JOURNAL OF COLOR SCIENCE AND TECHNOLOGY
Year:2012 | Volume:6 | Issue:3|Papers Count:14

Thermal control paints are coatings with special thermo-optical properties that carried out on the outer surface of spacecraft to control the input and output heat. In the present study, to evaluate the effects of different factors on these coatings, ZnO, TiO2 and synthesized pigments and two different compositions of potassium silicate binder with three pigments to binder ratios were used to produce different coatings. The fabricated coatings were applied on the grounded and anodized Al substrates. The design of experiment was performed by Taguchi method including nine experiments. The results of solar absorption and thermal emission indicated that the pigment type was the most important processing parameter and the type of substrate preparation had also a significant effect. In fact, the ZnO pigment had the higher thermal emission and the anodized substrate had the lower solar absorption. The binder composition and pigment to binder ratio had no significant effects on thermo-optical properties. The morphological analyses were carried out by FE-SEM, indicated that all pigments had the similar morphologies and suitable distribution in applied coatings. It can be concluded from the obtained results that the sample consisted of ZnO pigment, the resin with 44.25 solid percentages and SiO2/K2O equal to 1.925, pigment to resin ratio of 4:1 and anodized substrate, can be considered as a optimum specimen.

In this research, polyester nanocomposites containing three types of nanosilica particles as filler were prepared by melt compounding. The influence of type of fillers on various properties of nanocomposite were investigated by atomic force microscopy, scanning electron microscopy, polarized optical microscopy, differential scanning calorimetry, thermal gravimetric analysis, reflectance spectroscopy and light fastness. SEM was used to indicate presence of silica on surface of nanocomposites and it showed that surface roughness depends on hydrophilicity of nanosilica used. Optical microscopy images from nanocomposites containing silica illustrated the increment of the number of spherulites in the PET matrix with increase in silica percentage which were dependent on nano-silica type and content. Differential scanning calorimetry results of the nanocomposites showed a slight decrease in the melting temperature compared to pure PET. Results obtained from dyeing of polymers indicated that hydrophilic nanosilica particles improve the dyeability with disperse dyes at 110 and 130oC. Light fastness of dyed samples containing nanosilica was improved a little as compared with pure PET which could be attributed to certain interactions between nanosilica and dye in the polymer matrix.

In the present research, the synthesis of some new nano–scale metal chelates of an aromatic azo ligand has been reported. Toluidine red was synthesized by azo-coupling reactions of o-nitro-p-methyl phenyl diazonium salt with 2-naphthol and then its metal complexes were prepared with bulk Ni and Ni/SiO2 nanofine composite on the different pH and with the optimized conditions. The structures of products in overall yields of 75- 85% were deduced from their Atomic absorption and their UV, IR and NMR spectral data. According to XRD data, nano-scaled Toluidine Red-Ni complexes have monoclinic configuration and SEM technique have shown the size of particles are less than 100 nm. Also, nano metal complexes were evaluated in vitro for their antibacterial and antifungal activities against some bacteria and fungi. They have shown high activity against all species of them.

The purpose of the present work is to prepare of white silicone thermal control paint for spacecraft and investigation the effects of atomic oxygen (AO) and thermal cycling on the optical properties. The white paint includes zinc oxide-pigmented silicone resin. The behavior of silicone paint under AO and thermal cycling, were studied by the mass loss of paint specimen and complementary techniques including scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also the optical degradation in the reflectance spectra, solar absorptance and thermal emittance for silicone paint before and after AO and thermal cycle were investigated. Solar absorptance and thermal emittance of this paint were 0.256 and 0.870 respectively. The white silicone paint has promising AO and thermal cycling resistance properties that could be suitable for space applications.

Solvent- based paint sludge of automotive industry has a major contamination potential due to containing heavy metals and other toxic substances such as toluene. A range of cleaning techniques has been successfully developed to limit the environmental impact caused by wastewater of these industries, but timely and effective remediation is necessary. The present study aims to estimate the pollution quantity in Solvent- based paint sludge and decrease the pollutant up to environmental standards. Also, optimization of recovering processes of elements is other objective of this study. Titanium dioxide is the main pigment of automotive industry also it is an economical element with high cost. So, titanium dioxide was chosen to recovery from paint sludge. Therefore, sludge samples were collected from paint department of Iran Khodro Company. Then, several methods inclusive of flotation and electrolysis were carried out to recover titanium dioxide from samples. The concentrations of titanium dioxide in all samples were determined by XRF method. The results showed, electrolysis was the best method for recovering titanium dioxide from the paint sludge with70% purity.

Spectrophotometeric technique is common method for measuring concentrations in dye mixture solution, but there are several problems and disadvantages in this technique. Therefore, application of inexpensive and uncomplicated methods is desirable. This research explains a new method for dye concentration measurement by a scanner. In this method neural network is used to make relationship between scanner RGB values and dye concentration in mixture. Then, this new method is compared with normal spectrophotometric method. The obtained results indicate that the performance of neural network based scanner method is comparable with normal spectrophotometric method.

In this research, dissolution of a disperse dye in the presence of Tween 20 and Tween 80 and the effect of various parameters such as time, temperature and concentration of dispersing agents were investigated. In addition, dissolution kinetics of disperse dye in the presence of selected dispersing agents in various temperatures were studied. Results show that dissolution kinetics of the disperse dye follows an exponential equation. The rate of dissolution of disperse dye in the presence of Tween 80 is greater than Tween 20. The performance of Tween 80 and Tween 20 in dyeing of polyester fibers with disperse dye were studied and compared with the performance dispertane MF as a commercial dispersing agent. Results show that the performance of Tween 80 is almost equal to Dispertane MF.

In this research, in order to synthesize nano structure cobalt aluminate pigments hydrothermal method was used. First, appropriate amounts of CoCl2.6H2o and AlCl3.6H2 were disolved in distilled water and titrated by 3M NaOH and NaOH/Na2CO3 mineralizers with the molar ratio of 1:3 in order to achieve desired pH. Then samples were put into a teflon lined stainless steel autoclave and hydrothermally treated at different temperatures and times. Finally, the prepared precipitates were washed with distilled water, filtered and dried at 80oC. The powders were analyzed for the formed phases, colorimetry, and morphology and particle size distribution by XRD, CIELab, SEM and TEM. The XRD results showed that by increasing time and temperature of hydrothermal treatment, CoAl2O4 formed in expense of Co-Al-LDH and AlO (OH) phases. Also, by increasing hydrothermal time in a fixed temperature (245oC), because of decreasing Co-Al-LDH and formation of CoAl2O4, a* parameter decreased and b* parameter (representing blue color) became more negative. L* parameter also increased by increasing purity of the samples. Thus, the sample synthesized at 245oC for 24 hr with NaOH/Na2CO3 mineralizer was selected as the optimum sample. TEM analysis showed that the size of grains were about 100-150nm. Also particle size distribution results and SEM images showed agglomeration of particles in different hydrothermal times.

In order to modify the nanosilica surface from hydrophilic to hydrophobic one, and to have a better. dispersion of nanosilica in a non-polar media, nano silica surface treatment using methacryloxy propyl trimethoxy silane was performed. In this study three independent variables were explored. These factors included silane coupling agent concentration, bath pH and hydrolysis ratio. Particle analysis was performed to investigate the surface behavior of the treated nanosilica. pH of particles was determined in a mixture of water and ethanol. Apparent densities were measured using a Helium Pycnometer. FTIR Spectroscopy was used to study the surface chemistry of the treated nanosilica. Thermogravimetric analysis (TGA) and elemental analysis were employed to illustrate the quantitative amounts of grafted silane on the surface. It was revealed that pH of particles changed from 3.8 for pristine silica to 4.9 and 6.9 for the lowest and the highest grafted particles respectively. The results indicated that the silane/silica concentration had a strong effect on the grafting of silane on the silica surface. Based on the elemental analysis, carbon content of treated silica in different condition of experiments changed between 1.2 and 7.8 percent.

In this study, synthesis of a sorbitol based additive is reported which nowadays is used as a nucleating agent, also its effects on clarifying of polypropylene as a highly used material in plastic industry are investigated. The chemical structure of the additive was approved using IR and 1HNMR spectroscopy. Moreover, the appropriate performance of the additive as a nucleating agent in crystallization properties of polypropylene was revealed by differential scanning calorimetry (DSC). Measurement of color attributes and spectral reflectance and transmittance of the clarified polypropylene samples showed that all samples were colorless. In addition, characterization of the optical properties of the samples showed a 12.5 % and 33 % decrease in opacity and haze of the clarified samples, respectively.