Elastic evolution of a self-healing ionomer observed via acoustic and ultrasonic resonant spectroscopy.

Self-healing poly (ethylene co-methacrylic acid) ionomers (EMAA) are thermoplastic materials that when punctured, cut, shot or damaged in a variety of ways, are capable of autonomously reorganizing their physical structure to heal and, in many instances, permanently seal the damaged location. However, a complete picture of the mechanisms responsible for their unusual behavior is not well understood. In this article we report the observation of time dependent acoustic and ultrasonic spectral evolution, measured using resonant acoustic and ultrasonic spectroscopy, for both pre and post-damage EMAA samples. The results provide a means to differentiate healing phases, quantify healing timescales, and potentially elucidate the composition parameters that most significantly impact healing behavior.