LAUSR

Abstract A Carbon-fiber reinforced Hybrid- Matrix Composite (CHMC) was designed to improve the material damping property in conventional carbon-fiber reinforced epoxy (CF/E) through the interfacial reaction of two reactive polymeric compounds: still-curing epoxy-based phase I with a highly crosslinked morphology and lightly crosslinked still-curing polyurea elastomeric phase II. Chemical reactions of the hybridized interfacial matrix are discussed relative to phase reactions and tunable material damping in accordance with the migration of epoxy phase I species. Microstructures and micromechanical properties of CHMC are characterized using scanning electron microscopy and nanoindentation. Dynamic properties of CHMC are investigated via free vibration and forced vibration tests, and the results are compared to CF/E test results. Dynamic mechanical analysis reveals a cogent link between damping property (of the epoxy-polyurea interface) and lower tc ≈ 0, where proper design of the epoxy-polyurea interface can greatly improve material damping by using smaller epoxy curing times (tc, hours) just before topically applying reactive polyurea. As a result, loss modulus of the interface is seven to ten times larger for tc = 0 compared to polyurea-coated fully-cured epoxy. For tc > 3.5, the role of polyurea thickness hp on energy dissipation expectedly increases.