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The microscopic mechanism of size effect in silica-particle reinforced silicone rubber composites
Engineering Fracture Mechanics ( IF 5.4 ) Pub Date : 2021-08-12 , DOI: 10.1016/j.engfracmech.2021.107945
Jinhan Chen 1, 2 , Jian Liu 1, 2 , Zhilong Peng 1, 2 , Yin Yao 1, 2 , Shaohua Chen 1, 2
Affiliation  

Particle reinforced elastomer matrix composites always show a size-dependently mechanical behavior when the particle size shrinks down to micro- or even nano-scale. A systematic investigation on microscopic mechanisms of such a size effect is carried out in this paper based on tensile and tear experiments of silicone rubber elastomer filled with surface modified silica particles, in which the particle size ranges from tens of to several hundreds of nanometers. It is found that, when the particle content is fixed, the ultimate strength, fracture toughness and fracture tensile strain of the composite exhibit monotonic increase with the decrease of particle size. In the composite filled with monodispersed submicro-particles, the improved strength is due to the hindering effect of particles on the crack propagation and the strong interface bonding between particles and matrix, while the improved toughness is mainly resulted from the crack-pinning around particles. In the composite filled with nano-sized particles, both the filler-hindering effect and the strong interface still contribute to the strength of the composite, while not only the crack pinning but also the interface debonding around nanoparticle aggregates will toughen the composite. Furthermore, a hierarchical network structure consisting of differently-sized aggregates and bounded rubbers endows the composite with a better load bearing capacity than the one filled with separately distributed fillers. As a result, the composite filled with small nano-nanoparticles shows remarkably improved mechanical properties in comparison with the composite filled with submicro-particles. The present work should provide insights for optimally designing a flexible composite with both desirable strength and toughness.



中文翻译:

二氧化硅颗粒增强硅橡胶复合材料尺寸效应的微观机制

当颗粒尺寸缩小到微米级甚至纳米级时,颗粒增强弹性体基复合材料总是表现出与尺寸相关的机械行为。本文基于填充表面改性二氧化硅颗粒的硅橡胶弹性体的拉伸和撕裂实验,对这种尺寸效应的微观机制进行了系统的研究,其中粒径范围从几十到几百纳米。研究发现,当颗粒含量一定时,复合材料的极限强度、断裂韧性和断裂拉伸应变随着粒径的减小呈现单调增加的趋势。在填充有单分散亚微粒的复合材料中,强度的提高是由于粒子对裂纹扩展的阻碍作用以及粒子与基体之间的强界面结合,而韧性的提高主要是由于粒子周围的裂纹钉扎。在填充纳米颗粒的复合材料中,填料阻碍效应和强界面仍然有助于复合材料的强度,而不仅裂纹钉扎而且纳米颗粒聚集体周围的界面脱粘都会使复合材料增韧。此外,由不同尺寸的聚集体和有界橡胶组成的分层网络结构赋予复合材料比填充单独分布的填料的复合材料更好的承载能力。因此,与填充亚微米颗粒的复合材料相比,填充小纳米纳米颗粒的复合材料显示出显着改善的机械性能。目前的工作应该为优化设计具有理想强度和韧性的柔性复合材料提供见解。

更新日期:2021-08-15
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