Collaborative Research: New Approaches to Predicting Long-time Behavior of Polymer Glasses

合作研究：预测聚合物玻璃长期行为的新方法

• 批准号: 2330760
• 负责人: Mehrdad Negahban
• 金额: $ 22.53万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-04-01 至 2027-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2330760&HistoricalAwards=false
• 关键词: Collaborative; Research; New; Approaches; Predicting

Glasses are non-equilibrium materials and their properties vary with time, thermal history, and mechanical deformation. A major impediment to the insertion of polymeric glasses in applications ranging from dielectric thin films in electronics to structural composites for aerospace, automotive, and wind turbine applications is the inability to predict long-term performance. This lack of quantitative understanding of the mechanical and thermal behavior also adversely impacts the application and engineering of amorphous glassy polymeric materials. This award supports research to facilitate the prediction of long-term behavior of polymer glasses, and thus facilitate the design and engineering of this important class of materials in advanced composites and other applications of importance to national interests. In addition, graduate and undergraduate students will be trained in polymer physics and mechanics, modeling, and experimental methods related to polymer glasses. At North Carolina State University, outreach will be conducted with K-12 summer camps to promote interest in STEM through a curriculum that includes teamwork, creative problem solving, and design challenges. Outreach activites at University of Nebraska Lincoln will focus on lifelong learner adults interested in expanding their understanding of math, physics, and programing.The Back Stress Expansion model will be investigated in order to develop a robust, yet computationally simplified, methodology that is able to describe and predict the long-term performance of glassy polymers as a function of thermal and mechanical history, including nonlinear or large deformations. In order to obtain a quantitatively correct description of material behavior, the model will be extended by incorporating i) a distribution of relaxation times, ii) the transition from the super-Arrhenius temperature dependence of the relaxation times above the glass transition to a weaker temperature dependence in the glassy state, and iii) the full multi-dimensional framework to model non-isotropic deformations. The model will be tested and validated using new experimental data, including pressure dependent structural recovery, isochoric measurements in the glassy state, and non-linear viscoelastic measurements. These experiments, which will be performed on three important engineering thermoplastics - polycarbonate, polysulfone, poly(methyl methacrylate) - will not only provide new data to validate and refine the model but will also further our understanding of the physics and mechanics of glassy polymers.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.

眼镜是非平衡材料，其性能随时间，热历史和机械变形而变化。从电子产品中的电介质薄膜到航空航天，汽车和风力涡轮机应用的结构复合材料的应用中插入聚合物玻璃的主要障碍是无法预测长期性能。对机械和热行为的缺乏定量理解也对无定形玻璃聚合物材料的应用和工程产生了不利影响。该奖项支持研究，以促进聚合物眼镜的长期行为的预测，从而促进高级复合材料中这种重要类型材料的设计和工程，以及对国家利益的其他重要性应用。 此外，研究生和本科生将接受与聚合物眼镜有关的聚合物物理和机械，建模以及实验方法的培训。 在北卡罗来纳州立大学，将与K-12夏令营进行外展活动，以通过包括团队合作，创造性解决问题和设计挑战在内的课程来促进对STEM的兴趣。内布拉斯加州林肯大学的外展活动将专注于有兴趣扩大他们对数学，物理和编程的理解的终身学习者成年人。将调查反向压力扩展模型，以开发出强大但计算上的简化方法，能够描述和预测玻璃状聚合物的长期性能，包括热和机械史的长期性能，包括较大的历史，包括较大的历史或较大的型号。 为了获得对物质行为的定量正确描述，将通过合并i）放松时间的分布来扩展该模型，ii）从超过玻璃过渡到玻璃温度较弱的玻璃温度依赖性的超级Arrhenius温度依赖性的过渡，以及iii），iii iii）全面的多维框架向模型非相关性掉落型模型。 该模型将通过新的实验数据进行测试和验证，包括依赖压力的结构回收，玻璃状态的等速测量以及非线性粘弹性测量。 These experiments, which will be performed on three important engineering thermoplastics - polycarbonate, polysulfone, poly(methyl methacrylate) - will not only provide new data to validate and refine the model but will also further our understanding of the physics and mechanics of glassy polymers.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 标准。