Optothermal Properties Research Articles

Optothermal properties of fibers: 12-Interferometric investigation for thermally treated viscose fibers

The present article studies the structure of annealed viscose fibers interferometrically at a constant temperature of 100 ± 1°C at different times. The Pluta polarizing interference microscope has been used for determining the mean refractive indices and mean birefringence. The results were used to calculate the optical orientation function and the angle of orientation. The value (Δα/3α0), which depends on the molecular structure of the polymer, remains constant. Relationships between the mean refractive indices, birefringence, isotopic refgractive index, and polarizabilities per unit volume with different times were given for these fibers. The samples were subjected to X-ray diffraction to clarify the variation of crystallinity with the annealing conditions. Differential thermal analysis measurements were used to determine the glass transition temperature of viscose fiber. Measurements of the volume swelling parameter of the viscose fibers with different liquids were given. Also, determinations of Cauchy's constants, dispersive power, and dielectric constant at infinity were carried out. Illustrations are given using graphs and microinterferograms. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 361–369, 1999

Changes in Opto-Thermal Properties of PET Fibres during Annealing

The changes in refractive indices and the birefringence of polyester (Egyptian PET) fibres with different annealing conditions were studied by interferometry. The polarizing interference microscope was used to determine the mean refractive indices and mean birefringence of these fibres. An acoustic method has been used to measure densities. The results are used to calculate structural parameters such as the form birefringence, virtual refractive index, harmonic mean polarizability of the dielectric, the number of molecules per unit volume, and the specific refractivity of the isotropic dielectric. Also, the number of monomer units per unit volume and the refractive indices of the fully oriented fibre, when using monochromatic light vibrating parallel and perpendicular to the fibre axis, were calculated and found to be 1.803 and 1.562. The effect of the annealing conditions on the refractive index was studied. The generalized Lorentz-Lorenz equation given by de Vries was used to determine PET fibre structural parameters. Comparisons between the Hermans optical orientation function formula and the corrected formula by de Vries are given.

Changes in Opto-Thermal Properties of PET Fibres during Annealing

The changes in refractive indices and the birefringence of polyester (Egyptian PET) fibres with different annealing conditions were studied by interferometry. The polarizing interference microscope was used to determine the mean refractive indices and mean birefringence of these fibres. An acoustic method has been used to measure densities. The results are used to calculate structural parameters such as the form birefringence, virtual refractive index, harmonic mean polarizability of the dielectric, the number of molecules per unit volume, and the specific refractivity of the isotropic dielectric. Also, the number of monomer units per unit volume and the refractive indices of the fully oriented fibre, when using monochromatic light vibrating parallel and perpendicular to the fibre axis, were calculated and found to be 1.803 and 1.562. The effect of the annealing conditions on the refractive index was studied. The generalized Lorentz-Lorenz equation given by de Vries was used to determine PET fibre structural parameters. Comparisons between the Hermans optical orientation function formula and the corrected formula by de Vries are given.

Opto-thermal properties of fibres: Part 4: Correlation of the density and loss tangent change with some physical parameters of annealed nylon-6 fibres

Nylon-6 fibres were annealed at various temperatures (90–175°C) for time intervals from 1 to 10 hours. An acoustic method has been used for measuring the density and the mechanical loss factor of these fibres. The variation of refractive indices and birefringences of nylon-6 fibres was studied by two interferometric techniques: the multiple-beam interferometric method in transmission and the two-beam method by using the Pluta polarizing interference microscope. The X-ray diffraction technique was used to interpret the variations in optical and mechanical parameters obtained due to thermal treatments. Relations between the optical data, mechanical loss factor and density with different annealing conditions are given for these fibres. Illustrations are given using graphs and microinterferograms.

Opto-thermal properties of fibers. XI. The effect of thermal annealing of drawing behavior for Egyptian polyester fibers on the crystallinity and some optical parameters

The structure developed of annealed Egyptain poly(ethyleneterephthalate) (PET) fibers is studied interferometerically due to the drawing process. Using a two-beam Pluta polarizing interference microscope connected to a device to dynamically study the draw ratio with the birefringence changes, the relations of drawing changes with some optical parameters are given. The evaluation of density, the mean square density fluctuation η2, crystallinity, amorphous orientation, crystalline orientation functions, number of chains per unit volume Nc, and number of random links between the network junction points N has been found. The results obtained clarify the effect of annealing time and temperature with different draw ratios on the structure of PET fibers. Empirical formula is suggested to correlate the changes in fθ, θ, Δna, and A with the draw ratio. Microinterferograms and curves are given for illustration. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 68: 1371–1386, 1998

1-Opto-thermal properties of fibers annealing effect on the birefringence variations of polyester fibers

Polyester (Egyptian) fibers were annealed at constant temperature (190°C) with different annealing times. Density, crystallinity, mean square density fluctuation, mechanical loss factor, and molecular orientation were calculated. Densities and mechanical loss factor were determined using an acoustic method. Changes in the molecular orientation were evaluated from the resulting optical data using the polarizing Pluta interference microscope. Correlation of data obtained by one method with another leads to relational changes in optothermal properties and in the molecular orientation. Changes of refractive index profiles of annealed PET fibers are provided. Illustrations using graphs and microinterferograms are shown. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 555–565, 1998

Optothermal properties of fibers. X. Temperature dependence of the skin?core structure of nylon-6 fibers

Refractive indices and birefringence for skin and core changes with annealing, produced by different annealing conditions in nylon-6 fibers, were measured interferometrically. Applications were carried out using multiple-beam Fizeau fringes in transmission to determine Cauchy's constants and dispersive coefficients for the fibers. The resulting data were used to calculate the polarizability per unit volume for each layer. By optical microscopy, the geometrical parameters of the fiber cross section were found. The effect of temperature and time of annealing on the refractive index and birefringence for each layer were also investigated. The relationships between temperature and time of annealing with the optical parameters were drawn. Illustrations are given using microinterferograms and curves. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 695–709, 1997

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

A two-beam interferometric method is used to study the change of optical orientation functions and the molecular structure of annealed Egyptian poly(ethylene terephthalate)(PET) fibers. The acoustic method was used for measuring the density. The density results were used to calculate the degree of crystallinity of PET. It was found that annealing causes alignment to the fiber chains in the directions of the fiber axis. This alignment gives an increase in the optical orientation function and decrease in orientation angle. The value of Δα/3α 0 , which depends upon the molecular structure of the polymer, remains constant. The obtained results of the optical and the density clarify that new reorientations occurred due to annealing at different conditions. The changes of the refractive index profile of annealed PET fibers are given. Microinterfero-grams and curves are given for illustration.

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

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 175°C and at two constant times 7 and 9 h). Microinterferograms and curves are given for illustration. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:1293–1306, 1997

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

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 175°C and at two constant times 7 and 9 h). Microinterferograms and curves are given for illustration. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:1293–1306, 1997

Opto-thermal properties of fibers — 2. Structural characteristics of cold drawn annealed Egyptian polyester (PET) fibers

Egyptian poly(ethyleneterephthalate) (PET) fibers in the drawn state show considerable optical and mechanical anlsotropy. The polarizing interference microscope is used with a fiber manipulation device to study, dynamically, the variation of refractive indices and birefringence of PET fibers with the draw ratio. In addition, the resulting data were used to calculate the strain optical coefficient, Poisson's ratio, the mean square density fluctuation under different annealing conditions, as well as several other parameters and constants. Also, an empirical formula has been applied to demonstrate the variation of the cross-sectional area of PET fibers with draw ratio and the constants of this formula are determined. Microinterferograms are given for illustration. The change of refractive index profile of annealed PET fibers at different conditions are also shown.

Optothermal properties of fibers. II. Annealing effect on the birefringence variations of polyester fibers

The variation of refractive indices and birefringences of Egyptian-manufactured polyester fibers with different annealing times at constant temperature 160°C are studied by inter-ferometry. The polarizing interference microscope is used for determining the mean re-fractive indices and mean birefringence of these fibers. The results are used to calculate optical orientation function and the angle of orientation. Also, the acoustic method has been used for measuring the density and the mechanical loss factor of these fibers. Relations between the mean refractive indices, birefringence, polarizabilities, mechanical loss factors, and densities with annealing time are given for these fibers. Illustrations are given using graphs and microinterferograms. © 1996 John Wiley & Sons, Inc.

Optothermal properties of fibers. IV. Optical properties of nylon 66 fibers as a function of quenching process

In this work, optical properties of samples of nylon 66 fibers were quenched in coarse-grained ice after annealing in the temperature range 80-180°C for 1-10 h. Two independent techniques were used to study optical parameters in these fibers. The first technique is the application of the diffraction technique to study the effect of quenching on the swelling factors of these fibers for some different liquids at room temperature of 25 ± 1°C. The second method dealt with the application of multiple-beam Fizeau fringes in transmission to estimate the refractive indices and birefringence of the skin and core of these fibers. The obtained results were utilized to calculate the polarizability per unit volume, isotropic refractive indices, and the Cauchy's dispersion constants. The relationship between n s ∥ , ⊥, n c ∥ , ⊥, n a ∥ , ⊥, Δn s , Δn c , Δn a , n (iso)s , n (iso)c , and n (iso)a and different annealing times and temperatures is given for these fibers. Microinterferograms and curves are also given.

Optothermal properties of fibers. II. Annealing effect on the birefringence variations of polyester fibers

The variation of refractive indices and birefringences of Egyptian-manufactured polyester fibers with different annealing times at constant temperature 160°C are studied by interferometry. The polarizing interference microscope is used for determining the mean refractive indices and mean birefringence of these fibers. The results are used to calculate optical orientation function and the angle of orientation. Also, the acoustic method has been used for measuring the density and the mechanical loss factor of these fibers. Relations between the mean refractive indices, birefringence, polarizabilities, mechanical loss factors, and densities with annealing time are given for these fibers. Illustrations are given using graphs and microinterferograms.

Optothermal properties of fibers. III. Optical anisotropy in nylon 66 fibers as a function of annealing process

Nylon 66(ICI Polyamide 66, Carded & Combed Top) fibers were annealed in the temperature range 80–180°C for 1–10 h. Refractive indices and birefringence were measured interfer-ometrically. Two independent techniques were used to study the optical anisotropy in these fibers. The first technique was to study the effect of annealing on the swelling properties of fibers from its diffraction pattern using a He—Ne laser beam. The second was the application of multiple-beam Fizeau fringes in transmission to determine the skin and core refractive indices and double refraction of annealing samples. The application was carried out using multiple-beam Fizeau fringes in transmission to determine Cauchy's constants and the dispersive coefficient for the fiber layers. The resulting data were used to calculate the mean polarizability per unit volume and the isotropic refractive indices. Behavior of optical properties at different annealing conditions is discussed. The results obtained clarify the new reorientation, and each layer change occurred due to annealing at different conditions. Microinterferograms and curves are given for illustration. © 1996 John Wiley & Sons, Inc.

Optothermal properties of fibers. V. Optical anisotropy in silk fibers as a function of annealing process

Silk fibers (Best Yellow Italian Silk, Ford & Co. Ltd) were annealed at constant temperatures of 100 and 150°C for different times ranging from 1 to 10 h and for different temperatures ranging from 60 to 160 ± 1°C for a constant time of 2 h. Refractive indices and birefringence were measured interferometrically. Two Independent techniques were used to study the optical anisotropy in these fibers. The first technique was to study the effect of annealing on the swelling properties of fibers from its diffraction pattern using a HeNe laser beam. The second is the application of a double-refracting interference microscope. The double-beam technique is considered the most favorable technique in determining the mean re-fractive indices and the double refraction of the annealed samples. The behavior of optical properties at different annealing temperatures and times are discussed. The results obtained clarify that the reorientations occurred due to annealing at different conditions. Microin-terferograms and curves are given for illustration. © 1996 John Wiley & Sons, Inc.

Optothermal properties of fibers. VI. Effect of annealing on some of the optical and dynamic mechanical parameters of polyester fibers

Optothermal properties of fibers. VI. Effect of annealing on some of the optical and dynamic mechanical parameters of polyester fibers

Optothermal properties of fibers. VI. Effect of annealing on some of the optical and dynamic mechanical parameters of polyester fibers

Changes in the structure of annealed polyester fibers (Egyptian manufacture) at a constant time of 5 h and different temperatures (80-190°C) were studied interferometrically. The Pulta polarizing interference microscope was used for determining the mean refractive indices and mean birefringence of these fibers. The multiple-beam Fizeau fringes in transmission was also used for determining the refractive indices of the skin and core of these fibers. Also, the acoustic method was used for measuring the density and mechanical loss factor of these fibers. Relations between the mean refractive indices, birefringences polarizabilities per unit volume, and mechanical parameters of annealed polyester fibers with different temperatures are discussed to clarify the thermal effects. Illustrations are given using graphs and microinterferograms.

Optothermal properties of fibers. I. Relations between optical properties and change of the density and mechanical loss factor for annealed polyester fibers

AbstractPolyester (Egyptain manufacturers) fibers were annealed in the temperature range 80–190°C for time intervals from 1 to 10 h. The density of the annealed fibers was measured by a system based on the theory of vibrating strings. The fiber diameter was also determined, using the laser forward diffraction technique. Refractive indices and birefringence for annealed fibers at different temperatures and constant time, 1 h, were measured by the polarizing interference microscope. The behavior of fiber density and the mechanical loss factor at different annealing temperatures and times were discussed at different optical parameters. The results obtained clarify the effect of annealing time and temperatures on the optical, density, and mechanical loss factor behavior of polyester fibers. Microinterferograms are given for illustration. © 1995 John Wiley & Sons, Inc.

Optothermal Study of Hydrogenated Amorphous Silicon- Sulfur Alloys

The optothermal properties of doped and undoped amorphous silicon- sulfur alloys have been studied using the optothermal transient emission radiometry (OTTER) technique. The optothermal decay signal was found to depend on the concentration of incorporated sulfur atoms in the material. The results have been correlated with the density of gap- state defects induced by sulfur atoms as determined from subgap absorption measurements. The OTTER technique has proved to be a viable alternative method for measuring the relative densities of defect states in the band gaps of amorphous silicon- sulfur alloys.