Síntese e caracterização de compósitos Poli (fluoreto de vinilideno) /Bao, 3Na0, 7Ti0, 3Nb0, 703

Abstract

In this work, Bao, 3Na0, 7Ti0, 3Nb0, 703 (BTNN30/70) ceramics and polyvinylidene fluoride (PVDF)/BTNN30/70 composites, with 1:1 ratio, were synthesized and characterized. Their structural, microstructural, spectroscopic (infrared region (IR)) and dielectric properties were determined as a function of temperature and/or frequency. The IR characterizations for the PVDF sample show that this polymer presents characteristic bands of the α and β phases that were not identified by performing X-ray diffraction (XRD). Furthermore, the percentage of the β phase, in relation to the α phase, possibly increased after the consolidation of the polymer at 180 oC. Considering the composites, the IR characterizations show that there was not a significant shift of the characteristic IR bands for PVDF and BTNN30/70 ceramics consolidated at 180 ºC. However, the polymer's IR bands around 1200, 1152, 854 cm-1 were suppressed after consolidation. Dielectric characterizations show that the polymer somewhat blocks the dielectric response of the ceramic contained in the composite. Besides, of the four composites studied in this work, the better one, considering the dielectric response, is that consolidated at 170 ºC, because when compared to that consolidated at 180 ºC it presents the same dielectric constant and the same dielectric loss at 1 MHz (ε =22 e tg δ= 15%). However, for 1 kHz, the composite consolidated at 180 ºC presents a dielectric constant 12,5% higher than that consolidated at 170 oC (ε 180 = 48 e ε 170 = 42), while its dielectric loss increased of about 90% (tg δ170 = 4%, tg δ180 = 37%).