Optothermal properties of fibers. VII. Optical investigation of annealed nylon-6 fibers

Abstract

The influence of annealing on the birefringence of nylon-6 fibers was examined. These fibers were found to show considerable optical anisotropy. Three independent techniques were used to study the optical anisotropy in these fibers. The first technique to determine the diameter of the fiber from the diffraction pattern was using a He{Ne laser beam. The second technique was the application of the Becke-line technique to study the effect of annealing on the skin layer of these fibers at different temperatures for a constant time of 5 h. The third is the application of a double-refracting interference microscope (the Pluta polarizing interference microscope). The double-beam technique is considered as the most suitable technique for determining the mean refractive indices and the double refraction of the annealed samples at different temperatures. (155 and 175ЊC and at two constant times 7 and 9 h). Microinterferograms and curves are given for illustration.

Analysis of fibres using microscopy

“…4.1) (Baas 1975;Barakat and Hamza 1990;Donaldson 1992). Refractive index measurement has been used for polymer identification in artificial fibres such as nylon, to study core/coating layers (Barakat and Hamza 1990;Fouda et al 1997;El-Bakary 2007) and to measure the crosssectional shape of nylon fibres (Hamza et al 2002).…”

Opto-thermal properties of fibers. XV. A study of the drawing behavior of quenched poly(ethyleneterephthalates) fibers

“…Also, de Vries defined the invariant refractive index, which he call the “Virtual refractive index” n V by where the virtual refractive index n V replaces the isotropic refractive index equation, This equation [eq. (5)] leads to the harmonic mean polarizability of the dielectric α V by the following equation: Likewise, for the harmonic mean specific refractivity, we have Hermans28 defined the optical orientation function as ${\Delta n_a\over \Delta n_{\max}}$ where Δ n a is the measured birefringence, and Δ n max is the maximum birefringence for the fully oriented fiber. The value of Δ n max has been previously determined to be36 (0.24).…”

“…The optical orientation function and orientation angle can be calculated using the Hermans' equations31: The average value of the optical orientation function 〈 P 2 (θ)〉, due to Ward,32, 33 is given by which is the same function named by Hermans 28. 〈 P 2 (θ)〉 is related to the polarizability, as follows: where Φ | and Φ ⟂ are the polarizability parallel and perpendicular to the fiber axis, respectively, where Also, eq.…”

“…Several techniques have been proposed to measure orientation (including X‐ray scattering and Raman spectroscopy) 26. Among all these techniques, interferometry represents a very valuable technique to get an insight into the processes occurring at the molecular level 27, 28…”