Prediction of physical properties of polyethylene-based nanocomposites using molecular dynamics methods

Recently, attention has been drawn to polymer materials reinforced with carbon allotropes, including graphene. Creating new nanocomposite materials in the conditions of growing demand is a difficult task and requires significant material and time costs. The use of computer resources for modeling become an increasingly attractive way to obtain the necessary information about the dynamics of phenomena and physical processes in materials. Currently, the influence of non-functionalized nano-fillers with their arbitrary distribution in the matrix on the complex physico-mechanical properties of polymer nanocomposite materials is insufficiently researched. Molecular dynamics methods allow to deeper understand the dynamics and principles of structural changes in the material during its operation.It has been established that in the temperature range of (275–315) K, the elastic modulus of the PE-GR nanocomposite exceeds the corresponding values of PE-pure by 6.0% at 300 K and 6.7% at 275 K. The yield strength of PE-GR compared to PE-pure also increases: by 11.7% at 300 K and 8.9% at 275 K for α=1.36% and a deformation rate of 109 s−1. The graphs of linear temperature dependencies of mass isobaric heat capacity and coefficient of linear thermal expansion (CLTE) of PE-GR have increasing dependencies and intersect the corresponding PE-pure graphs in the range of (300–310) K depending on the graphene volume fraction. At a temperature of 280 K, the heat capacity values of PE-GR are 5–6% lower than PE-pure, and at 320 K, they are 3.1–5.3% higher. At 280 K, the CLTE values of PE-GR are 25–35% lower than PE-pure, and at 320 K, they are 11–17% higher.For the prediction of the physico-mechanical properties of PE-GR composites, nonlinear two-parameter dependencies of physico-mechanical properties in the temperature range of (280–320) K and the volume fraction of graphene (0–1.5) % have been obtained. These dependencies allow to develop new composite materials without conducting complex and time-consuming numerical experiments based on MD modeling. The obtained data will enable the modeling of the thermo-elastic-plastic state of PE-GR nanocomposite products in service conditions in a continuum approximation.