Plastic packaging and medical implants that are designed to disappear after use often fail because they break down too slowly or lose their strength too quickly. This project investigates how mechanical forces—like bending, stretching, or compression—accelerate or slow the chemical degradation of biodegradable polymers in water. The researcher will run controlled experiments on PLA (a common biodegradable plastic) while it is under load, and build computer models that couple the chemistry of hydrolysis with the physics of stress and diffusion. The goal is to answer a practical question: can engineers use mechanical stress to control exactly when and how a biodegradable device fails? If successful, the work could replace the current trial-and-error approach to designing biodegradable products. For packaging and agricultural films, that means more reliable breakdown timelines and less plastic pollution. For temporary medical implants such as stents or sutures, it means devices that stay strong long enough to heal tissue, then degrade on schedule without unexpected failure. The computational tools developed here would allow manufacturers to test designs virtually before making physical prototypes, saving time and cost.
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Biodegradable polymers are materials designed to gradually break down into harmless constituents, and eventually disappear after having fulfilled their structural function. They are attracting enormous interest as potential replacements to traditional inert plastics in an attempt to address the plastic pollution problem. Applications include sustainable packaging, agricultural films and fishing nets, among others. Biodegradable polymers are also materials of choice for the design of temporary biomedical implantable devices (e.g. stents, sutures, or orthopaedic fixtures), thanks to their biocompatibility and tunable mechanical properties. From an engineering design perspective, biodegradable polymers introduce new challenges due to seemingly contradictory requirements: they need to degrade relatively fast after having completed their intended function, but they must also maintain suitable mechanical properties (stiffness, strength, toughness) during service. Addressing these challenges requires a fundamental understanding of the coupled chemo-mechanical effects that dictate the performance of these materials. On the one hand, chemical degradation in water progressively decreases the mechanical properties of the material and causes swelling. On the other hand, mechanical stresses arising from externally-applied loads or geometrical imperfections significantly impact the degradation rate. The proposed research aims to elucidate the role of mechanics in the chemical degradation of polymers in aqueous environment. This will be achieved by integrating systematic experiments on model polymers (PLA) degrading under loads and new physics-based constitutive models coupling mechanics and chemistry (hydrolysis reaction and diffusion of water and reaction products). The proposed models will be implemented within robust computational tools enabling the in-silico testing of biodegradable components under complex loading conditions up to failure. Ultimately, the research aims to answer the following question: "can we harness mechanical effects to control the degradation rate and failure mode for specific applications?". The new knowledge, models and computational tools delivered by this project will be directly relevant for a broad range of applications in packaging, engineering and healthcare. Benefits include guidelines for the formulation of polymer systems with targeted mechanical and degradation properties, as well as design guidelines and predictive simulation tools at component level. These will reduce the need for costly and time-consuming trial-and-error experimental approaches, and improve performance and safety of biodegradable devices.
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