CAREER: Recycled Polymers of Enhanced Strength and Toughness: Predicting Failure and Unraveling Deformation to Enable Circular Transitions

This Faculty Early Career Development (CAREER) grant supports research that aims to understand the deformation and failure of recycled polymers, known as recyclates. Recyclates have been unable to replace virgin plastics because of their poor mechanical performance. This leads to resource depletion, waste, and pollution challenges. Preliminary work suggests that altering the internal structure of recyclates, by introducing distinct, self-assembled phases within them, improves their mechanical performance. However, investigating the deformation and failure of these self-assembled structures, which is necessary to enable their wider adoption and use, is extremely challenging due to their complex nature. This award supports fundamental research to predict how deformation and failure occurs in recyclates through sophisticated experiments and artificial intelligence. The findings will enhance scientific understanding and foster the development of advanced, recycled materials that could benefit multiple U.S. industries, advance sustainability, and conserve national resources. In parallel, the education, outreach, and borader impact activities aim to shape a diverse and agile U.S. workforce by offering new engineering skills and improving career prospects of marginalized individuals, with emphasis on individuals reentering the workforce from incarceration. This grant aims to support research that advances understanding of the deformation and failure of recyclates exhibiting self-assembled internal morphologies of improved strength and toughness through an integrated experimental and computational approach. The new mechanics discoveries by this research effort will enable the substitution of virgin plastics with recycled ones of similar mechanical performance resulting in circular transitions and addressing the pressing plastic pollution challenge. By exploiting the built-in energy potential present in immiscible polymer blends of heterogeneous recyclates, their internal architecture will be altered. This way, composites of enhanced mechanical properties with phase-separated, self-assembled three-dimensional morphologies, induced by thermophoresis, will be developed. The structure-property space of these recyclates will be explored and their complex failure and deformation will be investigated, while developing sophisticated experimental mechanics instrumentation to support such efforts. Coupling high-throughput, big-data generating experiments with state-of-the-art artificial intelligence algorithms will enable the prediction of failure evolution and the understanding of strength and toughness enhancement mechanisms. These predictions will unravel new deformation mechanisms for heterogeneous polymer composites. Such knowledge will also enable the establishment of new, reliable criteria for crack branching, curving and bifurcation, which have eluded researchers for decades. The research efforts will be closely tied to education, outreach, and broader impact activities which will work towards an integrated and inclusive mechanics education, by embedding sustainability in mechanics courses and engaging justice-impacted youth with engineering science. 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.