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Ansari M.F.,Indian Institute of Natural Resin and Gums | Sarkhel G.,Birla Institute of Technology | Goswami D.N.,Indian Institute of Natural Resin and Gums | Baboo B.,Indian Institute of Natural Resin and Gums
Pigment and Resin Technology | Year: 2013

Purpose - The purpose of this paper is to see the effect in the properties of shellac on blending with rosin (another natural resin) and study their changes during storage. Design/methodology/approach - Blending of rosin was done at seedlac (semi-pure lac) stage. Shellac was then prepared by bhatta (Indian country) process, in the form of button lac. Physico-chemical properties of the blends were studied at regular time intervals following standard procedures. Findings - Improvement in the physicochemical properties of shellac was noticed by blending with rosin to a great extent; less degradation in the properties of blends was observed with storage compared to those of parent shellac. Research limitations/implications - Because rosin possesses very high fluidity and life under heat, exact value of flow and life under heat of rosin and its blends with shellac having high rosin content could not be determined. Practical implications - The results give an idea to entrepreneurs, processors and industrialists of how much rosin is to be blended with shellac to bring improvements in its fluidity and life under heat for commercial exploitation, especially for inferior quality of shellac. Originality/value - Systematic study has been done for the first time, as no quantitative data was available on the changes in the different properties of shellac which take place on blending with rosin. © Emerald Group Publishing Limited. Source


Ansari M.F.,Indian Institute of Natural Resin and Gums | Sarkhel G.,Birla Institute of Technology | Goswami D.N.,Indian Institute of Natural Resin and Gums | Baboo B.,Indian Institute of Natural Resin and Gums
Pigment and Resin Technology | Year: 2014

Purpose-The purpose of this paper is to improve the properties of shellac by blending with epoxidised novolac resin for its use as coating material for metal surfaces. Design/methodology/approach-Epoxidised-novolac resin was synthesised by epoxidation of novolac resin, which in turn was synthesised by reaction of phenol with formaldehyde. The epoxidised-novolac resin was blended with different weight ratios of shellac ranging 10-50 weight per cent with an interval of 10 weight per cent. Films of the blends were studied for different coating properties using standard procedure.Findings-Significant improvement in coating properties of shellac such as gloss, scratch hardness and impact resistance was observed on blending with epoxidised novolac resin. Resistance towards water and alkali increased, while acid resistance decreased, with the increase in concentration of epoxidised novolac resin in the blends. Contact angle measurement revealed that blends showed more resistance towards polar solvent than non-polar ones. Research limitations/implications-Epoxidised-novolac resin used in the study was synthesised of epoxy equivalent of 187. Epoxidised-novolac resin of different epoxy equivalent can also be synthesised and used for blending and studying the properties. Practical implications-Blending of shellac with epoxidised-novolac resin improved the coating properties of shellac, which was further enhanced with the treatment of butylated melamine formaldehyde resin. The formulation can be used as coating material for metal surfaces. Originality/value-Blending of shellac with epoxidised-novolac resin was done for the first time. The formulation can be utilised for developing coating material for metal surfaces. © 2014 Emerald Group Publishing Limited. Source


Ansari M.F.,Indian Institute of Natural Resin and Gums | Sarkhel G.,Birla Institute of Technology | Goswami D.N.,Indian Institute of Natural Resin and Gums | Baboo B.,Indian Institute of Natural Resin and Gums
Pigment and Resin Technology | Year: 2013

Purpose - The purpose of this paper is to improve the properties of shellac by blending with novolac and to study the thermal behaviour of the blends with an ultimate aim to use as surface coating material. Design/methodology/approach - Novolac was synthesized by reaction of phenol with formaldehyde in a molar ratio of 1:0.8, in acidic condition. Blending of shellac with novolac was done in solution and films of the blends, prepared on glass slides and tin panels, were baked at 150°C for 15 minutes. Properties of the films were studied as per standard procedures. Findings - Films of shellac-novolac blends showed improvement in gloss and impact resistance compared to those of shellac alone. Gloss of blends increased with the increase in concentration of novolac and further increased on baking the films. Scratch hardness of shellac decreased on blending with novolac. Baked films of the blends showed resistance to heat and water. Films of shellac-novolac blends were found to be more resistant to polar solvents compared to non-polar solvents. Research limitations/implications - Shellac, prepared from kusmi seedlac, was used in the study. Besides shellac, dewaxed decolorized lac (DDL), dewaxed lac (DL) and bleached lac (BL) could also be used for study on blending with novolac. Practical implications - Blending of shellac with novolac improved the film properties of shellac. The study suggests that the compositions can be utilised in developing formulations of coating material with improved properties for metal surfaces. Originality/value - The formulations based on modification of shellac with novolac and study of the film properties utilising various instruments are novel. The formulations based on shellac and novolac can find applications in the field of surface coating with desired purposes. © 2013 Emerald Group Publishing Limited. All rights reserved. Source

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