Electric fatigue in poly(vinylidene fluoride-trifluoroethylene) 68/32 copolymer films under cyclic electric field.

Electric fatigue under cyclic loading was characterized for poly(vinylidene fluoride-trifluoroethylene) 68/32 copolymer films prepared under two processing conditions. For the copolymer films prepared by solution casting and then annealing (termed as unstretched films), the remanent polarization (Pr) decreases while the coercive field (Ec) increases as the field cycles. For the copolymer films prepared by stretching the solution-cast films and then annealing (termed as stretched films), both Pr and Ec decrease as the cycle number increases. Scanning electron microscopy observation and x-ray diffraction analysis were carried out to examine the morphology and microstructure changes during the electric field cycling. The differences in the polarization and electric fatigue behavior between the unstretched and the stretched copolymer films can be mainly attributed to the change of the crystallinity, the orientation degree of the polymer chains and electric dipoles, as well as the interfacial layer effects. [ABSTRACT FROM AUTHOR]