Thermal-induced crossover: Darcy-to-power law response in flow of polymer chains

Flow of polymer chains is studied as a function of temperature (T), filed ( E), and chain length (L-c) by a hybrid computer simulation. In low field, t he polymer flow rate density (j) shows a linear response, i.e., Darcy law, j = phi E at high temperatures and a power-law resonse j = phi E-delta at l ow temperatures. The power-law response exponent, delta is nonuniversal and depends on temperature (delta similar or equal to 1.0-2.0). The chain perm eability phi = A(L-c)T0.21+/-0.01 in the low temperature regime; the prefac tor A(Lc) decays with the chain length according to A similar to L-c(-0.18) . (C) 1999 Elsevier Science B.V. All rights reserved.