Bio‐based benzoxazines based on sesamol: Synthesis and properties

ABSTRACT Sesamol was used with furfurylamine, dehydroabietylamine, and stearylamine to prepare three fully‐bio‐based benzoxazines: S‐fa, S‐da, and S‐sa, respectively. Their structures were confirmed by Fourier transform infrared spectroscopy (FTIR), 1H‐NMR, and 13C‐NMR. FTIR and differential scanning calorimetry were performed to monitor the curing behaviors of S‐fa, S‐da, and S‐sa. The thermal stability of the corresponding polybenzoxazines was supported by thermogravimetric analysis, and all polymers showed high thermal stability. The limiting oxygen indexes of all three polybenzoxazines were higher than 30, suggestive of good flame retardancy. The use of polybenzoxazine for the corrosion protection of Q235 low‐carbon steel was also studied. The results of OCP curves and Tafel plots demonstrate that the polymer coatings provide good corrosion resistance and can be applied to this purpose. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48255.