The effects of electron irradiation on the molecular chemical structure, conformation, mobility, and phase transition of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer have been investigated with variable-temperature, solid-state F-19 nuclear magnetic resonance (NMR). It has been found that electron irradiation converts all-trans conformations of both VDF-rich and TrFE-containing segments into dynamically mixed trans-gauche conformations accompanied by a simultaneous ferroelectric-to-paraelectric (or amorphous) transition. The variable-temperature F-19 magic-angle-spinning spectra results show that the paraelectric phase melts at much lower temperatures in irradiated films than in an unirradiated sample. Moreover, F-19 NMR relaxation data (spin-lattice relaxation times in both the laboratory and rotating frames) reveal that electron irradiation enhances the molecular motion in paraelectric regions, whereas the molecular motion in a high-temperature amorphous melt (> 100 degrees C) is more constrained in irradiated films. Besides these physical changes, electron irradiation also induces the formation of several CF3 groups. (c) 2006 Wiley Periodicals, Inc.