Renewable source-based polyurethane coatings by using monoglycerides of vegetable oils and its modification by nano TiO2

Abstract

Purpose – The primary purpose of this work is to prepare the renewable source-based polyurethanes coatings which can be used to substitute petroleum-based materials. In the secondary purpose, the paper included improvement in the properties of said PU coatings using modified nano TiO2 for industrial PU coatings. Design/methodology/approach – The authors have synthesised low molecular weight polyols (monoglycerides) based on vegetable oils such as castor, linseed, coconut, mustard, sunflower and rice bran oils. These monoglycerides were successfully utilised in the preparation of polyurethane coatings. In order to improve the performance of these coatings, modified nano TiO2 was incorporated into them. The particle size of TiO2 was determined by transmission electron microscopy. Coatings prepared were characterised for their properties such as gloss, scratch resistance, impact resistance, flexibility, cross cut adhesion and chemical resistance. The thermal stability of coatings was also studied by thermo gravimetric analyzer. Findings – The polyurethane coatings prepared from six monoglycerides of different oils with polymeric diphenyl methane diisocyanate showed good chemical resistance and thermal stability. Coating properties like impact resistance, flexibility and adhesion were excellent for all of the prepared samples of PU coatings. PU coatings with excellent hardness up to 5B were found with the modification of nano TiO2 by silane coupling agent. The authors successfully prepared the renewable source-based (monoglycerides of oil) PU coatings. Practical implications – Practically the authors are able to convert renewable source that is vegetable oils into polyurethane coatings which may have strong potential to be used as industrial surface coating. The properties of the PU coatings were evaluated before and after the incorporation of different concentration of surface-modified nano TiO2 which revealed that the presence of 1 percent nano TiO2 showed significant enhancement in coating properties. Originality/value – The beauty of this work includes synthesis of polyurethanes coatings from renewable source material (monoglycerides of vegetable oils) to substitute petroleum-based materials. The incorporation of silane-modified TiO2 nanoparticles in renewable source-based PU coatings is another originality of the work. This article is also representing comparative study of various vegetable oils on PU coatings.