Understanding the curing behaviors and properties of phthalonitrile containing benzoxazine with a new type of aniline curing agent

Promoted polymerization of Phthalonitrile containing benzoxazine (BA-ph) was designed on basis of the catalysis performance of a type of aniline curing agent (2,6-bis(4-aminophenoxy)benzonitrile (BAB)). The curing processes and curing behaviors of BA-ph with BAB were investigated by differential scanning calorimetry (DSC) and gelatin time. With the assistance of orthogonal test analysis method, main factors that affected the pre-polymerization of BA-ph were studied and the appropriate pre-polymerization conditions were determined. According to the results of dynamic rheological analysis (DRA) and Fourier transform infrared spectroscopy (FTIR), possible curing mechanism of BA-ph with BAB were proposed. The results show that BAB could reduce the prepolymerization temperature of BA-ph resin, and increase its polymerization rate and crosslinking degree, and the BA-ph/BAB polymer mainly formed the aromatic heterocyclic structure of triazine rings, phthalocyanine rings and polyisoindoline rings. Then, thermal stability of BA-ph (BAB15%) polymers pretreated at different temperatures and prepared at 200 °C was analyzed to understand the cross-linked structures. Results indicated that BA-ph (BAB15%) polymers exhibit outstanding thermal properties (T5%>410 °C and integral program decomposition temperature (IPDT) reached 3342 °C). Mechanical properties and thermomechanical properties of glass fiber reinforced BA-ph composites were also investigated and exhibited excellent mechanical properties, to further reveal the effects of BAB on the polymerization of BA-ph resin and expand the application of high-performance resin-based composites.