Synthesis and Copolymerization of Fully Biobased Benzoxazines from Renewable Resources

A solventless method was adopted to synthesize two benzoxazine monomers from naturally occurring sources, i.e., eugenol (an extraction from dove), furfurylamine, stearylamine, and paraformaldehyde. The structure of the extracted eugenol and synthesized monomers were supported by FT-IR, H-1 NMR, C-13 NMR, and mass spectral analysis. The monomers were polymerized/copolymerized via ring-opening polymerization by heating as shown by FT-IR (disappearance of the peak due to oxazine ring at 920 cm(-1)) and differential scanning colorimetry (DSC). The exothermic peak associated with curing was observed between 198-254 degrees C. DSC analysis shows that the onset of curing temperature for the copolymers decreased linearly from 207-202 degrees C on increasing the content of F-Bz. The results from TGA analysis indicate that PF-Bz shows the maximum thermal stability when compared with PS-Bz and their copolymers. In the case of the copolymers, as the F-Bz content is increased, the thermal stability also increases. All the polymers also exhibit good flame retardant properties as shown by their LOI values (more than 26).