Abstract In order to study the effect of strong electron-withdrawing group on thermal properties of polybenzoxazine, 4-cyanophenol-based benzoxazines were prepared and their cured samples were investigated by FTIR, TGA, TGA-FTIR, Py-GC–MS and LOI tests. FTIR results indicate that nitrile group hardly polymerized and existed in polybenzoxazine at present cured conditions. TGA results show that the introduction of nitrile group in phenol could remarkably improve the char yield at 800 °C, thermal and thermo-oxidative stability of polybenzoxazine compared with the analogous polybenzoxazines without electron-withdrawing group. Moreover, nitrile group decreased the charge density of phenolic ring and made hydroxyl be cleared more easily, the free hydroxyl not only could oxidize −CH2- of −CH2-NR−CH2- in polybenzoxaizne into CO2 but also transformed into H2O, resulting in that there was always a volatilization of CO2 and H2O during thermal degradation process. Furthermore, the incorporation of nitrile group also increased significantly the flame retardancy of polybenzoxazine.

中文翻译：

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通过掺入 4-氰基苯酚提高聚苯并恶嗪的热性能

摘要 为了研究强吸电子基团对聚苯并恶嗪热性能的影响，制备了 4-氰基苯并恶嗪类化合物，并通过 FTIR、TGA、TGA-FTIR、Py-GC-MS 和 LOI 测试研究了其固化样品。 . FTIR结果表明，在目前的固化条件下，聚苯并恶嗪中几乎不存在腈基团聚合并存在。TGA结果表明，与不含吸电子基团的类似聚苯并恶嗪相比，在苯酚中引入腈基可以显着提高聚苯并恶嗪的800℃焦炭产率、热和热氧化稳定性。此外，腈基降低了酚环的电荷密度，使羟基更容易清除，游离羟基不仅可以将聚苯并恶嗪中-CH2-NR-CH2-的-CH2-氧化成CO2，而且还转化为H2O，导致在热降解过程中总是有CO2和H2O的挥发。此外，腈基的引入也显着提高了聚苯并恶嗪的阻燃性。