Theory of Viscoelasticity in Temporarily Crosslinked Polymers (II) Relaxation Spectrum and Steady Flow Viscosity

A molecular theoretical investigation about the relaxation spectrum of high polymeric substances within the range of long relaxation time has been pursued using a temporarily crosslinked network model, in which crosslinkages are created by the secondary valence of segments or by the entanglement of polymer molecules. Each chain is considered to be Gaussian and the so-called Rouse model corresponding to the macro-Brownian motion is set up. With use of the Rouse model and the concept of slipping of chains a theory is presented. The relaxation spectrum predicted by the theory is of the box type and the steady flow viscosity coefficient is proportional to the 3.4 power of molecular weight.