Study On Piezoelectric Damping Properties Of Piezoelectric Ceramic/Polymer Composites

For conductive fillers/piezoelectric ceramic/polymer composites, based on the piezoelectric and conductive theories, mechanical energy or sound energy can change into electric energy induced by piezoelectric ceramic's piezoelectric effect, and then these energy can be dissipated in form of heat energy through conductive network formed by conductive fillers in the system.In this paper, effects of components, ceramic varieties, polarization conditions on the piezoelectric performance and rheological behavior of the piezoelectric ceramic/polymer composites have been studied systematically. At the same time the optimum component and preparing method were discussed in order to obtain the high performance piezoelectric ceramic/polymer damping composites.Investigation of the piezoelectric performance for piezoelectric ceramic/polymer composites has been carried out. The results showed that different volume percent of piezoelectric ceramic influence the piezoelectric performance of composite system greatly. High piezoelectric constant and dielectric constant piezoelectric ceramic grain which used as functional element were selected, and mixed with polymers in 60-70% volume percent. These composites showed good piezoelectric performance and processiblity. Polarization is believed to be the key procedure for whether the composite system possesses piezoelectric performance or not. The results revealed that there exists an optimum polarization temperature and polarization intensity of electric field (Ep) for each system, under which regularly orientated polarization and excellent piezoelectric properties can be achieved. The piezoelectric constant (dji) changes with the polarization time under saturated electric field. The d33 increases rapidly with the polarization time at the initial stages of polarization, and approaches constant after certain time.The dynamic mechanical behavior of the polymer composites, dynamic storage modulus (G'\ dynamic loss modulus (G") and loss tangents (TanS), have been studied in this paper. For different ceramic, the higher structure of the ceramic filler is, the high value of Tan8 is. The lead zirconate titanate (PZT) /polymer compositepresented large Tan5 and dynamic modulus when the composites were exposed to higher polarization voltage and longer polarization time, because of the uniform dispersion of ceramic in polymer matrix and the strong interaction between grain and polymer. The morphology of the composites, namely the degree of the grains dispersion in polymer, can be observed through scanning electric microscope (SEM).Moreover, the dynamic rheological behaviors for conductive filler/piezoelectric ceramic/polymer composites have been studied. The results revealed that different conductive filler affected the dynamic modulus of the composite. Carbon fiber (CF)/BaTiO3/EVA system has better conductivity because CF can form conductive network easily in polymer. The curve of dynamic modulus versus the conductive filler volume percent showed that the dynamic modulus of the composites changed with increase of the filler volume percent and exhibited a transition phenomenon. It is believed that these results mentioned above were related to the filler dispersion and the interaction between filler and polymer.