Synthesis And Application Of A Triazine Derivative Containing Boron As Flame Retardant In Epoxy Resins

Traditional halogen flame retardants are easy to release toxic gases during the combustion process,which seriously endanger the environment and human health.The development of novel non-halogen,high efficiency,smoke suppression and low toxicity flame retardants is therefore important.Inogranic boron flame retardants caused a serious concern due to their high efficiency and anti-dripping.However,compared with inorganic boron flame retardants,the fire performance of organic boron flame retardants are less reported.In order to developmemt novel organic boron flame retardants,triazine derivatives 2,4,6-triphenoxy-1,3,5-triazine(TN)and 2,4,6-tris(4-boronphenoxy)-(1,3,5)-triazine(TNB)were synthesized and characterized by nuclear magnetic resonance spectroscopies and Fourier-transform infrared spectroscop.The chemical structures of TN and TNB are as follows.???Epoxy resin(EP)has been used in a wide range of applications due to its excellent mechanical properties,high adhesion and chemical resistances.However,EP burns easily,which greatly limits its application in a wider area.Thus,it is therefore necessary to improve the flame-retardant properties of EP.In this paper,we used TN and TNB as flame retardants,investigated their flame retardancy and possible flame retardant mechanisms on EP.The results showed that TN had no significant flame retardancy on EP,but with the increase of TNB content,the flame retardancy of EP increased gradually.When 20% TNB was added to EP,the limiting oxygen index(LOI)value reached 31.2%,achieved the UL 94 V-0 rating,the peak heat release rate(PHRR),total heat release(THR)and average mass loss rate(av-MLR)were decreased by 71.3%,27.8% and 92.0%,respectively,compared with pure EP.The flame retardant mechanism was investigated by X-ray diffraction,scanning electron microscopy,laser Raman spectroscopy,elemental analysis,and thermogravimetric analysis-infrared spectroscopy.The results show that TNB is not only a good charring agent,but also an intumescent flame retardant,which is effective in the gas and condensed phases simultaneously.The synergistic flame retardancy of TNB and APP was also studied.The results showed that when the mass ratio of TNB to APP was 1:2 and the total amount was 5%,the LOI of EP was 29.5%,achieved the UL 94 V-0 rating,and the PHRR and THR were decreased,TNB and APP has good synergistic flame retardant effect.