Institute of Science & Technology for Advanced Studies & Research ISTAR

Vallabh Vidyanagar, India

Institute of Science & Technology for Advanced Studies & Research ISTAR

Vallabh Vidyanagar, India
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Mishra V.,Institute of Science & Technology for Advanced Studies & Research ISTAR | Desai J.,Institute of Science & Technology for Advanced Studies & Research ISTAR | Desai J.,Sophisticated Instrumentation Center for Applied Research & Testing | Patel K.I.,Institute of Science & Technology for Advanced Studies & Research ISTAR
Journal of Coatings Technology Research | Year: 2017

Synthesis, characterization, and film performance of waterborne thiol–acrylate/thiol–epoxy hybrid coatings are highlighted in this article. A dimer acid-modified epoxy (DME) polyol, containing both hydroxyl and epoxy functional groups, was prepared by reacting epoxy resin (EEW = 190 g/equi) with dimer fatty acid at 2:1 molar ratio. Further, a base UV-curable polyurethane acrylate dispersion (UV-PUD), with a pendant epoxy functional group, was prepared by reacting polyol (DME), isophorone diisocyanate, and dimethylol propionic acid and end-capped with hydroxyethyl methacrylate with subsequent dispersion in water. Prepared intermediates were characterized for the parameters relevant to the study by physical, spectroscopic, and chemical methods. UV-curable thiol–acrylate/thiol–epoxy hybrid coatings were prepared by blending UV-PUD with trimethylolpropane tris(3-mercaptopropionate) (TMPMP) at four different thiol ratios (0, 0.3, 0.6, and 1.0) with respect to acrylate/epoxy groups. Cured films of the hybrid coating were identified by FTIR spectroscopy. The impact of thiol ratio on film performance was evaluated in terms of mechanical, chemical, thermal, and coating properties. The gel content measurements confirm that the addition of TMPMP increased the double bond conversion along with the epoxy group. Evaluation of cured samples shows the significant improvement in storage modulus, glass transition temperature, tensile strength, and hardness with increase in thiol ratio. The cured films possessed excellent water and acid resistance (<4%) even after 28 days of immersion. Moreover, the notable improvement was alkali resistance of cured films, i.e., as thiol ratio was increased from 0 to 1, weight loss in alkaline environment deceased from 49.5 to 4.5% after 28 days. Better properties of the thiol–acrylate/thiol–epoxy hybrid films will allow it as a potential application in low-volatile high-performance coatings. © 2017 American Coatings Association


Mishra V.K.,Institute of Science & Technology for Advanced Studies & Research ISTAR | Mishra V.K.,Sophisticated Instrumentation Center for Applied Research & Testing | Patel K.I.,Institute of Science & Technology for Advanced Studies & Research ISTAR
Journal of Dispersion Science and Technology | Year: 2015

A series of novel water-based UV-curable polyurethane dispersions (UV-PUDs) were synthesized by acetone process with anionic and nonionic stabilization in combination, which can address the requirements of volatile organic compounds (VOCs) directives for both indoor and outdoor applications. The nonionic stabilization was introduced in structure to improve electrolyte stability, shear stability, freeze/thaw stability, etc. The structure of UV-PUDs was characterized by Fourier transform infrared spectroscopy. Molecular weight and molecular weight distribution was characterized by gel permeation chromatography. Particle size was characterized by particle size analyzer. The thermal stability of the cured films was characterized by thermogravimetric analysis, and their performance properties were measured by standard methods. The obtained dispersions were stable for >8 months. It was found that both combinations of anionic and nonionic provide better colloidal stability against electrolytes and shear stability along with comparable performance properties. (Figure presented.). © 2015, Taylor & Francis Group, LLC.


Mishra V.K.,Institute of Science & Technology for Advanced Studies & Research ISTAR | Mishra V.K.,Sophisticated Instrumentation Center for Applied Research & Testing | Patel K.I.,Institute of Science & Technology for Advanced Studies & Research ISTAR
Journal of Dispersion Science and Technology | Year: 2015

Water-based self-emulsifying alkyd resins were prepared from soya oil fatty acid, phthalic anhydride, isophthalic acid, benzoic acid, and polyols with different functionality viz. 2-butyl-2-ethyl-1,3-propane diol, trimethylol propane, pentaerythritol, and di-pentaerythritol. Dimethylol propionic acid was used as internal emulsifier. The resin was neutralized with triethylamine, and finally dispersed in water to obtain water-based self-emulsifying alkyd resins. The effect of functionality of polyols used in synthesis, on various properties of water-based alkyd resins shows that, as the functionality increases surface coating properties viz. drying time, hardness, chemical and solvent resistance, has improved while flexibility and impact resistance decreased. © 2015, Copyright © Taylor & Francis Group, LLC.


PubMed | Institute of Science & Technology for Advanced Studies & Research ISTAR
Type: Journal Article | Journal: Journal of oleo science | Year: 2010

The present investigation aimed at finding out the effect of different degumming processes and on the use of some nontraditional alkaline material for refining of rice bran oil. Attempt was made to treat crude rice bran oil with H(2)O, and H(3)PO(4) for degumming followed by with alum or H(2)O for dewaxing. After removal of the gums and waxes the oil was neutralized with commonly used NaOH, and some nontraditional neutralizing agents like Na(2)CO(3) and NaHCO(3). Finally the oil was bleached traditionally using earth and charcoal and deodorized. The RBD oil was characterized by determining their color, peroxide value, content of unsaponifiable matter, and free fatty acids. Among the different processes tried degumming with 0.2 %, w/w, H(3)PO(4) followed by dewaxing with 2.0 %, w/w, H(2)O; bleaching with tonsil earth (1.5 %, w/w) and charcoal (0.5 %, w/w) and finally deodorization at 220 degrees C temperature and 2-4 mm Hg pressure resulted best quality oil in terms of the measured parameters. The characteristics of refined rice bran oil could be as content of FFA and UM 0.2 (%, w/w), 2.6 (%, w/w) respectively; color 10.9Y, 2.0R (in 2.54 cm Lovibond Tintometer cell); PV 3.3 (meq/kg). The oil yield is 78-85 % (by weight).

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