Thermal degradation and flame-retardant properties of epoxy acrylate resins modified with a novel flame retardant containing phosphorous and nitrogen

A novel monomer containing phosphorus and nitrogen (EBAPP) has been synthesized by allowing phenyl dichlorophosphate to react with ethylenediamine and 2-hydroxyethyl acrylate (HEA). The structure of EBAPP was characterized by FTIR, 1 H NMR and 31 P NMR. A series of flame-retardant resins was obtained by blending EBAPP with epoxy acrylate (EA) in different ratios and exposing to the UV-light. The flame-retardant properties of the resins were characterized by the limiting oxygen index (LOI) and microscale combustion calorimeter (MCC). The results showed that the incorporation of EBAPP into EA could improve the flame retardancy of EA. The thermal properties of the resins were investigated by thermogravimetric analysis (TGA) in air atmosphere, indicating that EBAPP could improve the char residues at high temperature. Moreover, the thermal degradation of EA/EBAPP resins were investigated by the real-time fourier transform infrared spectra (RTIR) and thermogravimetric analysis/infrared spectrometry (TGA-IR) analysis. The morphologies of the formed chars were observed by scanning electron microscopy (SEM), demonstrating that 20 wt% of EBAPP in EA exhibited the most effective flame retardancy due to the dense char layers formed during combustion.