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  • 1
    Electronic Resource
    Electronic Resource
    Intrinsic viscosity of polydisperse branched polymers (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 431-454 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relationships between molecular weight distribution and structure in polymerizations with long-chain branching were reviewed and extended. Results were applied to an experimental examination of intrinsic viscosity in polydisperse, trifunctionally branched systems. Several samples of poly(vinyl acetate) were prepared by bulk polymerization under conditions of very low radical concentration. The relative rate constants for monomer transfer, polymer transfer, and terminal double-bond polymerization were established from the variation of Mn and Mw with the extent of conversion. Average branching densities were then calculated for each sample and ranged as high as 1.5 branch points/molecule. Intrinsic viscosities [η]B were measured in three systems: a theta-solvent, a good solvent, and one that was intermediate in solvent interaction. These results were compared with calculated viscosities, [η]L, which would have been observed if all the molecules had been linear. The values of [η]B/[η]L were substantially the same in all three solvents. The variation of this ratio with branching density was compared with the theory of Zimm and Kilb as adapted to polydisperse systems. Discrepancies were noted, and the adequacy of present model distribution functions for branched polymers was questioned.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.160050304
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  • 2
    Electronic Resource
    Electronic Resource
    The viscoelastic behavior of isotactic polypropylene fibers (1962)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 6 (1962), S. 269-277 
    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: The stress-strain properties of isotactic polypropylene yarn have been studied over a wide range of strain rates up to 2,000,000% per minute. The testing equipment used included the Instron, three pneumatic and pneumatichydraulic type of high speed testers, the falling weight method, the rotating disc longitudinal impact and ballistic techniques. Evaluation of the behavior of polypropylene at strains of 2, 6, 12, and 16% shows the existence of two relaxation peaks, one at τ = 10-2 sec. and the other at about 102 sec. with a plateau of little time dependency in between. The data, especially at the shorter testing times, can be well represented by a single mechanical model composed of two Maxwell units in parallel. Information concerning the ultimate properties of isotactic polypropylene yarn was also obtained. The work-to-rupture values for polypropylene at most strain rates exceed those characteristic of any other available textile material.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1962.070062104
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  • 3
    Electronic Resource
    Electronic Resource
    Behavior of high strength parachute components at impact velocities up to 700 feet per second (1962)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 6 (1962), S. 338-351 
    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: A machine has been designed and constructed which is capable of evaluating high strength parachute components in the laboratory at impact speeds ranging from 200-750 ft./sec. The system consists mainly of a device for propelling various masses with photographic instrumentation for observing the impact. Measurement of missile deceleration gives applied force. Extension is measured for changes in gage marh on the test specimen. Energy absorbed can be calculated from the displacement of two ballistic pendulums. Results reveal that a t impact speeds force and strain waves are generated within the material which cause rapid changes in the forces measured. A theory has been proposed to explain this behavior. Energy measurements indicate a potential change in the stress-strain curve of nylon webbings and joints during impact. Improvements in energy absorption result.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1962.070062112
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  • 4
    Electronic Resource
    Electronic Resource
    The viscoelastic behavior of oriented polyvinyl alcohol fibers at large strains (1961)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 54 (1961), S. 53-63 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscoelastic spectra of oriented polyvinyl alcohol fibers have been determined at large strains (2, 5, and 8%). Stress relaxation data were obtained from constant strain rate experiments conducted at testing speeds from 20 to 2,000,000 %/min. and have been used to calculate viscoelastic parameters, E, E0 and tan δ. The heights of the relaxation spectra were found to increase with increasing rate of test, up to the maximum strain rates possible before critical velocity failure occurs.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1961.1205415905
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  • 5
    Electronic Resource
    Electronic Resource
    Infinite-dilution viscoelastic properties of fibrinogen and intermediate fibrin polymerThis investigation was part of the research program of the Rheology Research Center, University of Wisconsin. (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1957-1969 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The storage and loss shear moduli, G′ and G″, have been measured for dilute solutions of bovine fibrinogen in 68% aqueous glycerol and of intermediate fibrin polymer in 6M hexamethylene glycol, by the Birnboim-Schrag multiple-lumped resonator apparatus with titanium alloy resonators. The frequency range was 100-5800 Hz, the concentration range 1-6 g/l., and the temperatures 10.0 and 25.0°C. The shear moduli G′ and G″ at finite concentration, and the extrapolated instrinsic shear moduli [G′] and [G″], as functions of frequency, were compared with the predictions of various molecular theories. For fibrinogen, the frequency dependence agreed quite well with the calculations of Hassager for a trinodular rod as modified for the presence of small amounts of dimeric and trimeric aggregates which were deduced from parallel measurements of oscillatory flow birefringence. It was not possible, however, to distinguish between a linearly rigid configuration and one which is freely jointed at the central nodule. A model of a soft elastic sphere (simulating the cage model of Köppel) appeared to be very unlikely. The relaxation time for a rigid trinodular rod and the longest relaxation time for a jointed trinodular rod, calculated from molecular dimensions on the basis of electron microscope measurements, are somewhat smaller than the corresponding observed values; the discrepancy suggests that the molecule is swollen in solution. For the intermediate polymer (which was formed under conditions where ligation is expected), the frequency dependence agreed quite well with that predicted either for a prolate ellipsoid (Cerf-Scheraga-Saitō) or for a cylindrical rod (Yamakawa). The relaxation time obtained by fitting to theory agrees quite well with that calculated for a cylindrical rod with molecular dimensions based on a degree of polymerization of 20 and lateral binary association with staggered overlapping.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160910
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  • 6
    Electronic Resource
    Electronic Resource
    Flexibility of collagen determined from dilute solution viscoelastic measurements (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1747-1758 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The frequency dependences of the storage and loss shear moduli, G′ and G″, of pronase-treated collagen dissolved in acetate buffer at pH 4.0 were measured at 17.0°C by use of the Birnboim-Schrag multiple lumped resonator apparatus. Some of the solutions contained 70% glycerol. The infinite-dilution moduli were determined and compared with theoretical models for a rigid cylinder and a semiflexible rod. Only the latter could fit the data. A rotational time of 144 μs and a slowest flexural relaxation time of 21 μs, both reduced to water at 20°C, were determined from the fit. The intrinsic viscosity and rotational relaxation time correspond to a semiflexible rod with persistence length of about 170 nm and a Young's modulus of 4 × 1010 dyn/cm2.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220710
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