Segmental relaxation time, changes

C. Changes of the Segmental Relaxation Time and the Joharl-Goldstein Relaxation Time with Crosslink Density... 

Fig. 15. Tg-scaled plot of the segmental relaxation times of PMMA ( ), PnEMA (A), PnBMA (A), PnHMA (T), PnNMA (v), PnDMA ( ), and PnLMA (o). The Tg is operationally defined here as the temperature at which the segmental relaxation time is 100 s. There is change in the nature of the glasses when going from PMMA to the higher member of the series, which reflects in the change from fragile to strong behavior.

This equation makes it possible to obtain the dependence between the degree of closure and the cathodic potential at which the polymer is reduced. The probability ( ) of a conformational change that will allow the reduction and compaction of a segment can be expressed as the inverse of the relaxation time. If all the other terms of Eq. (9) are included in P, then... 

Some information concerning the intramolecular relaxation of the hyperbranched polymers can be obtained from an analysis of the viscoelastic characteristics within the range between the segmental and the terminal relaxation times. In contrast to the behavior of melts with linear chains, in the case of hyperbranched polymers, the range between the distinguished local and terminal relaxations can be characterized by the values of G and G" changing nearly in parallel and by the viscosity variation having a frequency with a considerably different exponent 0. This can be considered as an indication of the extremely broad spectrum of internal relaxations in these macromolecules. To illustrate this effect, the frequency dependences of the complex viscosities for both linear... 

The method employed for the evaluation was determination of deuterium NMR relaxation times as a measure of molecular motion. If radial differences in concentration, or solvation were present such that the segmental mobility of the structure varied significantly between layers, measurable changes in Tt and T2... 

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