The effect of microstructural evolution with hydrophilic-nanosilica (SiO2) concentration, ranging from 0 to 5 wt%, on mechanical properties and deformation micromechanisms of PP/EPDM/SiO2 (80/20/x) ternary blend-nanocomposites was investigated. Morphological observations revealed that, SiO2 nanoparticles tend to localize either around the dispersed EPDM particles or at the PP/EPDM interface, promoting the formation of three dimentional network-like EPDM/SiO2 composite structures dispersed in the PP matrix, especially at higher SiO2 loadings. This type of dispersion state was further confirmed by the rheological analysis. Synergistic toughening effect of soft EPDM particles and rigid SiO2 particles under Izod impact test was observed in these ternary systems, so that the materials with a better balance of stiffness/toughness were achieved. The results demonstrated that the extent of impact toughness increase is higher, where a large amount of the SiO2 nanoparticles surrounded the EPDM dispersed particles distributed in the PP matrix. This significant increase was attributed to the change in the size of stress concentration region and evolution of stress distribution throughout the material. The failure mechanisms were studied, and the underlying toughening micromechanisms were proposed.

中文翻译：

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PP/EPDM/SiO2 三元共混纳米复合材料的刚韧性平衡：微观结构演变的作用

研究了亲水性纳米二氧化硅 (SiO2) 浓度范围为 0 至 5 wt% 的微观结构演变对 PP/EPDM/SiO2 (80/20/x) 三元共混纳米复合材料的力学性能和变形微观机制的影响。形态观察表明，SiO2 纳米颗粒倾向于定位在分散的 EPDM 颗粒周围或 PP/EPDM 界面处，促进了分散在 PP 基体中的三维网络状 EPDM/SiO2 复合结构的形成，尤其是在较高的 SiO2 负载量下。流变分析进一步证实了这种分散状态。在这些三元体系中观察到软EPDM颗粒和刚性SiO2颗粒在Izod冲击试验下的协同增韧作用，从而获得了具有更好的刚度/韧性平衡的材料。结果表明，冲击韧性增加的程度更高，其中大量的SiO2纳米粒子包围了分布在PP基体中的EPDM分散粒子。这种显着增加归因于应力集中区域大小的变化和整个材料应力分布的演变。研究了失效机制，并提出了潜在的增韧微观机制。