Three-phase polymer electrolyte nanocomposite composed of polyvinyl-alcohol (PVA), manganese(II) chloride (MnCl2), and multiwall carbon nanotubes (MWCNTs) were prepared using the cast techniques. Impedance spectroscopy was used to investigate the AC electrical conductivity (σ_ac) of two- and three-phase samples with different weight ratios of multiwall carbon nanotubes (MWCNTs) over a wide frequency range and at various fixed temperatures (30 °C to 120 °C). The frequency-dependent nature of σ_ac was seen to follow Jonscher’s power law. The redistribution of accumulated charges was used to explain the change in the pre-exponent (n) and the constant (A) after the percolation threshold. As the temperature approached the glass transition temperature, the mobility of ions and polymeric chains also played an important role in this change. The Correlated Barrier Hopping (CBH) model was considered as the most predicted model for the samples at temperatures below 100 °C. However, the Quantum Mechanical Tunneling (QMT) model was predicted to be the most prevalent conduction model for temperatures greater than 100 °C. The values of the activation energy calculated from both Z” and M” are mostly close. Equivalent circuits were used to analyze the impedance spectra of the two- and three-phase samples. An attempt was made to explain the impedance behavior of the samples through the elements participating in the equivalent circuits.

There is no denying fact that nanoparticles of carbon nanotubes are employed to improve the performance of thermal stability in comparison with traditional nanoparticles, this is because nanoparticles of carbon nanotubes possess outstanding material properties. In this manuscript, a mathematical model of mixed convective flow based on carbon nanotubes suspended in ethylene glycol has been developed and derived by means of Fourier Sine transform. In order to analyze the thermophysical properties of nanofluid, the temperature and velocity profiles have been investigated through fractional derivative and integral transforms. The comparative analysis of single and multi-walled carbon nanotubes has been presented for the sake of enhancement of heat transfer. It is worth mentioning that embedded rheological parameters have shown the sensitivity for the enhancement of heat transfer with and without fractional techniques through graphical illustration.

Polymer blend electrolytes have been prepared using the casting technique. The electrolyte is composed of two polymers polyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP)) with a fixed ratio (50:50) loaded with varied ratios of FeCl₂ (0.5, 1, and 2wt.). The impedance analysis indicates that the AC conductivity increased as the temperature was following the power law. Nyquist plots for pure and blend composite samples present depressed semicircles at all temperatures. The conduction mechanism of the pure blend sample was based on a hopping mechanism, whereas the ionic conduction was applied to the blend composite sample. The activation energy for blend and blend composite samples was determined, and the two activation regions appeared for blend electrolyte samples. The results indicate a significant improvement in the electrical behavior of the polymeric blend (PVA/PVP) by adding a small weight percentage of FeCl₂ salt to the blend samples.

The purpose of this study was to investigate the thermal stability and the decomposition kinetics of ethylene–propylene–diene monomer (EPDM) composite samples loaded with and without lead powder (50, 100, and 200 phr lead) using thermogravimetric analysis (TGA). TGA was carried out at different heating rates (5, 10, 20, and 30 °C/min) under inert conditions in the temperature range of 50–650 °C. Lead addition did not significantly change the onset temperature or peak position corresponding to the maximum decomposition rate of the first derivative of the TGA curve (DTGA) (onset at about 455 °C and T_m at about 475 °C). Peak separation for the DTGA curves indicated that the main decomposition region for EPDM, the host rubber, overlapped the main decomposition region for volatile components. The decomposition activation energy (E_a) and pre-exponent factor (A) were estimated using the Friedman (FM), Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO) iso-conversional methods. Average activation energy values of around 231, 230, and 223 kJ/mol were obtained for the EPDM host composite using the FM, FWO, and KAS methods, respectively. For a sample loaded with 100 phr lead, the average activation energy values obtained via the same three methods were 150, 159, and 155 kJ/mole, respectively. The results obtained from the three methods were compared with results obtained using the Kissinger and Augis–Bennett/Boswell methods, and strong convergence was found among the results of the five methods. A significant change in the entropy of the sample was detected with the addition of lead powder. For the KAS method, the change in entropy, ΔS, was −3.7 for EPDM host rubber and −90 for a sample loaded with 100 phr lead, α = 0.5.

The rapid advancement of high-density electronic devices and data centres has heightened the demand for effective thermal management solutions capable of handling elevated heat fluxes within compact domains. Conventional cooling techniques often fail to meet these requirements efficiently. This study presents a numerical investigation of heat transfer enhancement in a mini-channel heat sink through the combined use of passive vortex generators (ribs) and externally applied magnetic fields. A two-dimensional simulation was conducted for a 40 mm × 4 mm mini-channel employing a 2% Fe₃O₄–water nanofluid, with magnets positioned at X = 15 mm and X = 25 mm to generate non-uniform magnetic fields ranging from 800 to 2000 G. Three rib configurations parallel, staggered, and ribbed were evaluated across a Reynolds number range of 50, 75, 100, 150, 180, and 210. Results indicate that the ribbed configuration provides the highest heat transfer improvement, achieving up to a 65% increase relative to the baseline, while the parallel arrangement attained the highest absolute Nusselt number. The friction factor increased with stronger magnetic fields but decreased with higher Reynolds numbers. The thermal enhancement factor remained consistently above unity, with peak values of 2.06 for ribbed, 1.77 for parallel, and 1.52 for staggered layouts. Overall, this study demonstrates that integrating rib-induced vortex generation with magnetic field effects offers a promising strategy for enhancing the thermal performance of mini-channel heat sinks, addressing the cooling demands of next-generation electronic and data centre applications.