A phosphorus-containing aliphatic amine curing agent towards intrinsic flame-retardant and smoke-suppressive epoxy resins

A phosphorus-containing aliphatic amine curing agent (DPT) was synthesized using triethylenetetramine (TETA) and diphenyl chlorophosphate (DPCP), and it served as a flame-retardant curing agent to reduce the fire risk of epoxy resin (EP) systems. The curing behaviors, thermal properties and flame retardancy of the DPT-containing EP systems were investigated in detail. The differential scanning calorimetry (DSC) analysis showed that the introduction of phosphorus-based group reduced the curing activity of -NH2/-NH- groups in DPT. The glass transition temperature (Tg) values of the DPT-containing EP systems were modestly lower than that of EP/TETA system. The EP cured by 29wt% DPT (EP/DPT-29) achieved a limiting oxygen index (LOI) of 27.1% and a UL-94 V-0 rating, and its peak heat release rate (PHRR) and total smoke production (TSP) were 51.6% and 37.8% lower than those of EP/TETA. The improved flame retardancy and smoke suppression of the DPT-containing EP systems was attributed to the bi-phase flame-retardant action of DPT.