Relaxation primary glass-rubber

In addition to the primary glass-rubber relaxation which follows the empirical shifts determined by Eq. (26), part of the recoverable compliance does not obey time-temperature superposition. The shortest time data at the lowest temperatures has a component which shifts according to the Arrhenius temperature dependence... 

Fig. 6. Transition map for PPG showing the primary glass-rubber relaxation (a process) and the secondary relaxation (J3 process)...

Usually the primary (P) glass-rubber relaxation cannot be resolved from the secondary relaxation at hypersonic frequencies. However, this is not always the case. The Brillouin frequencies Awd) and tan 8 for polypropylene glycol (PPG) (13) are plotted versus temperature in Figure 9. Two tempratures of maximum loss are observed. The higher temperature loss at 100 °G and a frequency of 4.40 GHz correlates very well with the primary glass-rubber relaxation line determined by dielectric relaxation at gigahertz frequencies (13), The lower temperature loss at 50°G and a frequency of 5.43 GHz correlates with an extension of the secondary transition line. The transition map is shown in Figure 10. 

In all the above three polymers only a single process is apparently observed in the time window for PCS (10-6 to 100 s). The shape of the relaxation function is independent of temperature. The temperature dependence of (r) follows the characteristic parameters observed for mechanical or dielectric studies of the primary (a) glass-rubber relaxation. Relaxation data obtained by many techniques is collected together in the classic monograph of McCrum, Read and Williams41. The data is presented in the form of transition maps where the frequencies of maximum loss are plotted logarithmically... 

Figure 8, Transition map for PIB. The hypersonic result corir siderahly extends the available frequency range. The primary (P) glass-rubber relaxation line and secondary (S) relaxation line are from Ref. 22.

Another major discrepancy between theory and experiment is exemplified in Figure 3-21. In this figure, the predicted relaxation according to the Rouse theory is compared with an experimental result for polystyrene in the primary transition region. It is clear that polystyrene undergoes its glass-to-rubber... 

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