Flame retardancy mechanisms of melamine cyanurate in combination with aluminum diethylphosphinate in epoxy resin

A novel flame-retardant (FR) epoxy (EP) composite based on melamine cyanurate (MCA) and aluminum diethylphosphinate (AlPi) was successfully prepared and its flame retardancy was systematically investigated. Firstly, the facile surface modification was adopted to effectively solve the aggregation of FRs in EP matrix during the curing process. The influence of modified MCA/AlPi on the fire behavior and thermal degradation of EP were studied by using limiting oxygen index (LOI), vertical burning (UL94) tests, thermogravimetric analysis and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The experimental results showed that EP/MCA/AlPi composite achieved UL-94V0 rating and LOI value of 33.0% at the optimum mass fraction of MCA/AlPi of 2/1. The chemical composition and structure of residue were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry and scanning electron microscopy. MCA mainly acted in gaseous phase during the initial combustion stage, and therefore to provide enough time for the formation of carbon layer in condenses phase. As a result, the synergistic effect of MCA and AlPi can effectively promote the formation of the char layer and the FR efficiency. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47223.