Driven by the need to reduce the carbon footprint of materials, natural fibres reinforced composites are increasingly used. Today, their level of maturity allows to consider their applications in fields where high performance such as flame retardancy are required. This article compares the fire retardant properties of flax laminates based on two thermosets resins, a bio‐based polybenzoxazine and a petroleum‐based epoxy, both considered for aeronautical applications. The effect of alkaline and silane surface modifications of the fibres on the properties of the composites was investigated. The treatments of the flax were proven to allow a better impregnation of the fibres by the matrices but at the same time more defects were observed. Regarding the fire behaviour of the composites, no difference of flammability was highlighted between the treated and untreated materials. The burnthrough resistance evaluation was performed using a small‐scale aeronautical test. The better performance of the epoxy‐based composite compare to the polybenzoxazine one was shown whereas charring is favoured for polybenzoxazine. The low deformability of the char formed when polybenzoxazine decomposes leads to the formation of cracks with the subsequent failure of the test.

中文翻译：

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亚麻织物/聚苯并恶嗪层压材料的制备和阻燃性

由于需要减少材料的碳足迹，因此越来越多地使用天然纤维增强的复合材料。如今，它们的成熟度使其可以考虑在要求高性能（例如阻燃性）的领域中应用。本文比较了基于两种热固性树脂（生物基聚苯并恶嗪和石油基环氧树脂）的亚麻层压板的阻燃性能，两者均被考虑用于航空领域。研究了纤维的碱和硅烷表面改性对复合材料性能的影响。亚麻处理被证明可以使基质更好地浸渍纤维，但同时观察到更多的缺陷。关于复合材料的防火性能，在处理过的材料和未处理的材料之间没有突出显示可燃性差异。耐烧穿性评估是使用小型航空试验进行的。结果表明，与聚苯并恶嗪相比，环氧基复合材料具有更好的性能，而聚苯并恶嗪则有利于炭化。当聚苯并恶嗪分解时形成的炭的低变形性导致裂纹的形成，随后的测试失败。