Microencapsulated Ammonium Polyphosphate with Glycidyl Methacrylate Shell: Application to Flame Retardant Epoxy Resin

A new microcapsule containing ammonium polyphosphate (APP) and glycidyl methacrylate (GMA) as core and shell material was synthesized by in situ polymerization technology. The structure and performance of microencapsulated ammonium polyphosphate (MCAPP) were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and water contact angle (WCA). The flame retardation of MCAPP and APP flame retarded epoxy resin (EP) composites were studied by limiting oxygen index (LOI), UL-94 test, and cone calorimeter. The results indicated that the microencapsulation of APP with the GMA led to an improvement of the hydrophobicity. Results also revealed that the flame retardancy of the EP/MCAPP composite was better than that of the EP/APP composite at the same additive loading. Moreover, the EP/MCAPP demonstrated better thermal stability, due to the stable char forming by APP and GMA shell and the better dispersion of MCAPP in the EP matrix.