Synthesis, Curing, and Thermal Stability of Low-Temperature-Cured Benzoxazine Resins Based on Natural Renewable Resources

For curing bio-based benzoxazine monomers completely below 200 °C, bio-based phloretic acid (PHA), p -coumaric acid ( p COA), and ferulic acid (FEA) containing a carboxylic group as a phenol source and furfurylamine (FA) as an amine source are used to prepare three full bio-based benzoxazines (PHA-fa, p COA-fa, and FEA-fa). Differential scanning calorimetry experimental results showed that PHA-fa, p COA-fa, and FEA-fa possessed low ring-opening polymerization temperatures and △ H values and could be cured completely below 200 °C. The obtained full bio-based polybenzoxazines (poly(PHA-fa), poly( p COA-fa), and poly(FEA-fa)) presented lower decomposition rates and higher residual char at 800 °C. In addition, poly(PHA-fa), poly( p COA-fa), and poly(FEA-fa) were predicted to have good flame retardancy due to low heat release capacity and total heat release values. From the above results, it is known that natural renewable resources, PHA, p COA, FEA, and FA, contribute to obtaining high-performance bio-based thermosets with excellent low-temperature curing performance and high char at 800 °C, which make them suitable for applications of plant fiber-reinforced composites.