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  • 11
    Electronic Resource
    Electronic Resource
    Frequency dependence of intrinsic viscosity of macromolecules with finite internal viscosity (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 179-193 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to explain the observed nonvanishing limiting value of dynamic intrinsic viscosity of polymer solutions at ω = ∞ one has considered the necklace model with finite resistance to the rate of coil deformation introduced long ago by Cerf for the study of gradient dependence of intrinsic viscosity and streaming birefringence. The calculation need not take into account change of hydrodynamic interaction as a consequence of coil deformation because the experimental data are always either obtained at very low gradient or extrapolated to zero gradient so that in the experiment the macromolecule has the same conformation as in the solution at rest. The model indeed yields a finite [η]′ω = ∞ in good agreement with experiments on polystyrene in Aroclor. According to the theory [η]′ω = ∞/[η]0 decreases with increasing molecular weight as M-1 and M-1/2 for the free-draining and impermeable coil, respectively. The absolute limiting value [η]∞′, therefore turns out to be nearly independent of M, at least for small values of internal viscosity. From the observed value [η]∞′/[η0] one can obtain the coefficient of internal viscosity of the macromolecule. The value for polystyrene in Aroclor calculated from dynamic experiments on rather concentrated solutions is close to that derived by Cerf from streaming birefringence observations of polystyrene in a series of solvents of widely differing viscosity.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.160050115
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  • 12
    Electronic Resource
    Electronic Resource
    NMR study of molecular motion in oriented long-chain alkanes. III. Oriented n-C32H66Presented at the Meeting of the American Physical Society, Philadelphia, Pa., March 1969. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 791-797 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The NMR second moment of a uniaxially oriented mat of single crystals of n-C32H66 (in the orthorhombic form) was measured at temperatures from -170°C to 70°C and at various alignment angles γ between the orientation axis (preferential direction of the molecular chains) and the NMR magnetic field. Accurate expressions are given for the NMR second moment of an orthorhombic normal paraffin CnH2n+2 of arbitrary molecular chain length n for n ≥ 10, in the following states of molecular motion: no motion (a rigid lattice), rotation of CH3 groups, and rotation of the chains around their axes with superimposed rotation of CH3 groups. In addition to these well-known motions, n-C32H66 is found to exhibit an α process. The corresponding decrease of the NMR second moment shows the dependence on γ predicted for “flip-flop” motion, i.e., rotational jumps of the chain molecules around their axes through 180° and a simultaneous translation along these axes by one CH2 group. The overall decrease in second moment occuring at the transition to the hexagonal rotator phase in n-C32H66 can be quantitatively accounted for. The dependence of this decrease on the alignment angle γ, however, is in disagreement with calculations based on a simple rotation of the chains around their axes. Considerable torsion of the chains superimposed on the rotation would improve agreement between theory and experiment.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080511
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  • 13
    Electronic Resource
    Electronic Resource
    Plastic deformation of polyethylene. I. Change of morphology during drawing of polyethylene of high density (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1723-1740 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The transformation of microspherulitic quenched and annealed polyethylene film into highly oriented drawn material with the characteristic fiber structure was investigated by small-angle and wide-angle x-ray measurements and by a study of the thermograms after the fuming nitric acid treatment. With the details of deformation depending slightly on the crystallinity, one observes generally a preferential tilt of the platelets against draw direction at draw ratios below 2. At least in annealed material, an increasing tilt of the molecule within the lamella is also observed, which leads at higher draw ratios to slipping of blocks in the crystallites. With further drawing a new fiber structure appears, which is practically independent of the thermal history of the original film. This fact is established by investigation of the crystal thickness by three different methods; investigations of small-angle scattering, study of the width of the (002) reflection, and investigation of the debris after treatment with fuming nitric acid.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160081009
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  • 14
    Electronic Resource
    Electronic Resource
    NMR observations of drawn polymers. VII. Nylon 66 fibersPresented in part at the Meeting of the American Physical Society, Dallas, Texas, March 1970. (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 1449-1469 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Wide-line NMR spectra have been obtained on an oriented sample of drawn nylon 66 fibers at temperatures between -196°C and 200°C and at alignment angles between the fiber axis and the magnetic field of 0°, 45°, and 90°. At -196°C, 20°C, and 180°C, the complete angle dependence of the NMR spectrum has been measured. The second moments of these spectra have been compared to theoretical second moments calculated for various models of chain segmental motion in an attempt to elucidate the mechanisms involved in the low-temperature segmental motion (γ process) and the high-temperature segmental motion (αc process). In agreement with earlier suggestions, the present results indicate that the γ process consists of segmental motion in noncrystalline regions. The overall decrease in second moment caused by the γ process is consistent with a model in which all noncrystalline segments rotate around axes nearly fixed in space. Furthermore, this decrease shows a pronounced dependence on the alignment angle. It is believed that this is due to tie molecules which become highly oriented along the fiber axis during drawing; their axes of rotation will therefore be nearly parallel to the fiber axis. The segments in noncrystalline entities such as chain folds and chain ends are less well oriented along the fiber axis and make an essentially isotropic contribution to the second moment decrease. The second moment at 180°C indicates the presence of considerable motion in the crystalline regions, and this motion is denoted the αc process. The second moment Sc of the crystalline regions is strongly dependent on the alignment angle, the predominant feature being a relatively high value of the second moment when the fiber axis is directed parallel to the magnetic field. This is in qualitative, but not quantitative, agreement with the motional model recently advanced by McMahon, which assumes full rotation of the chains around their axes. Excellent quantitative agreement with experiment has been obtained by superimposition of rotational oscillation around the chain axis of amplitude roughtly 50°, and torsion of the chains with neighboring CH2 groups oscillating around the C—C bond with a relative amplitude of about 40°. A model in which the chains perform rotational jumps of 60° between two equilibrium sites has also been considered (60° flip-flop motion). A distinction between this model and rotational oscillation has not been possible.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.160090806
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  • 15
    Electronic Resource
    Electronic Resource
    NMR observations of drawn polymers. IX. Chain mobilization and water mobility in nylon 66 (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 2033-2042 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Wide-line NMR spectra of nylon 66 fibers have been obtained at different alignment angles between the fiber axis and the magnetic field, at varying water contents (H2O and D2O), and at different temperatures. At 28°C the spectrum of the dry fibers consists of a nearly structureless broad line. At water regains of 1.4% by weight (dry basis) and higher a sharp line appears which originates from highly mobile water molecules. The width of this line decreases with increasing water content, implying an increase of water mobility. Moreover, the width is a function of the alignment angle; this shows that the water is not reorienting isotropically owing to specific water-polymer interaction. The amount of mobile water is always smaller than the amount of water absorbed. At water contents close to saturation, a mobile polymer line appears with a width intermediate between the broad line (immobile polymer) and the sharp water line. This line, most clearly observed at an alignment angle of 0°, is due to a shift of the αa process to lower temperatures in the presence of water. A similar line is observed in the dry fibers at 120°C. It is shown that the αa process decreases the NMR second moment only slightly. The shift of the high temperature drop in second moment to lower temperatures in the presence of water is therefore interpreted as due to a shift of the αc process, and not of the αa process, to lower temperatures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.160091108
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  • 16
    Electronic Resource
    Electronic Resource
    Crystallite size in drawn and then annealed polypropylene (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 1221-1236 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystallite sizes have been obtained from the breadth of equatorial x-ray reflections from polypropylene samples subjected to a draw ratio of 6 at 21°C and then annealed at 155°C, 140°C, and 120°C, respectively. For all samples it was found that the ratio of the dimension of the crystallite perpendicular to the {110} planes to that perpendicular to the (040) plane is a constant. The ratio of the lateral crystallite size to the meridional long period was also found to be constant, independent of annealing temperature. In contrast, the thickness of the crystallites in the direction parallel to the draw direction, as calculated from the meridonal long period and density data, was not proportional to the lateral crystallite size.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100704
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  • 17
    Electronic Resource
    Electronic Resource
    Plastic deformation of polypropylene. IV. Wide-angle x-ray scattering in the neck region (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 1237-1254 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Wide-angle x-ray scattering (WAXS) patterns of two polypropylene samples, a quenched sample drawn at 21°C and an annealed sample drawn at 100°C, were investigated in a range of values of draw ratio λ very closely spaced through the neck region. In both cases, a range of small λ where deformation occurred by spherulite deformation was followed by one of higher λ where microfibrils were formed. The contribution to the WAXS pattern of microfibrils could be clearly distinguished from that of deformed spherulites because of the better orientation parallel to the draw direction of the former as compared to the latter. Additionally, for a drawing temperature of 21°C, microfibrils crystallize in the “smectic” phase as compared to the monoclinic phase for the initial sample and deformed spherulites. At this temperature, plastic deformation proceeds through the spherulite deformation mechanism up to λ = 1.4 accompanied by an increase in chain orientation with increasing λ. For λ 〉 1.4 plastic deformation appears to occur exclusively through microfibril formation. For drawing at 100°C, spherulite deformation is accompanied by very little change in chain orientation up to λ = 2, where microfibril formation begins. For λ 〉 2 (Td = 100°C) plastic deformation is accompanied by both microfibril formation and some spherulite deformation as reflected by changes in both orientation and crystallite size. At this temperature the lateral crystallite size in the microfibrils is related to the long period according to the “equilibrium crystallite shape” previously found for annealed polypropylene.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100705
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  • 18
    Electronic Resource
    Electronic Resource
    Diffusive and hydraulic permeabilities of water in water-swollen polymer membranes (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 1117-1131 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The diffusive permeability of water P, which relates to diffusive flux of water under a concentration gradient of water (measured by diffusion of tritiated water), and the hydraulic permeability of water K, which relates to the water flux under a hydraulic pressure gradient are defined. For the case of diffusive transport one has P = KRT/ν1, where ν1 is the molar volume of water. The relationship between P and K was investigated as a function of hydration H, i.e., the volume fraction of water in swollen polymer membranes. The following characteristic features of water permeability are revealed. (a) In the lowhydration region (H 〈 0.2), water permeates by diffusion even under an applied hydraulic pressure gradient and KRT/ν1 = P. (b) In the higher hydration region KRT/ν1 is greater than P, and the ratio ω = KRT/ν1P increases nearly exponentially with decrease of (1-H)/H. Water in this region moves partly by bulk flow under an applied hydraulic pressure gradient but moves only by diffusion in the absence of a pressure gradient. (c) The dependence of log P on (1-H)/H is nearly linear in regions of both high and low hydration but the slopes are different. The transition occurs in about the same H range where the discrepancy between P and KRT/ν1 becomes significant. Excellent agreement was found between the experimental data for P as a function of H and the theoretical prediction based on the free-volume concept of diffusive transport in hydrated homogeneous membranes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.160090608
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  • 19
    Electronic Resource
    Electronic Resource
    Infrared studies of drawn polyethylene. II. Orientation behavior of highly drawn linear and ethyl-branched polyethylene (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 1191-1217 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Infrared dichroism is employed to study the orientation of chain molecules in linear and ethyl-branched polyethylene in the crystalline and noncrystalline regions during drawing and subsequent annealing. A crystalline (1894 cm-1) and a noncrystalline (1368 cm-1) band, as well as the bands at 909 cm-1 and 1375 cm-1 resulting from vinyl endgroups and methyl endgroups and sidegroups, are studied. For these bands relative orientation functions are derived and compared as a function of draw ratio and annealing temperature. It is shown that the relative orientation functions as derived from the dichroism of the noncrystalline, vinyl and methyl bands follow the same curve while the orientation function for the crystalline bands does not. These results support a two-phase model for partially crystalline polyethylene and additionally favor segregation of the endgroups and sidegroups in the noncrystalline component during crystallization. It is further shown that shrinkage occurs at the temperature at which the noncrystalline chain molecules start to disorient. From the dichroism of the methyl groups in ethyl-branched polyethylene, a value for the mean orientation of the noncrystalline chain molecules is calculated. We obtain for the orientation function of the noncrystalline regions at highest draw ratios (λ = 15-20), f = 0.35-0.57, while the chain molecules in the crystallites are nearly perfectly oriented (f ≈ 1.0). On the assumption that the noncrystalline component consists of folds, tie molecules, and chain ends, the different contributions of these components to the overall orientation are estimated. From these the relative number of CH2 groups incorporated into folds, tie molecules, and cilia can be derived. Further, on the basis of a simple structural model, the relative number of chains on the crystal surface contributing to the different noncrystalline components and their average length are estimated.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.160090703
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  • 20
    Electronic Resource
    Electronic Resource
    NMR study of molecular motion in oriented long-chain alkanes. I. Theoretical partPresented at the Meeting of the American Physical Society, Berkeley, California, March 1968. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 753-770 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several molecular mechanisms, proposed in the literature for the low- and high-temperature relaxation processes in linear polyethylene and commonly referred to as γ and α processes, are examined, and their effect on the second moment of the broad line NMR absorption is predicted quantitatively. The following models for the α process are discussed: rotational oscillation of the long chain molecules around their axes, general two-site models where the chain performs thermally activated rotational jumps through an angle τ between two equilibrium positions, a particular two-site model (τ = 180°) denoted as flip-flop motion, and the kink model. For the γ process, the following molecular mechanism are considered: the kink model, a vacancy with a chain end, the crankshaft mechanism. The decrease of the second moment caused by these motions is considered. Characteristic differences between the motional models are predicted with respect to the anisotropy of the decrease in second moment in a uniaxially oriented sample and/or the magnitude of the overall decrease. These differences allow an experimental distinction between the different models.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080509
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