2-羧乙基苯基次膦酸盐的合成及其在尼龙6中的阻燃应用

Synthesis of 2-Carboxyethylphenylphosphinate and Its Flame Retardant Application in Nylon 6

通过复分解反应合成了三种2-羧乙基苯基次膦酸盐(CEPCA、CEPAL、CEPSN)阻燃剂,其化学结构被傅里叶红外光谱(FTIR)、核磁共振氢谱( 1 H NMR)与元素分析所表征。随后,它们被分别加入尼龙6中制备阻燃复合材料(FRPA6),利用热重分析(TG)、垂直燃烧测试、极限氧指数( LOI )测试和扫描电子显微镜(SEM)对FRPA6的热性能、阻燃性能与残炭形貌进行了分析。结果表明,三种次膦酸盐的热稳定性较2-羧乙基苯基次膦酸(CEPPA)都有较大提升,CEPCA的热分解温度( T -5%)上升最明显,由223.4 ℃上升到539.1 ℃。从阻燃性能看,CEPAL的阻燃性能最佳,在添加量为20%时,其 LOI 为32.1%并达到UL94 V-1等级。CEPAL阻燃性能更好的原因在于,其燃烧后生成了更加致密、完整的炭层,这种炭层能有效隔热隔氧从而中断燃烧行为。

Three kinds of 2-carboxyethyl(phenyl)pophosphite(CEPCA,CEPAL,CEPSN)were synthesized by metathetical reaction.Their chemical structures were characterized by fourier transform infrared spectroscopy(FTIR),H-nuclear magnetic resonance( 1 H NMR)and elemental analysis.Then they were added into nylon 6 to prepare flame retardant composites(FRPA6).The thermal properties,flame retardancy and carbon residue morphology were tested by thermogravimetric analysis(TG),vertical burning test,limit oxygen index( LOI )test and scanning electron microscopy(SEM).The results show that the thermal stability of these three pophosphites is much higher than that of 2-carboxyethyl(phenyl)phosphinic acid(CEPPA)and the decomposition temperature( T -5%)of CEPCA increases most obviously from 223.4 ℃to 539.1 ℃.Besides,CEPAL has the best flame retardancy.When the addition amount is 20%,its LOI value is 32.1%and it could achieve UL94 V-1 rating.The reason for better flame retardancy of CEPAL is that CEPAL can form a denser and complete carbon layer during combustion.This carbon layer can effectively insulate against heat and oxygen,and interrupt combustion behavior.