Abstract We report a series of PI composite fibers containing polyhedral oligomeric silsesquioxane (POSS). These fibers were fabricated by a three-step process consisting of the in situ polycondensation of POSS and polyamic acid, wet spinning, and thermal imidization. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy proved that POSS enriched the surface of POSS/PI composite fibers during wet spinning. This surface enrichment enhanced the resistance to atomic oxygen (AO) erosion. After exposing the POSS/PI composite fibers to AO fluence up to 2.93 × 1020 atoms cm−2, the fibers still displayed excellent AO resistance. With increased POSS content from 0 wt% to 20 wt%, the retention of fracture strength and initial modulus considerably improved from 54% to 93% and from 64% to 91%, respectively. Moreover, the decay rates of fracture strength of the composite fibers obviously decreased at the same AO fluence with increased POSS content from 0 wt% to 20 wt%. AO erosion at a larger fluence further resulted in more effective AO resistance for composite fibers with higher POSS content. XPS results suggested as well that silicate passivated layers formed on the fiber surfaces after AO exposure, and these layers prevented the fibers from further AO erosion.

中文翻译：

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通过湿纺增强表面富集的 POSS/聚酰亚胺复合纤维对原子氧暴露的抵抗力

摘要 我们报道了一系列含有多面体低聚倍半硅氧烷 (POSS) 的 PI 复合纤维。这些纤维是通过三步法制造的，包括 POSS 和聚酰胺酸的原位缩聚、湿法纺丝和热亚胺化。X 射线光电子能谱 (XPS) 和能量色散 X 射线光谱证明 POSS 在湿纺过程中丰富了 POSS/PI 复合纤维的表面。这种表面富集增强了对原子氧 (AO) 侵蚀的抵抗力。将 POSS/PI 复合纤维暴露于高达 2.93 × 1020 原子 cm−2 的 AO 能量密度后，纤维仍显示出优异的抗 AO 性能。随着 POSS 含量从 0 wt% 增加到 20 wt%，断裂强度保持率和初始模量分别从 54% 到 93% 和从 64% 显着提高到 91%。而且，在相同的AO注量下，随着POSS含量从0 wt%增加到20 wt%，复合纤维的断裂强度衰减率明显降低。对于具有较高 POSS 含量的复合纤维，较大通量下的 AO 侵蚀进一步导致更有效的 AO 抗性。XPS 结果还表明，在 AO 暴露后，在纤维表面形成了硅酸盐钝化层，这些层阻止了纤维进一步受到 AO 侵蚀。