Synthesis and characterization of a phosphorus-containing flame retardant with double bonds and its application in bismaleimide resins

A novel phosphorus-containing flame retardant, bis(4-(allyloxy)phenyl)phenylphosphonate (APP) has been synthesized. The structure of APP has been systemically characterized using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR and 31P NMR). Subsequently, APP was added into bismaleimide (BMI) resin to prepare flame retardant materials, coded as P-DBMI resin. The effects of APP content on the mechanical properties of the P-DBMI resins have been studied. In addition, thermogravimetric kinetics, UL-94 tests, limited oxygen index (LOI), scanning electron microscopy and residual analysis were carried out to reveal the thermal properties and flame retardancy of P-DBMI resin. The results indicate that P-DBMI resin with good mechanical properties, thermal stability and flame retardancy were obtained.