Physico-Chemical Approaches to the Measurement of Anisotropy

Stein, Richard S.; Wilkes, Garth L.

doi:10.1007/978-94-010-9803-8_3

Cited by 68 publications

(44 citation statements)

References 116 publications

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“…The birefringent character of oriented polyethylene films is determined by the distribution of the orientation of the crystalline regions in them, by the film crystallinity, by any optical anisotropy (orientation) in the disordered ('amorphous') regions, and by form birefringence [9]. As pointed out in Section E the crystallinities of the five films are essentially equal.…”

Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 92%

The structure and properties of polyethylene films used in heavy lift balloons :

Khoury¹,

Crissman²,

Fanconi³

et al. 1985

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The following features of five polyethylene films used by NASA in the construction of heavy lift balloons have been examined: molecular weight, molecular weight distribution, branching, melting behavior, density, surface texture, birefringence, orientation of crystalline regions, uniaxial deformation in the machine and transverse directions, and the effect of sample geometry and strain rate on deformation behavior. The goal of this exploratory study was to determine whether there are significant differences in any of the above mentioned features, or combination of features between the films. The acquisition of such information is a first step towards determining whether there are any specific correlations between film characteristics and the incidence of catastrophic failure of balloons during ascent through the troposphere. This exploratory study has resulted in the identification of similarities and differences between various features of the films. Close similarities have been found in methyl group content, crystallinity, and peak melting temperature.The preferred orientations in the crystalline regions appear to be qualitatively similar or related. Differences among the films have been revealed in two features, namely between their molecular weights, and in the balance of the strain to break behavior in the machine direction relative to that in the transverse direction.

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Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 92%

The structure and properties of polyethylene films used in heavy lift balloons :

Khoury¹,

Crissman²,

Fanconi³

et al. 1985

View full text Add to dashboard Cite

show abstract

“…Birefringence dispersion control for polymers A Uchiyama et al design. Polymer birefringence has been thoroughly researched, [12][13][14][15][16] but the method of controlling birefringence dispersion of polymers for wide-banding has not yet been explored. We therefore examined the theoretical behavior of our new BDC system and then experimentally validated the new BDC theory and the effects of orientation functions on birefringence dispersion.…”

Section: Conventional Methods Two Typical Optical Designmentioning

confidence: 99%

“…The relationship between molecular orientation and birefringence has previously been suggested using the statistical segment model, [12][13][14][15] which is a hypothetical model that subdivides a linear polymer chain into cylindrical statistical segments having a vector n in each segment. Assuming that n has a statistical angular distribution, it can be described using equation (1):…”

Section: Theoretical Study Of Bdcmentioning

confidence: 99%

“…The form birefringence is also negligible because we do not use the form birefringence effect for our new design. Therefore, equation (14) can be transformed to equation (15).…”

Section: Theoretical Study Of Bdcmentioning

confidence: 99%

“…This equation is valid under the assumption that the refractive index of each component does not change in the multi-component system. Therefore, the same assumption is necessary for equation (15). This assumption is used later to discuss BDC using the multi-component polymer system.…”

Section: Theoretical Study Of Bdcmentioning

confidence: 99%

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Copolycarbonate optical films developed using birefringence dispersion control

Uchiyama

Ono

Ikeda

et al. 2012

Polym J

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A retardation film is a type of optical film that is widely used as a polarization transformation material to improve the image quality of flat panel displays (FPDs). One of the issues associated with retardation films has been the wide-banding of birefringence dispersion. A conventional optical design method that uses double-layered retardation films has been adopted to achieve wide-band properties. However, this conventional method has problems that have led to the demand for a single retardation film with wide-band birefringence properties. This situation motivated us to develop birefringence dispersion control (BDC) and to develop new polymers based on our novel molecular design. Wide-band characteristics are obtained using copolymers or miscible blends of polymers comprised of positive and negative anisotropic monomer units at specific volume fractions. The wide-band properties appear in a narrow range near the birefringence zero point, which is determined by the monomer volume fractions. The relationship between the orientation functions and birefringence dispersion is also clarified using theoretical studies, polarized IR and birefringence measurements. We have successfully industrialized a wide-band retardation film consisting of a newly developed copolycarbonate (co-PC) with a fluorene ring using the novel BDC theory. This film exhibits superior optical properties in FPDs.

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Opto-mechanical properties of fibres. Part 1. Optical properties and orientation of drawn polyethylene fibres

Fouda

Shabana

1999

Polym. Int.

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Changes in the structure of different drawn polyethylene (PE) fibres are studied by the Becke' line method and interferometrically. The Becke' line method is used to study the changes in the optical properties of the skin layer of PE undrawn fibres. A Pluta polarizing interference microscope is used to determine the mean refractive indices and mean birefringence of the drawn fibres. Some structural parameters, such as optical orientation function, electric polarizability difference and isotropic polarizability (Δα/3α0), are determined. This last parameter is found to be constant and depends only on the fibre structure. The number of molecules per unit volume and the distribution of segments at an angle with respect to the draw ratio are also determined. The generalized Lorentz–Lorenz equation given by de Vries is used to determine PE fibre structural parameters. A comparison between the experimental and those obtained using the Lorentz–Lorenz equation is given. A refractive index profile can assist fibre characterization. An empirical formula is suggested to correlate the changes in A, Δn, fθ and θ with the draw ratio, and its constants are determined. Microinterferograms and curves are given for illustration. © 1999 Society of Chemical Industry

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Physico-Chemical Approaches to the Measurement of Anisotropy

Cited by 68 publications

References 116 publications

The structure and properties of polyethylene films used in heavy lift balloons :

The structure and properties of polyethylene films used in heavy lift balloons :

Copolycarbonate optical films developed using birefringence dispersion control

Opto-mechanical properties of fibres. Part 1. Optical properties and orientation of drawn polyethylene fibres

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