Description: This Small Business Innovation Research Phase I project seeks to develop self-healing composites using carbon nanofibers in conjunction with encapsulated resin/hardener. Polymer matrix composites offering multiple advantages of lightweight, high strength and stiffness, vibration damping, and corrosion resistance are becoming widely used in aerospace and commercial applications. A primary weakness of structural composites is damage from impact, where resulting microcracks can propagate to allow delamination and/or fiber breakage of the composite, resulting in loss of the excellent physical properties for which composites are selected. Incorporation of carbon nanofibers (CNF) into the polymer matrix, resulting in a significant increase of the composite interphase, has been shown to mitigate microcrack formation. CNF additives in the matrix have also demonstrated improvement in interlaminar mechanical properties, thermal and electrical conductivity, vibration damping, and fire retardancy. A separate promising tool for addressing damage from impact is the emerging class of self-healing materials, having the ability to heal microcracks and restore mechanical and corrosion-resistant properties of the composite. In the proposed effort, a combination of these tools will be investigated to determine the feasibility of incorporating self-healing, while concurrently producing multifunctional improvements in interlaminar shear strength, modulus, fracture toughness, transport properties, fire retardancy and vibration damping.

Benefits: Nano-scale self-healing reinforcements could increase the service life and boost physical properties of composites used for aerospace applications and in commercial markets for windmill blades, sports equipment, automotive, and aerospace structural composites. For example, a reduction in the need to replace windmill blades will result in a lowering of the cost of wind energy and will contribute to the solution of defining economical and renewable energy alternatives for the future.

Self-healing nano-reinforced composites could be attractive for cryotanks due to carbon nanofibers ability to reinforce the matrix as well as mitigate micro-cracking combined with capability to repair damage from collisions with debris. In addition, self-healing multi-functional composites could be used for composite fan blades, fan casings or structural components in large-scale structures such as the Heavy Lift Vehicle or in in-space applications.