Abstract Hydroxy-terminated waterborne polyurethane (WPU) and oxazolidone-containing epoxy (OXEP) matrix were designed to realize two-stage interface enhancement of WPU sized aramid fiber/oxazolidone-containing epoxy (WAF/OXEP) composite, and the interfacial properties and interphase reinforcing mechanism were investigated. Compared with commercial aramid fiber (CAF), the surface roughness and energy of WAF were increased, and the fracture toughness and elongation at break of OXEP matrix were improved relative to those of general epoxy (GEP) matrix. In contrast to CAF/GEP and CAF/OXEP composites, the flexible interphase with high bonding capability from WPU sizing was constructed in WAF/GEP composite, which released interphase stress through deformation and improved interfacial adhesion. The hierarchical interphase encompassing inner modulus intermediate layer and outer flexible layer was established in WAF/OXEP composite, which could prevent crack propagation onto fiber surface and induce crack deflection through the enhancement of modulus and deformability of hierarchical interphase.

中文翻译：

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芳纶纤维复合材料的两阶段界面增强：水性聚氨酯施胶剂和含恶唑烷酮环氧树脂基体的分层界面的建立

摘要 设计端羟基水性聚氨酯 (WPU) 和含恶唑烷酮环氧树脂 (OXEP) 基体，实现 WPU 上浆芳纶/含恶唑烷酮环氧树脂 (WAF/OXEP) 复合材料的两阶段界面增强，以及界面性能和界面研究了强化机制。与商用芳纶纤维（CAF）相比，WAF的表面粗糙度和能量增加，OXEP基体的断裂韧性和断裂伸长率相对于一般环氧树脂（GEP）基体有所提高。与 CAF/GEP 和 CAF/OXEP 复合材料相比，WPU 施胶具有高粘合能力的柔性界面是在 WAF/GEP 复合材料中构建的，它通过变形释放界面应力并提高界面粘合力。