Mechanical Properties of Polyethylene/Carbon Nanotube Composites from Coarse-Grained Simulations.

Abstract

Advanced nanocomposite membranes incorporate nanomaterials within a polymer matrix to augment the mechanical strength of the resultant product. Characterizing these membranes through molecular modeling necessitates specialized approaches to accurately capture the length scales, time scales, and structural complexities inherent in polymers. To address these requirements, an efficient simulation protocol is proposed, utilizing coarse-grained (CG) molecular dynamics simulations to examine the mechanical properties of polyethylene/single-walled carbon nanotube (PE/SWCNT) composites. This methodology integrates CG potentials derived from the statistical associating fluid theory (SAFT-γ Mie) equation of state and a modified Tersoff potential as a model for SWCNTs. A qualitative correspondence with benchmark classical all-atom models, as well as available experimental data, is observed, alongside enhanced computational efficiency. Employing this CG model, the focus is directed at exploring the mechanical properties of PE/SWCNT composites under both tensile and compressive loading conditions. The investigation covered the influence of SWCNT size, dispersion, and weight fraction. The findings indicate that although SWCNTs enhance the mechanical strength of PE, the extent of enhancement marginally depends on the dispersion, filler size, and weight fraction. Fracture strengths may be elevated by 20% with a minor incorporation of SWCNTs. Under compression, the incorporation of SWCNTs into the composites results in a transformation from brittle to tough materials. These insights contribute to the optimization of PE/SWCNT composites, emphasizing the importance of considering multiple factors to fine-tune the desired mechanical performance.