Theory of Polymer Viscoelasticity — Entanglement and the Doi Edwards Reptation Model

Molecular Theory of Polymer Viscoelasticity — Entanglement and the Doi-Edwards (Reptation) Model 

An example is the molecular-weight dependence of zero-shear viscosity as shown in Fig. 4.7 for various nearly monodisperse polymers. As the molecular weight increases above a critical value Me, the viscosity increases much more rapidly than in the low-molecular-weight region below Me, exhibiting the well-known 3.4 power law.  

Another strong indication of the entanglement effect is the observation of a clear plateau in the linear relaxation modulus amj storage modulus spectrum when the polymer has a sufficiently high molecular 

As discussed below in this chapter, the Doi-Edwards theory models entanglements as slip-links. Having taken the effects of chain slippage through the links into account, the theory gives  

Experimental results of various polymers show that the critical molecular weight Me is about 2.4 times the value of Mg (determined according to Eq. (8.2)). This observation indicates the close relation between Mg and Mg. 

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