Natural fiber reinforced plastics (NFRPs) represent a promising category of emerging materials for sustainable industrial development owing to their renewability, degradability, and lightweight. However, the polarity mismatch between the fibers and polymer matrices weakens the mechanical properties of NFRPs. To address this issue, a novel hierarchical interface design was proposed here through the co-modification of silane coupling agents (SCAs) and zinc oxide nanorods (ZnO NRs), which exhibits not only high efficiency but also low energy consumption and environmental friendliness. Specifically, the hierarchical interface design was demonstrated on jute fibers (JFs)/polypropylene (PP) composites, where the JFs/ZnO interfaces were chemically bonded through complexation, chelation, or coordination using various SCAs; meanwhile, the ZnO/PP interfaces were physically bonded by interlocking effect. The experimental testing results indicated the exceptional mechanical properties of modified JFs and their composites. The JFs modified with 3-glycidyloxypropyltrimethoxysilane (KH560) and ZnO NRs exhibited an increase of 34.3% and 55.8% in single-fiber tensile strength and tensile modulus, respectively, compared to sololy ZnO coated JFs, and also showed an augment of 30.8% in the interfacial shear strength with PP resin. Thus, the transverse and longitudinal tensile strength of JFs/PP composites with combined modification of KH560 and ZnO NRs were 19.2% and 46.5% higher than untreated ones. The interfacial enhancement mechanism was ascribed to the synergistic effect of chemical bonding and physical interlocking, as revealed by molecular dynamics simulation and observation of fracture morphologies. The findings offer a cost-effective solution for developing JFs/PP composites with superior interfacial and mechanical properties, thereby promoting the practical applications and value of NFRPs.

中文翻译：

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黄麻纤维/聚丙烯复合材料的分层界面设计，以增强界面和机械性能

天然纤维增强塑料（NFRP）因其可再生性、可降解性和轻质性而成为可持续工业发展的一类有前景的新兴材料。然而，纤维和聚合物基体之间的极性不匹配削弱了 NFRP 的机械性能。为了解决这个问题，本文通过硅烷偶联剂（SCA）和氧化锌纳米棒（ZnO NRs）的共同修饰提出了一种新颖的分层界面设计，该设计不仅具有高效率，而且具有低能耗和环境友好的特点。具体而言，在黄麻纤维（JF）/聚丙烯（PP）复合材料上演示了分层界面设计，其中 JFs/ZnO 界面通过使用各种 SCA 络合、螯合或配位进行化学键合；同时，ZnO/PP界面通过互锁效应实现物理粘合。实验测试结果表明改性 JF 及其复合材料具有优异的机械性能。与单独涂覆 ZnO 的 JF 相比，用 3-缩水甘油氧基丙基三甲氧基硅烷 (KH560) 和 ZnO NR 改性的 JF 的单纤维拉伸强度和拉伸模量分别提高了 34.3% 和 55.8%，并且还表现出 30.8% 的增强。与PP树脂的界面剪切强度。因此，KH560和ZnO NRs联合改性的JFs/PP复合材料的横向和纵向拉伸强度比未处理的分别提高了19.2%和46.5%。分子动力学模拟和断裂形貌观察揭示了界面增强机制归因于化学键合和物理互锁的协同效应。研究结果为开发具有优异界面和机械性能的 JFs/PP 复合材料提供了一种经济高效的解决方案，从而促进了 NFRP 的实际应用和价值。