Synthesis of an acrylate constructed by phosphaphenanthrene and triazine-trione and its application in intrinsic flame retardant vinyl ester resin

An intrinsic flame retardant vinyl ester TGIC-AA-DOPO constructed by phosphaphenanthrene and triazine-trione groups was successfully synthesized via the reaction between 1,3,5-triglycidyl isocyanurate (TGIC), acrylic acid and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The structure of TGIC-AA-DOPO was characterized in detail by fourier transform infrared spectroscopy (FTIR), 1H and 31P nuclear magnetic resonance (NMR) and liquid chromatography-high resolution mass spectrometry (LC-HRMS). The intrinsic P-N-containing flame retardant vinyl ester resin (IFR-VER) was prepared after diluting TGIC-AA-DOPO with styrene (st) and triallyl isocyanurate (TAIC). The flame retardancy, thermal properties and combustion behavior of IFR-VER were respectively investigated by a series of tests involving limited oxygen index (LOI) measurement, UL-94 vertical burning test, cone calorimeter test, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The results showed that the as-obtained resin system exhibited a dramatic improvement in flame retardance. In the case of 40 wt% TAIC in resin system, the LOI value achieved 31%, leading to the UL-94 V-0 rating. In addition, compared with the 901-VER, the peak heat release rate (pk-HRR), average of heat release rate (av-HRR), total heat release (THR) and average effective heat of combustion (av-EHC) of the IFR-VER containing 40% TAIC diluent were decreased by 48%, 60%, 41% and 24% respectively. The diphase flame retardant effect of the prepared IFR-VER during combustion was demonstrated by the results of Py-GC/MS, FTIR, laser raman spectroscopy and scanning electron microscope (SEM).