Constructing phosphorus, nitrogen, silicon-co-contained boron nitride nanosheets to reinforce flame retardant properties of unsaturated polyester resin

In this work, we reported the synthesis of boron nitride nanosheets containing phosphorus, nitrogen and silicon co-existing elements as high-performance nanofillers in unsaturated polyester resin (UPR) for the first time and precisely performed structural characterization to confirm the covalent functionalization. After incorporating 3 wt% into UPR matrix, combustion behavior of UPR nanocomposites was investigated by cone calorimeter, demonstrating the obvious reduction of 28.2% and 38.0% in PHRR and THR, respectively. TG-IR-MS coupling technique was employed to reveal thermal degradation and toxic volatiles such as CO, phenyl derivatives, hydrocarbons. On the basis of gaseous and condensed phase, we reasonably proposed the flame retardant mechanism of boron nitride with phosphorus, nitrogen and silicon elements to increase flame retardant properties of UPR. It is expected to exploit covalent functionalization of boron nitride and its nanocomposites with high flame retardance.