DYNAMICS OF HETEROGENEOUS POLYMER NETWORKS

This paper discusses the effect of heterogeneities in cross-link densi ty on network dynamics. The dynamic effects of such networks are studi ed in two limits, at short times and at long times. It is shown that h eterogeneities in cross-link density alter the chain dynamics strongly . This has several effects on the segmental motion, ruled by an additi onal time scale that is set mainly by fluctuations in the cross-link d ensity. It is shown that the chains localize more strongly in the long -time limit as given in homogeneous rubbers. The localization of chain s is essential for the dynamic response of networks. The collective dy namics of the whole network is investigated by the use of a Forster tr ansfer model, which encounters the heterogeneities on larger scales. T his method has not been applied to networks previously and leads to pr edictions on creep dynamics and long-time moduli.