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Synthesis and application of a benzoxazine-type phosphorus-containing monomer on epoxy/benzoxazine copolymer: Thermal stability and compatibility with liquid oxygen
Polymer Degradation and Stability ( IF 6.3 ) Pub Date : 2018-10-02 , DOI: 10.1016/j.polymdegradstab.2018.10.002
Cong Peng , Chang Gao , Yuhuan Yuan , Zhanjun Wu , Dayu zhou

Alkene-terminated monofunctional benzoxazine monomer (A-BA) was synthesized using allylamine, phenol and paraformaldehyde. Subsequently, the phosphorous-containing benzoxazine monomer (PBA) was obtained through the addition reaction between 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and A-BA in toluene. Finally, epoxy/benzoxazine copolymer with chemically-bonded DOPO was prepared using the synthesized PBA as hardener of DGEBA. DMA results showed that polymer with the chemically-bonded DOPO possessed higher modulus and crosslink density than that with physical-blended DOPO. Thermal gravimetric analysis (TGA) showed that the epoxy/benzoxazine copolymer possessed much better thermal stability around 500 °C and the DOPO-containing epoxy/benzoxazine copolymer showed promoted behavior compared to the neat one. The char residue of the epoxy/benzoxazine copolymer revealed dense surface layer and unbroken original dimension which was in accordance with the TGA results and the phosphorous-rich cover was observed. The liquid oxygen (LOX) compatibility of the copolymers was evaluated through mechanical impact in accordance with ASTM D2512-95 which showed that the LOX compatibility of the epoxy/benzoxazine copolymers were better than the epoxy/amine ones and the epoxy/benzoxazine copolymer including PBA exhibited promoted stability in the impact test. The surface elemental composition of the specimen before and after mechanical impact was investigated by X-ray photoelectron spectroscopy (XPS) and increased oxidation state of phosphorus was observed which explained the mechanism of phosphorus on promoting the LOX compatibility of the copolymer.



中文翻译:

环氧/苯并恶嗪共聚物上苯并恶嗪型含磷单体的合成与应用:热稳定性和与液氧的相容性

使用烯丙胺,苯酚和多聚甲醛合成了末端为烯烃的单官能苯并恶嗪单体(A-BA)。随后,通过在甲苯中的9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和A-BA之间的加成反应获得含磷的苯并恶嗪单体(PBA)。最后,使用合成的PBA作为DGEBA的固化剂,制备了具有化学键合DOPO的环氧/苯并恶嗪共聚物。DMA结果表明,与化学键合的DOPO相比,化学键合的DOPO具有更高的模量和交联密度。热重分析(TGA)表明,环氧/苯并恶嗪共聚物在500°C左右具有更好的热稳定性,并且与纯净的相比,含DOPO的环氧/苯并恶嗪共聚物表现出增强的性能。环氧/苯并恶嗪共聚物的炭残留物显示出致密的表面层和完整的原始尺寸,这与TGA结果一致,并且观察到了富磷覆盖物。根据ASTM D2512-95通过机械冲击评估了共聚物的液氧(LOX)相容性,结果表明,环氧/苯并恶嗪共聚物的LOX相容性优于环氧/胺和包括PBA的环氧/苯并恶嗪共聚物在冲击试验中表现出增强的稳定性。通过X射线光电子能谱(XPS)研究了机械冲击前后样品的表面元素组成,并观察到磷的氧化态增加,这解释了磷促进共聚物的LOX相容性的机理。

更新日期:2018-10-02
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