نشریه علوم و فناوری رنگ
سال ششم شماره 2 (پیاپی 20، تابستان 1391)

In this study two series of castor oil-triethylenetetramine (TETA) derivative polyamidoamines were synthesized using castor oil, TETA, salicylic acid and dimethyl formamide (DMF) at room temperature. The prepared polyamidoamines were used for the curing of epoxy resins. It was found from the mechanical properties, as well as adhesion and water resistance that these polyamidoamine cured coatings, in addition to suitable flexibility, had higher adhesion to substrates compared to polyamine cured samples. The results showed a great enhancement in flexibility and adhesion properties of the epoxy coatings due to increasing castor oil weight ratio, and/ or using salicylic acid and DMF. Furthermore, polyamidoamines cured samples showed higher water resistance and better protection capability in hot water immersion tests than polyamine cured sample, despite the fact that their water absorption was higher. J. Color Sci. Tech. 6(2012), 87-94© Institute for Color Science and Technology.

In this research, the europium Eu-activated SrZn2Si2O7 phosphors were successfully prepared by sol-gel method in reductive and oxidative atmospheres. Thermogravimetric-differential thermal analysis (TG-DTA), X ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) and photoluminescence (PL) spectra were used to characterize the resulting products. Obtained phosphor in reductive atmosphere is efficiently excited in the wavelength range of 350-390 nm which matches to a near UV (NUV) emitting InGaN chip and emits strong band blue light peaking at 481 nm with color coordination x=0.176, y=0.193 due to 4f65d1(2D)$4f7(8S7/2) transition of Eu2+ ions. Also, synthesized phosphor in oxidative atmosphere emits at approximately 480 and 600 nm that attributed to f-d transitions of Eu2+ and f-f electronic transitions of Eu3+, respectively. Finally, the crystallite size of the products was estimated about 30 nm by using Scherrer’s equation that this measurement was consistent with TEM observations.

In this investigation the dye absorption behavior of modified polypropylene (PP) fibers were studied. The modified PP fibers were produced as polyblend polypropylene/poly(butylene terephthalate) (PP/PBT) fibers with an industrial melt spinning machine. The effects of two very important parameters including; draw ratio of fibers and molecular weight of dispersed dyes were considered on dye absorption of pure and modified PP fibers. The results of differential scanning calorimetric (DSC) analysis showed that increasing the draw ratio resulting in decreasing the dye absorption of both pure and modified PP fibers due to the increasing the total crystallinity of fibers. Also, the dye absorption of as-spun and drawn fiber samples have a significant dependency on molecular weight of the dispersed dyes too. So that the lowest dye absorption decrease between as-spun and drawn pure and modified PP fiber samples were observed in the medium molecular weight of the dispersed dye. Scanning electron micrographs of the PBT dispersed phase of polyblend fiber samples showed that the structural variations (such as crystallinity and amorphous regions) are more effective on dye absorption than the morphological properties. Fastness studies of dyed samples were carried out by washing and light fastness of PP modified fibers. The results showed that the mentioned fastnesses depend on both draw ratio of fibers and molecular weight of dispersed dyes.

In this paper, the oxidation of dyes from colored textile wastewater by activated carbon (AC)/hydrogen peroxide (H2O2) was investigated. Reactive Red 198 (RR198) and Reactive Black 5 (RB5) were used as model dyes. The surface characteristics of AC were investigated using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Dye oxidation by AC/H2O2 was studied using UV-Vis spectrophotometer and Ion chromatography (IC). The effects of AC dosage, initial dye concentration, pH and salt on dye oxidation were investigated. Kinetics analysis indicated that the dye oxidation rates could be approximated at pseudo-second order model. Formate anion was detected as dominant aliphatic intermediate. Results indicated that the AC/H2O2 could be used as an eco-friendly material to degrade dyes from colored wastewater.

Epoxy–clay nanocomposites were prepared by applying high- intensity ultrasound during the synthesis of clay – epoxy nanocomposites by two kinds of amineous curing agent, cycloaliphatic and amidoamine. Exfoliation and intercalation of nanoclay have a significant effect in improvement of physical and chemical epoxy coatings properties. The choice and condition of curing agent controls the contribution of nanoclay of these coatings.In this article, X-ray diffraction (XRD), Optical microscopy and Scanning Elecron Spectroscopy(SEM) analyses were carried out. The results of XRD showed that the distances between the silicate layer were increased from 18.02 A° to 38.5 and 41.6 A°, in two coating systems. The results of Scanning Elecron Spectroscopy(SEM) showed the nanoclay particles in the polyamidoamine coating are composed of 3% of nano with flake structure that increase the direction of the ions in the time of getting the metal surface. The result of optical microscopy also shows the appropriateness of the ultrasound method in preparing nanocomposits. By using the results of Electrochemical Impedance(EIS)and Salt spray, the corrosion resistance of nanocomposites were obtained. From electrochemical impedance spectroscopy, it was observed that nanocomposite coating epoxy-polyamidoamine, with the formulation consisting of 3% nanoclay had the excellent corrosion resistance in comparison to pure epoxy coating.

Since 1956, the reactive dyes due to having covalent bonds with the fibre and possessing excellent fastness properties, have a wide textile industrial application. During this period, most of the investigations are focused on synthesis of reactive dyes with novel reactive groups which firstly, have sufficient reactivity to covalent bonding with the fibre and secondly, have not that high reactivity to hydrolyze the reactive dyes during the dyeing process. Since, hydrolyzed dye during the dyeing process in the house effluent causing environmental issues. Therefore, in order to balance the amount of reactive dyes reactivity to covalent bonding with fibre instead water, the structural modifications of reactive dye including change in the type of reactive groups (triazine, diazine, dichloroquinoxaline, phosphonic acid and sulphatoethylsulphone), the number of reactive groups (monofunctional and bifunctional) and the type of bridging groups which make the linkage between chromogen and reactive group, have been applied. Monochlrotriazine and vinylsulphone are most important reactive groups in reactive dyes and also commercial bi-functional and tri-functional reactive dyes with good dyeing properties have introduced to the textile industry. A comprehensive literature review on development of commercial and synthesis reactive dyes has been provided in this paper. This article concentrated on developments of reactive groups’ type. The evaluation of studied patents and papers prove that there is still room for progress in this type of dyes.

In this study, the ability of cationic dyes removal from textile effluent in both singular and binary systems has been investigated by using Feldspar. Two cationic dyes, Basic Blue 41 and basic Red 18, were used as cationic dye models. The surface characteristics of Feldspar were studied using Fourier transform infra-red, Scanning electron microscope, and X-ray diffraction (XRD) techniques. Moreover, the influence of different process variables such as adsorbent dosage, dye concentration, initial pH, and the presence of different electrolytes were investigated. The adsorption isotherms of single and binary systems were determined. The monocomponent Langmuir isotherm model was applied to analyze the experimental data of single system and the isotherm constants were calculated for these two dyes. The monolayer coverage capacities of feldspar for Basic Blue 41 and Basic Red 18 dyes in the single system were found as 5.714 and 4.650 mg/g, respectively. Also, the equilibrium adsorption of binary system was analyzed using the extended Langmuir models. The adsorption kinetics of single and binary systems were studied by using pseudo-first-order and pseudo-second-order models. The pseudo-second-order model was the best choice between the kinetic models to describe the adsorption behaviour of both single and binary systems. According to the dependency of thermodynamic equilibrium constant (Ks) on temperatures, the thermodynamic parameters associated with the adsorption process were calculated. The negative values of 7G0 indicate that the adsorption process is spontaneous and the adsorption mechanism is physical adsorption. The positive values of 7H0 show that the adsorption processes are endothermic.

In this research, polymeric photonic crystals with fcc packing structure were prepared and studied. Firstly, monodispersed colloidal spheres with core-shell structure were synthesized; they consisted of a polystyrene (PS) core and a copolymer shell of butyl acrylate (BA) and methyl methacrylate (MMA). The sample with total solid content of 32% was obtained and total conversion of polymerization was about 98 %. Then, the latex was coagulated in methanol, filtered and dried. After complete drying, the samples were hot pressed to make thin films of one millimeter thickness. In this crystallization procedure, the soft shells of latex spheres permit melt-like flow and the cores were organized to fcc packing structure in the elastomeric matrix. Uv spectrometer measurement showed two different refracted picks before and after press proving ordered structure of particles after hot press molding of dried latex.

Since the automotive industry has been developed in producing high performance automotive coatings recently, demands for automotive coatings with high UV stability and good appearance in addition to low costs have been increased. For this purpose, in this research two different kinds of UV stabilizers, one hydroxyl phenyl triazine and the other based on Hindered Amine Light Stabilizer (HALS)components were used in clear coats of automotive coatings system. 1 Wt% of these additives were added to the clear coats using mechanical mixer device thereafter the effects of the absorbers on the appearance and some properties of the automotive coatings system were evaluated after exposing the coatings to accelerated weathering in a salt spray and also running a xenon test. Results showed that the presence of small amounts of the UV absorbers can improve the weathering resistance of the automotive coatings, besides it was found that hydroxyl phenyl triazine absorber had better effects than HALS. This can be related to alkaline nature of HALS and retarding effect in curing reactions. J. Color Sci. Tech.

The effects of Atomic oxygen on various materials have been widely investigated in recent years by in-flight and laboratory simulation experiments. The interaction of atomic oxygen with materials may result in surface erosion, changes in chemical composition and surface morphology, changes in optical properties, and formation of particulate and molecular contamination of the spacecraft surfaces. White and black silicon coatings were widely used in space applications, such as protection of underlying organic material or as thermal control coatings. In this study, poly dimethyl siloxane, oxime silan and carbon black were used to make RTV-MB thermal control coating. The effect of atomic oxygen on surface erosion, chemical composition, surface morphology and optical properties of this coating were investigated by FTIR, SEM, EDS, XRD, AFM, spectroreflectometer and portable infrared reflectometer. The results showed that exposure of RTV-MB coating to atomic oxygen, causes the near surface to lose its organic components and form SiO2, which acts as a protection layer and slows further oxidation. Therefore, RTV-MB coating can provide sufficient erosion resistant to atomic oxygen attacks in LEO.

Acid Red 206 (C40H20CaN4O8S2) is a textile dye with global usage which is found in sewage of textile manufacturing industries in large quantity. In this research the reaction of Acid Red 206 (AR206) in photocatalytic analysis was carried out in water with use of Taguchi method, Qualitek-4 software and catalyst suspension ZnFe2O4/Clinoptilolite and UV light radiation. To identify prepared catalyst, SEM image and XRD diffraction pattern were used. Based on Taguchi method the test results displayed the maximum photo catalytic activity. From kinetic view the reaction was first order and study of reaction rate was carried out with the use of first order kinetic equation and acceptable results were gained in this consideration. The effect of factors in photo catalytic analysis such as pH, the amount of hydrogen peroxide, photo catalyst and temperature of reaction, were examined and the most efficiency in optimum conditions (pH=5, hydrogen peroxide=1ml, nonophotocatalyst=75 ppm and temperature=20ºC) was observed. According to these results, a method was obtained for photo catalytic analysis with the use of ZnFe2O4/ Clinoptilolite catalyst and UV light radiation, which by its development in an industrial form; it can be used for analyzing the wastewater in loom or other industries.