Shock compression of semicrystalline polymers

Here, we study the shock wave response of semicrystalline polymers using coarse-grained molecular dynamics simulations. The crystallinity of the systems was controlled by using block copolymer-like chains with different volume fractions of crystallizable blocks. Our results indicate that the degree of initial crystallinity affects the speed of sound and the propagation velocity of shock waves at low compression velocities. However, at high compression velocities, the initial crystalline structures melt due to the passage of the shock, and the principal shock features resemble each other, independently of the crystallinity. We also found that the presence of crystalline regions helps disperse shocks, resulting in a monotonic increase in shock width with the degree of initial crystallinity. The shock-induced melting of crystalline structures was analyzed by an Avrami function, revealing similarities with conventional thermal melting. Our simulation results highlight the importance of crystalline regions and the presence of amorphous/crystal interfaces in contributing to the dispersion and dissipation of shocks and impact fronts traveling through semicrystalline polymeric materials.