ERI: Durability of Biocompatible Elastomers under Extreme Environments: Unveiling the Aging Mechanisms

塑料材料广泛用于结构应用和保护性薄层涂层。这些材料表现出许多理想的特性，已被用于复合材料，管道，生物设备，柔性电子产品和冲击缓解等应用。然而，由于化学和/或物理降解（通常称为老化），它们的使用在需要良好疲劳和/或冲击性能的应用中受到限制。当暴露于机械应力、热、湿度、紫外线和伽马辐射的极端环境时，这是一个重要的问题。该工程研究启动（ERI）奖支持旨在通过全面检查生物相容性弹性体的耐久性来应对这些挑战的研究。在医疗应用中，弹性体用于心脏器械，可承受动态载荷、体温、体液和氧气的极端条件。在其预期用途期间的自然老化可能会对患者造成致命后果，因此了解生物相容性弹性体的耐久性以防止使用中失效至关重要。该项目将通过与迪尔伯恩玩具图书馆合作为K-12学生组织活动来促进STEM教育。本项目的目标是找到环境老化生物相容性弹性体在使用中老化和加速老化条件下产生的机械和动态性能之间的相关性。通过广泛的实验和数值研究，该项目将揭示老化机制如何影响生物相容性弹性体的动态性能。将根据各种载荷条件和加速热老化条件下热老化和湿老化生物相容性弹性体的力学行为，开发基于生物力学的模型和时间-温度等效原理。具体而言，该提案将涉及：（1）热老化对弹性体的静态、粘性和疲劳行为的影响，（2）老化对疲劳引起的银纹和裂纹的产生、扩展和聚结的影响，以及（3）老化对连锁爬行机制的影响。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准。

Plastic materials are extensively used for structural applications and protective thin-layer coatings. These materials exhibit many desirable properties that have been utilized in applications like composites, piping, bio-devices, flexible electronics, and impact mitigation. However, their use is limited in applications that require good fatigue and/or impact performance due to chemical and/or physical degradation, commonly referred to as aging. This is a significant concern when exposed to extreme environments of mechanical stress, heat, humidity, ultra-violet, and gamma radiation. This Engineering Research Initiation (ERI) award supports research that aims to address these challenges by comprehensively examining the endurance of biocompatible elastomers. In medical applications, elastomers are used in heart devices which endure extreme conditions of dynamic loading, body temperature, body fluids, and oxygen. Natural aging during their intended use can result in fatal consequences for patients, thus it is crucial to understand the endurance of biocompatible elastomers to prevent in-service failure. This project will promote STEM education by collaborating with the Dearborn Toy Library in organizing activities for K-12 students. The goal of this project is to find a correlation between the mechanical and dynamic properties resulting from in-service aging and from accelerated aging conditions for environmentally aged biocompatible elastomers. Through extensive experimental and numerical investigations, this project will uncover how aging mechanisms affect the dynamic properties of biocompatible elastomers. A thermodynamics-based model and time-temperature equivalence principle will be developed based on the mechanical behavior of thermal- and humidity-aged biocompatible elastomers under various loading conditions and accelerated thermal aging conditions. Specifically, this proposal will address: (1) the effect of thermal aging on the static, viscous, and fatigue behavior of elastomers, (2) the effect of aging on the fatigue induced crazing and cracking initiation, propagation, and coalescence, and (3) the impact of aging on chain reptation mechanism.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.