Synthesis And Characterization Of Phosphorus-silicon Flame Retardant And Its Application In Epoxy Resin

In this paper,pentaerythrotol and phosphorus oxychloride as raw material for the synthesis of intermediate 2,6,7-Trioxa-1-phosphabicy-clo2.2.2octane-4-methanol,then the flame retardant vinyl methyl2(1-methoxy phospha-4-hydroxymethyl-2,6,7-three oxabicyclo[2.2.2]octane)silane(DPMVSi)wassynthesizedbyPEPAand Dichloro Methylvinylsilane(DCMVS).ThestructureofPEPAand DPMVSi was characterized by FTIR?LC-MS and1H NMR.In addition,a newtypeofpolymericphosphorusandsilico-containingflame retardant Poly-2-(9,10-dihydro-9-oxa-10-phosphine-10-oxide)-1,4-dip-he-noxy-methylvinylsilylether(PODOPBVS)wassuccessfully synthesized,using10-(2,5-dihydroxyphenyl)-9,10-dihyd-ro-9-oxa-10-ph osphine-10-oxide(ODOPB)and dichloromethylvinylsi-lane(DCMVS)as raw materials and imidazole as acid binding agent.The effect of solv-ent,acid binding agent and ODOPB on the yield of DCMVS was investigated by orthogonal test.The structure and thermal properties of the polymer PODOPBVS were characterized by FTIR,~1HNMR and TGA.EP/PODOPBVS composites were prepared by adding PODOPBVS into EP with different amounts.The thermal properties,mechanical properties and flame retardancy of epoxy resin(EP)composites were studied by TGA,DSC,tensile tester,impact tester,LOI,UL-94 vertical combustion test and cone calorimeter.The TGA results show that the thermal stability of EP composites increases with the increase of the amount of flame retardants,and the char residual at 700°C also increased.The DSC results displays that The addition of a flame retardant reduces the free volume in the EP molecule,thus increasing the Tg of EP composites.The tensile and impact tests show that the addition of flame retardant causes the mechanical properties of EP to with a small drop,LOI and the vertical combustion test results show thatTheadditionofflameretardantimprovestheLOIand combustibility of EP,and its flame retardant performance increases with the increase of the flame retardant.The cone calorimetric analysis shows that the addition of flame retardant can significantly improve the flame retardant properties of EP.Compared with neat EP,EP7's peak heat release rate(PHRR)and total heat release(THR)have decreased respectively.Otherwise,with the addition of the flame retardant the flame retardancy of the EP7 was significantly improved.In addition,the smoke release rate,the release rate of CO and CO2 of EP7 were obviously decreased.Furthermore,compared to neat EP,the char residual after cone calorimetric test of EP7 increased by 119%.The performance of the flame retardant added to the EP shows that the catalytic char formation of the phosphorus in the flame retardant and the high-temperature carbon-fixing of the silicon contribute to a significant increase in the amount of char residual,which is achieved through the rapid formation of the carbon layer.Covering and insulating the role of combustible gas,thus inhibiting the burning of EP to achieve the purpose of flame retardant.