Study On The Synthesis Of Epoxy Resin Flame Retardant And The Performance Of Flame Retardant Epoxy Resin

A novel phosphorus-nitrogen flame retardant,DOPO-M,was synthesized by the reaction of DOPO with melamine,and an intermediate AEDP was synthesized by the reaction of phosphorous acid with acetonitrile.Two phosphorus-nitrogen flame retardants,AAEDP and PAEPA,were synthesized by the reaction of AEDP with ammonia and phenylphosphine dichloride respectively.Their structures were characterized by infrared spectroscopy?FT-IR?,¹H NMR,³¹P NMR and mass spectrometry?ESI-MS?,and their thermal properties were analyzed by TGA.The initial decomposition temperatures of DOPO-M and AAEDP in air were 243.7 and127.2?,respectively.The initial decomposition temperatures of PAEPA in nitrogen were191.2?,which could meet the requirements of epoxy resin processing.Conditions.Three flame retardants were added into epoxy resin E-51 and their thermal and char-forming properties were characterized by TGA.The results showed that the initial decomposition temperature of DOPO-M/E-51 system in air was 320,319 and 318?,that of AAEDP/E-51 system in air was 308.1,307.0 and 303.4 ? and that of PAEPA/E-51 system in nitrogen was 314.74,301.00 and 254.04 ?.Compared with pure epoxy resin,the initial decomposition temperatures of the three systems were slightly reduced,and the thermal weight loss rate of the system was significantly reduced during the decomposition process.The quality of the residual system was significantly higher than that of pure epoxy resin after 450 ?,and the carbon residue at 800 ? was significantly increased.The flame retardancy and mechanical properties of the three systems were tested.The results showed that in the DOPO-M/E-51 system,when phosphorus content was2.57%,it can pass UL-94 V-0,LOI could reach 29.3%,tensile strength and impact strength were 38.2MPa and 4.3KJ/m²,respectively,which is the best overall performance;when the content of phosphorus in PAEPA/E-51 system is 2.958%,it can pass UL-94 V-0,LOI can reach 29.7%,tensile strength and impact strength can reach38 MPa and 6.417 KJ/m²,respectively,the comprehensive performance of the system is the best;when the content of phosphorus is 2.645%,it can pass UL-94 V-0,LOI can reach 31.3%,tensile strength and impact strength can reach 36.8 MPa and5.3KJ/m²,respectively,the comprehensive performance of is the best.The morphology of the residual carbon of the three systems was analyzed by scanning electron microscopy.There was no dense carbon layer on the surface of the residual carbon of the pure epoxy resin after combustion.The surface of the residual carbon of the epoxy resin with DOPO-M,AAEDP and PAEPA had obvious dense and expansive carbon layer,which showed good potential flame retardancy as a whole.