Tawakalt Mayowa Akintola

This research introduces a readily available and non-chemical combinatorial production approach, known as the laser-induced writing process, to achieve laser-processed conductive graphene traces. The laser-induced graphene (LIG) structure and properties can be improved by adjusting the laser conditions and printing parameters. This method demonstrates the ability of laser-induced graphene (LIG) to overcome the electrothermal issues encountered in electronic devices. To additively process the PEI structures and the laser-induced surface, a high-precision laser nScrypt printer with different power, speed, and printing parameters was used. Raman spectroscopy and scanning electron microscopy analysis revealed similar results for laser-induced graphene morphology and structural chemistry. Significantly, the 3.2 W laser-induced graphene crystalline size (La; 159 nm) is higher than the higher power (4 W; 29 nm) formation due to the surface temperature and oxidation. Under four-point probe electrical property measurements, at a laser power of 3.8 W, the resistivity of the co-processed structure was three orders of magnitude larger. The LIG structure and property improvement are possible by varying the laser conditions and the printing parameters. The lowest gauge factor (GF) found was 17 at 0.5% strain, and the highest GF found was 141.36 at 5%.

In this study, the importance of the preparation technique of Li₄Ti₅O₁₂ (LTO) anode on its performance in a lithium-ion capacitor (LIC) application was investigated. These desired characteristics include energy density, rate capability, and cycle life. The samples were prepared using three approaches, and the same sol-gel synthesis procedure is applied to obtain phase-pure samples and keep the structural properties similar. The influence of these methods on the LTO anodes was then explored in both half-cell and full-cell LIC devices with an activated carbon (AC) cathode. It was observed that the samples had similar specific capacities and energy densities at low specific currents. However, significant differences were observed in the samples’ morphological properties, the rate capability, and the full-cell cycle life performance. Electrochemical impedance spectroscopy was used to identify the electrochemical kinetics and revealed that the LIC with the best performance was influenced by the LTO anode having the least charge transfer and diffusion resistances prepared using a surfactant. This was due to the small particle size, good particle dispersion, and high specific surface area of the LTO anode. This result points to the importance of the choice of synthesis technique in LIC material’s overall performance.

In this work, polystyrene (PS) and boron nitrides nanotubes (BNNT) composites were fabricated, prepared, and characterized using modified direct mixing and sonication processes. The polymer composites were extruded into filaments (BNNTs at 10 wt. %) for 3D printing, utilizing the fused deposition modeling (FDM) technique to fabricate parts for mechanical and thermal applications. Using a direct mixing process, we found that the thermal conductivity and the mechanical strength of the PS-BNNT composite were respectively four times and two times higher compared to the sonication method. The thermal stability and glass transition temperatures were positively affected. A 2D microstructural mechanical entanglement model captured the exact geometry of the nanotubes using the MultiMechanics software, and the performance of the additive manufactured (AM) PS-BNNT composites part for thermomechanical application was simulated in COMSOL. The modified direct mixing process for PS-BNNT, which affects morphology, proved to be effective in achieving better interfacial bonding, indicating that BNNTs are promising fillers for improving thermal and mechanical properties, and are applicable for thermal management and electronic packaging.

Triboluminescence (TL) is a phenomenon of light emission induced by impact, stress, fracture, or an applied mechanical force. This phenomenon can be used to detect, evaluate, and predict mechanical failures in composites. In this report, we utilized manganese-doped zinc-sulphide (ZnS: Mn) and Polystyrene (PS) composite to fabricate a TL functional part via additive manufacturing. The morphology of the particles inside the polymer matrix were studied using scanning electron microscopy and micro CT scan. Thermoanalytical techniques such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were carried out to evaluate the thermal transitions and degradation of the composites. The mechanoluminescence performance of the printed samples is evaluated by three-point flexural test and observed to depend on processing conditions that can be utilized to achieve a strong light signal at different mechanical loads. The polymer composite fabrication and processing reduced particle size, enhanced particle dispersion, and altered the mechanical properties of the polymer to help increase the mechanoluminescence response up to 10 times in the 3D printed parts. The unique mechanoluminescence properties of 3D printed luminescent composite have great potential for structural monitoring applications.