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薄层涂层。这些材料具有许多理想的性能，已用于复合材料、管道、生物设备、柔性电子设备和冲击缓解等应用。然而，由于化学和/或物理降解（通常称为老化），它们的使用受到限制，需要良好的疲劳和/或冲击性能。当暴露在机械应力、高温、潮湿、紫外线和伽马辐射等极端环境中时，这是一个值得关注的问题。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解决这些挑战的研究。在医疗应用中，弹性体用于承受动态负荷、体温、体液和氧气等极端条件的心脏装置。在预期使用期间的自然老化可能会对患者造成致命的后果，因此了解生物相容性弹性体的耐久性以防止使用失效至关重要。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，促进STEM教育。该项目的目标是找到环境老化生物相容性弹性体在使用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特性。基于热湿老化生物相容性弹性体在不同载荷条件和加速热老化条件下的力学行为，建立了基于热力学的模型和时间-温度等效原理。具体而言，本提案将解决：(1)热老化对弹性体的静态、粘性和疲劳行为的影响，(2)老化对疲劳诱导的裂纹和裂纹的产生、扩展和合并的影响，以及(3)老化对链复制机制的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.