Two phosphorus-containing flame retardants, (bis(4-hydroxyphenyl)methyl)diphenyl phosphine oxide (DPO–PHE) and 1-(bis(4-hydroxyphenyl)methyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO–PHE) were synthesized and characterized. The two target compounds both were used as a flame retardant and a co-curing agent of 4,4′-diaminodiphenylsulfone of bisphenol A diglycidyl ether to prepare flame-retardant epoxy resins (EP/DPO–PHE and EP/DOPO–PHE). The thermal and flame-retardant properties of the thermosets were investigated by thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, and UL-94 vertical burning testing (UL-94). The results indicated that both flame retardants can improve the flame retardancy of epoxy thermosets. TGA results indicated that the char yields of EP/DPO–PHE–P-0.9 and EP/DOPO–PHE–P-0.9 thermosets were increased from 19.1% of EP/P-0 to 25.3% and 27.8%, respectively. Compared with that of EP/P-0, the LOI of the EP/DPO–PHE–P-0.5 thermoset increased from 23.7% to 30.1%, and the sample reached UL-94 V-0. Meanwhile, the LOI of the EP/DOPO–PHE–P-0.7 thermoset increased from 23.7% to 28.9%, and the sample reached UL-94 V-0. Cone calorimetry test, scanning electron microscopy of burning residues, and pyrolysis–gas chromatography/mass spectrometry indicated that both flame retardants mainly act through the gas–phase mechanism. In addition, no condensed-phase activity of DPO–PHE was observed, whereas the condensed-phase activity of DOPO–PHE was negligible. Immersion experiments showed that the water absorption activity of flame retardant epoxy resins fluctuates. Compared with DOPO–PHE, DPO–PHE was more effective as a higher flame-retardant and exhibited better characteristics for improving the T_g, thermal stability, and water absorption of modified resins.

两种含磷阻燃剂，（双（4-羟基苯基）甲基）二苯基氧化膦（DPO-PHE）和1-（双（4-羟基苯基）甲基）-9,10-二氢-9-氧杂-10-磷酸苯菲合成并表征了-10-氧化物（DOPO-PHE）。两种目标化合物均用作双酚A二缩水甘油醚的4,4'-二氨基二苯砜的阻燃剂和共固化剂，以制备阻燃环氧树脂（EP / DPO-PHE和EP / DOPO-PHE）。通过热重分析（TGA），极限氧指数（LOI）测量和UL-94垂直燃烧测试（UL-94）研究了热固性塑料的热和阻燃性能。结果表明，两种阻燃剂均可提高环氧热固性塑料的阻燃性。TGA结果表明，EP / DPO-PHE-P-0.9和EP / DOPO-PHE-P-0的焦炭收率。9种热固性塑料分别从EP / P-0的19.1％增加到25.3％和27.8％。与EP / P-0相比，EP / DPO-PHE-P-0.5热固性材料的LOI从23.7％增加到30.1％，样品达到UL-94 V-0。同时，EP / DOPO-PHE-P-0.7热固性材料的LOI从23.7％增加到28.9％，样品达到UL-94 V-0。锥形量热测试，燃烧残留物的扫描电子显微镜以及热解-气相色谱/质谱法表明，两种阻燃剂均主要通过气相机理起作用。此外，未观察到DPO–PHE的凝相活性，而DOPO–PHE的凝相活性可忽略不计。浸没实验表明，阻燃环氧树脂的吸水活性会发生波动。与DOPO–PHE相比，T _g，热稳定性和改性树脂的吸水率。