Journal of Textiles and Polymers
Volume:1 Issue: 1, Winter 2013

Diffusion of small molecules through the polymers has significant importance in different scientific and engineering fields such as medicine، textile industry، membrane separations، packaging in food industry، extraction of solvents and of contaminants، and etc. This paper reports the use of Fourier transform infrared-attenuated total reflectance (FTIR-ATR) and partial least squares (PLS) analysis to study the compositional change of polymer solution exposed to the certain atmosphere. Diffusion coefficient of tetrahydrofuran (THF) in solution of polystyrene was obtained by means of analyzing the spectral data collected by FTIR-ATR instrument. Desorption by which the solvent evaporates from boundary of polymer solution، with respect to the time، showed that three regions of compositional change appeared: plateau، steep slope، and gentle slope regions. Providing the desorption data from the second region which is the essential part of mass transfer، the value of diffusion coefficient of THF was obtained 5. 8 ×10-6 cm2/sec. Finally، affecting factors and limitations of FTIR-ATR technique on reliability of spectral data are discussed.

The reconstruction of spectral reflectances of different color charts from the corresponding RGB values is investigated. The pseudo inverse (PI), principal component analysis (PCA) and canonical correlation regression (CCR) as well as their weighted versions are employed to estimate the spectral reflectances of Kodak Q_60, Color checker SG and Munsell data sets from the responses of a digital camera which are contaminated with different levels of random and quantization noises.The root mean square (RMS) error between the reconstructed and actual reflectances as well as the CIELAB color difference values under illuminant A for CIE1964 standard observer are computed to evaluate the performances of the employed techniques. Two different modes of camera responses i.e. three and six channels types are considered. In addition, the responses of a three-channel camera are computed under two sets of illumination conditions to prepare two collections of RGB data. To analyze the performances of the methods, they are also evaluated in the cross media condition, i.e. using different training and testing packages. According to the results, the wPI method, which is the simplest method among the other spectral reconstruction techniques, shows the greatest robustness at different levels of quantization and random noises.

The purpose of the present work is to develop a computational model to simulate the effect of sewing machine needle impact on woven fabrics. This research presents a finite element model of woven fabric using commercial finite element software (ABAQUS 6. 8). In the model، the orthotropic properties of the fabric، the elastic nature of the yarn، the sliding contact between yarns and yarn breakage are included while employing solid elements. Experimental works are also performed to compare with the simulation results. In order to quantify the damage of woven fabrics punched by sewing needles in experimental and simulation work، a damage index is introduced. Same trends in experimental and simulation results reveal that the model can quantitatively differentiate the damage of fabrics impacted by sewing machine needles.

This work involves non solvent induced phase separation method for fabrication of polysulfone (PSf) flat sheet membranes. N-Methyl-2-Pyrrolidon (NMP) serves as the solvent while poly (ethylene glycol) (PEG 20000) is used as additive. A full-factorial experimental design was employed for individual and mutual assessment of parameters in the membranes. In this case, the individual and mutual impacts of such parameters as the polymer concentration, PEG concentration and the coagulation bath composition were investigated on the final structure and function as well as the performance of membranes. The structural analysis included measurement of porosity and observation of SEM images. In order to assess the performance of membranes, mechanical strength measurement was applied. Comparing F-values in the table of data of analysis of variance (ANOVA) indicates that the significance of parameters differs in porosity analysis from tensile strength. The effective parameters in the porosity analysis include, in terms of priority, coagulation bath composition, polymer concentration and PEG concentration while in tensile strength analysis, PEG concentration overtakes polymer concentration. This issue could contribute to simultaneous optimization of porosity and mechanical strength.

In this study, the finite element modeling with considering the two-dimensional Elastica curve is used. Then, a twisted shape of Elasticaiss investigated through applying a pair of equal unbalancing twisted torques to the ends of the elastic rod. In the loop model, the implicit method, nonlinear geometry, elastic properties and three-dimensional beam element are used. Implicit method is accurate and a simple method for problems of structural complexity without intervention of time. Finally, the proposed model is used as overlap and legs of the warp-knitted single bar fabric structure and uniaxial tensile behavior of the fabric in the low strain is modeled using ABAQUS software. The explicit method is used in the fabric simulation based on complexity, connection and interaction of the parts in the simulated fabric and the nonlinear geometry, elastic properties and three-dimensional beam element is used in fabric simulation like the loop model. The results of the actual fabric test under low strain with theoretical model are compared. The model results are more consistent with the results of experiments conducted at lower strain on the fabric.

To achieve ultra hydrophobic Poly (ethylene terephthalate), PET substrate, two liquid etching methods of alkaline hydrolysis and aminolysis were applied to influence surface topography. To create low surface energy a layer of fluorocarbon was coated on the surface. The preferences of two methods were investigated by SEM microscopy, 3M water and oil repellency, sliding angle, self-cleaning and tensile properties. The results indicated that both chemical etching methods are able to create proper surface roughness and there is no necessity to apply nano particles which have a lot of side effects. However, the conventional polyester weight reduction process, alkaline hydrolysis, compared to the aminolysis process, presents better procedure for industrial scale manufacturing of ultra hydrophobic polyester substrates, by which the etching effect more or less is limited to the substrate surface.

In this research, the effect of cyclic loading values, stroke value and weft density on the mechanical properties of woven fabrics is investigated. Six different woven fabrics, plain, rib2/2, twill1/3, twill1/7, satin1/7 and herringbone twill, with three different weft densities, are produced from polyester filament warp and weft yarns. Samples are then subjected to the fatigue test in warp wise and weft wise directions, under two stroke levels and four loading cycle values. The results indicate that, the trend of mechanical properties changes due to cyclic loading is approximately same for all fabrics. Increasing of cyclic loading increases the value of second modulus of fabrics and decreases the value of tensile strain of the samples while the maximum load of samples does not change. Besides, the increasing of fabric weft density raises the measured mechanical properties of all samples. Increasing of stroke value causes the increase in the second modulus and decreasing the tensile strain of fabrics and has no significant effect on the maximum load.