Collaborative Research: Spatial and Dynamic Heterogeneity and Nonlinear Viscoelastic Constitutive Behavior of Glasses and Their Nanocomposites as Probed by Nonlinear Spectroscopies

合作研究：非线性光谱探测玻璃及其纳米复合材料的空间和动态异质性以及非线性粘弹性本构行为

• 批准号: 2219347
• 负责人: Hongbing Lu
• 金额: $ 26.17万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2025-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2219347&HistoricalAwards=false
• 关键词: Collaborative; Research; Spatial; Dynamic; Heterogeneity; Collaborative; Research; Spatial; Dynamic; Heterogeneity

This research project will answer fundamental questions related to the performance of glassy polymers and their nanocomposites. These materials are important for a wide range of defense and commercial applications. Two mechanical spectroscopy techniques will be used to identify the unique “fingerprint” of these materials. Although normally used for soft materials, this research will employ this approach to investigate the nonlinear response of glassy polymers and their nanocomposites. The study combines experiment and computation to advance the science and engineering fundamentals of these advanced materials. The outreach programs at both universities provide opportunities for K-12 students and teachers to advance in their understanding and familiarity with STEM through activities exploring engineering, materials, and recycling. Students from underrepresented groups will be recruited to all activities of the work. The impact will be broadened by publication of results as well as technical presentation of the work at major conferences and incorporation of the findings in courses.The specific goals of the research are to use nanoparticle reinforced polymer glasses to elucidate the impact of different length scales and heterogeneity on the nonlinear viscoelasticity of polymer glasses and, simultaneously, their nanocomposites. The richness of the study arises from the facts that, in glass-forming systems including polymers, there is a consensus that the heterogeneities are on the scale of a few nanometers whereas in nanocomposites the size-scale range of interest can vary from that of the heterogeneity-scale of the polymer to the size of multiple particles, i.e., above 100 nm. There is significant evidence that properties of the polymer matrix itself are modified by the interphases and confinement effects, thus leading to a rich range of heterogeneity in these materials. The work uses the mechanical spectral hole burning (MSHB) and large amplitude oscillatory shear (LAOS) fingerprinting framework to elucidate the impact of different scales and heterogeneity on the nonlinear viscoelasticity of polymer glasses and their nanocomposites, something that has heretofore not been investigated. The intent is to systematically vary the scale and nature of the heterogeneity, to fingerprint it experimentally, and compare the results with computational models of behavior. The outcome will be a greatly improved understanding of how heterogeneity in glassy polymers and their nanocomposites impacts nonlinear behavior and, consequently, performance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该研究项目将回答与玻璃状聚合物及其纳米复合材料的性能有关的基本问题。这些材料对于广泛的国防和商业应用很重要。两种机械光谱技术将用于识别这些材料的独特“指纹”。尽管通常用于软材料，但该研究将采用这种方法来研究玻璃状聚合物及其纳米复合材料的非线性反应。该研究结合了实验和计算，以推动这些高级材料的科学和工程基础。两所大学的外展计划为K-12学生和老师提供了机会，可以通过探索工程，材料和回收利用的活动来促进他们对STEM的理解和熟悉。来自代表性不足小组的学生将被招募到工作的所有活动。通过出版结果以及在课程中发现的主要法规的技术介绍将扩大影响。研究的具体目标是使用纳米颗粒增强的聚合物眼镜来阐明不同的长度尺度和异质性对非线性粘弹性的影响。该研究的丰富性来自以下事实：在包括聚合物在内的玻璃制成系统中，有一个共识，即异质性的规模是几纳米，而在纳米复合物中，感兴趣的大小尺寸范围可能会与多种粒子的异质性尺寸与多个颗粒的大小相反，而多个微粒的大小。有大量证据表明，聚合物基质本身的性能是通过相互重点和限制效应来改变的，因此导致这些材料中的异质性范围丰富。该作品使用机械光谱孔燃烧（MSHB）和大型放大器振荡剪切（LAOS）指纹框架来阐明不同尺度和异质性对聚合物玻璃及其纳米复合材料非线性粘弹性的影响，这是未经研究的源是未经研究的。目的是系统地改变异质性的规模和性质，实验指纹，并将结果与​​行为的计算模型进行比较。结果将极大地改善对玻璃状聚合物中的异质性及其纳米复合材料的影响，从而影响非线性行为，并因此表现出色。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子和更广泛的影响审查标准来评估，通过评估来诚实地支持。