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  • 1
    Electronic Resource
    Electronic Resource
    Remarks on the "fast" and "slow" mode theories of interdiffusion (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 6680-6683 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00123a040
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  • 2
    Electronic Resource
    Electronic Resource
    Interdiffusion in dilute polymer mixtures. A subtle concentration effect (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 3222-3229 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dynamic light scattering has been used to investigate the diffusional dynamics in very dilute polystyrene/poly(propylene oxide), PS/PPO, polymer blends. Compared to previous investigations in the field, this system is more suitable for this type of investigation due to the significant refractive index difference between the two components and the fact that the matrix (PPO) dynamics do not interfere with the measurements. The tracer diffusion coefficient of PS thus obtained in the limit of infinite dilution scales as N−0.8±0.04PS with the PS degree of polymerization, i.e., behavior intermediate between the limits of nondraining Zimm and free-draining Rouse behavior. The effect of the addition of a third component even at tracer concentrations on the diffusion dynamics was investigated both experimentally and theoretically in the framework of the dynamic random phase approximation. Similarities and differences between theory and experiment were found that are rather due to a modification of hydrodynamic interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467568
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  • 3
    Electronic Resource
    Electronic Resource
    Addendum to the paper "On the dynamics of polyelectrolyte solutions'' (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 1712-1713 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Hydrodynamic effect on the relaxation modes for a system of charged particles is reexamined. This effect is shown to produce a decrease in the diffusion coefficient due to the cloud of particles surrounding each charge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451171
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  • 4
    Electronic Resource
    Electronic Resource
    Hypersonic velocity in binary polymer mixtures: Poly(dimethylsiloxane)–poly(ethylmethylsiloxane) (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 6866-6869 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The first Brillouin experiment on the blend poly(dimethylsiloxane)–poly(ethylmethylsiloxane) with critical concentration cursive-phiPDMS =0.53 and an upper critical solution temperature Tc =58 °C is reported. The theoretical calculation of the sound velocity cL in compressible binary mixture is based on the random phase approximation for a ternary incompressible system. According to this new result, the speed cL, in the absence of dispersion effects, depends mainly on free volume and segment–segment interaction potential and remains finite as the blend approaches Tc. The main experimental features are in agreement with the theoretical predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461497
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  • 5
    Electronic Resource
    Electronic Resource
    Diffusion of charged particles in tokamak-like stochastic magnetic and electric fields (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 3935-3951 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper the diffusion of guiding centers induced by stochastic magnetic and electric field fluctuations, with both time and space dependence, is analyzed for the case of tokamak plasmas. General experimental results on tokamak fluctuations are used to derive guiding-center equations that properly describe the particle motion. These equations assume uniform average magnetic and electric fields with random stationary Gaussian fluctuations that constitute a homogeneous and cylindrically symmetric turbulence. By applying Novikov's theorem, a Fokker–Planck equation for the probability distribution function is derived and an expression for the guiding-center diffusion coefficient is obtained. This coefficient not only contains the standard terms due to the stochastic wandering of the magnetic lines and the stochastic electric drift, but also new terms due to the stochastic curvature and ∇B drifts. The form of these terms is shown explicitly in terms of the correlation functions of the fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860349
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  • 6
    Electronic Resource
    Electronic Resource
    Phase Decomposition in Polymers (1992)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 43 (1992), S. 61-90 
    Details
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pc.43.100192.000425
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  • 7
    Electronic Resource
    Electronic Resource
    Optimal laser heating of plasmas with constant density (1987)
    Springer
    Journal of optimization theory and applications 52 (1987), S. 123-149 
    Details
    ISSN: 1573-2878
    Keywords: Optimal control theory ; plasmas ; laser heating ; singular controls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The laser heating of a plasma with constant density is analyzed using optimal control theory. Heating strategies that minimize the total energy spent, the heating time, or a linear combination of the two, for several values of weighting coefficients, are obtained by determining the optimal laser intensity associated with each point of the phase plane. A numerical example is used to illustrate the application of the theory. In this particular example, savings in the energy spent up to 75%, compared with the energy required using a constant laser pulse, are obtained when minimum energy trajectories are implemented. Strategies that minimize the heating time, however, did not yield a significant reduction in the heating time. Numerical results may depend strongly on the initial state of the system as well as on the final ion temperature of the plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00938468
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  • 8
    Electronic Resource
    Electronic Resource
    Measurement of single chain neutron scattering in concentrated polymer solutionsWork supported in part by the National Science Foundation Grants Nos. DMR-76-80152 and DMR 76-23697. (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 863-869 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For some time there have been measurements of single-chain form factors for small-angle neutron scattering (SANS) in bulk polymers and in concentrated solutions. These were done by mixing a fraction of completely deuterated polymer with the normal polymer. Until recently, it was believed that these experiments had to be performed using a small fraction of deuterated polymer to avoid interchain interference effects. However, the work of Williams et al. has shown that these experiments are better if one uses large fractions of marked polymer and determines both the single chain and interference contributions to the SANS cross section. We generalize the technique of Williams et al. somewhat and apply it to the measurement of the radius of gyration of polyisoprene in the bulk.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180417
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  • 9
    Electronic Resource
    Electronic Resource
    Commentary: Reflections on “Quasielastic scattering by dilute polymer solutions,” by A. Z. Akcasu and H. Gurol, J. Polym. Sci., Polym. Phys. Ed., 14, 1 (1976). (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2111-2112 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1996.931
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  • 10
    Electronic Resource
    Electronic Resource
    Concentration dependence of the first cumulant for partially labeled chains in dilute solutions (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 853-862 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We use Zimm's single-contact approximation to investigate the concentration dependence of the first cumulant for partially labeled chains in dilute solutions. This approximation allows us to express interchain properties (such as the interference part of the generalized mobility) in terms of static structure factors, which are then modeled using a Gaussian chain model. We present numerical results for three specific labeling sequences.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180220507
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