Self-healing materials science has seen significant advances in the last decade. Recent efforts have demonstrated healing in polymeric materials through chemical reaction, thermal treatment, and ultraviolet irradiation. The existing technology for healing polymeric materials through the aforementioned mechanisms produces an irreversible change in the material and makes it unsuitable for subsequent healing cycles. To overcome these disadvantages, we demonstrate a new composite self-healing material made from an ionomer (Surlyn) and carbon fiber that can sustain damage from medium-velocity impact and heal from the energy of the impact. Furthermore, the carbon fiber embedded in the polymer matrix results in resistive heating of the polymer matrix locally, melts the ionomer matrix around the damage, and heals the material at the damaged location. This paper presents methods to melt-process Surlyn with carbon fiber and demonstrates healing in the material through medium-velocity impact tests, resistive heating, and imaging through electron and optical microscopy. A new metric for quantifying self-healing in the sample, called width-heal ratio, is developed, and we report that the Surlyn-carbon fiber-based material under an optimal rate of heating and at the correct temperature has a width-heal ratio of >0.9, thereby demonstrating complete recovery from the damage. 1. Introduction Damage detection and self-healing are unique properties of biological materials and systems. In such systems, a damage event triggers internal processes that generate the healing response and extend the life of the material. This unique property of biological materials has served as the inspiration for self-healing materials in engineering. In the most common self-healing concepts developed to date, damage events are directly or electronically coupled to the release of the healing agents to heal the damage in the material. The most commonly used healing agents such as chemical binders, heat, and light alter the chemical composition and microstructure of the material to heal the damage and restore strength at the damage site. The capsule-based method developed by White and coworkers [1–4] uses a chemical binder that is released into the matrix of the composite material in the event of a damage. The binder combines with the matrix or hardening agent present in adjacent microcapsule to heal the damage. A variation of the microcapsule-based technique uses vascular networks filled with healing agents to heal structural damage [5–12]. In another variation of this method, hollow glass
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