Chain Dynamics of Ring and Linear Polyethylene Melts from Molecular Dynamics Simulations
- Chain Dynamics of Ring and Linear Polyethylene Melts from Molecular Dynamics Simulations
- 허가현; Cheol Jeong; Roland G. Winkler; Naida Lacevic; Richard H. Gee; Do Y. Yoon
- Issue Date
- VOL 44, NO 7, 2311-2315
- The dynamical characteristics of ring and linear polyethylene (PE)
molecules in the melt have been studied by employing atomistic molecular
dynamics simulations for linear PEs with carbon atom numbers N up to 500 and
rings with N up to 1500. The single-chain dynamic structure factors S(q,t) from
entangled linear PE melt chains, which show strong deviations from the Rouse
predictions, exhibit quantitative agreement with experimental results. Ring PE melt
chains also show a transition from the Rouse-type to entangled dynamics, as
indicated by the characteristics of S(q,t) and mean-square monomer displacements
g1(t). For entangled ring PE melts, we observe g1(t) ∼ t0.35 and the chain-length
dependence of diffusion coefficients DN ∝ N-1.9, very similar to entangled linear
chains. Moreover, the diffusion coefficients DN remain larger for the entangled rings
than the corresponding entangled linear chains, due to about a 3-fold larger chain length for entanglement. Since rings do not reptate, our results point toward other important dynamicalmodes, based on mutual relaxations of neighboring chains, for entangled polymers in general.
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