Molecular dynamic simulations of deformation behaviour of blended polyethylene

The tensile deformation behaviour of blended polyethylene (PE) was studied using molecular dynamic methods. The blended PE was modeled by blending linear chains with different molecular weights based on a united atom model. The mechanical response and microscopic conformational behaviours of blended PE were investigated at different strain rates and temperatures. The interatomic energy evolution displayed a similar trend to the stress-strain curve showing the stiffness of blended PE increase with a higher fraction of chain with high molecular weight. The microstructure metrics associated with free volume, orientation, entanglement and crystallisation were recorded as a function of strain in detail to obtain insight into the role of PE chains with different molecular weights for blended PE during deformation. The conformation evolution indicates that orientation and disentanglement are more noticeable in the short chain with low molecular weight in a blended PE system, while the long chain promotes the crystallisation of the initial chain structure. The chain entanglement evolution clearly shows some new flexion nodes created to entangle short chains again, implying that re-entanglement might exist during the tensile deformation.