Extreme enhancement of the nonlinear elastic response of elastomer nanoparticulate composites via interphases
Extreme enhancement of the nonlinear elastic response of elastomer nanoparticulate composites via interphases
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DOI：
10.1016/j.compositesb.2018.08.064
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
A. Meddeb;T. Tighe;Z. Ounaies;O. Lopez-Pamies
中科院分区：
文献类型：
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作者：
A. Meddeb;T. Tighe;Z. Ounaies;O. Lopez-Pamies
在过去的二十年中，向弹性体中添加少量纳米颗粒可以导致弹性体的弹性响应急剧增强，不仅在小变形下，而且更重要的是，在大变形下，这一点变得越来越不可否认。然而，由于在纳米颗粒的长度尺度上进行机械性能的直接定量测量的实验困难，以及与在纳米级不均匀性存在下分析大变形相关的数学挑战，导致这种增强的精确机制仍然没有得到解决。本文报道了一种结合实验/理论的研究，旨在揭示和量化背后的弹性体纳米颗粒复合材料的原型类增强弹性性能的精确机制：聚二甲基硅氧烷（PDMS）填充与各向同性分布的二氧化钛纳米粒子。合成的复合材料表现出显著增强的应力-拉伸响应，在所考虑的小变形和大变形的整个范围内，其特征在于相对于未填充的PDMS弹性体的响应增加高达约10倍。在合成过程中形成的不直接围绕纳米颗粒聚集体的PDMS弹性体区域比未填充的PDMS弹性体更软，而围绕聚集体的“相间”PDMS弹性体明显更硬。后者的机制被发现统治前者，并构成背后的复合材料的宏观弹性性能的大幅增强的主导机制。
Over the last two decades, it has become increasingly unarguable that the addition of a small amount of nanoparticles to elastomers can lead to a drastic enhancement of their elastic response not only at small deformations but, more importantly, at large deformations. Yet, because of the experimental difficulties of conducting direct quantitative measurements of mechanical properties at the length scale of the nanoparticles together with the mathematical challenges associated with the analysis of large deformations in the presence of nanoscale heterogeneities, the precise mechanisms responsible for such an enhancement have remained unresolved. This paper reports a combined experimental/theoretical investigation aimed at revealing and quantifying the precise mechanisms behind the enhanced elastic properties of a prototypical class of elastomer nanoparticulate composites: polydimethylsiloxane (PDMS) filled with an isotropic distribution of TiO2nanoparticles. The synthesized composites exhibit drastically enhanced stress-stretch responses, featuring up to about a 10-fold increase with respect to the response of the unfilled PDMS elastomer, over the entire spectrum of small and large deformations considered.Inter alia, it is found that the “bulk” PDMS elastomer — i.e., the regions of the PDMS elastomer not immediately surrounding the nanoparticle aggregates formed during the synthesis process — is softer than the unfilled PDMS elastomer, while the “interphasial” PDMS elastomer surrounding the aggregates is significantly stiffer. The latter mechanism is found to rule over the former and to constitute the dominant mechanism behind the drastic enhancements in the macroscopic elastic properties of the composites.