Biobased Polybenzoxazine Derived From Furfurylamine and Piceol With Low Cure Temperature and Advanced Properties for Composite Matrices

ABSTRACT

A novel benzoxazine made from furfurylamine, paraformaldehyde, and piceol, Bz‐FA‐HA, is assessed for applications in fiber reinforced (FR) composites. Piceol is a biobased phenolic compound derived from the roots of Norwegian spruce trees and contains a methyl ketone group at the para position. Bz‐FA‐HA is a liquid at room temperature, has a viscosity of < 0.5 Pa.s at 100°C, and a T _onset of cure at 132°C. The carbonyl is found to react with the furan ring, yielding a crosslinking reaction when cured above 180°C as indicated by differential scanning calorimetry and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. Poly(Bz‐FA‐HA) has a T _g  > 350°C, attributed to the crosslinking reaction. Furthermore, the storage modulus is > 3 GPa, regardless of cure temperature. Poly(Bz‐FA‐HA) has a char yield at 800°C of 65.0% (62.3% at 1000°C), and a T _onset of decomposition of 357°C in nitrogen. The resulting carbon formed during pyrolysis shrinks during the carbonization reaction and scanning electron microscopy imaging shows a cross‐section with micro cracks. The processability, advanced mechanical properties, and exceptional char yield make it a promising candidate as the matrix for FR composites.