Thermal investigation of ballistic self-healing capability of polymeric materials

Among smart materials, self-healing polymers have gained a raising interest in literature over the last few decades thanks to their capability to recover damage partially or totally, extending the lifetime of objects and simultaneously reducing material waste and saving energy. In this scenario, polymers in the form of ionomer and copolymers are a valid example of intrinsic self-healing thermoplastic material since, without adding any external healing agent, a thermal stimulus allows for spontaneous restoration of the material integrity after a ballistic impact. This smart functionality makes these polymers suitable for multilayer composites for spacecraft debris protection shields and self-sealing layers in tank reservoirs for low-velocity impact. The present work aims to understand the healing mechanisms of this new class of polymers by using thermal analysis. In particular, thermal stability was investigated by using Thermo-Gravimetric Analysis (TGA) while Differential Scanning Calorimetry (DSC) provided information on the crystallinity of the selected self-healing polymers. Finally, Dynamic-Mechanical Analysis has proven to be fundamental for the study of polymer transition temperature correlated to the activation of the healing phenomena.