Renewable furan-derived diamine as primary amine source to prepare fully bio-based bis-benzoxazine monomer under solvent-free condition

Abstract

Fully bio-based benzoxazine is classified into sustainable high-performance thermosetting resin and has become current focus in polybenzoxazine field. But lack of bio-based primary diamine restricted the preparation of bis-benzoxazine with high biomass content. In this report, renewable furan-containing diamine (PDFA) derived from furfurylamine was condensed with cardanol/eugenol and formaldehyde under solventless condition to obtain two biomass-based bis-benzoxazine monomers of BBOZ-Ca and BBOZ-Eu. The curing behaviors of two monomers were investigated by non-isothermal DSC method and the results showed that BBOZ-Ca possessed broad processing window comparing with BBOZ-Eu, the characteristic polymerization temperature and activation energy of two monomers were very close to each other, but the total heat releasing (enthalpy of polymerization) of BBOZ-Eu was higher than that of BBOZ-Ca due to its high oxazine content. The TGA results indicated that cured BBOZ-Eu had better thermal resistance than cured BBOZ-Ca, the char yield of cured BBOZ-Eu was 65.4% at 850 °C. Copolymerization with BBOZ-Eu effectively increased the char yield of cured BBOZ-Ca. Isothermal DMA was utilized to further investigate the curing kinetics and the results showed that the storage modulus increased rapidly when polymerization was initiated. The surface properties of cured films were studied using scanning electron microscope (SEM) images and contact angle measurement.