Activation energy, definition solvent effects

The most important effect of plasticization is the lowering of the Tg of the polymer, which was discussed in Section 6.D. Another effect of plasticization is that the activation energy for viscous flow of the solution at T>1.2-Tg is usually smaller than the activation energy of the pure polymer since ET)p Er S for most polymer-solvent combinations. Our preliminary calculations show that Equation 12.21 may often be preferable to Equation 12.19 for describing the behavior of Er SS, at least for Op l. This issue must, however, be considered in greater detail in order to reach more definitive conclusions. In particular, ET SS must be examined as a function of Op in the limit of Op—>1. Furthermore, the dependence of the behavior of ET SS as a function of Op on the strength of the interactions between the polymer and the solvent needs to be considered. 

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