Papers by Keyword: Physicochemical Properties

Abstract: The carbonized materials structure levels from molecular to macrostructure is analyzed. A study was conducted to find correlations between the granular carbonized materials electrical resistance and other substance physicochemical properties. It is proven theoretically and experimentally that determining the electrical resistance for a granular material, rather than a finely ground sample, is a more informative indicator for reflecting the microstructural features of the material, its reactivity, strength, and clarifying the carbonization conditions. A method is developed for determining the granular materials electrical resistance in the rotating drum interelectrode space, with determination of the indicator value in the cold and hot state for the substance under investigation. An indicator of the granular matter electrical resistance based on the heating time to 670 °C at a drum power supply constant voltage is introduced. Calculated dependencies is obtained for predicting, based on experiment results, some quality indicators for such a carbonized material as metallurgical coke: structural strength, apparent density, reactivity, gasification degree, and electrical resistivity. Better correlations is achieved with these indicators than with the standard electrical resistance on the "micropress" device, which indicates a better reflection of the carbonized materials substance supramolecular structure.

Abstract: Edible plastics/films or biopolymers are biodegradable materials which are normally applied as food packaging. This type of packaging has been used for centuries to protect food products by avoiding food deterioration and extending its shelf life. Due to the increasing concerns about health and the environment, edible films are made from biomaterials to produce safe, edible, and environmentally friendly materials. In this study, the biopolymer’s compositions are combined from different types of hydrocolloids (polysaccharides base) with gel forming ability and additives for better structure. The film is formed by applying wet formation (solvent casting technique) and dried at 55°C to create thin films. The thickness, tensile strength (TS), elongation at break (EBA), contact angle, water vapor transmission rate (WVTR), water solubility and oil solubility were determined at different proportions of used hydrocolloids. The plasticizer glycerol was added at different concentrations (10, 20, 30% w/w) for further investigation of the film’s properties.

Abstract: The paper contains the results of surface modification on the properties of the pure titanium Grade II, obtained by the SLM procedure. In the paper, the analysis of the results of physicochemical properties, such as pitting corrosion test and contact angle measurements and Surface Free Energy calculated were performed. Additionally, the microscopic observation with microchemical analysis, surface topography analysis using Atomic Force Microscopy, surface roughness measurements and wear test were performed too. The studies were carried out on three groups of samples in an initial state (1) (after mechanical treatment - mechanical grinding and polishing) and after surface modification by PVD method using CrN layer (2) and TiN layer (3). Based on the obtained results it can be concluded that the samples with TiN layer were characterized by the optimum properties.

Abstract: The work considers the main elements of the magneto-dimensional transformation properties in the ultradispersed metallic media (UDM) as a nanomodifier in the process of the formation of nanocompositional polymeric materials (NCPM) based on polyolefins () from a melt. It has been shown that UDM nanoparticles in a melt under the influence and interaction with a thermoplastic matrix are capable of transforming their magnetic properties (to the level of superparamagnetic), structural-dimensional parameters, and chemical potential. With this mutual influence, the nanomodifier has an active effect on the thermoplastic melt at all stages of the formation of the structure-property relationship: structureless ensembles of macromolecules → formation of clusters (domains), lamellas, crystallites → formation of a network of intermolecular entanglements → crystallization of the thermoplastic matrix → transition to a condensed state. An important component of the formation of a fine-crystalline anisotropic NCPM structure is the intramatrix orientation of the structural elements of the thermoplastic in the melt under the influence of the magneto-dimensional transformable manifestations of the nanomodifier. A consequence of the formation of a fine-crystalline anisotropic structure of the NCPM is an increased level of a complex of physicochemical properties (such as deformation-strength, rheological, etc.). An assumption is made about the possibility of the formation of coherent wave packets from clusters (domains) and lamellas of crystallites of matrix thermoplastic with a minimum three-dimensional geometry under the action of superparamagnetic forces of nanoparticles of the nanomodifier.

Abstract: Hematite is one of the most stable oxide phases and has been used as a rock-art pigment material in the prehistoric era. Hematite in the form of ochre has been widely used in rock art, burial rites, cosmetics, and decorations on pottery surfaces. Hematite has several hues, ranging from red to black. The variety of hues might arise due to the differences in physicochemical properties of hematite such as crystallinity, crystallite size, morphology, and electronic structure. The differences in physicochemical properties in hematite pigments might be originated from the differences in the pretreatment technique used before application. Herein, we have conducted a thorough study to investigate the evolution of the crystal structure of hematite under various temperatures. We aim to determine the temperature needed to change the hematite color and uncover the transformation of crystallographic properties as a function of sintering temperature. The hematite was synthesized using the precipitation method with Fe (NO₃)₃.6H₂O as a precursor and ammonia (NH₄OH) solution as a precipitating agent. The study of the hematite structural evolution was carried out by varying the sintering temperatures from 600 to 900 °C and analyzing the products after sintered using X-ray diffraction technique. The results showed that hematite hue was gradually darkened as the sintering temperature increased as a consequence of higher crystallinity and larger crystallite size of hematite crystal. This study confirms that the origin of color changes in hematite is due to the heating treatment of hematite material.

Abstract: The processing of palm oil from the fruits of the African oil palm generates an increasing amounts of solid waste. The production of beneficial products for various applications from the oil palm wastes would reduce the amount of unwanted materials produced and contribute to a healthier environment. In this research, fractions were derived from the filtrate of the oil palm deseeded fruit head ash by fractional crystallization. Their physicochemical properties, cation, and anion compositions were determined by standard methods. Three hygroscopic oil palm ash fractions, namely crystals, anhydrous, and sediment, were obtained from the filtrate of the soaked ash. The crystals fraction showed significantly higher mean values than the anhydrous and sediment in conductivity and total organic matter (p<0.0001 each), salinity (p<0.01 and p<0.0001), and total organic carbon (p<0.01), while anhydrous had higher total dissolved solids than the crystals (p<0.01) and sediments (p<0.05). pH and melting points for the crystals and anhydrous compounds were similar (11.07 and <330) and higher than that of the sediment (10.29 and 284.2). Compared to the crystals, anhydrous fractions reveal significantly lower values in iron, phosphate (p<0.01 individually), zinc, chloride, nitrate, and sulphate (p<0.05 each), while sediments had significantly higher zinc (p<0.05) and nitrate (p<0.0001) and lower iron, chloride (p<0.05 each), sulphate and phosphate (p<0.0001 respectively) mean values. From this study, the isolation of three fractions from the oil palm empty fruit bunch ash with different physicochemical properties and ionic compositions was achieved. These fractions may serve as useful resources for utilization in various fields of research and production processes.

Abstract: Areca nut extract provides a variety of pharmacological effects that are beneficial for skincare applications. A nanoemulsion of areca nut extract was developed to mask the intense color and to improve the water solubility of the extract. This work studied the impact of a co-solvent on the characteristics and stability of the nanoemulsion. Our former optimized nanoemulsion was modified by adding a common co-solvent, propylene glycol or polyethylene glycol 400 (PEG400), to the formula. Phase separation, particle characteristics, antioxidant activity, in vitro cytotoxicity, and stability of the modified nanoemulsion were evaluated. This work has shown the successful encapsulation of areca nut extract with a great improvement of stability, well-maintained antioxidant activity and low toxicity on normal human skin fibroblast.

Abstract: The buried environment of cross-linked polyethylene (XPLE) cable is relatively severe, and some ones are even immersed in water directly. In this paper, an XLPE cable was soaked in foul water to simulate the cable’s actual water area environment, lasting for three years. The water content in the insulation layers of water-soaked cable was measured by infrared spectrometer and moisture analyzer, and the crystal morphology and physicochemical properties of the insulation layers were investigated by differential Scanning Calorimeter (DSC), scanning electron microscopy (SEM) and tensile testing technology. The results showed that a small amount of water did enter into the cable insulation owing to the increasing of hydroxyl (-OH) content, and followed being verified by moisture analyzer. The degree of crystallinity of water-soaked cable insulating material is also increased, and the mechanical properties were deteriorated.

Abstract: In the present studies, different characterization techniques have been utilized to evaluate the stability of catalysts prepared by modified impregnation method. The results indicated that strong metal-support (Mo-support) interaction existed in the γ-Al₂O₃-CeO₂ supported catalyst with higher CeO₂ loading as compared to the Mo/γ-Al₂O₃ catalyst. This suggested that the addition of CeO₂ into the γ-Al₂O₃ enhanced the metal-support interaction, thus decreases the reducibility, depending on the CeO₂ loading. Similarly, the catalyst with higher CeO₂ loading exhibited lower Ce 3d and higher Mo 3d binding energies respectively, supporting the TPR results.

Abstract: Up to date, no extravagant attempts have been made to use the vegetable oil-based polyols as rejuvenator agents for aged asphalts. In this context, the nature and composition of these biodegradable products need to be identified and physicochemical properties of different nature of compounds need to be measured. Three different vegetable oil-based polyols designed as castor oil polyol, soybean flexible polyol, and soybean rigid polyol were characterized by FT-IR, TLC-FID, ¹H-NMR, and ¹³C-NMR and by the determination of some usual characteristics such as acid value, hydroxyl value, iodine value, and viscosity. It is speculated that the soybean flexible polyol may serve as a potential rejuvenator for aged asphalts.