Collaborative Research: Localized Frontal Curing-Assisted 3D Printing of Thermosetting Polymers

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This award supports a collaborative research project on a novel 3D printing method for thermosetting polymers, localized frontal curing-assisted 3D printing. Thermosetting polymers are widely used in aircraft, space shuttles, cars, boats, bridges, furniture, and so on. Currently available methods to manufacture thermosetting polymer parts include conventional molding and newly-developed mold-free 3D printing. These methods involve two steps: deposition processing and post-processing curing that are both energy-intensive and time-consuming. In localized frontal curing-assisted 3D printing, deposition and curing are completed simultaneously in a one-step process. An external heat source is used to initialize the curing process and the heat produced by the exothermic curing reaction enables curing to self-propagate through the material as it is deposited. The new method has the potential to impact product design, assembly, and the manufacture of products using thermosetting polymers. As a result it could potentially lead to significant changes and increased competitiveness in many industries of national interest, such as the automotive, aerospace, and marine industries. This project will engage graduate and undergraduate students in the research activities thus preparing them for the advanced manufacturing workforce. Outreach activities based on the research will be used at high school summer camps and for online videos to educate students and the general public about advanced manufacturing. There are four research objectives: (1) to determine effects of curing agent concentration and printing slice size on frontal velocity and front propagation distance; (2) to understand relationships between localized frontal velocity, viscoelastic behavior of thermosetting resins, and geometric fidelity of printed structures; (3) to test the hypothesis that a specific range of frontal velocity will result in higher interlayer bonding strength; and (4) to reveal effects of localized frontal velocity on the mechanical performance of printed structures. To achieve these objectives, the research team will employ both theoretical and experimental approaches. Specifically, effects of curing agent structures and concentration on frontal curing velocity and front propagation distance will be modelled and simulated based on the reaction kinetics and then verified by high-resolution infrared camera. Viscoelastic behavior of thermosetting resins will be studied via real-time rheology characterization and data fitting. Effects of frontal velocity on interlayer bonding strength and mechanical performance of printed structures will be revealed by experimental tests and statistical analysis.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.