Progress in Color, Colorants and Coatings
Volume:7 Issue: 4, Autumn 2014

The effect of nano-TiO2 particles on the corrosion properties of epoxybased coatings was investigated so that the nano titania particles were co-deposited together with epoxy resins on standard phosphated steel panels by cathodic electrodeposition technique. To evaluate its anticorrosion properties, the coating containing nano titania were compared with plain coating regarding to their immersion stability in 3.5% NaCl solution for 2880 hours (120 days). The scanning electron microscopy micrographs showed that the nano titania particles were dispersed appropriately within the coatings. Moreover, electrodeposition process was performed at a pH value of about 6.0 which lies below the isoelectric point of nano titania for the nano titania could be electrodeposited cathodic. The electrochemical impedance spectroscopy technique was used to investigate the corrosion properties of coatings. The resulted Nyquist graphs and Bode plots showed that the high corrosion resistance of the nano titania has caused an improvement in the correlating epoxy layers even after 120 days of immersing in 3.5% NaCl solution.

Non-pigmented and pigmented UV-curable coatings are being used extensively in adhesive, printing and electrical industries. One of the main obstacles for the extension of their use in other industries is the inferior curing of thick pigmented formulations. In this work, the pigmented and non-pigmented formulations containing different acrylate monomers with different structures and functionalities were applied to obtain pigmented acrylate films by UV exposure. The conversion and mechanical characteristics of the systems were correlated. The results showed that there was a significant interaction between the presence of pigment, the type of reactive diluents and mechanical properties of the coatings. It seems that cured films containing isobornyl acrylate had a good tensile strength. For obtaining higher hardness and Tg, monomers with higher functionality such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate was needed.

In this study, the adsorption of Reactive blue 19 onto pomegranate residualbased activated carbon was investigated in aqueous solution. The activated carbon prepared by phosphoric acid activation under air condition. PRAC was characterized for its surface chemistry by point of zero charge measurements, Scanning Electron Microscopy and nitrogen adsorption at 77 K. The effect of operational parameters including contact time, initial pH, adsorbent dose, initial dye concentration and particle size were studied. Results showed that an optimum dye removal efficiency (96.7%) was observed at initial pH=11, contact time of 5 min, adsorbent dose of 3.25 g/L, initial dye concentration of 200 mg/L, and particle size of 63-149μm. The adsorption process was found to follow the Temkin isotherm equation (R2=0.975) and second-order kinetic model (R2=0.999). Furthermore, thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated.

TiO2-SiO2 core-shell particles with monodisperse silica core and nanostructured titania shell were synthesized by a multi-step coating process. The monodisperse silica spheres were prepared by Stöber method and titania shell obtained from a colloidal sol prepared by a hydrolysis– condensation reaction. The titania sol was deposited on monodisperse silica spheres by a multi-step coating method based on electrostatic attraction. Characterization was performed by DLS, SEM, DTA-TG, FT-IR and XRD. Also, the photoactivity of the core-shell particles was evaluated using methyl orange degradation by UV–visible spectrophotometer. The mean particle size of the colloidal titania sol was determined about 20 nm. The particle size of TiO2-SiO2 core-shell was about 500 nm. The deposit of titania nanoparticles on silica spheres was caused to delay anatase-rutile transformation. The core-shell particles calcined at 650°C showed a higher photocatalytic activity than that of pure titania.

In this study, a new mild steel surface pretreatment solution is introduced based on phosphoric acid containing a benzimidazole derivative as inhibitor. In this way, three different benzimidazole derivatives namely benzimidazole, 2-methyl benzimidazole and 2-aminobenzimidazole were studied in the 1M H3PO4 using DC and AC electrochemical techniques. Results revealed the better corrosion inhibition performance of 2-aminobenzimidazole in the acidic medium. EDS analysis revealed that surface elemental composition of oxygen and phosphorus increased after pretreatment process, that could be attributed to formation of some compounds based on iron phosphate. EIS diagrams of the painted substrates showed that pre-treated mild steel using phosphoric acidinhibitor provided higher corrosion protection performance than untreated mild steel during immersion in 3.5% w/w NaCl solution. Furthermore, acid washing process enhanced adhesion and cathodic disbonding resistance of painted mild steel.

The enzymes immobilization is a crucially effective factor for biosensor preparation. Metal nanoparticles are potentially able to immobilize the enzymes due to their unique properties including large surface-to-volume ratio, high surface reaction activity, high catalytic efficiency, and strong adsorption ability. A novel and highly sensitive amperometric glucose biosensor was obtained using the inkjet printing of reducing agents and metal salts. In this method, AgNPs are reduced from silver nitrate using ascorbic acid solutions on paper as substrate. Inkjet deposited patterns are utilized as electrodes in different electrochemical experiments and their morphology were investigated by SEM imaging. Results of cyclic voltammetry tests revealed that the glucose oxidase could be highly stabilized and immobilized on the surface of silver nanoparticles. Furthermore, the biosensor has a very high sensitivity of 8 μA/ mm2 and a low detection limit of about 5 mM. These results demonstrate that inkjet printing AgNPs have potential applications in glucose biosensors. Prog. Color Colorants Coat. 7(2014), 285-294 © Institute for Color Science and Technology.

The purpose of this study was to investigate the effect of different type of alcohols and humectants in inks formulation, as well as the influence of paper surface morphology on the ink-jet printing properties. In order to investigate the influence of alcohol and humectant types on printing properties, the optimum ink containing C.I. Reactive Blue 21 (Ink2) was formulated with different type of alcohols and humectants. The results of optical density and water fastness evaluations indicated that, the prints depend more on paper] surface morphology rather than the type of alcohols and humectants in ink formulation. Optimum optical density and good water fastness properties were obtained on glossy coated ink-jet printed papers comprising optimum-diameter nano-porosities in their coating layer.