ULTRAHIGH FIELD-INDUCED STRAIN AND POLARIZATION RESPONSE IN ELECTRON-IRRADIATED POLY(VINYLIDENE FLUORIDE-TRIFLUOROETHYLENE) COPOLYMER

The influence of electron dosage on the field induced strain, dielectr ic constant, and polarization response has been investigated in electr on irradiated poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE) ) 50/50 copolymer. It was found that under suitable electron dosage an ultrahigh electrostrictive strain can be achieved. Interestingly, mat erial after irradiation exhibits many features resembling those of rel axer ferroelectrics, suggesting that the electron irradiation breaks u p the coherent polarization domain in normal ferroelectric P(VDF-TrFE) copolymer into nano-polar regions that transform the material into a relaxer ferroelectric. In addition, many of the material properties in cluding the field induced polarization, the electrostrictive strain, a nd elastic modulus exhibit irregular change (non-monotonical) with ele ctron dosage, indicating a complex relation among the crosslinking den sity, crystallinity, crystallite size, and molecular conformation in d etermining the material responses.