Papers by Keyword: Stearic Acid

Abstract: The periodontitis leads to the formation of periodontal pockets, which provide an ideal site for localized antimicrobial drug delivery for therapy. In this study, metronidazole (Met)-loaded in-situ matrix (ISM) systems were developed to assess their physical and drug release characteristics. Bleached shellac (BS) and fatty compounds such as beeswax, carnauba wax, candelilla wax, shellac wax, and stearic acid (SA) were tested as matrix-forming agents. ISM systems containing BS and SA in BS ratios of 2:1, 1:1, and 1:2 at 30% w/w were chosen because they resulted in clear, liquid-like ISMs. Increasing the BS content raised both the density and viscosity of the ISM. Upon injection into simulated crevicular fluid these liquid ISMs quickly formed solid matrices. Drug release was notably prolonged, with only around 6% released within the first day and sustained over six days. Met-loaded BS-SA ISM shows promise as a delivery system for intra-periodontal pocket route. However, further studies should focus on modulating release profile to improve drug delivery.

Abstract: Vulcanization of rubber compounds is a crucial step in the process of developing natural rubber end products. Selected components are then used to formulate a rubber compound, which is further treated to create vulcanized rubber. In this study, a palm oil-based zinc stearate compound (ZS) developed by the National Research and Innovation Agency (BRIN) was used as a replacement for ZnO and stearic acid, which were previously used as activator and co-activator in the process of vulcanization. The goal of this study was to create a compound made of rubber formulation for use in the hand grip. The zinc stearate applied in this study ranged from 4 to 6 phr. To examine the effect of applying zinc stearate to vulcanized rubber, three primary parameters - tensile strength, hardness, and elongation at break of the vulcanized rubber - were evaluated. The results of the tests revealed that adding zinc stearate at a loading rate of 4 phr gave the hardness value of 27 Shore A, the tensile strength of 19 MPa, and the elongation at break by 590%. With this mechanical characteristic, the formula was identified as the optimal choice for achieving a robust and deformation-resistant hand grip while ensuring user comfort.

Abstract: Wire explosion technique was explored for producing ZnO nanoparticles. The ZnO nanoparticles were spherical with diameters less than 20 nm. The as-prepared nanoparticles are a mixture of Zn and ZnO based on the XRD analysis. However, the remaining Zn was oxidized upon sonication in the presence of oxygen gas. The ZnO nanoparticles were dispersed in ethanol and deposited on glass before dipping in a stearic acid solution. The coated glass exhibited a static water contact angle of nearly 150°, indicating excellent water repellency.

Abstract: This study attempted to focus the light on the characterization possibility of the vulcanized, chlorinated, natural rubber products (as the commercial rubber band used in this study) as a shape memory smart material in the case of impregnating it with fused stearic acid by swelling mechanism. Where in this study, the ability of the commercial rubber band on fixing the stretching strain chosen in this study which is of 70% after removing the applied load off the rubber band, was measured after impregnating it with stearic acid (SA) material of weight ratio (30.4%) and swelling time=2hr. At the same time, measuring the ability of that rubber band on rid of this mechanical deformation once it is thermally stimulated and returning to its original shape (before the deformation) by subjugating it to the hot classical shape memory cycle (based on normal cooling at room temperature) with its two stages represented by the shape memory effect (SME) property activation and deactivation stages. Also, the techniques of differential scanning calorimetry (DSC) and x-ray diffraction (XRD) were used to know the agreement between these tests and the SME property test results (thermomechanical cycle test). Through the practical results of all the tests depending on the diagnosis, it was shown that the direct responsibility for the characterization of the commercial rubber band as a shape memory smart material is the stearic acid (SA) material, which acted as a lock in the rubber band structure that can be opened and closed with a temperature change within the melting range of (SA).

Abstract: This study investigated the influence of adding styrene-ethylene-butylene-styrene (SEBS) and stearic acid (SA) on poly (lactic) acid (PLA) with nano-alumina (Al₂O₃) filament composite for fused deposition modeling (FDM) 3D printing (3DP) application. The filament composites were produced via hot-melt extrusion using a twin-screw extruder. Materials characterization and mechanical testing were conducted to determine the effect of SEBS+SA. Fourier transform infrared spectroscopy (FTIR) illustrated the interaction of the aliphatic group of PLA and SEBS+SA. XRD data showed that the SEBS+SA has no significant effect on crystallinity, but the differential scanning calorimetry (DSC) data showed a decreasing trend. Due to the nature of SEBS+SA, the heat capacity increased to 1.222 J/g•C°. The cold crystallization, melting, and degradation temperatures were reduced by 18.34°C, 5.29°C, and 25.19°C, respectively. An increase in the developed filament composite’s processability was evident in the MFR data. The axial strain and the toughness of PLA with nanoAl₂O₃ were increased significantly by 402.54% and 48.20%, respectively. Furthermore, the SEM images revealed overlapping of intra-and interlayers of the 3D printed specimens.

Abstract: This study attempts to emphasize a pre-step for determining the permitted deformations (strains) extents. This is for changing the original molecular architecture shape for the materials understudy (rubber band/stearic acid (RB/based SA) and Rubber band without stearic acid (RB without SA)). It is necessary as a basic controlling step in the choosing process of the appropriate programming method to show the shape memory effect (SME) property. By this property, the polymers are either described as shape memory effect (SME) or conventional polymers. If the material was proved to have the shape memory effect (SME) property, then it will be allowed to predict many thermo-mechanical properties. So for these materials, the (stress-strain) curve zones have been classified according to the ability of the deformation history memory, which can be erased and programmed again after the immediate removement of the applied tensile force. This can be achieved by calculating the residual strain ratio. The comparative results showed that the elastic and plateau zones were classified respectively as valid for the study of the (SME) property. While for the Hardening strain and fracture zones, they were classified as bad and very bad respectively for the study of this property.

Abstract: The process of oxidation of hydrocarbon with oxygen proceeds with formation of the corresponding hydroperoxide as the primary product [1,2]. A catalyst is the most important factor that influences on the direction of flow of the oxidation reaction. Catalysts based on metals of variable valency, and their derivatives are the most active in reactions of oxidation of hydrocarbon [3].

Abstract: In this study, polymer composites were synthesized from date seeds (DS) powder as natural filler and low-density polyethylene (LLDPE) as polymer matrix. This composite was exposed into chemical modification using different content of Stearic Acid (SA) (3, 6 and 9 wt.%). The composite was fabricated by using the process of extrusion and injection molding respectively. The prepared samples were examined using TGA, DSC, FTIR, and Gel Content test. It can be clearly observed that all the treated samples have presented three-steps of decomposition as shown in TGA curves. It is also observed that the Tm, Tc, and degree of crystallinity of the modified LLDPE/DS biocomposites increased as SA increase. Thr FTIR spectra have shown different type of stretching bands, the band at 3346 - 3347 cm^-1 appeared because of hydroxyle (OH) groups that is described as a hydrophilicity measure. Beside, there was a minor decrease on the peak between 3346 and 3347 cm^-1 of modified composite, whichwas attributed to the hemicellulose removal from the modified composite. The gel content of the treated mples increased due to the increase of crosslinking between DS and LLDPE in existence of SA.

Abstract: Nanofibers have high cell affinity due to their fine structure and surface roughness, and are expected to be used as biomaterials. In particular, magnetic nanofibers containing magnetic particles are expected to be used for magnetically induced drug delivery systems and hyperthermia. However, due to the aggregation of the magnetic particles contained in the nanofibers, there is a problem that the aggregation location becomes a starting point of fracture and causes a decrease in tensile strength. In this study, to improve the dispersibility of magnetic particles in Magnetite/PLA nanofiber nonwoven fabrics for suppressing the decrease in tensile strength, magnetite is subjected to surface treatment with oleic acid or stearic acid and ultrasonic agitation. Magnetite/PLA nanofiber nonwoven fabric was prepared by the electrospinning method, and dispersion of magnetite in PLA nanofiber nonwoven fabric and tensile strength were evaluated. Magnetite dispersion was improved by the surface treatment and increasing the ultrasonic agitation time. In particular, by performing the stearic acid treatment and prolonging the ultrasonic agitation time, the magnetite dispersion tended to be improved. This treated Magnetite/PLA nanofiber nonwoven fabric showed higher tensile strength.

Abstract: The release of curcumin from chitosan-pectin-stearic acid films was studied in the variation of the pH of the buffer solutions, the addition of ethanol in the buffer solution, the amount of loaded curcumin, the amount of stearic acids in the films. The chitosan-pectin films were prepared by addition of 1% acetic acid solution of chitosan into 1% aqueous pectin solution, followed by addition of isopropanol solution of stearic acid. The films were characterized using FT-IR spectrophotometer. The study of curcumin release was performed by soaking the film in buffer-ethanol solutions for 6hand measuring the released curcumin by UV-Vis spectrophotometer. The kinetics of releasing curcumin was analyzed using Korsmeyer-Peppas equations. The result showed that the releasing of curcumin was influenced by the amount of loaded curcumin, the amount of stearic acid in the film and buffer pH of the solution. The optimum releasing rate at buffer pH 7 in 40% ethanol solution was obtained when the amount of curcumin loaded and stearic acid were c.a. 55.5 and 136.4 mg/g film, respectively, which the curcumin release achieved 66.04%. Releasing kinetics of the curcumin followed a Korsmeyer-Peppas model with a rate constant (k) of 7.5270 and n of 0.378. The curcumin release mechanism was mainly based on the diffusion mechanism.