Polyurea (PU) elastomers have become increasingly popular in recent years due to their exceptional blast mitigation, ballistic protection, and wear resistance properties. However, their applications as protective materials are often limited as a result of their high flammability. In this study, aromatic dianhydrides (ArDAs) were employed to capture the thermal decomposing products of PU during combustion and facilitate the generation of highly heat-resistant aromatic polyimides (i.e., end group capturing effect), thus enhancing the material's char-forming ability and improving its flame retardancy. The ArDAs were found to significantly reduce the peak heat release rate (PHRR), total heat release (THR), total smoke release (TSR), and total CO release (TCO) of PU, and meanwhile increased the amount of char residue. At 20 wt% content of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), PHRR, THR, TSR and TCO of PU were reduced by 70.6%, 32.5%, 44.7% and 58.8%, respectively, the char residue was increased by 405%, and the mechanical properties of PU were well maintained (88.5% tensile strength and 91.0% elongation at break of pure PU). These findings demonstrate that ArDAs could serve as a new kind of halogen/phosphorus-free flame retardant for PU elastomers.

中文翻译：

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使用芳香族二酐捕获聚脲弹性体端基以实现阻燃


近年来，聚脲 (PU) 弹性体因其卓越的防爆、防弹和耐磨性能而变得越来越受欢迎。然而，由于其高易燃性，它们作为防护材料的应用通常受到限制。本研究采用芳香族二酐（ArDAs）来捕获PU在燃烧过程中的热分解产物，并促进高耐热芳香族聚酰亚胺的生成（即端基捕获效应），从而增强材料的成炭能力和提高其阻燃性能。 ArDA 显着降低了 PU 的峰值热释放率 (PHRR)、总热释放量 (THR)、总烟气释放量 (TSR) 和总 CO 释放量 (TCO)，同时增加了残炭量。当3,3',4,4'-二苯甲酮四甲酸二酐（BTDA）含量为20 wt%时，PU的PHRR、THR、TSR和TCO分别降低了70.6%、32.5%、44.7%和58.8%，残留量增加了405%，并且PU的机械性能得到了很好的保持（纯PU的拉伸强度为88.5%，断裂伸长率为91.0%）。这些研究结果表明，ArDA 可以作为一种新型的 PU 弹性体无卤/磷阻燃剂。