Conformational relaxation of individual chain molecules in the entangled state has already been investigated by direct observation in fluorescent DNA experiments. Yet, possible connections between the quantity accessible in those experiments and well defined conformational measures have not been established so far. In this study, the relaxation behavior of the individual polymer conformation in the entangled state is simulated through the primitive chain network model, and compared to well known relaxations like that of stress or electric polarization. Inspired by the experiments, we use as a measure of the individual conformation the maximum distance between segments of a given polymer chain, which is often referred to as chain extension, and indicated by the symbol x. The relaxation behavior is calculated as auto-correlation function at equilibrium, suitably ensemble averaged to eliminate the noise. It is found that such x relaxation is significantly different from both stress relaxation and end-to-end dielectric relaxation, though the power-law exponent of the longest relaxation time vs. chain length appears to be the same for both the stress and the x measure.
2008 The Society of Rheology, Japan