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  • 1
    Electronic Resource
    Electronic Resource
    Test of the scaled particle theory for aligned hard spherocylinders using Monte Carlo simulation (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 5825-5830 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We obtained the chemical potential of a system of parallel hard spherocylinders by calculating the insertion probability of the particle. As a technique to obtain the insertion probability, we used a gradual insertion method together with Monte Carlo simulation. The simulation results provide a test of the scaled particle theory, suggesting a better approximation of the equation-of-state of the nematic phase of aligned long hard spherocylinders compared to the original scaled particle theory. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1454996
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of space charge on polarization reversal in a copolymer of vinylidene fluoride and trifluoroethylene (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 2026-2030 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polarization-reversal phenomena in ferroelectric copolymers of vinylidene fluoride and trifluoroethylene are affected by the time interval elapsed after poling of samples. Measurements of switching current demonstrated that this waiting effect is enhanced with the increase of space charges and switching curves with different waiting intervals satisfy the scaling rule when each switching curve is scaled by the switching time. These facts suggest that the electric field that reverses the spontaneous polarization decreases due to the electric field coming from space charges in the amorphous phase. A model with a prolate ellipsoid crystal and space charges in the amorphous phase explains such experimental facts. The difference of the waiting effect among samples crystallized under different conditions is also explained through the difference in the depolarization field coefficient of crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341733
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  • 3
    Electronic Resource
    Electronic Resource
    Nonlinear dielectric constant and ferroelectric-to-paraelectric phase transition in copolymers of vinylidene fluoride and trifluoroethylene (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3339-3342 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Second- and third-order dielectric constant ε2 and ε3 of three copolymers of vinylidene fluoride and trifluoroethylene were measured over a temperature range from 20 °C to higher than the ferroelectric-to-paraelectric phase transition temperature Tc . The thermodynamical theory predicts that ε2 is negative below Tc and vanishes at Tc , whereas, for the second-order transition, ε3 is positive below Tc but turns to negative at Tc and, for the first-order transition, ε3 does not change its sign below and above Tc . According to this criterion, it is concluded that the transition is of the second order for a copolymer with vinylidene fluoride fraction of 52 mole %, but of the first order for 65 and 73 mole % copolymers. This conclusion can explain the difference in slope of ε2 versus remanent polarization among the copolymers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339294
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of the hysteresis curve of ferroelectric polymers by a phenomenological relaxation theory (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 2139-2144 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple relaxation theory for the displacement versus electric field hysteresis of ferroelectric polymers is developed in which the relaxation time is assumed to be a function of electric field, as has been experimentally evidenced by polarization-reversal switching. The theory gives an analytical expression for the hysteresis curve. The coercive field Ec predicted by the theory agrees well with data on Ec as a function of temperature for poly(vinylidene fluoride) from -60 to 20°C and with data on Ec as a function of frequency for vinylidene fluoride/trifluoroethylene copolymer (73/27 molar ratio) at 20°C over the range 0.01-0.7 Hz.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180221211
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  • 5
    Electronic Resource
    Electronic Resource
    Depolarization field effect on the ferroelectric behavior of polymers (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1781-1791 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of the depolarization field in crystallites on the ferroelectric behavior of polymers is discussed on the assumption that the crystallite is a prolate ellipsoid with its major axis directed along the electric field. The theory relates the polarization P and the electric field E in the crystallite to the overall values P and E for the polymer. The determination of the P-E hysteresis of a crystallite from the P-E hysteresis is given with examples for poly(vinylidene fluoride) (PVDF) and vinylidene fluoride (VDF)-trifluoroethylene (TrFE) copolymer. The ratio R = J/(Ps - P), with J the switching current density and Ps the saturation polarization of polymer, is proved to be free from the depolarization field effect and the plot of logR against logarithmic time is shown to have merit for characterization of switching behavior. Examples of the curves are given for PVDF and VDF-TrFE copolymers. The temporal change of local electric field in the unreversed domains in the crystallite in the course of polarization reversal is predicted by the theory and this change is proved to be a significant mechanism of switching acceleration.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230904
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  • 6
    Electronic Resource
    Electronic Resource
    A method of calculating the activation energy spectra of polymers (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1913-1923 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Contraction experiments were performed on hot-stretched polystyrene during isothermal annealing and tempering. Activation energy spectra were obtained from the experimental data using the Primak theory. In the case of isothermal annealing the theory of Kimmel et al. with shift factors was used. There is an appreciable difference between this spectrum and that obtained from the tempering experiment by the original theory without shift factors. These two spectra should be the same according to the theory. In order to resolve the conflict, we have included a correlation between activation processes in the fundamental equation of the Primak theory. A new formula for calculating the activation energy spectra was obtained. For isothermal annealing, it can be written the same as that of Kimmel et al. The shift factor is also included in the formula for tempering. The activation energy spectra obtained by the new formula gives good agreement between the two methods.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180131006
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  • 7
    Electronic Resource
    Electronic Resource
    Ferroelectric switching characteristics of 73/27 copolymer of vinylidene fluoride and trifluoroethylene (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 909-921 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ferroelectric polarization-reversal switching of vinylidene fluoride - trifluoroethylene copolymer with 73 mol % of vinylidene fluoride is investigated under a variety of conditions in an attempt to derive detailed information on the polarization reversal of the polymer. The electric-field dependence of switching time ts obeys an exponential law. The temporal change of switching current density J is presented in the form J/(Ps - P) versus time (P is the polarization, and Ps is its saturation value), which is free of the depolarization-field effect and discriminates in a straightforward manner between acceleration and deceleration of switching. Effects of the annealing of samples upon ts are observed together with changes in the degree of crystallinity. Effects of space charge distribution upon ts are investigated by applying two successive pulses, positive and negative, with varied intervals tw between the two. The dynamics of space charge redistribution is elucidated from the tw dependence of the ts of the second pulse. The temperature dependence of ts indicates that the switching becomes critically fast as the phase-transition temperature is approached.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090240415
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of annealing of elongated nylon 6 (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 1539-1547 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The shrinkage of extended nylon 6 was studied by the methods of isothermal annealing and tempering. The shrinkage was discussed in comparison with that of amorphous polymer solids in the glass transition region. It was found that the annealing below the melting temperature of crystalline polymer solids showed two effects: one was the shrinkage of samples tracing the quasi-equilibrium states and the other was the relaxation process stabilizing the strain. The rate of shrinkage of nylon 6 during tempering became large at the two temperature ranges, i. e., one was the glass transition region and the other the neighborhood of elongation temperatures above 100°C. Because of the effect of relaxation stabilizing the strain, the rate of shrinkage during tempering decreased at intermediate temperatures between the two temperature ranges. A stabilizing effect also was found in the fact that γ type crystallites were stabilized during tempering.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800612
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  • 9
    Electronic Resource
    Electronic Resource
    Analysis of the effect of electrical conductance of ferroelectric polymers on D-E hysteresis curves measured by the sawyer-tower method (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1513-1521 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The D-E (electric displacement vs. field) hysteresis curve of a ferroelectric polymer is conventionally measured by the Sawyer-Tower method. The effect of the electrical conductance of the polymer on the measured hysteresis curve is theoretically analyzed and a new method is proposed for elimination of the error arising from the conductance. Examples of original and corrected hysteresis curves of vinylidene fluoride-trifluoroethylene copolymer are presented.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230805
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  • 10
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    Quantum twin spectra in nanocrystalline silicon (2017)
    American Physical Society
    Details
    Publication Date: 2017-10-10
    Electronic ISSN: 2475-9953
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by American Physical Society
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