Improved curing reactivity, thermal resistance and mechanical properties of furylamine‐based benzoxazine using melamine as an amine source

Abstract

AbstractBenzoxazine resin is known as a high‐performance thermosetting resin, but the relatively high curing temperature and low cross‐linking density limit its broad application. The furylamine based benzoxazines possess great comprehensive performances and show great potential as bio‐based materials. In this work, the benzoxazine precursors (BAfa‐ma) containing furylamine were synthesized by using melamine as diamine to promote the curing reactivity and thermal resistance of furylamine based benzoxazines. The Fourier transform infrared (FT‐TR) and proton nuclear magnetic resonance (1H NMR) spectroscopy were used to confirm the chemical structures of BAfa‐ma, and differential scanning calorimetric (DSC), and thermogravimetric analysis (TGA) were applied to verify the curing behavior and performance of obtained polymers. It is showed that there are less benzoxazine rings in BAfa‐ma as more melamine introduced, on the contrary, more phenolic hydroxyls and secondary amines appeared as built‐in catalysts. What's more, BAfa‐ma have higher reactivity, shorter gelation time and lower curing temperature. Additionally, more melamine would lead to higher crosslinking density and higher thermal resistance, poly(BAfa‐70ma) shows Tg up to 318.6 and 76.4°C higher than that of poly(BAfa). Moreover, the mechanical and dielectric properties of the corresponding glass fiber reinforced composites laminates are also investigated, and it is found that proper amount of melamine may be beneficial for higher mechanical strength.