Promoting ring-opening polymerization of benzoxazine and its thermal property through incorporation of pyrogallol-based benzoxazines

Both pyrogallol-furfurylamine-based and pyrogallol-aniline-based di-benzoxazines (PG-FA and PG-A) possess a free hydroxyl and latent catalytic characteristics. To decrease the ring-opening polymerization (ROP) temperature of benzoxazine based on phenol and 4,4 '-diaminodiphenylmethane (P-DDM) and increase simultaneously thermal property of its polymer, PG-FA and PG-A as catalysts were introduced into P-DDM. DSC and FTIR tests were used to investigate the effect of PG-FA and PG-A on the ROP of P-DDM; DMA, FTIR and TGA were performed to study their effects on the hydrogen bonds and thermal property of the cured P-DDM (PP-DDM). The results indicate that the ROP temperature of P-DDM remarkably decreased with the incorporation of PG-FA and PG-A. FTIR and DMA results illustrate that the total amounts of hydrogen bonds in PP-DDM increased with the addition of PG-FA or PG-A; however, its fraction of -OHMIDLINE HORIZONTAL ELLIPSISN (intra) and O-MIDLINE HORIZONTAL ELLIPSIS+HN (intra) hydrogen bonds decreased. The decrease in -OHMIDLINE HORIZONTAL ELLIPSISN hydrogen bonds made the cross-linked density of polybenzoxazine increase, resulting in that the thermal stability of PP-DDM enhanced with the introduction of PG-FA and PG-A.

Automated summary

By introducing PG-FA and PG-A as catalysts, the ROP temperature of P-DDM can be decreased, while the thermal stability of PP-DDM can be enhanced. This is mainly manifested by an increase in the total amount of hydrogen bonds and a decrease in the proportion of specific hydrogen bonds.