CAREER: Novel Coarse-Grained Simulations to Study Relationships Linking Morphology and Plastic Resistance in Semi-Crystalline Polymers

职业：新型粗粒度模拟研究半结晶聚合物形态和塑性阻力之间的关系

• 批准号: 1653830
• 负责人: Jay Oswald
• 金额: $ 50万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1653830&HistoricalAwards=false
• 关键词: CAREER; Novel; Coarse; Grained; Simulations

This Faculty Early Career Development (CAREER) program will support fundamental research on how material structure at the molecular scale affects macroscopic physical properties of semi-crystalline plastics, facilitated by the creation of a new multiscale methodology for accelerated computational simulations. Plastics are used in a vast range of products for their excellent properties including high strength to weight ratio, chemical resistance, and durability. Plastics are made of organic polymers, long molecules composed of many repeating units, whose structure and chemistry dictate the material properties. At the nanoscale, semi-crystalline polymers are composed of a mixture of regions in which long molecular chains are either highly ordered or disordered. The significantly different mechanical properties of these different phases can, when combined, lead to remarkably tough and stiff materials. Over the past decades, costly empirical efforts have been predominantly employed to progressively search for improved chemistries and material processing in order to create stronger and tougher plastics. Accurate and efficient simulation methods are needed to replace these empirical efforts, a critical step in shortening today?s 10-20 year materials development cycle. Therefore, results from this research will foster new innovation in plastics manufacturing, one of the few U.S. manufacturing sectors with a trade surplus, ultimately benefiting the U.S. economy and society. Furthermore, the integration of educational and outreach activities with this research effort will help to address national challenges in meeting future demands for an abundant, diverse, and talented engineering workforce. For example, efficient learning will be facilitated through an adaptive and intelligent web-based educational system and cooperative learning, the latter of which will also be used to identify mentors for focused high school student workshops. Coarse-grained molecular models are limited in the extent to which they can describe polymer mechanics due to well-known problems of representability and transferability. Furthermore, their usage has been typically limited to simulations of single phase materials such as polymer melts or polymer glasses. The scientific objective of this research effort is to create and validate a multiscale computational framework that provides a systematic approach for generating coarse-grained molecular models of semi-crystalline polymers, which are optimized so that they preserve the essential kinematic details of relevant inelastic deformation mechanisms. The research team will develop and train coarse-grained models, and conduct verification and validation of the models to ensure that the spectrum of relaxation timescales is preserved across the coarse-grained transformation. The team will also exercise the newly developed models to identify relationships between interphase structure and mechanical properties such as slip resistance.

该学院早期职业发展（CAREER）计划将支持关于分子尺度上的材料结构如何影响半结晶塑料宏观物理特性的基础研究，通过创建一种新的多尺度方法来加速计算模拟。塑料因其优异的性能，包括高强度重量比，耐化学性和耐久性，而用于各种产品中。塑料是由有机聚合物制成的，有机聚合物是由许多重复单元组成的长分子，其结构和化学性质决定了材料的性能。在纳米尺度下，半结晶聚合物由长分子链高度有序或无序的区域混合组成。这些不同相的显著不同的机械性能在组合时可以导致显著坚韧和刚性的材料。在过去的几十年里，主要采用昂贵的经验性努力来逐步寻找改进的化学和材料加工，以创造更坚固和更坚韧的塑料。准确和有效的模拟方法，需要取代这些经验的努力，在缩短今天的关键一步？材料开发周期为10-20年。因此，这项研究的结果将促进塑料制造业的新创新，这是美国少数几个贸易顺差的制造业之一，最终使美国经济和社会受益。 此外，将教育和宣传活动与这项研究工作相结合，将有助于解决国家在满足未来对丰富，多样化和有才华的工程劳动力的需求方面面临的挑战。例如，将通过一个适应性强的智能网络教育系统和合作学习促进有效学习，后者还将用于为重点高中学生讲习班确定导师。粗粒度的分子模型是有限的，在何种程度上，他们可以描述聚合物力学，由于众所周知的问题的可表示性和可转移性。 此外，它们的使用通常仅限于模拟单相材料，如聚合物熔体或聚合物玻璃。这项研究工作的科学目标是创建和验证一个多尺度计算框架，为生成半结晶聚合物的粗粒度分子模型提供系统的方法，这些模型经过优化，以便保留相关非弹性变形机制的基本运动学细节。 研究团队将开发和训练粗粒度模型，并对模型进行验证和确认，以确保松弛时间尺度的频谱在粗粒度转换中得到保留。该团队还将运用新开发的模型来确定界面结构与机械性能（如防滑性）之间的关系。