Intumescent flame retardant prepared by inverse suspension polymerization and its application in styrene-butadiene rubber

The sodium polyacrylate-in situ encapsulated intumescent flame retardant(IFR) was prepared in the inverse suspension polymerization of sodium acrylate by adding ammonium polyphosphate,pentaerythritol and melamine,and Fourier transform infrared spectroscopy was used to characterize the structure of the flame retardant.The effects of melamine amount and the mass ratio of ammonium polyphosphate to pentaerythritol on the flame retardancy of styrene-butadiene rubber(SBR) vulcanizates were investigated,the thermal property of flame retardant SBR was studied by thermogravimetry,and the combustion surface morphology of SBR filled with IFR was observed by scanning electron microscopy.The results showed that when the mass fraction of melamine was 3.0% in IFR system,the mass ratio of ammonium polyphosphate to pentaerythritol was 4.00 to 5.67,the carbon residue yield of the system was the highest and the flame retardancy was better.The flame retardancy of SBR with IFR was improved correspondingly.When the IFR mass fraction was 30% in styrene-butadiene rubber vulcanizate,the oxygen index of the flame retardant rubber could achieve up to 27.5%;the SBR filled with IFR could form a relatively dense layer of carbon foam when it was burned,indicating that the IFR had a better intumescent flame retardant effect on SBR.