Molecular Dynamics Study of an Amorphous Polyethylene/Silica Interface with Shear Tests

An amorphous polyethylene/silica (PE/S) interface exists in many materials. However, the research of the interfacial properties at microscale is lacking. Shear failure and adhesion properties of an amorphous PE/S interface are studied by molecular dynamics. The effects of PE chain length, the number of chains, and coupling agents on the shear behavior and interfacial adhesion are investigated. It is found that the modified silica (mS) surface induces an increase in the adhesion strength compared to unmodified S. The damage process and failure mode of the PE/S and PE/mS interface are analyzed at microscale. The contribution of bond length, bond angle, torsional potentials, and nonbonded energy is estimated as a function of the shear deformation to clarify the deformation mechanisms. The energy partitioning results indicate that the elastic, yield, and postyielding regions are mostly controlled by the nonbonded interactions. The dihedral motions of the chains also have an influence. Furthermore, the simulation results exhibit how the internal mechanism evolves with the shear deformation.