Bio-Based Benzoxazine Monomers and Polymers Based on Difuran Diamine（Dfda）

A new class of bio-based benzoxazine monomers based on difuran diamine (DFDA) obtained by the coupling of furfuryl amine using formaldehyde will be discussed. The benzoxazine monomers were synthesized by reacting DFDA with a number of bio-based phenolic compounds and formaldehyde. These systems were purified by precipitation. Depending on composition, the resulting solid powders melt at temperatures ranging between 70°C and 150°C to form low viscosity liquids that can be readily used to impregnate fiber reinforcements. Onset cure temperature also varies depending on composition in the range of 120°C-240°C. The resulting polybenzoxazines have Tg’s ranging from 220°C to 320°C. It was found that adding furan rings into the backbone of the polybenzoxazine network provides the added benefit of 800°C char yield as high as 70% as measured by TGA temperature ramps in an inert environment. In addition to promising processing and thermal characteristics useful for applications requiring high temperature ablation resistance, these materials contain high renewable content.