Creep Behavior for Combined Rouse-Reptation Mechanism

Abstract

Recoverable creep compliance J_R(t) was analytically calculated for polymer chains relaxing through the Rouse and reptation mechanisms at short and long time scales, respectively. The ratio of the longest relaxation times of these mechanisms, r_τ = τ_Rouse/τ_rep, was varied from 0.056 to 0.0033. The calculation indicated that the effect of the fast Rouse mechanism on the distribution of slow modes of J_R(t) decreases with decreasing r _τ but a considerable effect remains even for r_τ as small as 0.0033, i.e., even for the case of reptation-dominance in the terminal relaxation behavior. This result demonstrates an important difference between the creep and relaxation processes, the former being associated with a correlation (or interplay) of eigenmodes of chain motion due to the constant stress requirement.