CAREER: Additive Manufacturing of Polymer Composites via in-situ Polymerization

Traditional manufacturing of fiber-reinforced polymer composites is slow, energy-inefficient, and labor-intensive. It requires using expensive molds that severely limit the flexibility in the design and fabrication of complex composite structures. Additive manufacturing provides a promising alternative for rapidly creating desired composite structures without needing molds; however, additive manufacturing of high-quality fiber-reinforced composites is challenging, mainly because it is difficult to mix the matrix polymer with solid fiber reinforcements uniformly prior to deposition and then rigidize them in place along the desired print path. This Faculty Early Career Development (CAREER) award will support fundamental research that will enable additive manufacturing of composites containing a high concentration of carbon fibers by instantaneously rigidizing the composite material during the printing process. If successful, this project will lay a theoretical foundation for rapid manufacturing of composites without molds or even in midair. This project will provide hands-on activities to encourage Colorado’s middle and high school students, particularly women and Hispanic/Latinx students, in STEM education. New courses and experiential activities will be developed to train the next generation of composites workforce. Current approaches for the additive manufacturing of continuous fiber-reinforced polymer composites are mainly focused on using thermoplastic polymers or photocurable resins as the matrix polymer of composites, which typically have poor mechanical properties and/or are hard to process with a high volume-fraction of fibers. This project will investigate the manufacturing science of a new composite additive manufacturing method based on in-situ thermal polymerization of the matrix resin of composites. Central to this project is a new composite manufacturing platform that uses a remote stimulus to locally heat the thermo-responsive liquid resin of the composite filament to instantaneously polymerize and rigidize the printed composite. This project will elucidate the intrinsic interplay between process parameters, spatiotemporal variations in material composition and properties, and multiscale performance of printed composites. The proposed research is expected to uncover the mechanisms of interface formation and bonding control between adjacent layers. Experimental and numerical studies will be used to understand the viscoelastic deformation behavior and fiber distribution within filaments along multilayered, curvilinear paths during the manufacturing process. Finally, a new sensing and control framework will be developed to determine multiscale physical and thermochemical properties of materials during the manufacturing process and update the processing parameters on the fly to manufacture high-quality complex composite structures. 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.