CAREER: Pathways of Microplastics Creation: Multi-physics Study of Macroplastic Fragmentation, Foliation, and Fibration

职业：微塑料的产生途径：大塑料破碎、叶状和纤维化的多物理研究

• 批准号: 2145137
• 负责人: Maryam Shakiba
• 金额: $ 51.66万
• 依托单位: Virginia Polytechnic Institute and State University
• 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: 2022-05-01 至 2022-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2145137&HistoricalAwards=false
• 关键词: CAREER; Pathways; Microplastics; Creation; Multi

This Faculty Early Career Development (CAREER) grant supports research to understand the degradation mechanisms of macroplastics into microplastics under coupled effects of weathering and mechanical stresses. It is well-established that microplastics exist in our oceans in ever-increasing numbers and cause great ecological harm. Physical, mechanical, and chemical properties of macroplastics change during the degradation process and make it challenging to detect microplastics and estimate their lifetime in water. To address this challenge, it is critical to understand the formation mechanisms of microplastics and the rates at which they are produced. The objective of this research project is to discover the mechanics of degradation and develop predictive models which can estimate the fate of macroplastics. The outcome can help ocean environmental scientists and the manufacturing practices and recycling processes. The research activities will be complemented with a series of integrated educational activities to train the next generation of engineers and researchers in the multi-physics and mechanics of soft polymers through combinations of undergraduate and graduate students training and outreach to high-school students. The award will also be used to contribute to public knowledge infrastructure and create workshops for the polymer industry. Separate models exist for studying how polymers degrade due to two or three factors among mechanical loading, temperature, oxygen, salt-water, and UV irradiations. The principal emphasis of this project is on the nonlinear coupling effects of all these factors. Physics-based equations for degradation in microstructural properties will be established based on polymers' network statistics, chemistry kinetics, as well as stored and dissipative energies. The critical internal stress at which micro-cracks form in thin polymers will be determined using polymer statistics and conservation laws. A non-affine multiscale framework will be built upon the deformation and breakage in chains and crosslinks to predict heterogeneous damage initiation and propagation. A physics-guided machine learning algorithm will assist the development of the framework. The damage mechanisms, threshold, and transition from brittle to ductile under multi-physics conditions will be described. The particular questions to be answered include (1) effects of the microstructural morphology of macroplastics on the degradation process and the choice of a specific fracture pathway -- fragmentation, foliation, or fibration, (2) changes in mechanical properties due to thermo-chemo-UV internal stresses in soft polymeric materials, and (3) failure mechanisms in semi-crystalline and amorphous polymer under coupled conditions at different scales.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.

这项教师的早期职业发展（职业）赠款支持研究，以了解在风化和机械压力的耦合效果下，大型塑料对微塑料的降解机制。众所周知的是，微塑料在我们的海洋中存在着越来越多的数量，并造成了巨大的生态伤害。大型塑料的物理，机械和化学特性在降解过程中发生了变化，并使检测微塑料并估计其在水中的寿命使其具有挑战性。为了应对这一挑战，了解微塑料的形成机制及其产生的速率至关重要。该研究项目的目的是发现退化的机制并开发可以估计大型塑料命运的预测模型。结果可以帮助海洋环境科学家以及制造实践和回收过程。研究活动将通过一系列综合的教育活动进行补充，以通过本科生和研究生的培训和宣传对高中生的培训和推广，以培训软聚合物多物理和机制的下一代工程师和研究人员。该奖项还将用于为公共知识基础设施做出贡献，并为聚合物行业创建研讨会。存在单独的模型，用于研究在机械载荷，温度，氧，盐水和紫外线照射中由于两个或三个因素而导致的聚合物如何降解。该项目的主要重点是所有这些因素的非线性耦合效应。基于物理学的微观结构特性降解方程将基于聚合物的网络统计，化学动力学以及储存和耗散能量。将使用聚合物统计和保护法确定微裂纹形成微裂缝的临界内部应力。非携带的多尺度框架将建立在链条和交联的变形和断裂基础上，以预测异质的损害启动和传播。物理引导的机器学习算法将有助于开发框架。将描述在多物理条件下从脆性到延性的损伤机制，阈值和过渡。要回答的特定问题包括（1）大型塑料的微观结构形态对降解过程的影响以及选择特定的断裂途径的选择 - 碎片化，叶面或纤维化，（2）由于软化材料和（3）术语中的热力学内部应力和（3）半液体和AMINIMI-CRYSISIS INCRASTER INCRASTER INCRASTER INCRASTER INCRASTER INTRABLESISS的机械性能变化在不同的规模上，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优点和更广泛的影响评估标准评估值得支持。