Table of Contents - Volume 19 Number 3

Filler dispersion is an important issue for polymer-based composites. Fillers can be dispersed by melt or solution processing methods. Solution-based mixing offers various combinations including ultrasonication, mechanical stirring, or high shear mixing. Planetary high shear mixing is a simple method with high dispersion performance. Dispersion and wetting of the fillers are provided by not only planetary shear movement of the mixer but also by the decrease in viscosity of the polymer phase because of high shear. Although that is advantageous for the dispersion of nanofillers, it might be challenging for the particles that have morphology with loosely bonded layers. To observe the effects of high shear mixing on expanded vermiculite (VMT) filled styrene-[ethylene-(ethylene-propylene)]-styrene (SEEPS) flexible composites, two different VMTs were used with different particle sizes at various VMT ratios from 1 to 30 wt%. Morphological, structural, thermal, mechanical properties, flame spread character of the composites, and viscosity of the solutions were analyzed. From morphological analysis, high shear mixing was found to be effective in terms of decreasing particle size and filler dispersion. While mechanical properties showed decrease, thermal stability, and flame retardancy of the composites increased.

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In the present study, cobalt sulphide was successfully synthesised via a simple, one-step hydrothermal route. The material has been characterised via infrared (FTIR) spectroscopy, electron microscopy (FESEM), and X-ray diffraction (XRD). The FTIR spectrum reveals a peak at 1126 cm^-1, which corresponds to the S-O bending mode, and a peak at 663 cm^-1, which represents sulphide stretching. According to XRD analysis, cobalt sulphide formed with the CoS1.097 configuration. FESEM study reveals that cobalt sulphide hexagonal sheets with a thickness of less than 100 nm have been prepared that are further arranged in a floral pattern. Cobalt and sulphide concentrations were found to be proportional in EDX analyses. Further, Electrochemical testing was performed with a two-electrode setup, 6M KOH as the electrolyte, and various current collectors (including nickel foam and aluminium foil). The galvanostatic charge-discharge characteristics and capacitance values have been compared using impedance spectroscopy and other techniques. Details of the analysis are presented.

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Due to the superior mechanical and thermal properties of nanomaterials like multi-walled carbon nanotubes, aluminum alloys containing them play a significant role in the aerospace and automotive industries. By incorporating multi-walled carbon nanotubes by weight percentage of (0, 0.25, 0.50, and 0.75) in Aluminum silicon alloy. proper dispersion is done using ball milling equipment to get the proper bonding between Aluminium silicon alloy with MWCNT then subsequently powder metallurgy followed by extrusion technique. Wear study is carried out by varying load by 20N to 40N by maintaining sliding distance constant at 1000m and speed at 3.14m/sec. Wear test indicates for 20N load that wear rate is reduced by 46% for 2-layer FGM compared to AlSi-0.5WT% MWCNT, AlSi-0.25WT% MWCNT and 10% reduction in wear rate compared to AlSi-0.75WT% MWCNT. In case of 40N, wear rate is decreased by 162% for 2-layer when compared with AlSi-0.25WT% MWCNT and by 91% when compared to AlSi-0.5WT% MWCNT. As the percentage of MWCNT increases leads to decrease in wear rate in case of 20N & 40N load for 2-layer FGM compared to nanocomposites. Optical microscopy is done to reveal the proper bonding of AlSi with MWCNT. SEM analysis is carried out to determine wear mechanism.

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Zinc ferrite nanoparticles have wide range of the applications in the field of Electronics, Optoelectronics, Magnetics, Solar cell, Photocatalysts. With Al doping we modify their structural, magnetic and electrical properties of zinc ferrite (ZnFe₂O₄). In the present studies, zinc ferrite nanoparticles were prepared by sol gel method using glycine as combustion agent. The effects of Al doping concentration on the structural, morphological, optical, magnetic and electrical properties of zinc ferrites were studied. In x-ray diffraction patterns analysis confirmed the formation of the cubic spinel structure. We characterise scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) in the current work to examine the morphology of the nanomaterials. The UV-Vis optical investigation showed that Al⁺³ doping increased absorbance and significantly decreased energy band gap value (1.90 eV-2.01 eV). The magnetic properties of zinc ferrite NPs were studied by using vibrating samples magnetometer which showed samples of pure zinc ferrites and Al-doped zinc ferrite with paramgnetism. Dielectric properties were studied from impedance analyser. When aluminium concentration increases in the zinc ferrites, dielectric characteristic results were obtained in which dielectric constant (ɛ'), dielectric loss (ɛ'') and tangent loss decreased. Also when frequency increases above all three dielectric parameters remains stable at high frequency. The obtained results of pure and Al doped Zn ferrite are useful for high frequency applications.

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Aqueous glycol solutions are widely used as coolant in secondary refrigeration systems. Freezing point is one of the crucial properties used to characterize the performance of coolant. Instrumental methods are often complex and require expensive equipment. For selection of right coolant mixture there was a need for systematic study of aqueous-glycol-salt solution over a wide range of composition. The research work in this paper presents a novel and rapid way for freezing point characterization of the ternary coolant mixture. The freezing behavior of ternary mixture was studied for different blends of ethylene glycol (EG), propylene glycol (PG), sodium chloride (NaCl) and water. Two sets of ternary mixture TM1 (EG-NaCl-water) and TM2 (PG-NaCl-water) were evaluated experimentally at various concentrations of glycol and NaCl. Effect of glycol and salt concentration on freezing point depression was analyzed. The results demonstrated that ternary mixtures required less EG/PG for cost effective formulation of secondary coolant for different cooling application in dairy and food processing industry.

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Our previous study we extended an equation of state model for second order bulk modulus from recent predicted model and calculated variation of pressure with volume for several nanomaterials. Now we use such a model for few other nanomaterials like, TiO₂ (anatase), Ni (20 nm), CdSe (rock salt phase), AlN (Hexagonal), 3C-SiC (30 nm) and Rb₃C₆₀., compare with some other equation of state for nanomaterials and experimental data. The Microsoft Office software has been used to do the calculations. The studies gives great agreement with other EOS and experimental data. The study must be useful at high pressure when the experimental data are not available. So the given study must we useful at high pressure.

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