Synthesis And Application Of Polyphosphate Flame Retardant For Epoxy Resin

Epoxy Resin has been applied in various fields for its excellent comprehensive performance.However,its thermal properties and flame retardancy are poor,which directly affects the probability of fire,so it is necessary to modify the epoxy resin.Traditional halogen flame retardant toxic,harmful to the environment and life.Phosphorus flame retardant with high efficiency,low smoke,non-toxic,but it has the problem of low thermal stability.Polyphosphate ester flame retardants is a good solution to this shortcoming.And then combined with halogen-free flame retardants,e.g.ammonium polyphosphate(APP)and montmorillonite(MMT),used in epoxy resin can achieve more desirable results.The main research contents and results are as follows:(1)POPP and PBPP two kinds of flame retardants were synthesized by melting method.The functional groups were characterized by Fourier Transform Infrared Spectrometer(FTIR),and the Thermal Gravimetric Analysis(TGA)analyzed thermal properties.The result indicated that samples which containing POPP or PBPP have two decomposition stages,and its char residues were 36.39 % and 54.41 %.(2)Epoxy resin was cured by m-phenylenediamine,ethylenediamine and polyethylene polyamine,respectively.And the flame retardant properties of EP were tested by limiting oxygen index(LOI)and vertical burning test,and the mechanical properties were tested.It is concluded that m-phenylenediamine had the best curing effect and did not reduce the flame retardancy of EP.(3)Epoxy resin was modified with POPP and PBPP.With LOI and vertical burning test,TGA,Cone Calorimeter(CONE)and Scanning Electron Microscope(SEM)analysis of cured epoxy resin,thermal properties and morphology of residue char.The results showed that,POPP greatly improved the flame retardancy of EP,UL-94 reached V-0 level when adding POPP to 5 %,at this time,the content of phosphorus was only 0.67 %,but LOI was not as high as 24.2 %.LOI has been improved after adding MMT.The thermal decomposition temperature in TG is not much different.But the amount of residual char is obviously increased,indicating that the self-made flame retardants maintain the thermal stability of EP while adding carbon residue.Heat Release Rate(HRR)and Total Smoke Product(TSP)were significantly reduced in CONE.SEM showed that the residual char modified material had formed a closed carbon layer foam structure,its isolated heat and oxygen.It could effectively prevent combustion with good flame retardant effect.The above results in the complex APP and MMT,not only improved the LOI,and the amount of flame retardant addition could reach V-0 level;HRR and TSP are much lower with the increase of the amount of additive.And the formation of the expanded layered carbon layer could better prevent the combustion.But EP /PBPP,EP/PBPP/MMT brittle is too large to be made into splines for testing.Comprehensive results: POPP and PBPP modified EP achieved the desired effect,but the flame retardant efficiency of PBPP to EP is lower than POPP.In epoxy resin system,m-phenylenediamine is a good curing agent.Combine APP with MMT can get better flame retardant and thermal properties.It reduced the amount of flame retardants addition and saved the cost,which has a new application significance for the actual production.