Flow Modification and Molecular Dynamics Simulation of UHMWPE/HDPE Blends

Abstract

Molecular dynamics can predict and analyze polyethylene's mechanical properties, thermodynamic quantities, and other macroscopic properties at the molecular level. However, the molecular modeling of polyethylene is still not fully developed, the simulated systems often involve relatively low molecular weights and single components, and it cannot be well combined with the experiment to study the mechanical properties of UHMWPE/HDPE blends. Therefore, this paper combined experimental analysis with simulations to investigate the flow modification and tensile properties of UHMWPE/HDPE blends and established a semicrystalline UHMWPE/HDPE model. The result shows that the flow modification effect of HDPE is more pronounced at lower screw rotational speeds, and the UHMWPE/HDPE mass ratios of 6/4 and 5/5 can produce as-spun filaments with better surface quality at a screw speed of 5 r/min. As the HDPE content increases, the blends' molecular chain mobility and disentanglement capability improve. However, an excessively high HDPE content hinders the enhancement of blend orientation. When the UHMWPE/HDPE mass ratio is 6/4, the system achieves the highest degree of orientation, the fewest internal void defects, and the longest duration of strain hardening during drawing.