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了解聚乙烯结的应变和失败,使用具有机器学习潜力的分子动力学
Mark DelloStritto1, Michael L Klein1
1Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States.
The journal of physical chemistry letters
|August 28, 2024
概括
节点通过集中应力显著削弱聚乙烯 (PE) 链,导致它们比线性链更容易破裂. 这种分子水平的行为反映了宏观的绳索故障,显示了类似的应力点和棒滑动力学.
科学领域:
- 计算材料科学 计算材料科学
- 聚合物物理 聚合物物理
- 分子动力学分子动力学
背景情况:
- 聚乙烯 (PE) 链是具有多种应用的基本聚合物.
- 了解聚合物在分子水平上的机械故障对于材料设计至关重要.
- 节点可以以不可预测的方式改变聚合物链的机械性能.
研究的目的:
- 用神经网络潜力研究线性和结节聚乙烯链的机械故障.
- 为了比较PE链中不同类型的节点 (31,51,52) 的故障机制.
- 探索分子尺度PE结和宏观绳索故障之间的相似之处.
主要方法:
- 开发一个神经网络潜力 (NNP) 适用于碳化合物的电子结构数据.
- 在应变下对线性和结结的聚乙烯链进行模拟.
- 应力分布,应变能量和键/角度差异的分析.
主要成果:
- 由于压力分布均,线性PE链需要高应变才能断裂.
- 结结的PE链 (31,51,52) 将应力集中在结的入口/出口处,从而导致更早的故障.
- 结合长度和角度的同时应变最大化了应变能量.
- 节点增加C-C-C角度差异,促进较低的结合应变的破裂.
- 分子结表现出类似于宏观绳索的粘滑现象和故障点.
结论:
- 节点拓显著影响聚乙烯链的机械强度.
- 该NNP模型为聚合物链故障机制提供了准确的见解.
- 这项研究揭示了分子和宏观结的失败之间的令人信服的平行.
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