Beta loss relaxation

Physical aging affects significantly the mechanical damping in both the alpha and beta relaxation peaks. Figure 19 shows the decrease in the beta loss peak as a func-... 

The volumetric, elastic and dynamic properties of internally and externally plasticised PVC were studied and compared with those of unplasticised PVC. The glass transition temperature for the plasticised samples was markedly lowered and this decrease was more important for the externally plasticised ones. The positions of the loss peaks from dielectric alpha-relaxation measurements confirmed the higher efficiency of the external plasticisation. However, the shape of the dielectric alpha-relaxation function was altered only for the internally plasticised samples. The plasticisation effect was linked with a decrease in the intensity of the beta-relaxation process but no important changes in the activation energy of this process were observed. The results were discussed. 47 refs. 

Fig. 40. Loss tangent data from dynamic mechanical testing showing the effects of physical aging on the broad beta relaxation plateau...

Figure 23. Dielectric loss e" versus frequency at different temperatures, as indicated, showing the alpha relaxation process for a thin film of hyperbranched polyesters of 17 nm. Inset. Dielectric loss e" versus temperature at 49 kHz, showing the beta and the gamma relaxation processes for the same sample. Dotted lines serve as a guide for the reader.

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