Synthesis, Polymerization Kinetics and Thermal Properties of Benzoxazine Resin Containing ortho -Maleimide Functionality

A benzoxazine monomer with ortho-maleimide functionality has been synthesized using ortho-maleimide functional phenol, aniline and paraformaldehyde as starting materials. The chemical structure of this benzoxazine monomer is verified by 1H and 13C nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies, elemental analysis as well as high-resolution mass spectrometry. The polymerization behavior of benzoxazine has been studied by differential scanning calorimetry (DSC) and in situ FT-IR. Besides, the kinetic parameters have been calculated by non-isothermal DSC with different heating rates. The apparent activation energy value of the ortho-maleimide functional benzoxazine is calculated to be 72.43 kJ/mol based on the Starink method. In addition, our predicted thermograms based on the developed model fit well with the curves obtained from experimental DSC results. Moreover, DSC and thermogravimetric analyses (TGA) are used to determine the thermal properties of the cross-linked thermoset. The resulting polybenzoxazine derived from ortho-maleimide functional shows excellent thermal stability (Tg of 247 °C; Td5 of 333 °C), evidencing its great potential application in high-performance fields.