| High performance electroactive materials are key elements in advanced electromechanical devices with broad applications, including artificial muscles and organs, smart materials and structures, microelectromechanical systems (MEMS), and underwater acoustic devices. Recently, it was discovered that high longitudinal electrostrictive strain with high elastic energy density can be achieved in the high-energy electron irradiated poly (vinylidene fluoridetrifluoroethylene) (P(VDF-TrFE)) copolymer (HEEIP). This thesis investigated the transverse electromechanical responses of this newly developed electroactive polymer, since in many applications the transverse electromechanical response is utilized.; The transverse strain response of the HEEIP under different processing conditions was investigated. It was found that to enhance transverse strain response, the copolymer should be uniaxially stretched to about 5 times its original length prior to irradiation. In films so prepared, a transverse strain of 4% can be achieved, which, with a high elastic modulus, results in a high elastic energy density and high electromechanical coupling factor k31 (0.45).; Transverse strain under different mechanical load was investigated, since whether a polymer material can maintain a high strain level when subjected to high external stresses is a concern. It was found that the high strain response in HEEIP maintains up to 45 MPa tensile stress.; The electromechanical properties of HEEIP were also characterized using the resonance method to investigate high frequency material performance. It was found that the transverse electromechanical coupling factor k31 remains constant up to 100 kHz.; Flextensional actuators and transducers were designed and fabricated in which a multilayer stack of HEEIP was employed as the active component. It was found that with a suitable selection of the glue layer, which bonds the active polymer films together, the multilayer could exhibit near the same level of strain response. A flextensional actuator was fabricated. It was shown that a displacement of 1 mm can be produced along the thickness direction under 10N load for a flextensional actuator, with a few mm thick and 30 x 25mm2 in lateral directions.; Micro-actuators based on HEEIP were designed, fabricated, and characterized in this work. Results showed that the high performance material enables the microactuator to generate 60 μm displacement with 1 mm lateral dimension microactuator, with a high load capability and high displacement voltage ratio (DVR). (Abstract shortened by UMI.)... |
