Development of Polyvinylidene fluoride PVDF and its Composites Copolymer for Transducer Applications

Abstract

Poly (vinylidene fluoride) (PVDF) is an attractive piezoelectric polymer, which is highly flexible, biocompatible and has low cost. Piezoelectric polymer PVDF finds a wide range of applications in all the fields such as strain sensors, pressure sensor, mechanical actuators, micro energy harvesters and in structural health monitoring. These applications can be classified broadly into medical instrumentation, robotics, optical devices, computer and office automation, energy conversions, ultrasonic and underwater transducers, electroacoustic transducers, etc. PVDF films are not easily available in India. However, in international market, PVDF sensors are available but with limited thicknesses and dimensions. The main goal of the thesis was to develop PVDF films and its composites, which can be tailor made, for various applications. PVDF films were therefore prepared and methods were optimized using different techniques viz., solvent cast, extrusion and hot press method. These films were tailor made with different dimensions and the electroding pattern to suit variety of applications. The films were characterized using X-ray diffraction, differential scanning calorimeter, Raman spectra, infrared spectra, tensile testing, and scanning electron microscopy. newlineChoosing an appropriate combination and combining two or more materials is a way to achieve desirable properties, which is not possible with the individual component. Mixing of different fillers in PVDF matrix also result in composite having the properties of both the components. The material to be mixed was chosen depending on the requirement of the properties for example higher piezoelectric charge coefficient, higher mechanical strength, large energy storage capacity. In present thesis, composites films were prepared with PVDF as matrix and Lead Zirconate Titanate (PZT), Carbon nanotubes (CNT), Polyaniline (PANI), Onium and copolymers as fillers. The films were characterized to check for its suitability as sensor, actuator and energy harvesters. The thesis covers