Preparation Of New Phosphorus Nitrogen Flame Retardant And Study On Flame Retardant Epoxy Resin

Epoxy resin?EP?has been recognized as a kind of high performance thermoset resins,owing to its excellent properties such as outstanding mechanical properties,low shrinkage and dielectric constant and excellent processing performance.It is widely used in various fields such as adhesives,electrical insulation,coating protection,composite materials and electronic components.However,But the high flammability of epoxy resins leads easily to secondary combustion with the melting droplets after being removed from the fire.And it has become a restriction on the application and need to be resolved urgently.The current research about epoxy resin flame retardant modification is aim to achieve a balance of compatibility,flame retardant properties,mechanical properties.Therefore,to synthesize a flame retardant with good compatibility and high performance has very important application value.In this paper,epoxy resin was modified by a reactive flame retardant with a multifunctional phosphazene and imine or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide?DOPO?composite structure.The influence of two different flame retardant structures and the related content with mechanical properties was discussed,and the conclusions are as follows.?1?A multifunctional amine-terminated phosphazene/imine compound reactive flame retardant?PAA?was synthesized as a co-curing agent with hexachl-orocyclotriphosphazene,p-hydroxybenzaldehyde and p-phenylenediamine,and the flame-retardant epoxy resin?PAA/EP?was prepared.The results show that when the PAA content is 20 wt%,the resin has the best overall performance,and its bending strength,tensile strength,elongation at break,and impact strength are 126.3 MPa,80.5 MPa,5.4%,and 44.0 KJ/m²,respectively.T_5%is about 342.0?,the residual rate is 29.8%,the LOI value is 28.6%,and it reaches V-0 level.?2?In order to improve the flame retardant efficiency and the compatibility,hexachlorocyclotriphosphazene,hydroquinone,epichlorohydrin and DOPO were used as raw materials to synthesize a multifunctional epoxy-terminated phosphazene/DOPO composite reactive flame retardant?PZ-DOPO?as an epoxy comonomer,and flame retardant epoxy resin?PZ-DOPO/EP?was prepared.The results show that,when compared with PAA,PZ-DOPO has better compatibility and flame retardant effect on epoxy resin.Although the residual of PZ-DOPO/EP is lower than the PAA/EP,owing to the obvious synergistic flame retardant effect between the phosphazene and DOPO structures,PZ-DOPO/EP with the phosphorus content 1wt%?addition of PZ-DOPO is about 13.5 wt%?can reach to V-0 level,the LOI value is 27.5%,and the residual rate is 19.2 wt%.The corresponding bending strength,tensile strength,elongation at break,and impact strength of the PZ-DOPO/EP were 145.9 MPa,97.2 MPa,4.8%,and 47.7 KJ/m²,respectively.T_5%and T_g are 325.9?and 180.3?,respectively.So the addition of PZ-DOPO has significantly improved the overall performance of epoxy resins.