Untersuchung des Infrarot-Dichroismus in fl�ssig-kristallinen Schichten ohne Verwendung von polarisiertem Licht

Kelker, H.; Hatz, R.; Wirzing, G.

doi:10.1007/bf00428520

Cited by 33 publications

(5 citation statements)

References 18 publications

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Mentioning

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Order By: Relevance

“…Comparison of the measured absorbance with that of the same sample in the isotropic state shows orientation and order parameter for the different vibrations [9]. On the first glance the results we obtained in this way are contradictory to the ones stated before: both transition moments are indicated to be perpendicular to the director.…”

Section: -Phenylethylisocyanatecontrasting

confidence: 79%

Orientation of the Chiral Solutes in Induced Cholesteric Solutions

Korte

Chingduang

1980

Springer Series in Chemical Physics

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Section: -Phenylethylisocyanatecontrasting

confidence: 79%

Orientation of the Chiral Solutes in Induced Cholesteric Solutions

Korte

Chingduang

1980

Springer Series in Chemical Physics

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“…To characterize the alignment we introduce the ratio where A an is the absorbance of the anisotropic film after annealing and A iso is the absorbance of the film in the isotropic state at the same wavelength of maximum absorbance before annealing, as in Figure . We relate R to an order parameter S θ by where θ is the angle between the transition dipole of the cyanobiphenyl chromophore and the normal to the plane.…”

Section: Methodsmentioning

confidence: 99%

Self-Ordering within Thin Films of Poly(olefin sulfone)s

et al. 1998

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A study has been performed of the manner in which two structural features of poly(olefin sulfone)s, helical backbones and calamitic side chains, create order in films. For this purpose copolymers were prepared with one (polymer I) or two (polymer III) cyanobiphenyls per residue, and terpolymers were prepared with both such residues diluted to below the 5% level within an otherwise poly(eicosene sulfone) chain (respectively, polymers II and IV). The polymers all have ordered phases according to X-ray powder diffraction studies on samples cooled from the melt, a layer spacing of about 45 Å being detected in the films as in the bulk. Those polymers with mainly eicosene sulfone residues had crystalline phases with large domains, the layers deriving from the helical backbones alone, the smectic A phases of the parent poly(eicosene sulfone) being either suppressed or reduced in extent by the presence of the aromatic moieties, which were almost randomly orientated. Those with one or two cyanobiphenyls per residue were liquid crystalline. In the latter the layer spacing derives from both backbone and side chains and is reduced when the residues bear a second mesogen as a consequence of a constraining effect from the stiff backbone, as a novel model predicts. The spacers give rise to a glass transition and segregate the planes in which the stiff backbones are assembled from the regions in which the aromatic groups aggregate on account of the strong pi-pi interactions. Amorphous and optically isotropic spun cast films of these polymers became ordered on cooling from the melt or just on annealing, with the order, as determined by studies on the optical properties, being homeotropic for the aromatics and being planar for the backbones in a monodomain. For this arrangement we introduce the term homeo-planar smectic. Order parameters as high as 0.63 were measured for polymer I, from a clear film. The cyanobiphenyl chromophores formed H aggregates, with blue shifts in absorption and red shifts in fluoresence, and a little surprisingly these resulted in a circular dichroism, detectable when the films were inspected at an angle of 45 degrees to the normal.

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“…Molecular orientation of TLCP phase in the film specimen was assessed by using infrared dichroism technique 20–22. The FTIR spectrometer (Perkin Elmer system 2000) equipped with an aluminum wire grid polarizer was used to record the absorption spectra with polarized direction parallel and perpendicular to the orientation (machine) direction.…”

Section: Methodsmentioning

confidence: 99%

Liquid crystalline copolyester/polyethylene in situ composite film: Rheology, morphology, molecular orientation, and tensile properties

Nakinpong

Bualek-Limcharoen

Bhutton

et al. 2002

J of Applied Polymer Sci

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A thermotropic liquid crystalline copolyester (TLCP) was blended with low density polyethylene using a corotating twin screw extruder and then fabricated by extrusion through a miniextruder as cast film. Rheological behavior, morphology, and tensile properties of the blends were investigated. Melt viscosities of neat components and blends measured by using plate-and-plate and capillary rheometers at 240°C, in the shear rate range 1-10 4 s Ϫ1 , showed similar shear thinning effect. The viscosity values measured by the two techniques in the overlapping range of shear rate are found to be identical, which is in accord with the Cox-Merz rule. Addition of TLCP slightly reduces the matrix melt viscosity. TLCP dispersed phase in the extruded strand appeared in the form of spherical droplets. These droplets were elongated into fibrils with high aspect ratio (length to width) at the film extrusion step. As a result, the Young's modulus in machine direction (MD) of the composite film was greatly enhanced. At 20 wt % of TLCP, the MD Young's modulus was found to be about 16-fold increase compared to that of the neat polyethylene film. However, the elongation at break sharply dropped with the increase of TLCP content.

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Untersuchung des Infrarot-Dichroismus in fl�ssig-kristallinen Schichten ohne Verwendung von polarisiertem Licht

Cited by 33 publications

References 18 publications

Orientation of the Chiral Solutes in Induced Cholesteric Solutions

Orientation of the Chiral Solutes in Induced Cholesteric Solutions

Self-Ordering within Thin Films of Poly(olefin sulfone)s

Liquid crystalline copolyester/polyethylene in situ composite film: Rheology, morphology, molecular orientation, and tensile properties

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