Analysis of Nanomechanical Properties of Polyethylene Using Molecular Dynamics Simulation

The nanomechanical properties of polymers are sensitively affected by subtle differences in molecular structures. When the modulus of high-density polyethylene (HDPE) was measured with an atomic force microscopy (AFM)-based nanomechanical mapping mode, the modulus exhibited a wide distribution ranging up to 4 GPa depending on the measuring position, although the average was 1 GPa. Therefore, the relationship between surface structures, contacting states, and the mechanical properties for HDPE was analyzed in this study by reproducing the motion of contact using molecular dynamics (MD) simulation constructed with silicon atoms and linear polyethylene (PE). As a result, the same digits of moduli as AFM were obtained by using MD and it was confirmed that the force–deformation curves showed important features related to PE structures at each measurement position. The features were also confirmed in the AFM results, which indicate that the difference in molecular behavior associated with the contact position affects the nanomechanical properties of the real specimen.