Results 211 to 220 of about 32,634 (235)

Optical anisotropy of hydroxypropylcellulose macromolecules

Polymer Science U.S.S.R., 1990
A flow birefringence investigation was carried out for hydroxypropylcellulose solutions in DMAA and tetrachloroethane. An experimental plot of the optical coefficient of shear [n]/[η] versus MM was compared with a theoretical plot for rigid vermicular chains, and the equilibrium rigidity of the macromolecules was determined from the optical data.
I.N. Shtennikova, G.F. Kolbina, V.P. Shibaev, I.V. Yedaeva   +3 more
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Optical anisotropy of polyimide

Journal of Applied Polymer Science, 1990
AbstractOptical anisotropy of polyimide films prepared from polyamic acid solutions was investigated by conoscopic observation and refractive index measurements. The conoscopic figure (crossed pattern) characteristic of a negative uniaxial crystal with its optic axis perpendicular to the film plane was observed for samples imidized on substrates ...
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Optical Anisotropy of Polycarbonates

1988
The large optical anisotropy of bisphenol-A polycarbonate is mainly caused by the presence of the anisotropically polarising phenyl groups all located in the polymer backbone. By introducing an aromatic group in the polymer side-chain via the bisphenol-moiety we have tried to increase the perpendicular polarisability to obtain a smaller anisotropy of ...
G. H. Werumeus Buning, R. Wimberger-Friedl, H. Janeschitz-Kriegl, T. M. Ford   +3 more
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Optical anisotropies of polyoxyethylene oligomers

Journal of the Chemical Society, Faraday Transactions 2, 1972
The mean-squared optical anisotropies 〈γ2〉 of four oligomers of polyoxyethylene glycol dimethyl ether have been determined from measurements of depolarized Rayleigh scattering by carbon tetrachloride solutions at 25°C. They have been interpreted using the valence optical scheme and rotational isomeric state theory.
G. D. Patterson, P. J. Flory
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Optical Activity Anisotropy of Benzil

The Journal of Physical Chemistry C, 2017
Optical activity (OA) along the optic axis of crystalline benzil has been measured by many over the past 150 years. However, the OA anisotropy remains uncharacterized due to difficulties in sample preparation as well as competition with linear birefringence (LB). The challenges associated with measuring OA along low-symmetry directions in crystals have
Kenta Nakagawa, Alexander T. Martin, Shane M. Nichols, Veronica L. Murphy, Bart Kahr, Toru Asahi   +5 more
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Optical Anisotropy of Nematic Compounds

Molecular Crystals and Liquid Crystals, 1974
Abstract The calculation of the principal polarizabilities of nematic compounds with reference to the two approaches using either the Vuks formulae or the Neugebauer's relations is discussed. The polarizabilities and internal field constants have been calculated from the birefringence data in the nematic phase of seven compounds viz., (i) p ...
H. S. Subramhanyam, C. S. Prabha, D. Krishnamurti   +2 more
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Optical Anisotropies in Modified Polycarbonates

Japanese Journal of Applied Physics, 1991
A new series of modified polycarbonates were prepared by the substitution of ortho hydrogen (for carbonate group) of main chain phenyl group by methyl, phenyl and cyclohexyl groups. The relationships between chemical structures and stress-optical coefficients in the glassy state (C g), refractive index anisotropy of constructive ...
Kazuyoshi Shigematsu, Shigenori Shirouzu, Shuji Sakamoto, Haruo Shikuma, Sohshi Togawa Sohshi Togawa, Takashi Nakagawa Takashi Nakagawa   +5 more
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Optical anisotropy of semiconductor nanowires

2009 IEEE/LEOS Winter Topicals Meeting Series, 2009
A novel class of optically anisotropic materials is presented. Layers of semiconductor nanowires fabricated in a bottom-up process exhibit a large in-plane birefringence and show quarter-wavelength retardation for a wavelength of 690 nm. These nanowire metamaterials are promising materials for optical gas- and biosensing.
Diedenhofen, S.L., Muskens, O.L., Bakkers, E.P.A.M., Gómez Rivas, J.   +3 more
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Dielectric Anisotropy and Optical Transitions.pdf

2022
Similar to thermodynamic phase transitions in matter, readily apparent changes in optical response arise in the transition from isotropic to anisotropic optical phases. Treating the anisotropy of the dielectric permittivity as a control parameter, which changes continuously from zero to a nonzero finite value at the transition, in this work we describe
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Optical anisotropy of tethered chains

Macromolecules, 1992
Expressions are derived for the static intrinsic birefringence and dichroism of tethered, flexible chains and particularly for lamellar and cylindrical block copolymers. Both quantities are predicted to be directly proportional to the stretching of the individual chains, given by the ratio L 2 / 0 .
Timothy P. Lodge, Glenn H. Fredrickson
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