Self-healing in fiber-reinforced polymer composites via bioinspired microvascular networks

A recently developed technique for creating biomimetic microvascular networks in woven fiber reinforced polymer composites has been shown to impart multifunctional capabilities in otherwise quiescent, structural materials by means of simple fluid circulation [1]. An array of applications including thermal regulation, chemical reaction and gas absorption, magnetic field modulation, and conductivity accession have already been demonstrated for potential commercialization. Here we extend the microvascular-based technology to include a self-healing strategy for improvement in the damage resilience of fiber reinforced composite materials. Specifically, we have investigated healing a 2D woven E-glass composite after Mode-I interply delamination in a Double Cantilever Beam (DCB) geometry. A two-part healing chemistry based on a commercially available themioset epoxy formulation is employed to rebond the fractured interface. Both components are initially sequestered in separate channels in a vascularized DCB specimen. Upon loading and subsequent crack propagation through the network, the healing agents are released and polymerize on contact to create new polymer material in the crack plane. An attractive feature of this system is the virtually limitless supply of healing agents leading to the potential for repair of macro-scale damage over multiple cycles. Furthermore, the polymerization reaction occurs at room temperature under nonstoichiometric conditions, enabling practical in-situ healing. Through repeated mechanical testing of the healed DCB specimens, we demonstrate a significant recovery of the virgin fracture toughness for this new class of self-healing composite materials.