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Shreepathi S.,Asian Paints Research and Technology Center | Bajaj P.,Indian Institute of Technology Bombay | Mallik B.P.,Asian Paints Research and Technology Center
Electrochimica Acta | Year: 2010

Effect of zinc content in the epoxy zinc rich coating on the mechanism of corrosion protection was investigated using electrochemical impedance spectroscopy (EIS). The zinc content in the coating (on dry film) was varied from 40% to 90% in steps of 10%. Open circuit potential (OCP) measurements and salt spray tests were also carried out to generate supporting evidences and to deepen the understanding in the area of zinc rich coatings. The healing or bridging ability of these coatings was studied by making a scribe on the coating and monitoring the evolution of OCP. EIS was also utilized to screen the amount of zinc particles required to provide efficient galvanic protection and to study the effect of purity of Zn on corrosion protection performance. Both EIS and OCP measurements indicate that coatings containing 40% Zn (on dry film) provides very good barrier protection coming mainly from polymer whereas the one containing >80% Zn provides excellent galvanic protection to the steel substrate. When the zinc loading is between 60% and 70%, coatings neither show barrier protection nor galvanic protection. © 2010 Elsevier Ltd. All rights reserved. Source


Guin A.K.,Asian Paints Research and Technology Center | Guin A.K.,Tata Steel | Mallik B.P.,Asian Paints Research and Technology Center | Shreepathi S.,Asian Paints Research and Technology Center
Progress in Organic Coatings | Year: 2015

Effect of different curing agents on the mechanical, chemical resistance and anticorrosive properties of tank linings based on phenolic + novolac epoxies has been studied. Proportion of two epoxies was chosen by monitoring the processing viscosity of the coating. Parts of hardener required for 100 g of the above resin (phr) was scrutinized using differential scanning calorimetry and flexibility measurements. As a result, five coatings were finalized and their mechanical properties were investigated by dynamic mechanical analyzer. Anticorrosive properties of these coatings were studied using electrochemical impedance measurements and neutral salt spray exposure test. Chemical resistance of these coatings was investigated by monitoring the weight change of the coating during immersion. Coatings cured with modified cycloaliphatic amine (amine value = 350), in spite of lower cross-link density, exhibited superior anticorrosive properties and reasonably good chemical resistance. Electrochemical impedance results correlated fairly well with actual solvent resistance property of the coating. © 2014 Elsevier B.V. Source


Bhosale N.,Asian Paints Research and Technology Center | Shaik A.,Asian Paints Research and Technology Center | Mandal S.K.,Asian Paints Research and Technology Center
RSC Advances | Year: 2015

Novel acrylated alkoxysilane castor oil (AASCO) with hydrolysable -Si-OCH3 was synthesized from castor oil, maleic anhydride and different weight percentages of 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), via free radical copolymerization. The AASCO was characterized by 1H, 13C Nuclear Magnetic Resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) techniques. This AASCO was further reacted with isophorone diisocyanate at NCO : OH ratio of 1.6 : 1 to get the isocyanate terminated silica hybrid polyurethane prepolymers. This work provides an effective and promising way to modify the castor oil backbone for high-performance coating application. The present work deals with the structural modifications of castor oil (CO), a renewable resource, to develop functional organic-inorganic hybrid polymers and their polyurethane-urea/silica (PU-urea/Si) coatings. For this purpose, a new acrylated alkoxysilane castor oil (AASCO) with hydrolysable -Si-OCH3 was synthesized from CO, maleic anhydride and different weight percentages of 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), via free radical copolymerization. The AASCO was characterized by 1H, 13C Nuclear Magnetic Resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) techniques. This AASCO was further reacted with isophorone diisocyanate at NCO : OH ratio of 1.6 : 1 to get the isocyanate terminated silica hybrid polyurethane prepolymers. The thermo-mechanical properties of the coating films were studied using Dynamic Mechanical Analysis (DMA), Thermogravimetric Analysis (TGA) and Universal Testing Machine (UTM). The coating films were evaluated for their salt spray resistance, swelling and contact angle (CA) properties. The CO modified silane based hybrid coatings have shown better mechanical, viscoelastic and CA properties when compared to control (CO based PU-urea) coatings. Similarly, the hybrid coating films with higher TMSPMA content have shown better thermal stability, less swelling and enhanced CA properties [water CA (102°), diiodomethane CA (72.75°)] and also exhibited excellent corrosion resistance properties. © The Royal Society of Chemistry. Source


Christopher K.R.,Asian Paints Research and Technology Center | Pal A.,Asian Paints Research and Technology Center | Mirchandani G.,Asian Paints Research and Technology Center | Dhar T.,Asian Paints Research and Technology Center
Progress in Organic Coatings | Year: 2014

Poly acrylic siloxane coatings are generating a lot of interest due to their high durability and superior performance properties in different applications. However, synthesis of high siloxane containing acrylic binder through emulsion polymerization is a challenge. Herein, we present a study on the synthesis and characterization of polystyrene-acrylate/polysiloxane core shell latex systems through regular seeded emulsion polymerization. Hybrid polymers have been characterized for their physical, chemical, thermal and surface properties using different characterizing techniques like FTIR, DSC, DMA, SEM, TEM, DLS and contact angle measurements. Incorporation of polysiloxane in the shell of the polymer particle was found to improve hydrophobicity and mechanical properties. Exterior paints prepared using the hybrid polymers as binders exhibited superior performance properties like weather ability and dirt pick up resistance. © 2014 Elsevier B.V. Source

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