Synthesis Of Triazine Charring-foaming Agents And Evaluations On Its Flame Retardation In Polypropylene

Polypropylene(PP)is widely applied in various fields by virtue of non-toxicity,low density and excellent chemical resistance.However,its further application is limited on account of its inflammability.The triazine flame retardants exhibit many advantages,such as lower volatility,higher flame retardant efficiency,innocuity,good compatibility,better thermal stability and so on.Thus,the trazine derivatives are synthesized continuously and used as flame retardant in PP.In this paper,six novel triazine derivatives have been designed and synthesized.Meanwhile,their application has been investigated.Intermediate 1 was synthesized via cyanuric chloride and morpholine in 3% NaCl solution with NaOH as acid-binding agent.The aqueous solution of intermediate 1 and ethylenediamine(molar ratio of intermediate 1 and ethylenediamine is 1:1.2)was refluxed for 15 h to afford the product M2-CFA.M4-CFA,M6-CFA,E2-CFA,E4-CFA and E6-CFA were similarly synthesized.As shown by the thermal gravimetric analysis(TGA)results,M2-CFA,M4-CFA and M6-CFA displayed nice thermal stability.Thus,M6-CFA,M4-CFA and M2-CFA were combined with APP and SiO2,respectively,resulting three novel intumescent flame retardant systems(IFRs),which were added to PP by melt blending to form intumescent flame retardant polypropylene composite materials(IFR-PP).Limiting oxygen index(LOI),vertical combustion method(UL-94)and TGA were employed to examine the influence of IFRs on the flame retardancy and thermal stability of PP.The results indicated that LOI value of PP increased from 17% to over 30%,and all through UL-94 V-0 rating,without droplet generation throughout the test.Furthermore,the morphology and microstructures of the residual char formed during combustion were studied by SEM,XRD,Raman spectroscopy and FT-IR.It was found that PP2 presented the best flame retardant among PP1,PP2 and PP3.The morphology of the char layer of PP2 formed was complete,smooth,dense and continuous and the degree of graphitization is higher than PP1 and PP3,which were attributed to its good flame retardancy.Therefore,M2-CFA,M4-CFA and M6-CFA have good flame retardant performance,in which M4-CFA is the best.