Copolymerization of bisphthalonitrile/benzoxazine blends: Curing behavior, thermomechanical and thermal properties

A high-performance copolymer was successfully prepared by blending bisphenol-A based bisphthalonitrile monomer (BAPh) with phenol-aniline-based benzoxazine monomer (P-a). The obtained copolymers exhibited excellent thermal stability and thermomechanical properties. The Fourier transform infrared (FTIR) spectra of BAPh/P-a 5:5 system at different curing procedure proved the curing reaction mechanism. In addition, differential scanning calorimetry (DSC) curves showed that the curing reaction of the BAPh was induced by the active hydroxyl produced by the ring-opening polymerization of P-a; compared to the neat monomers, the curing temperature of the copolymer decreased and the curing speed improved. The evolution of thermal gravimetric analysis (TGA) curves revealed that the poly(BAPh/P-a)-5:5 displayed highest T5%, T10%, and char yield. The dynamic mechanical analysis (DMA) proved that the glass transition temperature and storage modulus of copolymers with the BAPh monomer as the matrix increased with the content of P-a increase, while copolymers with P-a as the matrix obtained nearly same results. The poly(BAPh/P-a) -5:5 exhibited best thermal and thermomechanical properties among different composition copolymers.