BaTiO3/polyurethane （BaTiO3/PU） nanocomposite elastomers were prepared from barium titanate nanoparticles, polyester polyol, 2, 4-toluene diisocyanate, 1,4-butanediol and 1, 1, 1-trimethanol propane by the one-step method. The density, hardness and dielectric constant of BaTiO3/PU nanocomposite elastomers increased with the increase of the content of BaTiO3 nanoparticles in nanocomposites. The electrostrictive properties of BaTiO3/PU nanocomposite elastomers were investigated by the digital speckle correlation method （DSCM）. It was found that through the on-and-off of the electric field, the electrostrictive strains of BaTiO3/PU nanocomposite elastomers revealed corresponding shrinkage and recovery. The electrostrictive coefficient of BaTiO3/PU nanocomposite elastomers was greater than that of the corresponding polyurethane elastomers, and the electrostrictive coefficient of composites decreased with the increase of the content of barium titanate nanoparticles.
A new method for measuring the characteristic of electrostriction by a digital speckle correlation method （DSCM） is presented. The in-plane displacement is obtained by using the DSCM, and the out-plane displacement is obtained by the geometrical relation of the triangle theory. In this application, high field electrostrictive strains of barium titanate/polyurethane elastomer composite materials are measured. The electrostrictive strain is evaluated when the application of an electric field is repeated, and then the electrostrictive coefficient of the sample is obtained. To improve the measuring accuracy, the bilinear interpolation of gray value is used to obtain the sub-pixel gray value. The results are compared with those obtained from the surface fitting algorithm. The experimental results demonstrate that the electrostrictive response of polyurethane increases with the introduction of barium titanate into polyurethane. And by using the DSCM, the measurement of the characteristic of electrostriction can be done quickly and accurately. The DSCM provides an effective tool for the evaluation of electrostrictive response.
