ON COMPATIBILITY OF THE COX-MERZ RULE WITH THE MODEL OF DOI AND EDWARDS

A recently suggested relaxation mechanism which is expected to be domi nant in fast flows of polymer melts is combined here with the tube mod el of Doi and Edwards, and the corresponding constitutive equation is derived. The mechanism consists of the renewal of topology by convecti ve displacement of entanglements. Detailed predictions for the flow cu rve in steady shear are obtained in order to test the agreement with t he Cox-Merz rule. With respect to the basic tube model, significant pr ogress is achieved.