Dynamics of concentrated polymer systems. Part 3.—The constitutive equation

The rheological constitutive equation of a condensed polymer system is presented based on the primitive chain model presented in Parts 1 and 2. The constitutive equation has the form of a BKZ equation and gives an explicit form for the memory kernel with the dependence of the rheological parameters on molecular weight and concentration. An interesting point is that it predicts a stress superposition law in the regime of non-linear viscoelasticity. The general features agree with experiments fairly well.