Synthesis and Characterization of Green Polyurethane Coatings Derived from Niger‐Seed‐Oil‐Based Polyesteramide Polyols
2022
Doke, Ranjeet B. | Paraskar, Pavan M. | Rajput, Yogeshsing N. | Kulkarni, Ravindra D.
Polymeric researchers are trying to use renewable resources for polymeric resins in the coating industry to reduce fossil or petroleum feedstock reliance significantly. The present research attempts to develop a polyurethane (PU) coating for the first time from Niger seed oil (NSO). The polyesteramide polyols are synthesized by amidation of Niger seed oil with diethanolamine and further esterification with different biobased dicarboxylic acids (phthalic, itaconic, and dimer) to introduce a required functionality of hydroxyl group. Spectroscopic studies of Niger‐seed‐oil‐based fatty diethanolamide and polyesteramide polyols are carried out by Fourier‐transform infrared spectroscopy and proton nuclear magnetic resonance. The polyurethane coatings are prepared from synthesized polyesteramide polyols and hexamethylene diisocyanate biuret (HDI‐B). The cross‐link density of PU coatings demonstrated by gel content method and the corrosion study is carried by salt water immersion technique. The PU coatings are also studied for glass transition temperature (Tg) and thermal stability by differential scanning calorimetry and thermogravimetric analysis. Practical Applications: The long aliphatic chain provides flexibility, whereas the rigid structure of polyols enhances the hardness of PU coating. The phthalic‐based PU metal coatings depict excellent hardness, gloss, hydrophobicity, and chemical resistance compared to itaconic and dimer‐acid‐based PU.
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