Shock-induced Para-crystallinity in PPTA

The outstanding strength-to-weight ratio of para-aramid fibers, such as Kevlar and Twaron, can be largely attributed to their high content of p-phenylene terephthalamides (PPTA) crystals. Here, we perform non-adiabatic shock loading on large PPTA crystal models along different low-index crystallographic directions using reactive molecular-dynamics simulations. Results reveal an anisotropic shock response displaying elastic, plastic, and phase transformation from crystalline to para-crystalline configuration. The simulation results provide an atomistic view on the effects of shock in para-aramid synthetic fibers.