Microstructure and electromechanical responses in semicrystalline ferroelectric relaxor polymer blends

Ferroelectric relaxor poly(vinylidene fluoride-trifluoroethylene-1,1-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer with VDF/TrFE/CFE composition of 59.2/34.6/7.2 (mole %) exhibits a high dielectric constant (similar to 50) around room temperature and strong electromechanical response. It can form miscible blends with poly(methyl methacrylate) (PMMA). This paper reports the results of a systematic investigation of the influence of PMMA on the microstructure and electromechanical responses of the terpolymer blends with PMMA content up to 10 wt %. It was found that the crystallinity of the blends decreases nearly linearly with increased PMMA content. Since the dielectric constant and polarization response of P(VDF-TrFE-CFE) terpolymer are mainly from the crystalline region, these properties accordingly exhibit proportional reduction with increased PMMA concentration. Nevertheless, a small amount (similar to 5 wt %, for instance) of PMMA can raise the elastic modulus of the blend quite markedly while the field-induced strain level is not affected very much. Consequently, the elastic energy density can be enhanced in the blends. As a result, the electromechanical efficiency of blends in the composition range investigated is also significantly improved. In addition, the mechanical loss factor is dramatically decreased at room temperature by blending with PMMA. (c) 2006 American Institute of Physics.