The electron irradiation effect on 80/20 poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymers was studied by FTIR spectra and X-ray diffraction. Infrared spectra showed decreasing intensity of bands at 1430, 1286, 846, and 505 cm(-1), the appearance and intensity increasing with irradiation doses of bands at 768, 601, and 1735 cm(-1), which revealed the conformational change after irradiation. The X-ray diffraction patterns exhibited a de-crease of volume fraction of ferroelectric phase and expansion of the lattice space. The electron-irradiated P(VDF-TrFE) films showed structural changes and polar phase to nonpolar phase transformation. (C) 2004 Wiley Periodicals, Inc.