Synthesis of aminopyrazine‐based fire resistant additive and its application in epoxy resin

Abstract A new fire retardency APD was synthesized successfully by the condensation between 2‐aminopyrazine and DOPO, and target product APD was characterized by NMR. Absorption peak at 12.6 ppm in 31 P NMR verified complete consumption of the reactant DOPO and further confirmed the structure of APD. The safety of epoxy resin (EP) in fire disaster was dramatically improved by introduction of APD. Epoxy resin modified with 8% APD succeeded in vertical burning (UL‐94) test with V‐0 rating and limited oxygen index (LOI) of EP/8% APD was also improved to 33.9%. Cone calorimeter (CC) test further exhibited fire resistant effect of APD on EP in detail. 11.0 g APD reduced total heat release of 100 g EP to 35.1% and reduced total smoke product of 100 g EP to 19.9%. Char residue from CC test of EP/8% APD was analyzed by Raman, XPS, SEM, and FTIR tests. The results of these tests indicated that compact morphology of char residue from EP/8% APD possessed a positive effect in blocking fire spread. Highlights APD was synthesized and fire resistant EP was made. EP/APD acquired outstanding fire resistance and moderate mechanical properties. APD played fire resistant role in gas phase and condensed phase.