Molecular Mobility in Polycarbonate Glasses During Active Deformation

主动变形过程中聚碳酸酯玻璃的分子迁移率

• 批准号: 1104770
• 负责人: Mark Ediger
• 金额: $ 40.5万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1104770&HistoricalAwards=false
• 关键词: Molecular; Mobility; Polycarbonate; Glasses; During

TECHNICAL SUMMARY:When a polymer glass is deformed, molecular mobility in the glass can be enhanced by many orders of magnitude even when the sample temperature does not change appreciably. Researchers from the University of Wisconsin-Madison will use a recently developed optical photobleaching technique to quantify changes in molecular mobility during the deformation of polycarbonate glasses. Within the framework of current models, changes in mobility are responsible for the non-linear mechanical response of polymer glasses. During deformation, the position of the system on the potential energy landscape can be altered. Understanding these changes is the central objective of this work because it is critical for an improved understanding of polymer glass deformation. Both constant strain-rate and constant stress deformations will be utilized. Constant strain-rate experiments provide controlled access to yield and thus allow changes in molecular mobility to be observed as the system is pulled up the energy landscape. Stress-aging experiments have been interpreted as the system being pulled down the energy landscape; mobility measurements during stress-aging will test this interpretation. The comparison of experimental results with simulations and model predictions should result in an increased fundamental understanding of glass deformation and better prediction capabilities. NON-TECHNICAL SUMMARY:Polymer glasses are widely used in our society. These materials can be seen everyday as bulletproof glass, compact disks, safety glasses, and automobile headlamp covers. In next generation commercial aircraft such as the Boeing 787, the wings and fuselage will be made of polymer glass (in a composite with other materials). For such applications, polymer glasses are used because of their ability to deform under stress without breaking. By increasing our fundamental understanding of polymer glass deformation, this research project at the University of Wisconsin-Madison will likely lead to an improved ability to predict the mechanical properties of polymer glasses. Better predictions, in turn, will lead to further applications for these materials in areas like the transportation sector, where lightweight materials save energy and thus contribute to a decrease in greenhouse gas emissions. Each year, these researchers will conduct a three-week summer enrichment course for 15 high school students, most of whom will be from groups underrepresented in science and engineering. For two hours each day, these researchers will provide activities designed to increase interest in science/engineering and to develop critical skills required for success in college.

技术总结：当聚合物玻璃变形时，即使样品温度没有明显变化，玻璃中的分子迁移率也可以提高许多数量级。 威斯康星大学麦迪逊分校的研究人员将使用最近开发的光学光漂白技术来量化聚碳酸酯玻璃变形过程中分子流动性的变化。 在当前模型的框架内，流动性的变化是负责聚合物玻璃的非线性机械响应。 在变形过程中，系统在势能面上的位置可以改变。 了解这些变化是这项工作的中心目标，因为它是一个更好地理解聚合物玻璃变形的关键。 将使用恒定应变率和恒定应力变形。 恒定的应变速率实验提供了受控的产量，从而允许观察分子迁移率的变化，因为系统被拉上了能量景观。 应力老化实验已被解释为系统被拉下的能量景观，在应力老化过程中的流动性测量将测试这种解释。实验结果与模拟和模型预测的比较，应导致增加玻璃变形的基本理解和更好的预测能力。非技术总结：聚合物玻璃在我们的社会中得到广泛应用。 这些材料每天都可以看到防弹玻璃，光盘，安全眼镜和汽车前灯罩。 在下一代商用飞机中，如波音787，机翼和机身将由聚合物玻璃（与其他材料复合）制成。 对于这样的应用，使用聚合物玻璃，因为它们在应力下变形而不断裂的能力。 通过增加我们对聚合物玻璃变形的基本理解，威斯康星大学麦迪逊分校的这项研究项目可能会提高预测聚合物玻璃机械性能的能力。 更好的预测反过来将导致这些材料在交通运输等领域的进一步应用，在这些领域，轻质材料可以节省能源，从而有助于减少温室气体排放。 每年，这些研究人员将为15名高中生举办为期三周的暑期强化课程，其中大多数将来自科学和工程领域代表性不足的群体。 每天两个小时，这些研究人员将提供旨在提高科学/工程兴趣的活动，并培养在大学取得成功所需的关键技能。