To further explore the molecular origin of the βa dielectric process in P(VDF-TrFE), electric poling exper-iments were performed. In normal ferroelectric materials, electrical poling usually improves the polar-ordering in the crystalline region and reduces the domain wall density, and so dielectric dispersion originating from domain wall motion should be weakened [23, 24]. After poling at 100 MV/m at 50◦C for 10 min, the F-P transition of the copolymer is clearly sharpened due to the formation of larger polarization domains. The βa process, however, is weakened considerably after poling (Fig. 9), and its location shifts to slightly higher frequencies compared with the unpoled samples. The low-frequency dielectric constant in the glass transition region also decreases after poling. Since a poling field of 100 MV/m at 50◦C will not have a marked effect on the crystallinity (converting amorphous chain segments into crystallites), the decrease in strength of the βa process is attributed to reduction in the density of domain wall and other defects in the crystalline phase due to poling. The result is consistent with the scenario that there is a quite significant contribution to the βa process from the domain walls and other defects in the crystalline phase.