Molecular Dynamics Simulations of Stretch-Induced Crystal Changes in Crystallized Polyethylene/Carbon Nanotubes Nanocomposites

Understanding deformation mechanisms in semi-crystalline polymers during stretching is useful for guiding the processing of high-performance polymer products. In the current work, molecular dynamics simulations were performed to investigate the crystal changes in crystallized polyethylene/carbon nanotube nanocomposites during uniaxial stretching. Both crystal fragmentation and melting occur at low strains. Crystals with small sizes are easier to melt, while those with large sizes would break into smaller crystals. In addition, crystals in interfacial regions are more likely to melt or break due to the orientation motion of carbon nanotubes. It was also found that the recrystallization process is closely related to the stretch-induced orientation of chain segments. After orientation of chain segments along stretching direction is saturated, the recrystallization of highly oriented segments dominates. The current simulation findings are effective complements to the theories of the mechanism of plastic deformation in semicrystalline polymers.