Molecular Dynamics Simulation of Volatile Odors Diffusion in Recycled Polyethylene

One of the potential risks of recycled polyethylene used in food packaging is the migration of volatile odors in it. In this study, molecular dynamics simulation was used to investigate the diffusion behavior of toluene, 2, 4-dimethylheptane, α-pinene, limonene, diphenyl ether and α-isomethylionone in recycled polyethylene at different temperatures. The diffusion coefficients of odors in recycled polyethylene were calculated by mean square displacement curve and compared with experimental values and Limm-Hollifield model values. We analyzed the diffusion behavior of odors from the aspects of topological structure parameters, interaction energy with PE, diffusion activation energy and movement trajectory. The results showed that the diffusion of the odors is influenced by many factors. Molecules with larger volume, radius of gyration and spherical structure are difficult to move, so they have smaller diffusion coefficient. When the solubility parameters of odors are similar to polyethylene, the compatibility between them is good and the molecules are hard to diffuse. From the perspective of energy, the larger the interaction energy with polyethylene and diffusion activation energy of odors, the greater the energy required for molecular movement, and the slower the diffusion process. The trajectories of the odors at different temperatures are long-term vibrations and instantaneous jump, but the range of motion is larger at high temperature, and the trajectories show obvious clusters. © 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.