High electromechanical coupling factor and electrostrictive strain over broad frequency range in electrostrictive poly(vinylidene fluoride-trifluoroethylene) copolymer films

Electromechanical coupling factor is one of the most important parameters f or measuring the performance of materials for electromechanical transductio n applications. In this paper, we will show that a transverse electromechan ical coupling factor k(31) of more than 0.45 can be achieved in poly(vinyli dene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer under certain elec tron irradiation treatment conditions. Tn addition, the effective piezoelec tric coefficients of the irradiated copolymer have been found to increase m arkedly in comparison to non-irradiated copolymers. Experimental evidences also indicate that the improved electrostrictive strains in irradiated copo lymer films can be maintained over a broad frequency and temperature range.