فصلنامه علوم و فناوری نساجی
سال چهارم شماره 1 (بهار 1393)

The plasma finishing treatment is an economical and facile technique for modification of a fabric surface in microscopic scale without using chemicals. Current work focuses on the influence of hydrolysis treatment on the fabric conductivity and its corresponding homogeneity compared to chemical etching. The SEM images indicate the positive effect of plasma treatment on the surface roughness and changes in the morphology of the fabric''s texture. This may suggest the necessity for inclusion of sensitizer and catalyst into the surface of the fabric to increase its conductivity and homogeneity. The measurement shows a significant drop in electrical resistance from1. 2 to 0. 2 Ω/cm2، respectively for chemically-hydrolysis compared to plasma-treatmed fabric. The homogenous coverage of single filaments by copper nanoparticles on the fabric surface formed by electroless plating shows a range of particle size below 100 nm، which is very much smaller than those formed by copper particles of about 500 nm reduced by chemical hydrolysis.

The conventional process for the production of viscose fibers in reducing the degree of polymerization of cellulose in the stage of ageing is to use alkaline solution of caustic soda and high concentrations of carbon disulfide over a long period of time. In this study, attempts have been made to treat wood pulp by electron beam irradiation so to reduce the degree of polymerization of cellulose. In such cases, the irradiated material may be dissolved in lower alkaline and carbon disulfide concentrations. Thus, treatment by electron irradiation may shorten the manufacturing process, more control on the degree of polymerization and a significant reduction in the consumption of chemicals and at the end to reduce environmental pollution. For comparison, the samples were prepared by conventional processing methods practiced in industry and electron beam treatment with irradiation dose of 5, 10 and 15 kGy. The prepared samples were characterized by water and dye absorption tests, solubility tests, Fourier transform infrared(FTIR) spectroscopy, scanning electron microscopy)SEM(, differential scanning calorimeter (DSC) and tensile properties. The results indicated that, an irradiated sample with 15 kGy dose exhibits maximum solubility, moisture and dye uptake. SEM results indicated a striated structure in the longitudinal and regular structural fibers and ridged cross sections. The results of DSC indicated the highest enthalpy of vaporization in the irradiated sample with 15 kGy dose that was in agreement with the results of water and dye absorptions. A high degradation temperature of the irradiated sample with 15 kGy dose revealed its high thermal stability. However, the irradiated sample with 15 kGy dose displayed maximum tensile strength but a decrease in 10% compared to a sample prepared by conventional process.

Today, to increase customer's assurance and enthusiasm in purchasing carpets a minimum of two criteria must be met, including its degree of comfort and permanency in retaining its original appearance. In this study, first, the physical properties of hand-knotted carpets and the qualitative changes most effective in the service life of the carpets are introduced, and then by questionnaire method in gathering information from individual purchaser the efficacies of the properties have been classified. By using the Minitab software the properties have been grouped in terms of top most prioritized effects. This evaluation was carried in a population of 56 people comprised of academic and commercial experts. The results of ANOVA tables under Tukey method have attested to the high efficacy of “resilient pile yarns” by a high percentage of spring rates in response to compression performance of the piles layers. Accordingly, the cohesion in reflexive properties of the pile yarns and durability in the design and patterns of the carpets are related to the stable surface quality. Seven selected functional properties in the first and second groups were proposed to manufacturers for more careful consideration and accuracy in the production design of hand-knotted carpets. Moreover, guaranteeing some or all the selected properties is recommended to be made to customers in order to assure their confidence in the lifetime performance of the carpet.

Different samples were mercerized to evaluate the interactive effect of temperature and alkali concentration on dye absorption of plain knitted fabrics. The mass of dye picked up by mercerized knitted fabric was estimated by assessment of the wastewater of dyeing process. In order to observe the microstructural changes of the mercerized fabrics, FTIR spectra were recorded for gray fabric and mercerized samples with maximum dye absorption. The results of this study showed that, absorption performance of the mercerized samples was much more superior to that of gray fabric. The dyeing rate increased by alkali concentration at low temperature. Optimum alkali concentration dropped by increases in temperature as in bath temperatures of 40 and 60°C the optimum alkali concentrations were 250 and 200 g/L respectively. In addition to above results, dye absorption decreased by further increase in bath temperature. With the increase in alkali concentration, although the absorption peak appeared at 40°C but the mass of the dye picked up by the fabrics was decreased. Finally, the alkali concentration of 200 g/L at temperature of 60°C were considered the most suitable conditions for mercerization of cotton plain knitted fabric.

The treatment of simulated textile wastewater was examined by advanced oxidation processes based on ozonation and UV irradiation, as individual and combined methods. For this purpose, two ultraviolet light sources)i.e., low pressure UV-C 9 W and medium pressure UV-C 150 W lamps(were used and the effect of each one on wastewater treatment was determined individually and in combination with ozonation process. Three conventional commercial reactive dyes) Blue 4, Red 45, and Orange 14(were used in this study. The rates of color and COD removals by oxidation of the systems were studied at neutral and alkaline pH. The ozonation process was enhanced by UV irradiation using low-pressure or medium-pressure UV-C lamps and the removal efficiencies of COD and TOC were increased to some extent. Regardless of the dye chemical structures, complete color removal, 95% COD and 56% TOC were achieved by a combination of ozonation and UV irradiation.

Chitosan is a natural abundant polymer which has attracted huge interests in biomedical, biological, pharmaceutical and wastewater treatment industries due to its biocompatible, biodegradable and nontoxicity properties. Considering that chitosan can be electrospun, many research works are focused in this area. Polymeric nanofibers, as one of the most known nanotechnology products, have huge potential applications in many fields due to their high aspect ratio and porosity, capable of forming three-dimensional structures and having great mechanical and biological properties. However there are some problems during electrospinning of chitosan which can be solved by using soluble chitosan derivatives, special solvents) mixture of organic acids (and blend it with other polymers. Considering the above matters, this review surveys the various approaches for investigation of chitosan properties and its successful electrospinning efficiency. Further applications of chitosan nanofibers are extended and discussed in relation to biomedical fields like tissue engineering scaffolds and wound dressing.