Optothermal properties of fibers. VIII. Structure orientation study of annealed Egyptian polyester fibers

El‐Sharkawy

1999

J. Appl. Polym. Sci.

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Studies of the mechanical and optical properties of undrawn uniaxially stretched polyester PET (Egyptian manufacture) fibers by annealing and cold drawing were performed. The optical properties and strain produced in PET fibers at different conditions were measured interferometrically at room temperature. A two-beam interferometric technique was used to determine refractive indices and birefringence of the investigated PET samples with strain produced by different stresses. Using a microstrain device attached to a microscope stage and through the application of the appropriate mathematical equations, the refractive indices and the birefringence values were determined as a function of the draw ratios. The resulting data were utilized to calculate the polarizability per unit volume, the number of molecules per unit volume, Poisson's ratio, the strain optical coefficient, and several other parameters and constants. Also, some structural parameters are determined, such as form birefringence, the virtual refractive index, the harmonic mean polarizability of the dielectric, the harmonic mean specific refractivity, and the isotropic refractive index. The generalized Lorentz-Lorenz equation given by de Vries is used to determine PET fiber structure parameters. Comparison between the results have been compared with Hermans' optical orientation function. Relationships between the various optical parameters and the draw ratios are plotted, and the effect of draw ratio on the refractive index profile is studied. Microinterferograms are given for illustration.

“…For the annealing conditions used, the procedures were outlined in our previous publications,30, 40 and then quenched in ice.…”

Section: Resultsmentioning

confidence: 99%

Section: Theoretical Considerationsmentioning

confidence: 98%

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

El‐Sharkawy

1999

J. Appl. Polym. Sci.

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“…The mean values of the refractive indices of the fiber and the total mean birefringence were calculated using the equations that were extensively used in our previous publications 15–18. The Kuhen–Treloar type theory gives19 where F θ is the Herman orientation function20; N c is the number of chains per unit volume that depends on the number of crystallites in the polymer material; and D is the draw ratio, where D = l d / l u and D = 1 + d , d is the strain, l d is the fiber length before drawing, and l u is the length after drawing.…”

Section: Theoreticalmentioning

confidence: 99%

Optothermal properties of fiber morphology on nylon 66 fibers due to annealing and drawing processes

J of Applied Polymer Sci

2002

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ABSTRACT:The changes produced by the effects of annealed and drawn fibers on the microstructure and macrostructure of nylon 66 fibers are considered. The optical properties and strain produced in nylon 66 fibers under different conditions are measured interferometrically at room temperature. Structural parameters are calculated such as the average work per chain, the work per unit volume, the reduction in entropy due to elongation, and the work stored in the body as strain energy. The evaluation of the density aided the calculation of the crystallinity, the mean square density fluctuation, the isotropic refractive index, the harmonic mean polarizability of the dielectric, and the harmonic mean specific refractivity. In addition, the resulting data are utilized to calculate the optical stress coefficient and the optical configuration and to apply the Mooney-Rivlin equation to determine its constants. Also, the number of crystals per unit volume and the average orientation angle for uniaxial stretching are calculated by the extension ratio. The relations between the optical, mechanical, and thermal changes with different parameters are given for the studied fibers.

“…The changes in the optical anisotropy and orientation for polymer fibers by creep extension can be evaluated interferometrically by the measurement of refractive indices and birefringence of these fibers. Synthetic fibers in the drawn or extended state show considerable optical and mechanical anisotropy 12–17. The automated multiple‐beam Fizeau fringes system is an accurate and nondestructive technique in the field of fiber research 18, 19.…”

Section: Introductionmentioning

confidence: 99%

Interferometric study of creep deformation and some structural properties of polypropylene fiber at three different temperatures

J of Applied Polymer Sci

El‐Farahaty

Seisa

2008

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Influence of temperature on creep deformation for polypropylene PP fiber under a constant load was studied interferometrically. The automated multiple-beam Fizeau system in transmission was equipped with a mechanical creep device attached to a wedge interferometer. This system was used to determine the optical properties (n k , n ? , and Dn) of PP fiber during the creep process at constant loading with varying temperature. The creep compliance was drawn as a function of both time and temperature. An empirical formula was suggested to describe the creep compliance curves for PP fibers and the constants of this formula were determined. Two Kelvin elements combined in series were used to provide an accurate fit to the experimental compliance curves. The stress-strain curve via creep was studied to determine some mechanical parameter of PP fibers, Young's modulus E, yield stress r y , and yield strain e y . The optical orientation function f(y), the dielectric constant d, the dielectric susceptibility v, the surface reflectivity R, and the average work per chain W 0 were also calculated.