P(VDF-TrFE)/PLZT Composites Preparation And Performance Studies

Polymer-ceramics composites have became a reseach focus because one single of them could not meet the demand of electronic devices. As is known, although perovskite ceramics possess a higher dielectric constant and a larger pizeoelectric performance than as-cast polymer, it is not easy shaped for its high modulus and brittleness. Therefore,in this work, a hydrogenised poly (vinylidene Fluoride-trifluoroethylene) (P(VDF-TrFE)) was synthesized by an atom transfer radical polymerization (ATRP) method from commercial poly (vinylidene Fluoride-chlorotrifluor ethylene) (P(VDF-CTFE). And then lead lanthanum zirconate titanate(PLZT) powder was obtained from sol-gel processing method. Based on that,P(VDF-TrFE)/ PLZT composites was compounded by a solution-casting method. The related experiments show that the obtaining composites has many advantages such as a high dielectric constant, a large pizeoelectric property, and a favorable flexible performance. The main works of this thesis was listed as follows.1) Considering the high price and difficult synthesize processing, P(VDF-TrFE)was synthesized by ATRP method from P(VDF-CTFE) whose atom Cl in CTFE units was completely replaced by atom H. The molecular structure was proved by NMR and XRD which shows TrFE molar content is 20%.2) To reduce the crystaline grain size and improve the activity of ceramics particles, sol-gel synthetic method was used to get the PLZT materials. After polarizing the ceramic plate at a certain electric filed, a large piezoelectric value of 121pC/N was obtained in 33 direction of the sample.3) By using solution-cast process, the P(VDF-TrFE)/PLZT nanocomposites with variuos PLZT weight content from 5wt% to 25wt% were obtained. Then the dependence of dielectric, ferroelectric, and piezoelelctric properties on the PLZT volume was expressed. It is shown that dielectric constant of the composites increases firstly and then reduces as the volume of PLZT ceramics. And a very large relative dielectric constant of 85 at 100 Hz was obtained at P(VDF-TrFE)/PLZT80/20wt%sample. When polarized at 150MV/m, the piezoelectric value of -32 pC/N was founded in 33 direction.As a result, the introducing of perovskite ceramics could improve the dielectric and piezoelectric performance of the fluoropolymer significantly, which provides a reference of potential application of this kind of composites in piezoelectric area.