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

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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.