Structure and Dynamics of Polyethylene Nanocomposites

The structure and dynamics of linear monodisperse polyethylene (PE) melts (C160H322 and C440H882) containing homogeneously distributed spherical nanoparticles were investigated. The PE chains were simulated using a coarse-grained model and a Monte Carlo algorithm. Two variables were considered: (i) the wall-to-wall distance between particles d and (ii) the interaction energy between monomers and particles. The various chain structures changed greatly with d while the monomer-particle interaction had little effect. The average size, shape, and orientation of PE chains did not differ significantly from those of a neat melt. Bridge segments were more stretched relative to segments in the neat melt, and the stretch increased with increasing d. However, the number of bridge segments decreased markedly with increasing d. The chain dynamics were monitored by computing the Rouse relaxation modes and the MSD. The dynamics were slowed by both geometric (confinement by fillers) and energetic (monomerparticle energetic interaction) effects.