POS2-0792
Bridging the strain-rate gap in polyethylene creep: all-atom molecular dynamics simulation with Burgers and Ree-Eyring models
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Seoyeon Ko (Department of chemistry, Sogang University)
Co-Author(s)
Abstract
Creep, the viscoelastic, time-dependent deformation that occurs under a constant stress, governs the long-term mechanical reliability of polymers. Hence, describing the creep behavior requires a constitutive model that links molecular-scale flow to the macroscopic response. Molecular dynamics (MD) simulation can capture the underlying molecular mechanisms, yet the strain-rate gap between simulation and experiment remains a central obstacle. Previous MD studies, using united-atom (UA) and all-atom (AA) models, have reproduced polymer creep, while activated-flow descriptions, such as the Ree-Eyring equation, have bridged simulated behavior toward experimental rates. However, the link addressed mainly the yield stress rather than the full creep response. In our study, we focused on explaining the full creep response using an all-atom MD simulation of polyethylene (PE) to connect the two regimes constitutively. Creep is simulated at constant stress near the glass transition temperature range, 300 K, and each curve is fitted with the four-element Burgers model. The Burgers model enables us to separate the instantaneous-elastic, retarded-elastic, and viscous-flow contributions in the creep of PE, and to extract the viscosity. The viscosity’s stress dependence is described by the Ree-Eyring equation, which superposes parallel activated processes, yielding the activation volume and flow parameters that govern the low-strain-rate regime. Since polyethylene is semicrystalline, the framework is applied to models of differing crystallinity. The effective flow parameters of PE will be compared with the extracted viscosity. This bottom-up route aims to connect atomistic creep simulations to the experimentally accessible, macroscopic creep of PE.
