Despite great advances in thermoplastic polyamide elastomers (TPAEs), it is still a significant challenge for preparing flame-retardant TPAEs with facile strategies. In this work, a series of novel intrinsically flame-retardant TPAEs (PA6PTMG-xCEPPAs) containing polyamide 6 as the hard segment, poly(tetramethylene glycol) (PTMG) as the soft segment, and 2-carboxyethyl phenyl phosphonic acid (CEPPA) as a phosphorus-based flame-retardant unit were successfully synthesized through a facile one-step synthetic method. The properties of as-prepared PA6PTMG-xCEPPA were fine-tuned by varying the CEPPA content after determining the ratio of soft and hard segments. Results showed that increasing the CEPPA content significantly enhanced the flame retardancy of PA6PTMG-xCEPPA. The resultant PA6PTMG-4CEPPA and PA6PTMG-6CEPPA could obtain limiting oxygen index (LOI) values of approximately 25.0 and 28.4%, respectively, both meeting V-0 rating in UL-94 tests. The flame-retardant mechanism can be ascribed to involve char layer formation in the condensed phase and free-radical quenching in the gas phase. However, with increasing CEPPA unit content, the intrinsic viscosity, thermal properties, crystallinity, mechanical properties, and spinnability of the as-prepared PA6PTMG-xCEPPA decreased. Fortunately, PA6PTMG-4CEPPA with superior flame retardancy still presented excellent spinnability, and the corresponding elastic fibers had 83.3% elongation at break and 1.57 cN/dtex tensile strength, indicating its outstanding comprehensive properties. Therefore, the as-prepared intrinsically flame-retardant TPAEs possess promising potential for widespread application across various industrial sectors.

中文翻译：

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新型本质阻燃热塑性聚酰胺 6 弹性体的一步合成：结构、性能和可纺性


尽管热塑性聚酰胺弹性体 （TPAE） 取得了巨大进步，但使用简单的策略制备阻燃 TPAE 仍然是一个重大挑战。本工作通过简单的一步合成方法，成功合成了一系列以聚酰胺 6 为硬链段、以聚四亚甲基二醇 （PTMG） 为软链段、2-羧乙基苯基膦酸 （CEPPA） 为磷系阻燃单元的新型本质阻燃 TPAE （PA6PTMG-xCEPPAs）。在确定软链段和硬链段的比例后，通过改变 CEPPA 含量来微调所制备的 PA6PTMG-xCEPPA 的性能。结果表明，增加 CEPPA 含量显著增强了 PA6PTMG-xCEPPA 的阻燃性。所得 PA6PTMG-4CEPPA 和 PA6PTMG-6CEPPA 可分别获得约 25.0% 和 28.4% 的极限氧指数 （LOI） 值，均符合 UL-94 测试中的 V-0 等级。阻燃机制可归因于在凝聚相中形成碳层，在气相中自由基猝灭。然而，随着 CEPPA 单位含量的增加，所制备的 PA6PTMG-xCEPPA 的特性粘度、热性能、结晶度、机械性能和可纺性均有所降低。幸运的是，具有优异阻燃性的 PA6PTMG-4CEPPA 仍然表现出优异的可纺性，相应的弹性纤维具有 83.3% 的断裂伸长率和 1.57 cN/dtex 的拉伸强度，表明其出色的综合性能。因此，所制备的本质阻燃 TPAE 具有在各个工业领域广泛应用的潜力。