Structural and physical studies of PVC/PVDF doped Nano lithium salt for electrochemical applications

  Polymer blend of poly (vinyl chloride) and poly(vinylidene fluoride) of nominal composition (30PVC/70PVDF) wt:wt were prepared in the form of thin films using casting technique. Samples of the same composition doped with gradient concentration of nano lithium salt (LTO) were prepared and studied. Proposed filler was characterized using Fourier transform infrared spectroscopy (FTIR), UV/vis. optical absorption, X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Electron diffraction (ED).  Obtained data approve the crystalline nano structure of filler with a cubic structure of average size (25-30 nm). Prepared nano composites were then investigated using different spectroscopic methods. XRD reveals the amorphous nature of the base polymer blend with tendency for increase in crystallinity with increasing the content of lithium salt. FTIR shows a preservation of the main vibrational spectral bands in their position with small variation in the area and intensity of some spectral bands related to the interaction between polymer and filler. &nbsp

Structural and optical characteristics of poly(vinyl alcohol)/carboxymethyl cellulose/ curcumin nanocomposites

ABSTRACT. Curcumin nanoparticles (CurNP’s) were successfully synthesized, characterized, and used as a cross-linking dopant of polyvinyl alcohol/ sodium carboxymethyl cellulose (PVA/CMC) semi-natural polymer blend. Synthesized nanocomposite films of (PVA/CMC/CurNP’s) were characterized using Fourier transforms infrared FTIR spectroscopy and tested for their resistance of different bacterial grams. Obtained data shows that studied PVA polymerized and cross-linked with CMC as a result for hydrogen bonding between the carboxylic groups and with the non-substituted hydroxyl groups of the cellulose molecule. The optical energy gap was found to be sensitive for the CurNP’s doping level, and the indirect transition was dominant in the studied samples. The addition of CurNP’s appears to increase the activity index of all samples against both gram-negative and positive bacteria, and their activity increases with increasing dopant level until a specific optimal concentration.                     KEY WORDS: Curcumin nanoparticles, Semi-natural polymer blend, Antibacterial, FTIR, Optical energy gap   Bull. Chem. Soc. Ethiop. 2021, 35(3), 615-624. DOI: https://dx.doi.org/10.4314/bcse.v35i3.1

Corrosion mechanism and bioactivity of borate glasses analogue to Hench’s bioglass

Bioactive borate glasses (from the system Na2O-CaO-B2O3-P2O5) and corresponding glass-ceramics as a new class of scaffold material were prepared by full replacement of SiO2 with B2O3 in Hench patented bioactive glass. The prepared samples were investigated by differential thermal analysis (DTA), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The DTA data were used to find out the proper heat treatment temperatures for preparation of the appropriate glass-ceramics with high crystallinity. The prepared crystalline glass-ceramics derivatives were examined by XRD to identify the crystalline phases that were precipitated during controlled thermal treatment. The FTIR spectroscopy was used to justify the formation of hydroxyapatite as an indication of the bioactivity potential or activity of the studied ternary borate glasses or corresponding glass-ceramics after immersion in aqueous phosphate solution. The corrosion results are interpreted on the basis of suggested recent views on the corrosion mechanism of such modified borate glasses in relation to their composition and constitution

Molecular structure and optical attributes of (Na-CMC/SA) natural polymer blend

ABSTRACT. Biopolymers are referred to the bio-degradable polymer that is derived from living organisms in nature or synthesized from renewable materials but needs polymerization. There are consisting of monomeric units that bond together through a covalent bond to obtain large molecules. A biopolymeric blend of sodium carboxymethyl cellulose/sodium alginate (Na-CMC/SA) film was prepared by the casting/solvent evaporation method. In addition to the molecular structure, the optical and molecular geometry of the collected films were characterized. XRD of binary blend investigated the interaction and miscibility among two biopolymers. FTIR of the blend spectrum explicated the conferring of the two polymer group’s vibrations. UV/Vis and optical studies appeared a peak in the binary at the wavelength (227 nm) which explained the high combination between two polymers. Molecular geometry clarifies the assignment of vibrational spectra of pure polymers which implied the important role of the (C=O) group as eventful regions for the two polymers.   KEY WORDS: Sodium carboxymethyl cellulose, Sodium alginate, Na-CMC/SA, FTIR, XRD, UV/Vis   Bull. Chem. Soc. Ethiop. 2022, 36(3), 707-716.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i3.19                                                     &nbsp

Preparation and Characterization of Silver and Gold Nanoparticles and Study Influence on Physical Properties of PVA/PVP nanocomposites

Gold nanoparticles (Au NPs) and Silver nanoparticles (Ag NPs) ware prepared by green synthesis extraction using the Chenopodium murale leaf extract, the obtained (Ag NPs and Au NPs) were investigated by UV/Vis. absorption spectroscopy, transmission electron microscopy, Zetasizer, XRD. The plant extraction leads to produce nanoparticles of spherical shape with size range from 4 to 22 nm. Polyvinyl alcohol (PVA) and polyvinyl Pyrolidone (PVP) blend with mixed silver and gold nanoparticles were prepared by casting method. Amorphous feather of doping polymers blend was characterized by X-ray diffraction. Significant changes within the polymer matrix were monitored from infrared spectroscopy which indicates the interaction between polymer blend and mixed nanoparticles. Both indirect and direct optical energy gaps are calculated and discussed

Copper-based glass-ceramic as an efficient catalyst in the synthesis of pyrazolo[1,5-a] pyrimidineunder solvent-free condition with docking validation as Covid-19 main protease (Mpro) inhibitor

Copper-based oxide glass-ceramic was successfully synthesized through the single-step melt annealing technique. Synthesized glass-ceramics was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) supported with energy dispersive X-ray (EDX) and mapping. Pyrazolo[1,5-a]pyrimidines 5a-f were synthesized via the reaction of 5-amino-1H-pyrazole-4-carboxamide (1) with enaminones 2a-f in the presence of synthesized oxide glass-ceramic catalyst powder under solvent-free condition. The molecular docking study demonstrated that the COVID-19 main protease (MPro) inhibitor.                     KEY WORDS: Pyrazolopyrimidine, Enaminones, Copper-based catalysis, Solvent-free, COVID-19   Bull. Chem. Soc. Ethiop. 2021, 35(1), 185-196. DOI: https://dx.doi.org/10.4314/bcse.v35i1.1

Effect of aluminum oxide on the structure and conduction behaviors of silver borate glasses

ABSTRACT. The current study focuses on glass preparation and characterization in the glass system of chemical formula xAl2O3 (35-x) Ag2O.65B2O3 (0≤x≤35 mol%), where Ag2O is replaced with Al2O3. To examine a wide range of both structure and morphology of the prepared glasses, nuclear magnetic resonance (NMR) of 27Al nuclei, X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM) are used. In Al2O3-rich glass, the well-formed AlO6, AlO5, and AlO4 structural groups are the well-formed units. In samples of (20 and 30 mol % Al2O3), tetrahedral AlO4 and traces from AlO6 units could be detected. At lower concentrations of Al2O3 (10 mol%), the dominant forming unit is only AlO4 groups containing non-bridging oxygen bonds (NBO). The XRD spectra confirm the amorphous nature of the glasses of Al2O3 ˂20 mol% while glasses of higher Al2O3 concentrations contain crystalline Ag2Al2B2O7 formed due to the higher oxygen packaging of the mixed AlO5 and AlO4 compared with that of glasses containing only AlO4 species only. The morphology of crystalline units is confirmed from TEM to differ from that of an amorphous composition. The increase of activation energy and the hardness number of the glasses led to an increase in the durability of the investigated glasses.   KEY WORDS: Aluminum borate glass, NMR, Coordination of aluminum atom, Conductivity, Crystallization process Bull. Chem. Soc. Ethiop. 2022, 36(3), 597-606.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i3.9                                                       &nbsp

Effect of MWCNT doping on the structural and optical properties of PVC/PVDF polymer blend

Thin film samples of pristine polyvinyl chloride (PVC), poly vinyldine fluoride (PVDF) in combination with their blend in addition to samples containing factorial mass fraction of multi wall carbon nano-tubes (MWCNTs) in the dopant level were prepared via routine casting technique using tetrahydrofurane (THF) as a common solvent. X-ray diffraction and transmission electron microscopy (TEM) depict the nano-scale (15-25 nm) of functionalized MWCNTs with no surface damage results from functionalization process.X-ray diffraction (XRD) shows a semi-crystalline nature of PVDF with evidence for more than one phase namely a and b phases. The fraction of b phase was calculated and correlated to the dopant content. FTIR optical absorption spectra revels a preservation of the main vibrational bands before and after addition of MWCNTs in the doping level with a presence of new small band 1151 cm-1 assigned for the interaction and complexation between constituents

Optimum PID Controller with Fuzzy Self-Tuning for DC Servo Motor

DC motors are simple and controllable, making them a popular choice for various applications. However, the speed and load characteristics of DC motors can change, making it difficult to control them effectively. This paper proposes an optimum PID controller with fuzzy self-tuning for DC servo motors. The controller uses two steps to adjust the PID gains: The ACS algorithm is employed to identify the optimal PID gains in the first step. A fuzzy logic (FLC) controller is employed in the second stage to further fine-tune the gains. The FLC considers two cost functions: the first function is the sum of the squares of the error between the controlled output and reference input. The second function is a mathematical expression that specifies the required characteristics of the system response. The fuzzy self-tune then uses a set of rules to adjust the PID gains in response to changes in the system. The rules are based on the two cost functions designed to maintain the optimum PID gains for various operating settings. The outcomes of the two functions are: Kp = 5.2381, Ki = 7.0427, and Kd = 0.49468, with rising time = 0.2503, overshoot = 2.5079, and settling time = 10.4824 in the first cost function. The second cost function outcomes are Kp = 8.1381; Ki = 8.6427; and Kd = 0.49468. The FST-PID controller's performance is evaluated using Matlab-Simulink. The proposed controller was tested on a DC servo motor, and the results showed good performance in both steady-state and transient responses. The controller also maintained the optimum PID gains in the event of changes or disturbances. So, the motor's speed can effectively control under a variety of conditions

Green synthesis of mixed metallic nanoparticles using room temperature self-assembly

Bimetallic nanoparticles of silver (Ag) and gold (Au) were synthesized at room temperature using Curcumin. Reduction process of silver and gold ions with different molar ratios leads to production of different nanostructures including alloys and core-shells. Produced nanoparticles were characterized simultaneously with FTIR, UV/vis. spectroscopy, transmission electron microscopy (TEM), and Energy-dispersive X-ray (EDAX). UV/vis. optical absorption spectra of as synthesized nanoparticles reveals presence of surface palsmon resonance (SPR) of both silver at (425 nm) and gold at (540 nm) with small shift and broadness of gold band after mixing with resucing and capping agent in natural extract which suggest presence of bimetallic nano structure (Au/Ag). FTIR and EDAX data approve the presence of bimetallic nano structure combined with curcumin extract. TEM micrographs shows that silver and gold can be synthesized separately in the form of nano particles using curcumin extract. Synthesis of gold nano particles in presence of silver effectively enhance and control formation of bi-metallic structure