Abstract Understanding the thermal pyrolysis of epoxies and their copolymers is important for identifying structural changes resultant from thermal transients, enabling identification of failure modes of high-performance composite materials. This work expands our understanding of the thermal pyrolysis of cured epoxies and the role of temperature and composition on products, pathways, and relative rates. Numerous researchers have explored the pyrolysis of bisphenol A (BPA) epoxy. Significantly fewer have studied bisphenol F (BPF), and copolymers of BPA and BPF have been neglected. In this work, a multifunctional pyrolysis gas chromatography mass spectrometer (PY-GC-MS) was used to investigate the degradation mechanism of homopolymerized BPA, BPF epoxies and their copolymers. For polymer identification, pyrolysis thermograms >450 °C resulted in the most extensive fragmentation and is useful for material identification, though lower temperatures show different degradation product profiles that provide mechanistic insight into thermal degradation pathways. Temperature greatly influences the accessible pyrolysis pathways of BPA, revealing dual mechanisms of formation for products p-isopropylphenol and p-isopropenylphenol. For BPF at low pyrolysis temperature the p,p-bisphenol F isomer is produced at significantly lower relative abundance compared to the abundance at higher temperatures tested, but production of the other two isomers changes little with respect to temperature. This suggests the epoxy components consisting of the p,p-bisphenol F isomer have higher thermally stability. Overall, the copolymer epoxies were found to have similar degradation products in stoichiometric distributions. The major exception was the formation of the p,p-bisphenol F isomer, which shows evidence of thermal stabilizing effects from addition of BPA epoxy.

中文翻译：

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温度对均聚双酚 A/F 环氧树脂和共聚物的可及热解途径的影响

摘要 了解环氧树脂及其共聚物的热解对于识别由热瞬变引起的结构变化非常重要，从而能够识别高性能复合材料的失效模式。这项工作扩展了我们对固化环氧树脂的热解以及温度和成分对产品、途径和相对速率的作用的理解。许多研究人员已经探索了双酚 A (BPA) 环氧树脂的热解。研究双酚 F (BPF) 的人明显更少，而 BPA 和 BPF 的共聚物则被忽略了。在这项工作中，多功能热解气相色谱质谱仪 (PY-GC-MS) 用于研究均聚 BPA、BPF 环氧树脂及其共聚物的降解机制。用于聚合物鉴定、热解热谱图 > 450 °C 导致最广泛的碎裂，可用于材料鉴定，但较低的温度显示不同的降解产物曲线，提供对热降解途径的机械洞察力。温度极大地影响 BPA 的热解途径，揭示了产物对异丙基苯酚和对异丙烯基苯酚的双重形成机制。对于低热解温度下的 BPF，与测试的较高温度下的丰度相比，p,p-双酚 F 异构体的相对丰度明显较低，但其他两种异构体的产量随温度变化很小。这表明由 p,p-双酚 F 异构体组成的环氧组分具有更高的热稳定性。全面的，发现共聚物环氧树脂在化学计量分布中具有相似的降解产物。主要的例外是 p,p-双酚 F 异构体的形成，这表明添加 BPA 环氧树脂具有热稳定作用的证据。