Synthesis and characterization of a new reactive hyperbranched polyphosphate ester, and its modification on benzoxazine-bisoxazoline resins

A new reactive hyperbranched polyphosphate ester (HPPE) was synthesized by one step reaction. The structure of HPPE was characterized by H-1 NMR, FTIR, and inherent viscosity. High performance flame retardant modified benzoxazine-bisoxazoline resins were obtained by the additional reaction with HPPE. Differential scanning calorimetry showed that there was an obvious shift in the exothermic peak of BPH5 (mass ratio of Ba-1,3-PBO and HPPE was 95:5) from 225 to 202 degrees C, comparing with that of BPH0 (pure benzoxazine-bisoxazoline resins). It meant that the curing reaction could be catalyzed and accelerated by HPPE. The impact strength experiments illustrated that the maximum impact strength of modified resins may reach 19.2 kJ/m(2). The char yield at 700 degrees C of BPH5, BPH15, and BPH30 were 3.34, 4.47, and 7.75%, respectively. The benzoxazine-bisoxazoline resins modified by HPPE showed good flame retardancy.