Development of a quasi-static test method to investigate the origin of self-healing in ionomers under ballistic conditions

Ionomers are known to exhibit a unique self-healing capacity under ballistic impact by sharp projectiles. As the kinetics of the event is such that a systematic exploration of the relevant mechanisms are impossible, a novel quasi-static test method was developed to identify the relevant processes. The method mimics the self-healing process by pulling a pre-heated disk-shaped object through the ionomeric polymer rapidly and in a controlled manner. The advantage of this method over other reported methods is that the penetrant is completely removed from the impact zone and thus does not interfere with the self-healing process. Due to the controlled manner of the test, quantitative information can be obtained which allows for further mechanistic studies. The two key parameters which optimise the mimicry of the healing process investigated are (1) the localised heating of the impact region and (2) the speed of the impact. Both variables have been shown to play an important role in healing from both a macroscopic and micro-structural perspective.