Cooperatively rearranging region CRR

In the AG theory, z defines the size of a cooperatively rearranging region (CRR) at Tg, which is necessarily its maximum value. Donth (1982) has evaluated the size of a CRR by assuming that the region is sufficiently big for the application of thermodynamic relations. From fluctuation theory,... 

Fig. 25 Effect of spatial confinement on the cooperatively rearranging region (CRR)...

As the temperature is decreased below Tg, free rotation of the individual molecules decreases and molecular motions become restricted. In this temperature region, the collective movement of cooperatively rearranging regions (CRR) of the molecules dominates. Decrease of temperature leads to an increase in the size of the CRRs and hence to the decrease of configurational entropy below Tg (Metatla and Soldera 2007). Any description of relaxation time below Tg therefore has to consider the contribution of configurational entropy (Eq. 2.21) ... 

Table 1 Comparison of the shear activation volumes of p- and a-relaxations with the volumes of cooperatively rearranging region (CRR) at Tg (DSC data) and Kuhn segment volumes in glassy...

The fluctuation theory of glass transition allows estimation of the volume V of the so-called cooperatively rearranging regions (CRR) [8, 94] ... 

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