含磷液氧相容环氧树脂的热降解行为

Thermal degradation behaviors of phosphorus-containing liquid oxygen-compatible epoxy resin

碳纤维/环氧树脂复合材料液氧贮箱对重型火箭和空天飞机等新一代航天器减重具有重要意义。然而,环氧树脂与液氧不相容制约了其应用。采用热重分析、Kissinger方法、Coasts-Redfern方法、热重-红外-气质联用技术对10-(2,5-二羟基苯基)-10-氢-9-氧杂-10-磷杂菲-10-氧化物(ODOPB)改性液氧相容环氧树脂(ODOPB-EP)的热降解行为及机制进行了研究。结果表明:ODOPB-EP的热降解机制为相边界反应,对应的降解机制函数g(α)=1−(1−α)^(1/3),α为转化率。在热降解过程中,树脂先从C−N和C−O弱键处断裂,随着温度升高,释放出苯酚及其衍生物等芳香类物质,且ODOPB在树脂中会分解产生联苯等物质,在这个过程中会伴随着含磷自由基的释放,在气相能起到淬灭作用,有利于提高树脂的液氧相容性,为探明聚合物的液氧相容机制提供了理论基础。

The liquid oxygen tanks that made of carbon fiber/epoxy resin composites are vital for weight reduction in new generation spacecraft such as heavy rockets and space shuttles.However,the incompatibility of epoxy resin with liquid oxygen limits their application.Thermogravimetric analyser,the Kissinger method,the Coasts-Redfern method and thermogravimetric-infrared-gas chromatography/mass spectrometry were used to investigate the thermal degradation behaviors and mechanism of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphafi-10-oxide(ODOPB)-modified liquid oxygen-compatible epoxy resin(ODOPB-EP).The results show that the thermal degradation mechanism of ODOPB-EP is a phase boundary reaction,corresponding to the degradation mechanism function g(α)=1−(1−α)^(1/3),α is conversion rate.During the thermal degradation process,the resin breaks from the weak bonds of C−N and C−O.With the increase of temperature,aromatic substances such as phenol and its derivatives are released.Besides,ODOPB part in resin produces biphenyl and other substances,accompanied by the release of phosphorus-containing radicals.The phosphorus-containing radicals could exert quenching effects,which is conducive to improving the compatibility of the resin with liquid oxygen.This study provides a theoretic basis for verifying the compatible mechanism of polymers with liquid oxygen.