Developing thermally resistant and strong biobased resin from benzoxazine synthesized using green solvents

Developing thermally resistant and strong biobased resin from benzoxazine synthesized using green solvents is still an important and challenging issue. Herein, starting from biomasses, a new bifunctional benzoxazine monomer (ST-fa) was synthesized using green solvents (ethanol, ethyl acetate) during the whole synthesis and purification processes. The curing behavior and kinetics of ST-fa were studied with differential scanning calorimetry. Results show that ST-fa has outstanding process-ability reflected by lower melting point (102 °C), lower curing temperature (224 °C) and lower curing reaction activation energy. The investigation on the comprehensive performances of cured resin of ST-fa, coded as Poly(ST-fa), shows that Poly(ST-fa) not only has excellent thermal resistance (glass transition temperature: 325 °C; initial thermal decomposition temperature: 394 °C), but also has high tensile properties. These attractively high comprehensive properties of Poly(ST-fa) are derived from the structure with high crosslinking density and high rigidity formed by ring-opening reaction of bifunctional benzoxazine and the crosslinking of the furan group.