纳米复合材料动态硬化机制的研究
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- 英文论文题名：Study of dynamic hardening mechanism of nano composite materials
- 论文作者：王艳磊 ; 徐志平
- 英文论文作者：Yanlei Wang ; Zhiping Xu ; Department of Engineering Mechanics ; Tsinghua University
- 年：2016
- 作者机构：清华大学航天航空学院工程力学系;
- 论文关键词：纳米材料 ; 复合材料 ; 石墨烯 ; 高分子材料 ; 动态硬化
- 英文论文关键词：Nano materials ; Composite materials ; Graphene ; Polymer materials ; Dynamic hardening
- 会议召开时间：2016-11-25
- 会议录名称：2016年航空科学与技术全国博士生学术论坛摘要集
- 语种：中文
- 分类号：TB33;TB383.1
- 学会代码：XBHH
- 会议名称：2016年航空科学与技术全国博士生学术论坛
- 会议地点：中国陕西西安
- 主办单位：西北工业大学研究生院、中国高校航空学院院长联席会
- 学会名称：西北工业大学航空学院
- 页数：1
- 文件大小：471k
- 原文格式：D
- 会议级别：全国
摘要
微观结构的重组以及动态硬化的性质对于复合材料自适应外界环境的刺激有重大意义,但是对于大部分合成的材料,随着力学加载次数的增加,材料的模量都会逐渐降低并最终导致破坏。在本文中,我们研究了一种化学-物理交联形成的系统,基于石墨烯的PDMS纳米复合材料,该材料在低频周期性压缩载荷加载下储能模量会逐渐提升,表现出动态硬化的性质。分子动力学计算以及交联密度的变化表明在周期性载荷作用下,石墨烯表面的高分子链会逐渐变的有序以及平整进而形成中间相,中间相的形成对应于物理交联密度的增加,最终引起动态硬化现象。我们通过研究还发现化学交联的密度以及温度同样会影响该材料的自硬化性质。动态硬化机制的理解对于自适应复合材料以及人工肌肉工程的应用具有重大的意义。
The ability to rearrange microstructures and self-stiffen in response to external mechanical stimuli is critical for biological tissues to adapt to the environment. For most synthetic materials, however, even subjecting to repeated mechanical stress lower than their yield point would lead to structural failure. Here we report that the graphene-based polydimethylsiloxane(PDMS) nanocomposite, a chemically and physically cross-linked system, exhibits an increase in the storage modulus under low-frequency, low-amplitude dynamic compression loading. Crosslinking density statistics and molecular dynamics calculations show that the dynamic self-stiffening are attributed to the increase in physical crosslinking density resulted from the re-alignment and re-orientation of polymer chains along the surface of nanofillers that constitute an interphase. Consequently, the interfacial interaction between PDMS and nanofillers and the polymer chain mobility, which depends on the degree of chemical crosslinking and temperature, are important factors defining the observed performance of self-stiffening. Our understanding of the dynamic self-stiffening mechanism lays the ground for the future development of adaptive structural materials and biocompatible, load-bearing materials for tissue engineering.
The ability to rearrange microstructures and self-stiffen in response to external mechanical stimuli is critical for biological tissues to adapt to the environment. For most synthetic materials, however, even subjecting to repeated mechanical stress lower than their yield point would lead to structural failure. Here we report that the graphene-based polydimethylsiloxane(PDMS) nanocomposite, a chemically and physically cross-linked system, exhibits an increase in the storage modulus under low-frequency, low-amplitude dynamic compression loading. Crosslinking density statistics and molecular dynamics calculations show that the dynamic self-stiffening are attributed to the increase in physical crosslinking density resulted from the re-alignment and re-orientation of polymer chains along the surface of nanofillers that constitute an interphase. Consequently, the interfacial interaction between PDMS and nanofillers and the polymer chain mobility, which depends on the degree of chemical crosslinking and temperature, are important factors defining the observed performance of self-stiffening. Our understanding of the dynamic self-stiffening mechanism lays the ground for the future development of adaptive structural materials and biocompatible, load-bearing materials for tissue engineering.
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