Temperature Dependence for Semi-Crystalline Polymers

For semi-crystalline polymers with melting points of more than 100 °C above the glass transition temperature and for amorphous polymers far above the glass transition temperature Tg (at around T = Tg + 190°C), the shift factors obtained from time-temperature superposition can be plotted in the form of an Arrhenius plot for thermally activated processes  

R is the gas constant and Ea the flow activation energy. The latter is a material-specific factor that is not dependent on the molar mass of the polymer and for thermorheological simple polymers also is not dependent on the shear stress. The activation energy Ea for polymer melts varies between 25 and 80 kj/mol. It can be determined from the slope of the line in the Arrhenius plot. 

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