نشریه علوم و فناوری رنگ
سال هشتم شماره 2 (پیاپی 28، تابستان 1393)

Nowadays, concealment of textile and equipments in military industries has received specific interest in various countries. In this research, by application of nano- Carbon Black (CB) and micro- Carbon Active (CA) in a specific print formulation on cotton/nylon (Co/PA) fabric to produce khaki color, the required standard Vis-NIR reflectance for a successful obscure for desert environment was matched. Reflectance behavior of samples showed that by application of CB rare value in khaki printing formulations could tune spectral level in order to match the reference khaki reflectance in Vis-NIR range. Air permeability of sample was increased by adding CB particles to the printing paste. Evaluation of contact angle with water depicted that when concentration of carbon absorbing pigments raise, surface contact angle increase and the water entirely absorb at the long time. Also, color fastness of printed samples against washing, light and rubbing were good achieved.

The aim of this study was to investigate the effect of surface fat removal of two fatty wood species, jujube (Ziziphus jujuba) and pistachio (Pistacia mutica) on the adhesion strength of transparent coatings. Test specimens were prepared from wood with 8% moisture content and dimensions of 300×100×10 mm. The specimen’s surfaces were rinsed with thinner and industrial acetone, separately and covered with clear coat (sealer, clear and acid catalyzed). The results showed that the surface fat removal had significant effect on adhesion strength of applied coatings on wood surface. In both species the maximum value of adhesion strength was resulted in surface fat removed by industrial acetone. Finally, the maximum value of adhesion strength was also resulted from sealer - clear and acid catalyzed coating applied on surface fat removed jujube with acetone.

Digital color cameras are being taken attention for color appearance measurement. However, exploiting these devices needs some device calibrations. One of the most important tunings is the quality of lighting. Inhomogeneous lighting may cause some difficulties in measurements. Although the multiplicative inhomogeniteiy correction method has been used in many papers, none of them has ever rationalized this method. In this paper multiplicative inhomogeniteiy correction has been proved using linear model of camera. Moreover the effect of two correction methods including multiplicative and additive methods on the result of characterization of camera has been studied. The results showed that multiplicative correction method gives a better performance comparing other methods. Also, a proof has been given for efficiency of multiplicative correction method.

In this study, an accelerated electrochemical test was introduced as modified AC/DC/AC test. This test consists of D.C. polarization, soaking and dry cycles. The evaluated coating was cathodic electrocoating that electrodeposited on phosphated mild steel substrate with an average thickness of 20 microns and cured in three different conditions. In this research, the protective behavior of cathodic electrocoatings was investigated using the modified AC/DC/AC test, EIS and salt spray tests. Results showed that cathodic electrocoatings with low crosslinking density have better resistance against mechanical stresses during the modified AC/DC/AC test because of their more flexibility. On the other hand, due to the poor resistance against electrochemical stresses, final loss of protective properties of low-crosslinked electrocoatings are notable. The study manifests good correlation between the results of carried tests which the acceleration of coating degradation under the modified AC/DC/AC test conditions is the most.

In this study, the surface of aluminium alloy 1050 was prepared by different methods of including (1) degreasing, (2) alkaline etching, (3) alkaline etching followed by acid washing and (4) mechanical polishing before alkaline etching followed by acid washing. The electrochemical properties of the samples and their surface morphology and composition were studied by DC polarization technique, open circuit potential (OCP) measurements in 3.5% (w/w) NaCl solution and scanning electron microscope (SEM) equipped with energy dispersive x-ray spectroscopy (EDS). Results revealed that method (3) could be the most effective way of oxide layer removal and cathodic sites reduction from the surface of aluminum. Also the results obtained from pull off adhesion test showed adhesion improvement for the surface prepared sample through method (3) in comparison with methods (1) and (2).

This work intends to study the effect of boron carbide (B4C) as filler (1 wt. %) on thermal stability of the resole resin. Thermal properties was studied by means of thermo gravimetric analysis (TGA) to evaluate char yield and differential scanning calorimetric (DSC) to evaluate the resin curing behavior and boron carbide effects on curing reaction heat. Results showed increase of char yield and decrease of curing reaction heating the presence of B4C. The results of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy dispersive x ray spectroscopy (SEM-EDS) revealed conversion of the B4C to B2O3 which resulted in volume expansion and compensation of the resin shrinkage, which led to the high thermal stability of the compounded resin.

Dyes belong to organic compound families with complex structure due to their toxicity, carcinogenic and lack of biodegradability propertie's are considered as a serious environmental pollutant. The objective of this paper is to investigate decolorization of Reactive Blue 19 from contaminated water by potassium peroxydisulfate and solar light in the presence of solar parabolic concentrator. Solar irradiation intensity will be increased. In this case radiation after reflecting will be concentrated on the focal path of collector. The more light intensity, the more enhancement production of sulfate radical from persulfate would be. In this study evaluation of effective parameter has been investigated. Regards to the results from homogenous photo-oxidation in presence of solar concentrator has been introduced and considered as a superior option for removal of dyes from textile' industry wastewater. Using this collector dramatically increase the performance of advanced oxidation processes respects 98% of RB19 has been mineralized during 60 min in optimal condition.

In the present study, attempts were made to investigate the possibility of developing a two dimensional appearance chart to make provisions for a straightforward assessment and control of appearance quality of achromatic automotive finishes. To this end, four series of random test samples in which the three geometric appearance attributes, namely specular gloss, distinctness of image and orange peel varied simultaneously were prepared using metallic black, metallic grey, metallic silver and solid white automotive finishes. The samples were visually evaluated by a panel of 16 observers, utilizing grey scale technique. Analyzing the results of correlation between visually quantified total appearance and instrumentally measured specular gloss, distinctness of image and orange peel attributes of random samples showed that there is a good correlation between instrumentally measured distinctness of image and the Wave scan Wd parameters, and the corresponding visually evaluated data at the four investigated achromatic levels.Using these two parameters, a two dimensional appearance chart was developed for achromatic automotive finishes under investigation. Discrete acceptable, tolerable and unacceptable tolerance regions were determined for distinctness of image and Wd parameters, separately for horizontal and vertical automotive body parts, using the results of visual inspections of 6 expert auditors of the Iran Khodro car manufacturing company on 28 randomly selected car bodies with different achromatic levels.

In this research the effect of lightness, chroma and hue angle is investigated to select the preferred black among the 216 black fabrics. The rank ordering method was used to visually assess black samples in two steps, i.e., finding the black samples and selecting the preferred black among samples which most of observers detected them as blacks. Performing of 3130 visual assessment experiments shows the effect of hue attribute in blackness perception and preference. In fact, observers mostly selected and preferred the cyanish-bluish blacks while they did not prefer the reddish blacks. Besides, among two blacks with the same chroma and hue angle, the darker one was preferred. For black samples with the same lightness and hues, the blackness preference was related to the sample which is more neutral. Finally, it was found that lightness, chroma and hue angle influence in blackness perception and preference, simultaneously.