Engineering topics

Pavlović, Vladimir

Publications and source records attributed to Pavlović, Vladimir.

3 records

DOE OSTI2023

Effect of the filler morphology on the crystallization behavior and dielectric properties of the polyvinylidene fluoride‐based composite

Abstract Ceramic/polymer composites can be chemically stable, mechanically strong, and flexible, which make them candidates for electric devices, such as pressure or temperature sensors, energy storage or harvesting devices, actuators, and so forth. Depending on the application, various electrical properties are of importance. Polymers usually have low dielectric permittivity, but increased dielectric permittivity can be achieved by the addition of the ceramic fillers with high dielectric constant. With the aim to enhance dielectric properties of the composite without loss of flexibility, 5 wt% of BaTiO 3 ‐Fe 2 O 3 powder was added into a polyvinylidene fluoride matrix. The powder was prepared by different synthesis conditions to produce core/shell structures. The effect of the phase composition and morphology of the BaTiO 3 ‐Fe 2 O 3 core/shell filler on the structure and lattice dynamics of the polymer composites was investigated. Based on the results of the thermal analysis, various parameters of ceramic/polymer composites were determined. Differences in the phase composition and morphology of the filler have an influence on the formation of various polyvinylidene fluoride allomorphs and the degree of crystallinity. Furthermore, the dielectric performances of pure polyvinylidene fluoride and the polymer/ceramic composites were measured.

Polymer Science↗

DOE OSTI2023

Toward improved PVDF-BaTiO 3 composite dielectrics: mechanical activation of the filler versus filler content

Abstract Barium titanate (BT) perovskite particles were surface modified by means of mechanical treatment and used as inorganic component in polyvinylidene fluoride (PVDF) based composites. The changes in electrical properties of the composite films with increasing in filler content were followed by dielectric spectroscopy, breakdown strength andD-Emeasurements. A comparison of the properties of the composites prepared with untreated and mechanically activated particles revealed that there is a significant difference in their performances at low filler concentrations (<20 wt%). Introduction of the surface modified ceramic particles into PVDF matrix led to an increase of the dielectric constant without affecting significantly the electrical breakdown strength. In contrast, when as received BT particles were used a filler, both dielectric constants and breakdown strengths of the composite films were lower than the corresponding values observed for the pure PVDF. At higher concentrations, however, the influence of pre-treatment of the filler on the effective electrical properties becomes less significant. The obtained results were discussed in terms of the pronounced crystallization of polarβandγcrystal phases of PVDF in the presence of surface modified BT fillers, which is confirmed by Raman spectroscopy.

Physics↗

DOE OSTI2022

Hydroxyapatite/TiO 2 Nanomaterial with Defined Microstructural and Good Antimicrobial Properties

Due to the growing number of people infected with the new coronavirus globally, which weakens immunity, there has been an increase in bacterial infections. Hence, knowledge about simple and low-cost synthesis methods of materials with good structural and antimicrobial properties is of great importance. A material obtained through the combination of a nanoscale hydroxyapatite material (with good biocompatibility) and titanium dioxide (with good degradation properties of organic molecules) can absorb and decompose bacteria. In this investigation, three different synthesis routes used to prepare hydroxyapatite/titanium dioxide nanomaterials are examined. The morphology and semiquantitative chemical composition are characterized by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX). The obtained materials’ phase and structural characterization are determined using the X-ray powder diffraction method (XRD). The crystallite sizes of the obtained materials are in the range of 8 nm to 15 nm. Based on XRD peak positions, the hexagonal hydroxyapatite phases are formed in all samples along with TiO 2 anatase and rutile phases. According to SEM and TEM analyses, the morphology of the prepared samples differs depending on the synthesis route. The EDX analysis confirmed the presence of Ti, Ca, P, and O in the obtained materials. The IR spectroscopy verified the vibration bands characteristic for HAp and titanium. The investigated materials show excellent antimicrobial and photocatalytic properties.

60 APPLIED LIFE SCIENCES↗