Study On Synthesis Of Reactive Phosphorusnitrogen Flame Retardant(BPOAP) And Its Flame-retardant Polyamide 66

Polyamide has been widely used in automotive,mechanical,electronic,chemical and other industries because of its excellent comprehensive properties.However,the applications of PA66 are limited because of its poor fire resistance.The limiting oxygen index(LOI)of PA66 is only 24,and the level of PA66 reaches V-2 level.Additive flame retardant has been applied for achieving flame-retardant PA66.Nevertheless,there is a variety of problems such as poor compatibility and decline in mechanical properties.In this paper,an active flame retardant containing PhosphorousNitrogen is synthesized,which possesses high phosphorus content.The modified inherent flameretardant PA66 was prepared through polymerization reaction.A novel reactive Phosphorus-Nitrogen flame retardant,2,2-bis(4-(phenoxy-phenylphosphine oxide)-(aminobenzoic acid))propane(BPOAP),was synthesized by the reaction of bisphenol A(BPA),Dichlorophenylphosphine oxide(DCPPO)and para aminobenzoic acid(PABA).The optimum synthesis conditions of BPOAP were determined.FTIR,NMR and elemental analysis results of BPOAP showed that the chemical structure of BPOAP was confirmed.The phosphorus content of BPOAP was as high as 8.25%.The TGA results indicated that the initial decomposition temperature of BPOAP was about 230?,exceeding the polymerization temperature(210?).The carbon residual rate was 42% when the temperature reached 600?.BPOAP salt,which owned similar structure to PA66 salt,was synthesized by BPOAP and hexamethylendiamine.Flame-retardant PA66(FR-PA66)was prepared by polymerizing of BPOAP salt and PA66 salt.FTIR results showed that BPOAP had been embedded in PA66 molecular chain.FR-PA66 was prepared successfully.Flame retardant properties of FR-PA66 improved with the increasing of BPOAP content.The LOI value and UL-94 level respectively reached 28 and V-0 level,when the addition of BPOAP was 4.5%.The total heat release(THR)and total smoke production(TSP)values of FR-PA66 were 25.57%,14.71% less than that of pure PA66,which indicated that FR-PA66 owned better flame retardant properties.The introduction of BPOAP declined the melting temperature,glass transition temperature and crystallinity of FR-PA66,while the initial decomposition temperature and maximum decomposition temperature of FR-PA66 were enhanced.The intrinsic viscosity and viscosity average molecular weight of FR-PA66 were lower than that of pure-PA66.It was found that addition of BPOAP had little effects on the mechanical properties of PA66.