Atomistic insights into the migration and diffusion behavior of crosslinking byproducts in polyethylene networks

The accumulation of crosslinking byproducts, such as cumyl alcohol and acetophenone, in polyethylene (PE) insulation accelerates the degradation of high-voltage direct current (HVDC) cables through space charge formation and electrical tree propagation. Since conventional degassing processes cannot entirely eliminate these crosslinking byproducts, characterizing their residual dynamic behavior is of paramount importance. This work presents a comprehensive molecular dynamics (MD) simulation study to quantify the diffusion kinetics of these byproducts within the PE network. By systematically varying temperature and concentration, we reveal the role of intermolecular interactions in governing diffusion dynamics. The results indicate that electrostatic interactions are the primary driving force for byproduct aggregation. Compared with acetophenone, cumyl alcohol forms denser and more stable molecular clusters, which severely restricts its mobility and yields a much lower diffusion coefficient. Moreover, thermal activation significantly enhances the diffusion rates of both species. Consequently, these insights not only elucidate the underlying molecular mechanisms of byproduct diffusion, but also serve as a vital theoretical complement to macroscopic experimental observations.