Molecular dynamics simulation of diffusion behavior of cyclohexane in natural rubber during reclamation

Reclaiming oil is a common additive involved in many physical rubber reclamation processes. In this work, molecular dynamics simulation is used to investigate the diffusion of oil in natural rubber (NR) under different temperatures and pressures. The structures of polyisoprene and cyclohexane molecules are constructed. The diffusion coefficients (Ds) of cyclohexane molecules in polyisoprene under different temperatures and pressures are calculated. The free volumes are also obtained to better understand the change in microstructure. The diffusion experiments of oil in NR samples under different temperatures and pressures are also conducted. The simulation results show that D increases as the temperature rises, especially at temperatures above 400 K, while the pressure does not affect D significantly. The fractional free volume calculated from the free volume and occupied volume exhibits a similar trend to that of D. Furthermore, the calculated Ds agree well with the experimental results. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40347.