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  • Polymer and Materials Science  (24)
  • monomeric friction coefficient (ε)  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Dielectric relaxations in the liquid and glassy states of 47% polypropylene oxide in toluene as diluent (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 2049-2057 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular relaxations in 47-wt % polypropylene oxide of molecular weight 4000 in toluene as diluent have been studied by dielectric permittivity and loss measurements from 77 to 320 K, in the frequency range 1 Hz to 2 × 105 Hz. One relaxation process (β process) is observed in the glassy state below Tg (= 148 K), and two processes are observed in the supercooled liquid at T 〉 Tg. Relative to the amplitude of the fast relaxation process (i.e., the local segmental motions of the polymer chain), the amplitude of the slow process is increased and that of the β process decreased on dilution of the pure polymer. The β process has an Arrhenius energy of 17 kJ mol-1. The rates of the two relaxations at T 〉 Tg follow the Vogel-Fulcher-Tamman equation and seem to merge on cooling the liquid towards Tg. The relative temperatures at which the three relaxation processes occur at the rate of 1 kHz remain largely unaffected on dilution. The increase in static permittivity of the solution on cooling is more than anticipated from the temperature effects alone. It is suggested that the increase is due to the enhanced short-range orientational correlation of the dipoles, which may involve H bonding.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090240911
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  • 2
    Electronic Resource
    Electronic Resource
    A dielectric study of secondary relaxations and the “memory effect” in two compatible polystyrene blends (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 1587-1595 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric permittivities and loss tangents of 10 and 30% poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-polystyrene (PS) blends and 10 and 25% poly(vinyl methyl ether) (PVME)-polystyrene blends have been measured from 80 to 360 K at 1 and 10 kHz. The PPO-PS blends have two secondary relaxations below Tg and the PVME-PS blends have three regions. All blends have a β process which appears near 290 K, is independent of PPO or PVME concentration, and is associated with the local modes of motions of PS chains. It is suggested that the β process of PS allows a dipolar reorientation of the PPO or PS chain segments by creating more favorable surroundings for the motions of the latter. The effect of physical aging in the PPO-PS blend is substantial but the “memory effect” is significantly less. This is due to the lower contribution to tanδ from the β process of the blend.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090240715
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  • 3
    Electronic Resource
    Electronic Resource
    Sorption and diffusion of carbon dioxide in single-phase polystyrene/poly(vinylmethylether) blends (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2723-2730 
    Details
    ISSN: 0887-6266
    Keywords: polystyrene ; poly(vinylmethylether) ; blends ; carbon dioxide ; sorption ; diffusion ; plasticization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The sorption and transport properties of CO2 in miscible PS/PVME blends at 20°C are reported as a function of pressure from 1 to 15 atm. The complex shape of isotherms for glassy blends and the concentration-dependent diffusion coefficient for rubbery blends reveal a plasticization by sorbed CO2. The significant depression in Tg has to be taken into account in the analysis of the sorption data. Diffusion coefficient for CO2 passes through a minimum when plotted against the blend composition. Such a behavior can be quantitatively related to the negative volume mixing of the PS/PVME system in the framework of the theories based on unoccupied volume. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Fourier transform infrared study of conformational changes occurring at the yield point in uniaxially drawn polymers (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 355-368 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fourier-transform infrared measurements on atactic and amorphous isotactic polystyrenes have been made during application of strain. On passing through the yield point, spectra indicate an increase of the amount of higher-energy conformation. In atactic polystyrene it corresponds to an increase of gauche conformations whatever the state may be: pure or plasticized samples, blend with another compatible polymer, or styrene-acrylonitrile copolymer. In amorphous isotactic polystyrene an increase of higher-energy trans conformation is observed. These results strongly support the theory developed by Robertson to explain plastic deformation of polymers.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1989.090270210
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of tacticity on orientation and relaxation in uniaxially stretched polymethylmethacrylates (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2007-2017 
    Details
    ISSN: 0887-6266
    Keywords: polymethylmethacrylate (PMMA) ; syndiotactic ; isotactic ; orientation ; relaxation ; infrared dichroic ratio ; entanglements ; monomeric friction coefficient (ε) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Orientation and relaxation behavior in uniaxially stretched stereoregular polymethyl-methacrylate (PMMA) was investigated. When compared at a reference temperature T = Tg + constant, isotactic PMMA orients more readily and relaxes slightly faster than the conventional or syndiotactic polymers. Orientation relaxation of the different PMMAs can be reduced to a unique master curve, whatever the tacticity, when the results are compared at same monomeric friction coefficient. © 1996 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Time-temperature superposition and dynamic mechanical behavior of atactic polystyrene (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 1235-1251 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical behavior of monodisperse atactic polystyrene (mol. wt. 98,000) has been measured in the frequency range, 10-5 to 10 Hz and temperature range 359-374K. The time-temperature superposition of the entire data in the frequency range of overlap seems less satisfactory in both the real and imaginary components of the complex shear modulus, G′ and G″, respectively. The lack of adequate superposition becomes pronounced in the tan φ (G″/G′) plots. The tan φ plots provide a more discerning criteria for the superposition than the G′ or G″ spectra.An analysis based on an earlier model for anelastic deformation shows that of the several changes that may occur in the dynamic mechanical behavior on heating of polystyrene, the predominant ones are both an increase in the size of the microshear domains and the correlations of movement of segments near entanglements. These decrease the contribution to the modulus on heating near Tg so that the time-temperature superposition is vitiated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250605
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  • 7
    Electronic Resource
    Electronic Resource
    Orientation and relaxation in uniaxially stretched styrene-co-methyl methacrylate random copolymers (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2539-2548 
    Details
    ISSN: 0887-6266
    Keywords: styrene-methyl methacrylate copolymers ; orientation ; relaxation ; FT-IR spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Orientation and relaxation behavior in uniaxially stretched styrene-co-methyl methacrylate random copolymers was investigated. When compared at a reference temperature T = Tg + constant, orientation of methyl methacrylate units (MMA) decreases while styrene units orientation increases with a decrease in the styrene percentage. This behavior can be related to intermolecular interactions between MMA units and to the stiffness of styrene-MMA units, which do not undergo conformational changes upon stretching. Both monomer units relax the same in a given copolymer and chain relaxation increases when the styrene percentage increases. Orientation relaxation of styrene and MMA units can be reduced to two general relaxation master curves whatever the blend composition, when the results are compared at same monomeric friction coefficient. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090321511
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of transport phenomena in cellulose diacetate membranes. I. Relation between dialysis coefficients and membrane morphology and hydrationPaper presented in part at the 26th International Congress I.U.P.A.C., held in Tokyo, Japan, September 4-10, 1977. (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 985-998 
    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: Transport properties were determined for various Loeb-type membranes which exhibit strong structure differences from one to another. Using linear relations of thermodynamics of irreversible processes for the homogeneous ones, correlations were found between the specific transport coefficients and the states of water in the membrane medium. In the case of heterogeneous membranes a schematic multilayer model, using in an appropriate way Darcy's law, was worked out in accordance with electron micrographs of membrane cross sections. It enables us to correlate the membrane hydraulic permeability with the relative extent of four typical structures A, B, C, and D. In addition, this model provides both the hydraulic specific permeabilities of these types of structure and their hydration characteristics.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240412
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  • 9
    Electronic Resource
    Electronic Resource
    Physicochemical processes occurring during the formation of cellulose diacetate membranes. Research of criteria for optimizing membrane performance. V. Cellulose diacetate-acetone-water-inorganic salt casting solutions (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 1883-1913 
    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: Consideration was given to the effects of casting conditions upon the performance and structure of membranes prepared from CA-acetone-water-inorganic salt solutions. Treating casting solutions as polymer-solvent-nonsolvent ternary systems, the data on equilibrium phase separation conditions were plotted in a triangular diagram for solutions containing Al(NO3)3, KSCN, Mg(ClO4)2 or no additive. Measurements of casting solution viscosity, membrane thickness, freezing and nonfreezing water contents were used to supplement flux and retention data of membranes made by varying the inorganic salt and holding time in a systematic way. With the aid of scanning and transmission electron microscopy, it was concluded that membranes may consist of one, two, three, or four layers. The data and correlations obtained allow us to propose a mechanism of formation for each of these layers.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070250908
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamics of macromolecular chains. V. Interpretation of the dielectric relaxation data (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1-9 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The autocorrelation function of orientations, derived for the model of conformational jumps in a chain described in a tetrahedral lattice, has been tentatively applied to dielectric relaxation data. The complex dielectric relaxation of polymers can be interpreted by the aid of only two relaxation processes. In the case of poly(p-chlorostyrene) in solution, the characteristic times that we have calculated agree favorably with the fluorescence-depolarization results. The model has been shown to be consistent with the empirical decay function exp[- (t/τ)β] proposed by Williams.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.180150101
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