Abstract In this study, the self-stiffening under cyclic dynamic strain has been observed in polymeric blends containing polyacrylonitrile (PAN) and various contents of thermoplastic polyurethanes (TPU). The increase of the stiffness depends on the phase diagram of the blend, and it was found that the efficiency of self-stiffening decreases when phase separation occurs. Also, TPU containing alternative hard and soft blocks. When the hard block content in TPU increases, the self-stiffening becomes more effective. The interactions between PAN and TPU were investigated by different characterization methods. The soft and hard blocks of TPU plays different roles on the self-stiffening of the PAN/TPU blends, and the interface in between hard blocks and PAN matrix is crucial for the mechanical enhancement. These results indicate that the interface in between polymer chains with significant property difference could possibly lead to unique behaviors. Here, we observe that the fatigue life of PAN films under cyclic strains increases to more than 28 times, as well as the cyclization peak shifts to lower temperature and becomes broader with the addition of 0.5 wt % TPU. These interfaces induced unique behaviors, such as self-stiffening and longer fatigue life, would be valuable for the future developments of adaptable structural materials.

中文翻译：

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聚丙烯腈/热塑性聚氨酯复合材料中的动态自硬化

摘要 在这项研究中，在含有聚丙烯腈 (PAN) 和各种含量的热塑性聚氨酯 (TPU) 的聚合物共混物中观察到循环动态应变下的自硬化。刚度的增加取决于共混物的相图，并且发现当发生相分离时自强化效率降低。此外，TPU 包含替代的硬块和软块。当 TPU 中的硬嵌段含量增加时，自硬变得更加有效。通过不同的表征方法研究了 PAN 和 TPU 之间的相互作用。TPU 的软硬块对 PAN/TPU 共混物的自硬化作用不同，硬块和 PAN 基体之间的界面对机械增强至关重要。这些结果表明，具有显着性质差异的聚合物链之间的界面可能会导致独特的行为。在这里，我们观察到 PAN 薄膜在循环应变下的疲劳寿命增加到 28 倍以上，并且环化峰向较低温度移动并随着添加 0.5 wt% TPU 变得更宽。这些界面引起了独特的行为，例如自刚度和更长的疲劳寿命，对于适应性结构材料的未来发展将是有价值的。