results indicate that the BI diblock is a single phase material whereas binary blends of the two homopolymers are two-phase in nature. Ternary blends of the two homopolymers with diblock and binary blends of a single homopolymer with diblock can be one or two phase materials depending on the sample composition and the ratio of B to I units in the diblock. All evidence From the dynamic, thermomechanical and microscopic experiments is used to elucidate the influence of the diblock in these polymer blends.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170823
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis, characterization, and viscoelastic behavior of single-phase interpenetrating polystyrene networks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 284-293 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Single phase interpenetrating polystyrene networks were synthesized using a room temperature photopolymerization method. Divinylbenzene was used for crosslinking both networks in most cases; a few IPNs were prepared using acrylic acid anhydride to provide labile crosslinkages in the primary network. The IPNs were characterized by means of equilibrium swelling in toluene. The results of these experiments closely approached the predictions of a swelling equation derived under the assumption that the two networks were elastically independent. Deviations from the swelling equation predictions could be explained in terms of contributions from internetwork entanglements. Small amplitude dynamic mechanical measurements indicated that the presence of the small amount (∼10 percent) of tight primary network chains had no perceptible effect on the linear viscoelastic properties.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190410
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  • 9
    Electronic Resource
    Electronic Resource
    Time and strain dependent thermal expansion of carbon-black filled SBR elastomers (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 668-673 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Length-temperature measurements were made on unfilled and carbon-black filled vulcanizates of styrene-butadiene rubber. As in earlier experiments on polybutadiene, transients in thermal expansion behavior were observed following abrupt changes in the temperature. The nature of this time dependence was not dramatically affected by either the level of equilibrium strain or the structure and loading of the carbon-black filler. Both the magnitude of the linear coefficient of thermal expansion and the point of thermoelastic inversion were sensitive to the presence of carbon-black. A model based on considerations of occluded rubber and strain amplification in the free rubbery matrix was used successfully to rationalize the observed behavior of the filled compounds.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180811
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of morphology on stress relaxation of polypropylene (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 883-887 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Samples of isotactic polypropylene having different morphologies and crystallinities were prepared and subjected to stress-relaxation experiments at different levels of strain. The relaxation moduli were determined in the range of temperature between - 20 and 40°C over a period of time from 1 to 1000 seconds. Using the time-temperature superposition principle, the activation energy values of the shift factors aT were determined and the master curves were obtained for the various structures. Increasing crystallinity and/or crystalline aggregate size increases the relaxation modulus of the material and changes both shape and location of the spectrum of relaxation times so that no simple method can be found to correlate the various master curves.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231605
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