Search

Two novel bio‐based benzoxazine monomers containing imide or amide group (HPIDD‐fa and HPBA‐fa) were synthesized from raw materials of benzoyl chloride/phthalic anhydride, tyramine, furfurylamine and paraformaldehyde via a two‐step reaction. Fourier transform infrared spectroscopy (FT‐IR), proton and carbon nuclear magnetic resonance (NMR) spectroscopies were performed to characterize the structures of the benzoxazine monomers. The curing behavior was investigated by using differential scanning calorimetry (DSC) and in situ FT‐IR, and the DSC results indicate that the peak curing temperatures of HPIDD‐fa and HPBA‐fa are centered at 248.5 and 230.1°C, respectively. In addition, thermogravimetric analysis (TGA) suggests that the newly developed bio‐based benzoxazine‐derived polybenzoxazines present excellent thermal stability with Td10 (temperature at 10% weight loss) of 385 and 368°C for poly(HPIDD‐fa) and poly(HPBA‐fa), respectively. The current investigation suggests that our newly obtained bio‐based thermosetting resins are promising materials for high‐tech applications. [ABSTRACT FROM AUTHOR]

A novel polycyclic naphthoxazine resin (NSA‐thiq) is synthesized via N, O‐acetal forming reaction between o‐hydroxyl naphthaldehyde and 1,2,3,4‐tetrahydroisoquinoline. The chemical structure of the monomer is investigated and confirmed by 1H and 13C NMR, Fourier‐transform infrared (FT‐IR) spectroscopy, and high‐resolution mass spectrometry. Besides, the ring‐opening polymerization behavior similar to ordinary benzoxazine resins is observed by differential scanning calorimetry (DSC) and in situ FT‐IR analyses, leading to the formation of the phenolic cross‐linked network. Notably, DSC thermograms indicate that the newly obtained polycyclic naphthoxazine resin exhibits much lower polymerization temperatures compared to many other reported benzoxazine or naphthoxazine resins. Moreover, the corresponding polybenzoxazine (poly(NSA‐thiq)) shows comparable thermal stability in comparison with thermosets derived from monobenzoxazine resins. As a consequence of these unique performances, NSA‐thiq is applied as a property modifier for a commercialized benzoxazine resin (BA‐a). The glass transition temperature of copolymeric thermosets is enhanced without sacrificing too much thermal stability and heat resistance. Here, another series of naphthoxazine thermosetting resin is explored, which can provide more examples for constructing composites based on thermoset polymers. [ABSTRACT FROM AUTHOR]