Exfoliated Graphite Composite Research Articles

Conductive Filament Composites from Waste Battery Rod-Derived Exfoliated Graphite for Fused Deposition Modeling 3D Printing: A Two-Level Factorial Design Optimization Study

This study used carbon rods from spent zinc-carbon batteries as a source of exfoliated graphite (EG) to produce conductive filament composites for fused deposition modeling 3D printing. The EG filler was prepared through microwave irradiation, while the resulting 3D printable electroconductive EG composites were prepared using polylactic acid (PLA) and polyethylene glycol (PEG) as the polymer matrix and compatibilizer, respectively, via a sonication-assisted solution blending and melt extrusion process. A two-level full factorial design was employed to fully investigate the influence of filament production parameters such as EG loading, PEG:PLA ratio, and sonication time on the resistivity (i.e., conductivity-1) of the prepared composites. Analysis of variance showed that both EG loading and sonication time had significant effects on the resistivity of the composites. The optimum electrical resistivity of the new EG filament composites was found to be 916.418 Ω-cm (maximum conductivity = 1.091 x10-3 S/cm) at EG loading = 45 % w/w, PEG:PLA ratio = 1:10, and sonication time = 2 hours. The conductivity of the 3D printed composites was also correlated with EG amount by the power law model of percolation theory, resulting in an electrical percolation threshold at around 35 % w/w of EG. Our filament composites enable the fabrication of high-value conductive materials from waste resources for sustainable additive manufacturing in the electronics industry.

Magnetic Properties of Fullerene–Thermally Exfoliated Graphite Composites Doped with Sodium

The magnetic properties (field range H = 0–50 kOe, temperature range T = 3–300 K), and structural features of a sodium-doped carbon composite material based on fullerene C60 and thermally exfoliated graphite (TEG) are studied. The material is obtained with different ratios of the components by sintering at a pressure of 7 GPa and T = 600°C, at which it is found that significant amorphization of the crystal lattice of the initial C60 occurs. The dia-, para-, and ferromagnetic components (MD, MPM, and MFM) were separated from the total magnetic moment of the samples under study. It is found that a sodium dopant has no effect on the magnetic properties of the composite. Analysis of the MPM(H) field dependences by using the Brillouin function for the fullerene-containing sample (i.e., without TEG) makes it possible to determine the quantum number of the total angular momentum of paramagnetic (PM) centers. Its value is found to be J = 1, which corresponds to elementary magnetic moment μPM = 2μB of a PM center. The concentration of PM centers is estimated at the level of NPM ≈ (2–5) × 1018 g–1 for most samples, including the material without TEG. The introduction of TEG into the initial composition and an increase in its proportion in the composite leads to a strong increase in the magnetic moment, which is explained by an increase in both the J value and the concentration of PM centers.

Silver Nanoparticles-Loaded Exfoliated Graphite and Its Anti-Bacterial Performance

One antibacterial material was prepared from exfoliated graphite (EG) decorated with silver nanoparticles (AgNPs). The EG was prepared by the graphite intercalated compound process, AgNPs were prepared by chemical reduction of AgNO3 in the presence of NaBH4. The AgNPs-loaded EG (Ag-EG) composite was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption, mercury intrusion porosimetry, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The antibacterial effect of the Ag-EG was evaluated by using the zone of inhibition method. The loaded AgNPs were highly dispersed on EG sheets and most of them have a size less than 10 nm. The Ag loading slightly increased the surface area of EG. It is shown that the Ag-EG had antibacterial activity and anti-adhesion properties against Pseudomonas aeruginosa and Staphylococcus aureus. It suggests that Ag-EG composites could be used in a variety of industrial applications that require an antibacterial effect.

One-step microwave preparation of a Mn3O4 nanoparticles/exfoliated graphite composite as superior anode materials for Li-ion batteries

The fabrication of exfoliated graphite (EG) is highly polluting due to the discharge of large amount of manganese-contained wastewater. Here, a facile and green chemistry route is developed to prepare a Mn3O4 nanoparticles (NPs)/EG composite by artfully tuning the traditional fabrication process of EG. During this treatment, Mn3O4-NPs with high crystallinity and uniform dimension of ∼7nm are found to be homogeneously and firmly anchored on the surface of EG. The composite as an anode material of Li-ion batteries exhibits favorable electrochemical performances, such as decay-free charge capacity of 655mAhg−1 extending to 120 cycles and excellent rate capability.

Preparation of Nylon-6/flake graphite derivatives composites with antistatic property and thermal stability

Nylon-6/flake graphite (FG) composite, Nylon-6/graphene intercalation compounds (GIC) composite and Nylon-6/exfoliated graphite (EG) composite were prepared by FG, GIC, EG and caprolactam via in situ polymerization, and the volume resistivities of Nylon-6/flake graphite derivatives composites were also investigated. Meanwhile, the structure of Nylon-6/EG composite was characterized and the thermal stability of Nylon-6/EG composite was investigated as well. When the mass percents of FG, GIC and EG were 1%, 2–4% and 1%, the volume resistivities of flake graphite derivatives composites would reach 7.5×106Ωcm, 3.6×108–1.4×106Ωcm and 2.3×106Ωcm. When the mass percent of EG increases from 0% to 9%, the thermal stability temperature of Nylon-6/EG composite would enhance from 70 to 196°C. This shows that Nylon-6/flake graphite derivatives composites can have the antistatic property and thermal stability synchronously.

Preparation and characterization of Nylon-6/exfoliated graphite composite via a combination method of in situ polymerization and thermal expansion

Nylon-6/exfoliated graphite (Nylon-6/EG) composite was prepared via a combination method of in situ polymerization and thermal expansion and characterized via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Otherwise, the resistivity value of Nylon-6/EG composite was measured, and the volume resistivity value was calculated as well as. The characterization showed that Nylon-6/EG composite had the morphology of the graphite worm and was structured by EG and Nylon-6, which covered on the surface of EG. The result exhibited that the volume resistivity of Nylon-6/EG composite would decrease when the dosage of EG increased. When the mass percent of EG was 1%, the the volume resistivity value of Nylon-6/EG composite could reach 2.3 × 106 Ω cm. This shows that the combination method not only is very effective and reliable but also can play an important role in preparing antistatic Nylon-6 composite.

Conducting Polymers - Exfoliated Graphite Composites as Catalysts for Oxygen Reduction

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