Calculation of the equilibrium polarization of vinylidene fluoride-trifluoroethylene copolymers using the iteration method

The calculating method of the equilibrium polarization Pe of non-uniformly polarized crystal is presented and the method is applied to the idealized single crystal of the vinylidene fluoride-trifluoroethylene random copolymer (VDF/TrFE). VDF/TrFE copolymers have a large enhancement of the polarization, compared with β-phase poly (vinylidene fluoride) (PVDF) crystal, wherein the electrostatic interaction has no tendency toward the enhancement of polarization. This is due to the effective increase in the electrostatic inter-molecular interaction in comparison with the intramolecular interaction. The stability of the electrostatic interaction is discussed in relation to the polarization.