Smoothed Gaussian molecular fields: an evaluation of molecular alignment problems

2012 ◽  
pp. 189-204
Author(s):  
Laurence Leherte ◽  
Daniel P. Vercauteren
Keyword(s):  
Molecular Alignment ◽  
Molecular Fields

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

Molecular Alignment of Homoleptic Iridium Phosphors in Organic Light‐Emitting Diodes

2021 ◽  
pp. 2102882
Author(s):  
Moon Chul Jung ◽  
John Facendola ◽  
Jongchan Kim ◽  
Daniel Sylvinson Muthiah Ravinson ◽  
Peter I. Djurovich ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Molecular Alignment ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light

Photodeformable Azobenzene-Containing Polyimide with Flexible Linkers and Molecular Alignment

2021 ◽  
pp. 469-475
Author(s):  
Panpan Zhang ◽  
Zhongxu Lan ◽  
Jia Wei ◽  
Yanlei Yu
Keyword(s):  
Molecular Alignment

scholarly journals Molecular alignment echoes probing collision-induced rotational-speed changes

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
J.-M. Hartmann ◽  
J. Ma ◽  
T. Delahaye ◽  
F. Billard ◽  
E. Hertz ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Molecular Alignment

Strong molecular alignment in anisotropic fluid media

1996 ◽  
Vol 260 (3-4) ◽  
pp. 441-446 ◽  
Author(s):  
A.J. Bain ◽  
P. Chandna ◽  
G. Butcher
Keyword(s):  
Molecular Alignment ◽  
Anisotropic Fluid ◽  
Fluid Media

scholarly journals On the determination of molecular fields. —II. From the equation of state of a gas

1924 ◽  
Vol 106 (738) ◽  
pp. 463-477 ◽  
Keyword(s):  
Equation Of State ◽  
Molecular Model ◽  
Virial Coefficients ◽  
Preceding Paper ◽  
Molecular Field ◽  
Inverse Power ◽  
Theoretical Expression ◽  
Inverse Power Law ◽  
Special Cases ◽  
Molecular Fields

The investigation of a preceding paper has shown that the temperature variation of viscosity, as determined experimentally, can be satisfactorily explained in many gases on the assumption that the repulsive and attractive parts of the molecular field are each according to an inverse power of the distance. In some cases, in argon, for example, it was further shown that the experimental facts can be explained by more than one molecular model, from which we inferred that viscosity results alone are insufficient to determine precisely the nature of molecular fields. The object of the present paper is to ascertain whether a molecular model of the same type will also explain available experimental data concerning the equation of state of a gas, and if so, whether the results so obtained, when taken in conjunction with those obtained from viscosity, will definitely fix the molecular field. Such an investigation is made possible by the elaborate analysis by Kamerlingh Onnes of the observational material. He has expressed the results in the form of an empirical equation of state of the type pv = A + B/ v + C/ v 2 + D/ v 4 + E/ v 6 + F/ v 8 , where the coefficients A ... F, called by him virial coefficients , are determined as functions of the temperature to fit the observations. Now it is possible by various methods to obtain a theoretical expression for B as a function of the temperature and a strict comparison can then be made between theory and experiment. Unfortunately the solution for B, although applicable to any molecular model of spherical symmetry, is purely formal and contains an integral which can be evaluated only in special cases. This has been done up to now for only two simple models, viz., a van der Waals molecule, and a molecule repelling according to an inverse power law (without attraction), but it is shown in this paper that it can also be evaluated in the case of the model, which was successful in explaining viscosity results. As the two other models just mentioned are particular cases of this, the appropriate formulæ for B are easily deduced from the general one given here.

Temperature Gradients Through EHD Films and Molecular Alignment Evidenced By Infrared Spectroscopy

1981 ◽  
Vol 103 (1) ◽  
pp. 65-73 ◽  
Author(s):  
V. W. King ◽  
J. L. Lauer
Keyword(s):  
Absorption Spectrum ◽  
Emission Spectra ◽  
Infrared Emission ◽  
Molecular Alignment ◽  
Temperature Gradients ◽  
Spectral Change ◽  
Continuum Source ◽  
Polyphenyl Ether ◽  
Elementary Analysis ◽  
Gap Width

Partial and complete emission band reversals have been observed in the infrared emission spectra from portions of operating sliding contacts. An elementary analysis has been carried out to show that partial reversals are due to temperature gradients in the fluid film—the film acts both as a radiation-emitter and absorber, and that total reversals—an emission spectrum appears as an absorption spectrum—are likely to be due to a continuum source, such as hot solid asperities. The total energy radiated under the latter conditions exceeds that under the others. A decrease in gap width with increased load was accompanied by a dramatic spectral change in the case of 5P4E polyphenyl ether, which is indicative of molecular alignment.

New Molecular Alignment Models of Bubble Domains and Striped Domains in Cholesteric-Nematic Mixtures

1981 ◽  
Vol 75 (1) ◽  
pp. 47-67 ◽  
Author(s):  
Shoji Hirata ◽  
Tadashi Akahane ◽  
Toshiharu Tako
Keyword(s):  
Molecular Alignment
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