Ultraviolet-light induced Frontal Polymerization in Additive Manufacturing and Repairing of Thermoset Polymer Composite - Understanding the Role of Fiber Reinforcement Phases

Syracuse University, Syracuse NY

Investigators

Abstract

Ultraviolet (UV) light induced frontal polymerization, a self-sustaining exothermic chemical reaction, is a promising technique for additive manufacturing of thermoset polymers, potentially applicable to fiber-reinforced thermoset composites. However, the role of fiber phases in frontal polymerization remain elusive, particularly, how it determines curing and resultant mechanical performance is not fully understood. This award supports fundamental research to study and understand the mechanisms governing fiber-phase behavior in frontal polymerization through an integrated approach of experimental investigations and computational modeling. The new knowledge acquired is expected to not only promote scientific advancement in additive manufacturing and polymer processing, but also benefit U.S. industries in a broad range of applications such as airframes, flexible biosensors, wind turbine blades and marine structures, etc. This project will also integrate composites additive manufacturing into course materials. Additionally, the team will broaden the participation of underrepresented groups in STEM through summer research opportunities to the pool of Native Indian undergraduates and to high school students from a school district, where most local Native Indian students attend. The objective of this research is to understand how fiber reinforcement phases influence UV-induced frontal polymerization processing of thermoset composites, including curing kinetics, part microstructures and mechanical performance. The presence of fibers in thermoset resins will complicate heat-transfer rates and gradients, which may alter UV energy required to activate polymerization and shape the front propagation. To tackle this fundamental challenge, fiber composites of different configurations, e.g., varying weight fractions of initiators, will be investigated into frontal polymerization at varying UV energy levels. Curing performance, such as the speed and degree of the cure, along with the resultant microstructural and mechanical characteristics, such as porosity and tensile properties, will be experimentally characterized using in-situ thermal imaging and post-cure material analysis and mechanical testing. In addition, physics-based reaction-diffusion models, complemented by neural network machine learning algorithms will be developed to understand the behavior of processing phenomena and be validated by experimental results. Furthermore, experiments of additive manufacturing and repairing will be conducted by integrating frontal polymerization into an automated fiber placement 3D printer to evaluate curing and mechanical performance of fiber reinforced thermoset composites with different configurations. The fundamental understanding gained is expected to establish the quantitative relationship between curing and mechanical performance of fiber-reinforced thermoset composites and the interplay of the fiber configurations, UV-light energy and curing kinetics of thermoset resins. 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.