The structural changes of irradiated and recrystallized copolymers of vinylidene fluoride and trifluoroethylene [P(VDF-TrFE)] (80/20) copolymers have been investigated through IR spectra, X-ray, and DSC. It is found that recrystallization has a reverse effect on irradiated P(VDFTrFE) copolymers, by which the irradiated samples are turned back to original nonirradiated state partially. During recrystallization, trans-gauche sequences are replaced by all-trans conformation gradually and the irradiated P(VDF-TrFE) (80/ 20) copolymers change from nonpolar phase to polar one. The average crystallite size of polar phase is larger than that in irradiated samples, and the difference between recrystallized and irradiated samples reduces gradually with irradiation dosage. The C=C and conjugated C=C bonds are also found in the recrystallized-irradiated P(VDF-TrFE) (80/20) due to rearrangement of broken bonds. (c) 2006 Wiley Periodicals, Inc.