磷杂菲衍生物的合成及对环氧树脂阻燃性能与热降解行为的影响

Synthesis of Phosphaphenanthrene Derivative and Flame Retardancy and Thermal Degradation Behavior of Epoxy Resin Composites

以9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物(DOPS)与对苯醌为原料,合成10-(2,5-二羟基苯基)-10-氢-9-氧杂-10-磷杂菲-10硫化物(DOPS-HQ),采用傅里叶变换红外光谱、核磁共振和高分辨质谱确定其结构,并将其应用于环氧树脂(EP)的阻燃改性。采用热重分析、垂直燃烧、极限氧指数、锥形量热和热重-红外光谱联用(TG-FTIR)等手段研究了阻燃剂DOPS-HQ对EP的热稳定性、热降解行为及阻燃性能的影响。结果表明,阻燃剂DOPS-HQ能提高复合材料的热稳定性和残炭量,改善材料的阻燃性能,降低其热释放速率峰值(PHRR)和总热释放量(THR)。当DOPS-HQ的质量分数为15%时,复合材料的极限氧指数(LOI)值提高至32.5%,达到UL-94 V-0级,其PHRR和THR分别降低了32.7%和38.2%。TG-FTIR结果表明,DOPS-HQ/EP在热降解过程中会产生含磷自由基(PO·,HPO_(2)·,PO_(2)·等)作为H·,O·或HO·自由基的捕捉剂,从而主要在气相中发挥阻燃作用。

10-(2,5-Dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-sulfide(DOPS-HQ)was synthesized from 9,10-dihydro-9-oxa-10-phosphophene-10-sulfide(DOPS)and p-benzoquinone,and used to modify epoxy resin(EP).The structure was determined by Fourier transform infrared spectroscopy(FT-IR),NMR and high resolution mass spectrometry(HR MS).The effects of DOPS-HQ on the thermal stability,thermal degradation behavior and flame retardancy of EP were further investigated by thermogravimetric analysis(TG),vertical flame test(UL-94),limit oxygen index(LOI)test,cone calorimeter test(CONE)and thermogravimetric-infrared spectroscopy analysis(TGIR).The results show that the flame retardant DOPS-HQ can promote the thermal stability and char formation,improve the flame retardancy and decrease its peak heat release rate(PHRR)and total heat release(THR).At the flame-retardant mass fraction of 15%,LOI value of DOPS-HQ/EP increases to 32.5%,the vertical combustion grade reaches UL-94 V-0,and its PHRR and THR are decreased by 32.7%and 38.2%respectively.The results of TG-IR show that DOPS-HQ/EP will generate phosphorus-containing radicals(PO·,HPO_(2)·,PO_(2)·)during thermal degradation as H·,O·or HO·radical scavengers,so DOPS-HQ plays a flame retardant role in gas phase.