Molecular Influence in Microparticle Impact Response of Elastomers

Segmented elastomers have gained attention for their performance against high-velocity impacts through tailored segmental dynamics. The influence of molecular moieties has also been reported to be important on the dynamic behavior of polymers. In this work, we present impact measurements of laser-launched supersonic micro-particle impacts on polyurea and polyurethane elastomers. In a laser-induced projectile impact test (LIPIT), we accelerate solid microparticles to supersonic velocities up to 1 km/s through a laser-ablation process. The impact events are observed in situ using an ultra-high-speed multi-frame camera that can record up to 16 images with time resolution of each frame as short as 5 ns. We study the high-strain rate deformation response of elastomers to unravel the relation between microstructure and high-rate properties. In particular, we are interested in the influence of the nature and the extent of hydrogen bonding and the role of intermolecular interaction in the dynamic response of these polymers. We demonstrate that LIPIT is capable of quantifying the variation in dynamic stiffening observed among these elastomers upon impact at strain rate ~10⁸ s^-1.