Dynamic Study of Deformation and Adhesion of an Amorphous Polyethylene/Graphene Interface: A Simulation Study

Abstract

In this paper, molecular dynamics tensile simulations of an amorphous polyethylene/graphene (PE/G) interface are carried out to investigate its adhesion strength. The effect of PE chain length and number and functionalization of G surface on the tensile behavior and interfacial adhesion is studied. The results show that the adhesion strength enhances with increasing chain length and number of the PE chains. In addition, the functionalization of G surface causes an increase in the adhesion strength comparing to unfunctionalized G due to deformation of a larger volume of the PE chains relying on the functionalized G. The contribution of bond length, bond angle, torsional potentials, and nonbonded energy is estimated as a function of interface elongation to clarify the deformation mechanisms within different tensile regions. The energy partitioning results indicate that the elastic, yield, and early postyielding regions are mostly controlled by the nonbonded interactions. However, the dihedral motions of the chains in addition to nonbonded interactions show a significant role in the disentanglement region, a part of postyielding and separation region. Furthermore, the simulation results exhibit how the internal mechanism associated with density profile, chain entanglements, and ordering can be evolved with increasing the interface elongation.

Study on failure mechanism of Cu-polyethylene-Cu sandwich structure by molecular dynamics simulation

“…Each physical quantity listed in Table 1 was averaged by three samples to carry out a statistical analysis. It can be observed that T g of different systems are around 250 K, which are within the experimental range from 190 to 300 K [36].…”

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

“…In order to investigate the effect of chain length and the number of the PE chains (i.e., (C 2 H 4 ) n ) on the simulation results, three types of PE cells with different combinations of the chain length and the number of chains are considered. The entanglement length of PE chains is in the range of 6090–carbon atoms [ 10 ]. Therefore, 150 carbon atoms around twice the entanglement length [ 22 ] are considered to investigate the effect of entanglements on the shear simulations of the interfaces.…”

“…To build an interface model, the S or mS is introduced to the PE surface at the distance (i.e., 0.5 nm) less than the cutoff radius. The simulated polymer box is further enlarged to 1100 Å in the normal direction to assure that the adjoining systems do not interact in this direction during the interface creation and elongation when the three-dimensional (3D) periodic boundary conditions are applied [ 10 ]. First, the resultant system is heated up to 500 K for 500 ps and then equilibrated at 300 K with a cooling rate of 0.2 K/ps.…”

“…This deformation process is continued until the final failure of the interface occurs. Displacement of 1.0 Å in 1 ns is equal to a rate of 0.1 m/s −1 , a high separation rate when compared with those that were used in standard laboratory tests [ 10 ]. The shear stress is calculated using the virial theorem [ 37 ] by considering the kinetic and potential energy of all the particles throughout the middle unconstrained PE zone.…”

“…In particular, the integrity of the bonded material system can be studied from a fundamental perspective by monitoring the interactions between two materials along the interfacial region at a molecular level by MD. Recently, some researchers used it to study the properties of bi-material systems, such as the chitin/protein interface [ 9 ], polyethylene/graphene interface [ 10 ], epoxy/S interface [ 11 ], carbon fiber reinforced polymers/wood interface [ 12 ], polyimides/S glass interface [ 13 ], hexagonal boron nitride/polyethylene interface [ 14 ], dihydroxyphenylalanine/S interface [ 15 ], S/polystyrene interface [ 16 ], carbon nanotubes/epoxy interface [ 17 ], polyvinylidene fluoride binder/copper interface [ 18 ], epoxy/copper interface [ 19 ], etc. The tensile strength, shear strength, effects of strain rate, effects of cell size, effects of conversion, effects of temperature, interaction bonding energy, effects of entanglement, failure mode, confined condition, density profile, and failure strain have been extensively investigated.…”