Production, design and control of P(VDF-TrFE-CTFE) relaxor-ferroelectric actuators

Abstract

The amount of research and development in smart materials is increasing every year. These smart materials offer a solution to integrated and distributed actuation and sensing. Pressure sensors, acoustic transducers, deformable mirrors, micro-robotics and stiffness control of flapping wings are some applicationswhere these smart materials show great promise over their external actuated counterparts. New materials are developed and reported regularly, P(VDF-TrFE-CTFE) a relaxor-ferroelectric polymer is such a smart material. Relaxor ferroelectric materials can convert electrical signals to mechanical strain and vice versa, allowing the possibility to act as an actuator and sensor in one. This relatively new material has some promising parameters, with a dielectric constant of 50, Young’s modulus of 0.4 GPa, coupling factor of 0.3 and transparency above 88%, where 100% is no disruption of light at all. With these properties P(VDF-TrFE-CTFE) can serve as a useful component in mechatronic systems. In this thesis, the possibilities in production and enhancement of P(VDF-TrFE-CTFE) are discussed and experimentally validated. The piezoelectric and electrostrictive response in such polymers are formed through polarisation and annealing processes. This thesis shall prove as a guide to achieve the maximum electromechanical performance of a relaxor-ferroelectric polymer, a new method to successfully polarise this relaxor ferroelectric polymer is presented and a novel way to remove residual stresses after spin casting of thin film polymers is proposed.