Effect of pendant functional groups on curing kinetics and final properties of cardanol-based benzoxazines
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The present study reveals the effect of pendant functional groups on curing and final properties of cardanol-derived benzoxazines. Three benzoxazines are synthesized by choosing three functional amines, namely aniline, 4-aminophenol, and 4-aminobenzoic acid. The structure of the benzoxazines is confirmed by chemical as well as spectroscopic analysis. Curing kinetics of benzoxazines is studied using nonisothermal differential scanning calorimetry (DSC) at four different heating rates: 5, 10, 15, and 20 degrees per minute. Further, kinetic models of Kissinger and Flynn–Wall–Ozawa are applied to determine the kinetic parameters of the curing reaction. Curing kinetics and modeling studies reveal that benzoxazine containing phenolic OH requires lower energy of activation for curing as compared to carboxyl functional benzoxazine and neat benzoxazine. Moreover, coatings are applied on mild steel (MS) panels and evaluated for mechanical, chemical, and thermal properties.
KeywordsCardanol Benzoxazines Curing kinetics Kissinger Ozawa–Flynn–Wall
The authors would like to thank Cardolite Specialty Chemicals, India, for providing NC-700 sample. The authors would like to thank Ms. Sonali (IIT Bombay, India) for providing proton NMR analysis of products. This research was funded by UGC-BSR [F.25-1/2014-15 (BSR)/No. F.7-314/2010(BSR)].
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