Static and dynamic properties of mid-size liquid n- alkanes, C-12 similar to C-400: a molecular dynamics simulation study

摘要

abstract_textpIn this paper, we have extended our previous study of the static and dynamic properties (self-diffusion coefficient D-self and friction coefficient zeta) of liquid n-alkane systems up C-400 at several temperatures (similar to 2300 K) using molecular dynamics (MD) simulations in the canonical ensembles. For the small n-alkanes with n = 120 (n: the chain length), the chains are clearly LeftAngleBracket;R-ee2/6R(g2)RightAngleBracket; = 1 (1.06 similar to 1.44), which leads to the conclusion that the liquid n-alkanes are far away from the ideal chain regime. But for the n-alkanes of n = 160, the chains are LeftAngleBracket;R-ee2/6R(g2)RightAngleBracket; approximate to 1, indicating that they are Gaussian. It is found that the long chains of these n-alkanes at high temperatures show abnormalities in density and friction coefficient. We observed a clear transition in the power law dependence of n-alkane self-diffusion coefficient on the molecular weight (M) of n-alkane, D-self similar to M-gamma, occurs in the range C-120 similar to C-160 at temperatures of 318, and 618 K, corresponding to a crossover from the 'oligomer' to the 'Rouse' regime. The entanglement lengths (N-e) are calculated by the Z1 code and discussed shortly./p/abstract_text