Microvascular based self-healing polymeric foam

A self-healing microvascular polymeric foam has been developed to improve the resilience of rigid foam core materials for sandwich structures. We investigated the healing of brittle polyisocyanurate (PIR) foam after mode-I crack separation in a 3-point single edge notch bend (SENB) specimen. A two-part healing chemistry based on a commercially available polyurethane (PUR) foam formulation is employed to rebond the interface. Both components are initially sequestered in separate channels in a vascularized SENB geometry. Upon loading and subsequent crack propagation through the network, the healing agents are released and polymerize on contact to create new foam material in the crack plane. An attractive feature of this system is the volumetric expansion of the healing chemistry, demonstrating the ability to repair macro-scale damage. The foaming reaction occurs on the order of minutes at room temperature, enabling rapid in-situ healing. Furthermore, by using a vascular delivery technique, multiple damage–recovery cycles are achieved at consistently high healing efficiencies. Through repeated mechanical testing, we have demonstrated over 100% recovery in fracture toughness for this new class of bioinspired, self-healing cellular materials.