Multitasking Performance of Fe3O4/BaTiO3/Epoxy Resin Hybrid Nanocomposites

Abstract

In this study, hybrid nanocomposites consisting of Fe₃O₄/BaTiO₃/epoxy resin were prepared with varying amounts of filer content. Structural and morphological characterization, conducted via X-Ray Diffraction patterns and Scanning Electron Microscopy images, revealed the successful fabrication of composites and fine dispersion of inclusions. Thermomechanical properties are studied via Differential Scanning Calorimetry, Thermogravimetric Analysis, Dynamic Mechanical Analysis and static mechanical tests. Hybrid composites exhibit enhanced thermal stability and improved mechanical response. Indicatively, Young's modulus, tensile strength and fracture toughness increase from 1.26 GPa, 22.25 MPa, and 3.03 kJ/m³ for the neat epoxy to 1.39 GPa, 45.73 MPa, and 41.08 kJ/m³ for the composites with 20 or 15 parts per hundred resin per mass (phr) of Fe₃O₄, respectively. Electrical behavior is investigated via Broadband Dielectric Spectroscopy and ac conductivity measurements. The real part of dielectric permittivity reaches the value of 11.11 at 30 °C for the composite with 40 phr of Fe₃O₄. The ability to store and retrieve electric energy on the nanocomposites is examined with the following parameters: the filler content and the applied voltage under dc conditions. Retrieved energy reaches 79.23% of the stored one, for the system with 15 phr of Fe₃O₄. Magnetic response is studied via a Vibrating Sample Magnetometer. Magnetic saturation, for the system with the highest magnetic filler content, obtains the value of 25.38 Am²/kg, while pure magnetic powder attains the value of 86.75 Am²/kg. Finally, the multifunctional performance of the nanocomposites is assessed regarding all the exerted stimuli and the optimum behavior is discussed.

Keywords: electrical properties; energy storing/retrieving; hybrid nanocomposites; magnetic response; multifunctionality; thermomechanical behavior.

Figure 1

Schematic representation of materials’ multifunctionality.

Figure 2

XRD patterns of all studied hybrid composites and the employed fillers at room temperature (RT). Comparative XRD patterns from barium titanate micro-particles at RT and 170°C and from the 5 phr Fe₃O₄/10 phr BaTiO₃/epoxy composite at RT.

Figure 3

SEM images from the composites: 5 phr Fe₃O₄/10 phr BaTiO₃ (a) and 40 phr Fe₃O₄/10 phr BaTiO₃ (b). The indicated scale bar corresponds to 200 nm.

Figure 4

Storage modulus (a) and loss modulus (b) as a function of temperature for all studied systems. Left inset max E’ versus filler content. Right inset TGA thermographs.

Figure 5

(a) Real part of dielectric permittivity, (b) loss tanδ, and (c) σ_ac as a function of frequency and temperature for the 40 phr Fe₃O₄/10 phr BaTiO₃/epoxy hybrid composite.

Figure 6

Young’s modulus, tensile strength (T_s), and fracture toughness for all studied systems.

Figure 7

(a) Real part of dielectric permittivity as a function of frequency at 30 °C, and (b) loss modulus index as a function of frequency at 160 °C, for all studied systems.

Figure 8

DRF, at 0.1 Hz, versus temperature for all the examined hybrid composites.

Figure 9

Charging (storing) energy (a), discharging (retrieving) energy (b), and relative discharging (retrieving) energy (c), as a function of time at room temperature.

Figure 10

(a) Magnetic hysteresis loops for all hybrid composites, inset depicts the hysteresis loop of magnetite powder. (b) Magnetic saturation as a function of the Fe₃O₄ content.