REPTATION OF A POLYMER-CHAIN BY CONFORMAL TRANSITIONS IN THE ENTANGLED REGIME

We study a model for reptation, where motion along the contour of the chain is due to displacements caused by singlet- or double-bond rotati ons (local jumps) followed by rearrangements of the neighboring units, rather than ''kink motion.'' We recover the usual scaling behavior of the diffusion coefficients and relaxation times with the chain mass. Moreover, the effective activation energy that is found from the local jump model for translational motion of the chain center of mass compa res favorably with experiment and is independent of the molecular weig ht for large enough chains.