Collaborative: Brittle Epoxies Rendered Ductile- Crazing in Thermosetting Epoxy Nanocomposites

银纹化是聚合物中的裂纹被高度排列的聚合物纤维桥接的现象。发现官能化碳纳米管的添加引发热固性环氧树脂中的银纹，热固性环氧树脂是一类不表现出银纹的聚合物。本计画的目的是了解官能化碳奈米管在热固性环氧聚合物中引发银纹的机制。为此，将研究由这些纳米管引起的结构变化对环氧树脂的固化化学的影响。这些结构变化和银纹化机制之间的关系将被建立。此外，将研究多尺度静态和动态应力不均匀性对材料力学响应的影响。 控制热固性环氧树脂银纹的能力可以显着提高其韧性和延展性，而不会降低其机械强度。鉴于环氧树脂在结构应用中的广泛使用，这有望转化为重要的实际应用。 这项工作的结果将提供一个基本的了解机制，功能化的碳纳米管添加剂可以引发在热固性环氧树脂银纹。这可以导致一类新的纳米复合热固性聚合物的开发，其具有显著增强的韧性、延展性和抗疲劳性，同时增强聚合物的强度和刚度。涉及热固性环氧树脂的各种应用，例如油漆、涂料、粘合剂、工业工具、复合材料以及半导体和电子包装行业将受益于这项研究。 为了将研究和教学结合起来，将在课程中以及在科学博物馆教授的科学课程中引入特别设计的互动模块。 推广活动还将包括实验示范和介绍给高中学生和教师。

Crazing is the phenomenon by which cracks in polymers are bridged by highly aligned polymer fibers. The addition of functionalized carbon nanotubes is found to initiate crazing in thermosetting epoxies which are a class of polymers that do not exhibit crazing. The objective of this project is to understand the mechanism by which crazing is initiated in thermosetting epoxy polymers by the addition of functionalized carbon nanotubes. To this end, the effect of structural changes induced by these nanotubes on the cure chemistry of the epoxy will be studied. The relationship between these structural changes and the mechanism of crazing will be established. Furthermore, the effect of multiscale static and dynamic stress heterogeneities on the mechanical response of the material will be studied. An ability to control crazing in thermosetting epoxies could significantly enhance their toughness and ductility without reducing their mechanical strength. Given the widespread use of epoxies in structural applications this is expected to translate into significant practical applications. The results of this work will provide a fundamental understanding of the mechanisms by which functionalized carbon nanotube additives can initiate crazing in thermosetting epoxies. This can lead to the development of a new class of nanocomposite thermosetting polymers with significantly enhanced toughness, ductility and fatigue resistance, while at the same time enhancing the strength and stiffness of the polymer. A variety of applications involving thermosetting epoxies such as paints, coatings, adhesives, industrial tooling, composites as well as the semi-conductor and electronics packaging industries will benefit from this research. In order to integrate research and teaching, specially designed interactive modules will be introduced into the curriculum as well as in the science courses taught at a science museum. The outreach activities will also include experimental demonstrations and presentations to high school students and teachers.