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  • Physics  (56)
  • Life Sciences
  • STRUCTURAL MECHANICS
  • Wiley-Blackwell  (56)
  • 1970-1974  (56)
  • 1960-1964
  • 1970  (56)
  • 1
    Electronic Resource
    Electronic Resource
    Crystallization kinetics of dilute polyethylene solutions (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 869-882 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallization kinetics of a high molecular weight fraction of linear polyethylene was studied in dilute solutions of p-xylene, n-hexadecane, and decalin by dilatometric methods. For all solvents and temperatures, the experimental isotherms could be quantitatively described by the Avrami formulation for the complete transformation. This result is unique in the realm of polymer crystallization, since marked deviations from this theory are usually observed in more concentrated systems. The Avrami exponent is found to be n = 4 in all cases. The temperature coefficients of the rate constants are indicative of a nucleation controlled process. The data fit either a two-dimensional or three-dimensional nucleation mode, and a discrimination can not be made between these two cases. The interfacial free energies are found to be independent of the solvent medium. It is also shown that, irrespective of the type of nucleation control governing the kinetics, the same type governs the crystallite thickness of the lamella-like crystals that are formed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080604
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  • 2
    Electronic Resource
    Electronic Resource
    Uses of electron paramagnetic resonance in studying fracture (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 8 (1970), S. 237-252 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The uses of electron paramagnetic resonance (EPR) in studying aspects of polymer fracture are discussed. The sensitivity of EPR is such that all phases of fracture are not amenable to investigation by these means. This paper attempts to define those areas where the authors' experience would indicate that success might or might not be expected. A discussion of the difference between the tensile fracture of drawn polymer fibers, in which strong signals are obtained, and cast and molded materials is given.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.150080122
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  • 3
    Electronic Resource
    Electronic Resource
    Diffusion of radioactively tagged 1,1-diphenylethane and n-hexadecane through rubbery polymers: Dependence on temperature and dilution with solvent (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 991-998 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The diffusion of 1,1-diphenylethane in trace amounts through eight rubbery polymers has been studied by radioactive tagging of this penetrant with 14C. For several polymers, the dependence on temperature and on dilution (swelling) by untagged diphenylethane was investigated. In the diluted systems, tagged n-hexadecane was also used as a trace penetrant. The temperature and concentration dependences were interpreted rather successfully in terms of the free volume. In comparing different polymers, with a 4000-fold range of diffusion coefficients, the translatory friction coefficient of 1,1-diphenylethane was found to be proportional to that of n-hexadecane to the power 1.06. This is interpreted qualitatively by the free volume concept to indicate a slightly less efficient mobility mechanism for the diphenylethane.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080613
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular weight distribution for diactive polymers formed by instantaneous initiation, transfer to monomer, and no termination (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1235-1237 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080717
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  • 5
    Electronic Resource
    Electronic Resource
    Liquid-liquid phase separation in multicomponent polymer solutions. IX. Concentration-dependent pair interaction parameter from critical miscibility data on the system polystyrene-cyclohexane (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1261-1278 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Critical miscibility data obtained from measurements of phase-volume ratios have been used to calculate the concentration dependence of the pair interaction parameter for the system polystyrene-cyclohexane. The measured temperature and concentration ranges are 11-30°C and 4-18% polymer by weight, respectively. With the Gibbs free energy of mixing expressed in polymer segment mole fractions, x*, the pair interaction parameter is g(x*, T) = 0.4961 + 71.92/T + 0.2312x* + 0.0750x*2. In a polymer volume fraction formulation the parameter is g(ϕ, T) = 0.4099 + 90.65/T + 0.2064 ϕ + 0.0518 ϕ2, which approximates to χ(ϕ, T) = 0.2035 + 90.65/T + 0.3092 ϕ + 0.1554 ϕ2. Comparison of the temperature and concentration dependence with that obtained by other authors shows very good agreement, even when extensive extrapolations in temperature and concentration are applied. The present function is believed to be the most accurate. Solutions of mixtures of two narrow-distribution polystyrenes in cyclohexane show separation into three liquid phases under the exact conditions predicted by theoretical calculation with the present pair-interaction function.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080802
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of molecular structure on polyethylene melt rheology. II. Shear-dependent viscosity (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 127-141 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The investigation of the effect of molecular structural variables on the melt viscosity of polyethylene was extended to the shear dependent region by application of a reduced variables treatment following, in a formal sense, that of Bueche. Viscosity-shear rate data were obtained for a series of experimentally polymerized linear polyethylene samples having a range of molecular weights and molecular weight distributions as characterized primarily by gel permeation chromatography. These data could be superimposed on a single reduced variables flow curve using parameters which were a function only of temperature, limiting Newtonian viscosity, M̄w, and M̄w/M̄n. The same treatment was successfully applied also to branched (low-density) fraction data discussed in a previous paper, with additional correction for long-chain branching. However, different reduced variables curves were obtained for the branched and linear cases.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080110
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  • 7
    Electronic Resource
    Electronic Resource
    Polymerization of monolayers. V. Tacticity of the insertion poly(methyl methacrylate)Paper presented at the I.U.P.A.C. Macromolecular Symposium in Budapest, August 1969. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1599-1615 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Insertion poly(methyl methacrylate) (PMMA) formed within a monolayer of monomer adsorbed on montmorillonite was studied by means of NMR spectroscopy and shown to be composed of short stereosequences with a predominant isotactic component. The stereospecificity of the insertion PMMA can be understood in terms of the organization of the monomer adsorbed on the surface of the mineral. The monolayer of monomer is assumed to be composed of monads and isotactic diads due to dipole-ion interactions between the molecules of methyl methacrylate and exchangeable cations. Results of experiments relating factors such as temperature, density of ion population of the surface, and the nature of ions are discussed. It is shown that the populations of isotactic and syndiotactic triads Pi and Ps determined experimentally in the insertion PMMA are in a reasonable agreement with values calculated from the model. It is shown, furthermore, that Pi increases with increase in the density of the ion population, in agreement with the equations derived from the model.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080913
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal history and melting behavior of poly(ethylene terephthalate) (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2141-2151 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low molecular weight poly(ethylene terephthalate) samples were crystallized isothermally at 120-245°C from both the amorphous state and the melt. Isothermal annealing of these polymers at 215°C provided polymers which exhibited multiple melting peaks in thermal analysis, referred to as form I and form II, as assigned by Bell and Dumbleton. In these samples the peak temperature of the form II melting endotherm and the average crystallite size are dependent on the temperature of initial crystallization. This result requires a mechanism for retaining some structural feature during the conversion from morphological form I to form II. DSC thermograms obtained at varying heating rates on samples showing only form II endotherms support the assignment of superheating as the cause of the shift to higher peak temperatures with increasing heating rate.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160081210
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  • 9
    Electronic Resource
    Electronic Resource
    Melting behavior of linear polyethylene crystallized by solution stirring (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 225-242 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Calorimetric and dilatometric studies have been made of the fusion process of linear polyethylene crystals precipitated by high speed stirring from solution. It is shown that long-time annealing at elevated temperatures alleviates the superheating observed when rapid heating rates are employed. By the annealing procedures that have been adopted, a small but demonstrable fraction of high melting material can be produced whose melting temperature depends on the crystallization temperature. For crystallization at 105°C, followed by annealing at 142°C, a melting temperature of 146.0 ± 0.5°C is observed. The dissolution temperature in xylene, determined for the same sample, is consistent with the high melting temperature observed for the pure polymer. It is recognized that a state of high axial orientation need not necessarily be identified with extended chain crystals. Consequently, the increased melting temperature can result from either an increase in the crystallite size or a reduced interfacial free energy relative to crystallites produced by the more conventional mode of crystallization.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080204
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of the width of a narrow molecular weight distribution by gel-permeation chromatography (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 411-415 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A recycle gel-permeation chromatography (GPC) method for extrapolating to infinite resolution is proposed. From the GPC calibration curve, the extrapolated elution peak width volume can be converted into peak width in decades of molecular weight. For an essentially Gaussian distribution, the weight-average/number-average molecular weight ratio can be determined from a calculated conversion table.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080307
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