Molecular Dynamics of Poly(ethylene‐2,5‐furanoate) (PEF) as a Function of the Degree of Crystallinity by Dielectric Spectroscopy and Calorimetry

Abstract

The segmental and local dynamics of the bio‐based polyester poly(ethylene‐2,5‐furanoate) (PEF) are investigated by dielectric spectroscopy (DS) at atmospheric pressure as a function of temperature and frequency for samples prepared with different degrees of crystallinity. Crystallization significantly alters the segmental process as this is manifested in the dielectric strength and the distribution of relaxation times. Enhanced crystallinity by the different annealing protocols increases the glass temperature of the mobile amorphous fraction. A two‐phase model is adequate in describing the dynamics associated with the β ‐process within the glassy state. However, the same model fails in describing the segmental dynamics at and above the glass temperature. The combined differential scanning calorimetry and DS results provide evidence that for samples with a degree of crystallinity of ≈40%, approximately a third of segments are located within the restricted amorphous fraction. image