Entanglement molecular weight determination from plateau

Since pc 1/2, we observe that Me 2Mg, as commonly observed. Mg is determined from the onset of the rubbery plateau by dynamic mechanical spectroscopy and Me is determined at the onset of the highly entangled zero-shear viscosity law, T) M. This provides a new interpretation of the critical entanglement molecular weight Mg, as the molecular weight at which entanglement percolation occurs while the dynamics changes from Rouse to reptation. It also represents the... 

We return now to the difference in behavior between the two types of PMMA with molecular weights of 1.5 x 10 and 3.6 x 10 . We note that the rubbery modulus of the type with the higher molecular weight reaches a plateau at /iR = 3.4 MPa. As we discuss in Chapter 6 on rubber elasticity, the entanglement molecular weight Me can be determined from this modulus through the statistical theory of rubber elasticity (Ferry, 1980) as... 

Various characteristic molecular weights can be defined from the molecular weight dependences of the rheological properties, including the molecular weight between entanglements. Mg, determined from the plateau modulus... 

FIGURE 6.13 Characteristic molecular weight at which the viscosity exhibits a change in M-dependence versus the molecular weight between entanglements determined from the plateau modulus (Roland, 2011 Fetters et al., 1999). 

Applying the kinetic theory of rubber-like elasticity (62,109) to the entanglement network one can determine the molecular weight between entanglements Me from the plateau compliance Jn or plateau modulus Gn (62) ... 

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