Increase In Weight Percentage Research Articles

Shielding characteristics of a new epoxy resin reinforced by PbO nanoparticles and PbO micro for protection against X-ray and investigation of their cytotoxicity effects and photocatalytic activity

In this research, for the first time, lead oxide nanoparticles (PbO-NPs) were synthesized using Trigonella feonumgraecum plant seeds as a stabilizer and Pb (NO3)2 salt as lead precursor. The results of the XRD pattern displayed the synthesized NPs have an orthorhombic crystalline structure. According to FESEM images, the NPs had a mean size of about 18.62 nm with a spherical morphology. Also, the cytotoxicity of NPs was evaluated on the Hep G2 cancer cell line, and the IC50 value was reported as 267.07 μg/mL. Next, the photocatalytic performance of the synthesized PbO-NPs was investigated for removing methylene orange (MO) pigment under UVA light, which led to the destruction of about 94% after 120 min. Finally, to investigate the protective property of PbO-NPs against X-ray, a polymer nanocomposite of epoxy resin/PbO-NPs was prepared with different weight percentages. In the same way, other samples were also prepared, and then their ability to attenuate X-ray was studied with an X-ray tube with a voltage of 52 kV for the palm and 80 kV for the thigh of an average person, respectively. The measurement results show that with the increasing weight percentage of the fillers, the samples' linear and mass attenuation coefficient increases, which means an increase in the efficiency of the samples in X-ray attenuation. Generally, epoxy resin/PbO-NPs samples show a better effect than other samples. Therefore, these types of shields can attract more attention due to their lightness, cost-effectiveness, and far fewer environmental hazards than common lead shields.

Electroactive additives into polyurethanes for high corrosion resistance coatings for mild steel

AbstractThere is a demand for innovative coatings such as polyurethane (PU) in industrial and commercial sectors to effectively combat corrosion on mild steel substrates. In this work, novel redox‐active polyurea (PUr) additives such as PUr‐diamine capped trimer (DCTA) and PUr‐diamine‐capped tetraaniline (DCTAni), derived from DCTA and DCTAni, were synthesized to enhance the anticorrosion properties of PU coatings. These are characterized using 1H nuclear magnetic resonance spectroscopy, Fourier transformed infrared, and high‐resolution mass spectrometry technical methods. These additives (2, 5, and 10 wt%) were dispersed in a polyurethane‐urea (PUU) matrix, which was synthesized from PTMG‐2000, and IPDI with dihydrazide adipate as a chain extender. The electroactivity of the coatings were evaluated using cyclic voltammetry (CV) and ultraviolet–visible spectroscopy. Furthermore, anticorrosion performance was assessed through electrochemical impedance spectroscopy and Tafel potentiodynamic polarization measurements. The optimal corrosion protection was achieved with increasing weight percent (wt%) of additive in PUU, showing a trend of 10% > 5% > 2%. Coatings reported maximum polarization resistance (Rp) of 122.15 MΩ, with corrosion rates (CR) as low as 2.38 × 10−6 mm/year. Accelerated salt spray testing over 600 h in a 5 wt% NaCl salt fog confirmed the coatings' durability. The microstructures of PUr particles were determined through FESEM characterization. Additive‐blended PUUs exhibited moderate tensile strength and elongation at break compared to the reference PUU matrix. The hydrophobicity of both the reference sample (PUU) and the additive‐blended coatings was measured, with the highest recorded value being at 93.1 ± 0.048 for 10 wt%. Thermal gravimetric analysis demonstrated polymer degradation with a maximum of T5% observed at 304.1°C.

Experimental exploration of nano-phase change material composites for thermal management in Lithium-ion batteries

The present study reports an experimental investigation carried out for the thermal management of cylindrical lithium-ion battery simulators using aluminum oxide (nano particle)-eicosane (phase change material) composites. The experiment involves varying the power input from 4 to 10 W in 2 W increments and adjusting the weight percentage of nanoparticles (wt%) from 0.5 to 0.9 in 0.2 wt% intervals. The examination of battery temperature evolutions in response to heating power, a comprehensive heat transfer analysis incorporating the Nusselt number, the determination of the maximum temperature difference, thermal resistance analysis, and the exploration of temperature variations in the absence of Phase Change Material (PCM) are considered. The results show that an increase in the weight percentage of alumina nanoparticles in phase-change material cannot always improve the thermal performance. The results of the present study give guidelines for designing battery thermal management systems. The power levels used in the experiment vary from 4 W to 10 W in steps of 2 W. For a power level of 4 W, the heat flux is 1.088 kW/m2, and for a power level of 10 W, the heat flux is 2.72 kW/m2.

Study of gamma, neutron, and proton interaction parameters of some immunotherapy drugs using EpiXs, NGCal, and PSTAR software

Abstract In proton therapy, the protons are used to destroy the cancer cells efficiently at the Bragg peak without much damage to normal cells. The protons can also produce neutrons, protons, and high-energy gamma rays through nuclear reactions with cancerous and healthy tissues as well as with beamline components. The effective observed dose in the therapy is enhanced due to the interaction of nuclear particles with cancerous tissues. Such nuclear particles can have several effects on drugs used in immunotherapy, such as immunotherapy in combination with proton therapy, which has been used to treat cancer. In the present investigations, the gamma, neutron, and protons interaction parameters of some immunotherapy drugs, such as dostarlimab, atezolizumab, ipilimumab, nivolumab, and pembrolizumab, are determined by using EpiXs, NGCal, and PSTAR software. It is found that the EBF and EABF for all selected immunotherapy drugs increase with increasing penetration depth, peaking at 100 keV. The peaking is more symmetric at a higher penetration depth of 40 mfp than at a lower one of 1 mfp. At lower energies of gamma photons, the EBF values increase exponentially, and at higher energies, they increase linearly with increasing penetration depth for all selected drugs. Mass attenuation factors are slightly higher for thermal neutrons than for fast neutrons for selected immunotherapeutic drugs, indicating that thermal neutrons more actively participate in these drugs than fast neutrons. The mass attenuation factor for both fast and thermal neutrons increases with increasing weight percentages of hydrogen and is found to be higher for thermal neutrons. This is the first study in the literature to investigate the radiation interaction parameters for immunotherapy drugs, and it is helpful in radiation therapy and dosimetry.

Grain size effects on the infrared spectrum of mineral mixtures with dark components: New laboratory experiments to interpret low-albedo rocky planetary surfaces

Context. A number of bodies in the Solar System are characterized by dark surfaces, from carbonaceous asteroids to the enigmatic surface of Phobos and Deimos. Our understanding of the spectroscopic behavior of low-albedo surfaces remains incomplete. To improve the interpretation of remote sensing data, laboratory studies continue to serve as a pivotal tool for unveiling the physical state and composition of such surfaces. Aims. Several processes can be simulated in the laboratory, however, the preparation and analysis of a complex mixing of analog material is one of the most fundamental among them, while also being one of the most complex when multiple components are used. In this work, we aim to study how dark material mixed with basaltic material at different grain sizes can affect the spectroscopic features from the near- to mid- infrared (1.25–25 µm). Methods. Our sample set includes four series of basaltic mix (feldspar and pyroxene) at different grain sizes from <50 µm to 1000 µm, mixed with amorphous carbon at increasing weight percentages ranging from 1% to 50%. We analyzed several features on the spectrum of each mineral mixture. In particular, we investigated the behavior of the: (i) near-infrared slope; (ii) 2.7 µm OH-stretching band; (iii) Christiansen features; and (iv) Reststrahlen band and Transparency feature. Results. The measurements presented in this work, which take into account a large wavelength range for the first time, point toward a critical effect of dark material, but with a different outcomes for each grain size. Some of the most interesting results involve the slope trend of modification with dark material and the variant behavior of the Reststrahlen band and Transparency feature. Conclusions. This dataset will offer a key support in the interpretation of data collected on dark surfaces by past and future space missions. This knowledge will be also important in the context of linking analyses of returned samples with remote sensing data collected on planetary surfaces.

Green Synthesis, Characterization, and Evaluation of the Antimicrobial Properties and Compressive Strength of Hydroxyapatite Nanoparticle-Incorporated Glass Ionomer Cement.

Background Glass ionomer cement (GIC) plays a vital role in dental restorative procedures, serving purposes such as filling, luting, and adhesion. However, its inadequate mechanical properties pose challenges, especially in areas experiencing significant stress. To overcome this limitation, nanohydroxyapatite (nHA), known for its bioactive phosphate content, is added to the GIC at specific concentrations to improve its properties. Aim We aim to evaluate the antimicrobial property and compressive strength of green-mediated nHA-incorporated GIC. Material and methods Green synthesis of hydroxyapatite nanoparticles was prepared using Moringa oleifera extract in a solvent form and eggshell waste served as the calcium source. These nHApowders were then integrated into the GICat varying concentrations (3%, 5%, and 10%) designated as Group I, Group II, and Group III, respectively, while Group IV (control) consisted of conventional GIC. Specimens were fabricated and subjected to chemical structure analysis through Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), and scanning electron microscopy (SEM). The antimicrobial activity and compressive strength of all groups were investigated. The antimicrobial activity against Streptococcus mutans and Lactobacillus was evaluated through the minimum inhibitory concentration (MIC) test, while compressive strength was evaluated by measuring the maximum force endured by the specimen before fracturing. Data analysis utilized IBM SPSS Statistics software, employing repeated measures ANOVA to determine mean MIC values and compressive strength, with Tukey's posthoc test for pairwise comparisons. Results The results of the study showed that the antimicrobial efficacy of nHA GIC improved with increasing weight percent (% wt) of the additive, exhibiting significantly enhanced activity against Streptococcus mutans and Lactobacillus compared to the control group (Group IV) with statistical significance (p < 0.05). Moreover, the compressive strength exhibited notable enhancements in the modified groups, including Group I (172.55 ± 0.76), Group II (178.16 ± 0.760), and Group III (182.45 ± 0.950), when compared to the control (162.46 ± 1.606), with statistically significant differences (p < 0.05). Conclusion The study demonstrates that the incorporation of green-mediated nHA-containing GIC results in superior antimicrobial efficacy and compressive strength compared to the control group (Group IV). In particular, the highest concentration of nHA-modified GIC (10%) exhibited the most favorable antimicrobial properties along with increased strength. Therefore, utilizing green-mediated nHA in the GIC shows promise as an effective restorative material. Future investigations should delve into the molecular chemistry and bonding mechanisms to further explore its potential.

Exploring luminescence in transparent Glass–Ceramic coating: Study on Pr3+/ Dy3+ Co-doped SrO–Al2O3–SiO2 Glass–Ceramic particles

This study aimed to fabricate transparent glass–ceramic coatings with luminescent characteristics. To this end, a SrO–Al2O3–SiO2 glass–ceramic system doped with Pr3+ and Dy3+ ions, referred to as luminescent glass–ceramic (LGC), was synthesized via melting at 1550 °C for 1 h. LGCs were added as mill additives to the transparent glass–ceramic coating recipe at increasing weight percentages of 5, 10, 20, and 40% (5Pr, 10Pr, 20Pr, and 40Pr, respectively). The coating specimens fabricated through the wet spraying technique were vitrified and recrystallized at 820 °C for 4 min, resulting in an LGC coating. Further, the chemical composition, phase structure, thermal behavior, and bonding characteristics of the LGC systems were analyzed, and spectrofluorometer and scanning electron microscope (SEM) analyses were performed after the coating procedure. The SEM indicated an increase in particle intensity per unit surface area. The spectrofluorometric analysis revealed that the standard sample did not display any discernible peaks; however, samples supplemented with particles exhibit emission bands at wavelengths of 485 (4F9/2 → 6H15/2, blue) and 575 nm (4F9/2 → 6H13/2, yellow) for Dy3+ ions and at 485 nm (3P0→3H4, blue) for Pr3+ ions. According to the CIE color graph, an increase in the quantity of added particles resulted in the region shifting toward the green–white area from the center of the blue–green region in the standard sample.

Efficacy of Three Remineralizing Agents on Erosion of Root Dentin by Cola Drink: An In Vitro Study

Abstract Objective The aim of the study was to investigate the effects of silver diamine fluoride (38% SDF), sodium fluoride (NaF) varnish, and casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) on cola-eroded root dentin microhardness and mineral alteration in vitro. Materials and Methods Forty human root dentin slabs were exposed to alternating 10 cycles of cola drink and artificial saliva, repeated 3 times at 6-hour intervals. Specimens were randomly assigned to four groups: control (deionized water), 38% SDF, NaF varnish, and CPP-ACPF. All specimens underwent the second erosion process. Microhardness was measured at baseline (KHN0), pretreatment (KHN1), and posttreatment (KHN2). The mean difference of microhardness (ΔKHN2-1) was analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc tests (α = 0.05). The chemical composition and surface morphology were assessed using energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM). Results All experimental groups exhibited dentinal tubule occlusion. Both 38% SDF and NaF varnish demonstrated a statistically significant increase in microhardness compared to CPP-ACPF. However, CPP-ACPF was comparable to the control group. EDS analysis showed an increase in weight percentage of fluorine in all groups. Furthermore, silver and chlorine were detected in the 38% SDF group. Conclusion All treatments enhanced eroded root dentin microhardness, with 38% SDF and NaF varnish demonstrating superior acid resistance and preventing morphological changes induced by cola re-immersion.

Exchange-spring behavior in Ni0.3Cu0.2Zn0.5Fe2O4/PbFe12O19 nanocomposite

The structural and magnetic properties of the (1-x)Ni0.3Cu0.2Zn0.5Fe2O4/(x)PbFe12O19 nanocomposites were investigated, where x is the weight percentage of PbFe12O19 (hard phase) ranging from 0 to 100%. The magnetic measurement curves show a magnetic phase transition from soft to hard ferrimagnetic with an increasing weight percentage of the hard PbFe12O19 phase. For weight percentages of 30%, 45%, and 60% of PbFe12O19, the M r/M s ratio is more than 0.5 and they show a normal single-phase magnetic behaviour, indicating the formation of a strong exchange coupling in these samples. Compared to the single-phase Ni0.3Cu0.2Zn0.5Fe2O4 (soft phase), the saturation magnetization of the composites decreases significantly from 34.45 to 16.1 emu g−1 with increasing PbFe12O19 content, while the coercivity increases from 62 to 861 Oe. Although increasing the PbFe12O19 content reduces the saturation magnetization and increases the coercivity of the soft magnetic phase, this may provide a significant way to tune the magnetic properties with desired coercivity and saturation magnetization.

Flexible bandwidth-enhanced metamaterial absorbers with epoxy/graphene nanoplatelets-silver nanowire polymer composites as substrates

The realm of flexible devices has seen considerable advancement in recent technology due to their ability to bend and conform to particular shapes. Flexible metamaterial absorbers offer the advantage of combining the features of conventional metamaterials with the attributes of conformal systems, thereby opening new avenues in electromagnetic technology. This work involves the realization of flexible metamaterial absorbers with epoxy/graphene nanoplatelets-silver nanowire (GnP-AgNW) polymer composites as substrates; with a bandwidth enhancement achieved by incorporating losses in the substrate and combining resonances in the unit cell. A novel in-situ technique is employed to synthesize the nanohybrid GnP-AgNW (GA) with different weight percentages of AgNWs grown on GnP (GAx; x = 10, 15, 20 wt%). The dielectric measurements of the polymers showed that an increase in weight percentages of AgNWs in the composite enhanced the dielectric constant as well as losses of the polymer (εr՛: 7.7 to 8.8 and εr՛՛: 0.62 to 1.12). The numerical study on the designed flexible metamaterial absorbers with these substrates of thickness 1.4 mm showed a maximum absorptivity of 99% with a bandwidth (having absorption >90%) varying between 1.2 and 1.86 GHz. The experimental measurements on the fabricated metamaterial absorber were found to match the simulation results closely. The polymer composites demonstrated in this work are attractive candidates as substrates for metamaterial absorbers for conformal applications. This paper approaches the problem of bandwidth enhancement of metamaterial absorbers by material engineering along with the resonant structure optimization leading to a synergetic effect in the properties of absorber.

Fracture and Toughening of Mycelium-based Biocomposites

This study presents a combined experimental and analytical study of the fracture behavior and toughening mechanisms of bioprocessed mycelium-based biocomposites. The composites comprise hemicellulose hemp ducts (as nutritional and reinforcing components) intertwined with increasing weight percentages of laterite particles. Single-edge notched fracture experiments and in-situ observations of crack growth were used to explore the effects of varying proportions of laterite on the composite resistance-curve behavior. The toughening mechanisms, fracture modes, and crack-microstructure interactions were also elucidated. Since crack-bridging and crack-deflection were observed to be the dominant toughening mechanisms, they were modeled using fracture mechanics approaches. Crack-bridging was shown to dominate the toughening at lower weight fractions of laterite (0–20 wt%). However, as the laterite content increases (20–40 wt%), a combination of crack-bridging and crack-deflection was observed. Finally, at higher laterite weight fractions (>40 wt%), crack-tip shielding occurred primarily via crack deflection. The fracture mechanics predictions of resistance-curve behavior are shown to be consistent with the experimental measurements. The results suggest that mycelium-based and mycelium-laterite composites can be engineered with tunable fracture toughness. The implications of the results are also discussed for the development of sustainable building materials.

Experimental Analysis of the Mechanical and Machining Properties of an Aluminium Hybrid Metal Matrix Composite

In the current research, titanium carbide (TiC) is used to reinforce the aluminium alloy (AA 6063) in stir-cast hybrid composites at concentrations of 5, 10, and 15 weight percent together with 3 weight percent of graphite. The application of this developed composite is mainly used for automobile suspension parts. The portrayal of characters was performed, and the mechanical properties of the fabricated samples were investigated. Composites with different TiC weight percentages have their mechanical properties, including hardness, tensile strength, compressive strength, and flexural strength, measured and assessed. The results are shows that AA 6063 alloy with 3 wt. percentage of graphite with an increasing weight percentage of TiC composites are better in the mechanical property. The hardness of the AA 6063 alloy composites is greater than that of the base matrix alloy. The tensile strength of Al 6063 alloy composites has been reported to grow with increasing TiC particle content and to be significantly higher than the strength of the matrix alloy. Also, the SEM microstructure images clearly shows that 15 weight percentage of TiC with 3 weight percentage of Graphite shows the maximum distribution in the matrix.

Biopolymer-coated composites for enhanced dielectric and electromagnetic interference shielding applications - a green initiative

The utilization of natural fibre-reinforced polymer composites has been tremendously growing in various applications of automotive and aerospace components. In this aspect, the researcher’s community is approaching the global market with new ideas for developing a complete eco-friendly, sustainable, and green composite. Plant-based composites have received great interest from the initial stage due to their unique features, such as lightweight, corrosion resistance, specific properties, excellent mechanical and thermal properties. This research article attempts a novel technique of coating the fibres with polylactic acid (PLA) as a part of surface modification which improves fibre properties. Then the fibres were reinforced with various weight percentages of conductive fillers, such as Copper (Cu), Alumina (Al2O3), and Graphene (Gr), to improve the electrical properties using the hand layup technique. Then the fabricated samples were tested for dielectric and electromagnetic interference (EMI) shielding effectiveness (SE) using resonance and open shielded method. Based on the test results, it was noted that the dielectric strength (K) and shielding effectiveness (SE) of the composites started to increase with the increase of weight percentage of conductive fillers, which highlighted that by incorporating conductive fillers, the fibres started losing their insulation properties. The composites with 0.9 wt% of nanofillers achieved maximum SEabs of −19.61 dB and a SEtotal of −22.67 dB at a frequency range of 8–12 GHz.

NEW WOOD DUST REINFORCED RECYCLED POLYPROPYLENE COMPOSITE FILAMENT AND TRADITIONAL POLYPROPYLENE FILAMENT FOR FDM APPLICATIONS: LIFE CYCLE ASSESSMENT STUDY

Life Cycle Assessment (LCA) is an effective method for determining the environmental impact of a composite material over its lifetime. Consequently, it is important to the composites sector, particularly for Fused Deposition Modelling (FDM) filament manufacturers as a material selection tool when determining the usability of recycled material utilised in component design phases. This article investigates the LCA framework of utilising wood dust as reinforced material and recycled polypropylene material in the production of composite filament for the FDM sector. Eco Audit, a feature of the CES Edupack programme, was utilised to evaluate the LCA from an environmental standpoint for product makers. Using recycled polypropylene containing an increasing weight percentage of wood dust to produce new types of composite filament materials reduces energy consumption (MJ) and lowers the carbon footprint (kg). This is because the quantity of energy required for recycling is far less than that required for initial manufacture. When compared to the new polypropylene material that is used to create filament, this study reveals a 56% and 37% reduction in energy consumption and CO2 emissions, respectively. This is a considerable improvement from an environmental point of view.

Mechanical and metallurgical characterization of B4C and SiC reinforced stir casted AA6061 hybrid MMC

The present work was the novel investigation of mechanical and metallurgical characteristics of stir casted AA6061 based metal matrix composites (MMC) and hybrid MMCs. The reinforcements utilized in the investigation were silicon carbide and boron carbide. The thirteen stir casted MMC and hybrid MMC samples were tested for ultimate tensile strength, microhardness, fractography and wear performance. The stir casting process had enhanced the reinforcement distribution within the aluminium matrix. The enhancement in ultimate tensile strength was observed due to the addition of reinforcements in increasing weight percentages with the hybrid MMC exhibiting peak ultimate strength which was a 32.17% improvement against the non-reinforced AA6061 alloy. The formation of reinforcement particulates had enhanced microhardness of the specimens with the peak microhardness observed for boron carbide reinforced MMC exhibiting microhardness 25.41% higher than the base alloy. The hybrid MMC exhibited ductile fracture with highest elongation corresponding to the highest ultimate tensile strength. The wear performance analysis revealed reduced wear rates for the particulate reinforced specimen with highest weight percentage of reinforcements.

STUDYING SOME OF PHYSICAL PROPERTIES FOR POLYMER REINFORCED WITH CHOPPED CARBON FIBERS (CCF) COMPOSITES

The research includes the study of some physical. Properties (thermal conductive and dielectric strength) for two types of polymer composites; epoxy resin (EP) reinforced by chopped carbon fibers (CCF) and unsaturated polyester resin (UPE) reinforced by chopped carbon fibers at different weight percentage (1%, 3%, 5%, 7%). Hand –lay up. Method was used to prepare sheets of composites (EP, UPE, EP/CCF, and UPE/CCF) on. glass mold which were cut according to the standard dimensions of the thermal conductive and dielectric strength tests specimens. The results showed that the. Sample of UPE/CCF have highest values of thermal conductive at weight. percentage (7%) compared with prepared samples at other weight percentage. Also the results showed that the thermal conductive of. Pure UPE and EP increased with increase in weight percentage of carbon fibers addition. On the other hand, the results showed that the polyester composites have higher values of thermal conductive compared with epoxy composites. Also the results showed that higher value of dielectric strength at weight. Percentage (1%) for both types from prepared composites of carbon fibers.In addition, the results showed that the polyester composites have higher values of dielectric strength compared with epoxy composites.

On the Development of an Intelligent Poly(aniline-co-o-toluidine)/Fe3O4/Alkyd Coating for Corrosion Protection in Carbon Steel

The corrosion of metals and alloys presents a significant challenge in many industries, demanding constant maintenance, and thereby increasing costs. In response to this problem, the smart corrosion protection coating has emerged as a promising solution. By enabling the immediate detection of, and response to, environmental changes, such as in the temperature and pH, these smart coatings contribute significantly to extending a material’s lifespan, and reducing maintenance expenses. In this study, nanomagnetic [poly(aniline-co-o-toluidine)/Fe3O4] systems were prepared and used as a self-healing corrosion inhibitor, mixed with alkyd paint at different weight percentages (5–25%). The composites were used as a coating on carbon steel (C1010), and their corrosion protection performance was tested in 0.1 mol/L HCl, using electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and FTIR analyses. The results showed an adequate corrosion inhibition performance for the developed composites, compared to the alkyd paint alone, reaching an inhibition efficiency of 80% at 20 wt.% of composite. Adding increasing weight percentages of the developed composites to the paints led to a significant increase in the corrosion resistance, accompanied by a remarkable decrease in the double-layer capacitance. Thus, these developed composites show excellent potential as a corrosion protection formulation in paints.

Influence of Oxygen Uptake on Pitch Carbon Fiber.

Carbon fiber precursor materials, such as polyacrylonitrile, pitch, and cellulose/rayon, require thermal stabilization to maintain structural integrity during conversion into carbon fiber. Thermal stabilization mitigates undesirable decomposition and liquification of the fibers during the carbonization process. Generally, the thermal stabilization of mesophase pitch consists of the attachment of oxygen-containing functional groups onto the polymeric structure. In this study, the oxidation of mesophase pitch precursor fibers at various weight percentage increases (1, 3.5, 5, 7.5 wt%) and temperatures (260, 280, 290 °C) using in situ differential scanning calorimetry and thermogravimetric analysis isinvestigated. The results areanalyzed to determine the effect of temperature and weight percentage increase on the stabilization process of the fibers, and the fibers aresubsequently carbonized and tested for tensile mechanical performance. Thefindings provide insight into the relationship between stabilization conditions, fiber microstructure, and mechanical properties of the resulting carbon fibers.

Detailed physicochemical study and thermodynamic aspects of the interaction between nonionic cellulose derivative hydroxyethyl cellulose and anionic surfactant sodium N-dodecanoyl sarcosinate in aqueous media

BackgroundThe scheme of this work was to study the interaction between hydroxyethyl cellulose (HEC), a non-ionic, water soluble biopolymer and sodium N-dodecanoyl sarcosinate (SDDS), a novel, environmentally friendly amino acid-based anionic surfactant in aqueous medium. The study of this type of interaction is relatively less complicated compared to that between a polymer and a surfactant with opposite charges. MethodsThe critical micelle concentration (CMC) of HEC-induced SDDS has been determined by various physicochemical methods such as tensiometry, conductometry, fluorimetry and microcalorimetry. Several thermodynamic and surface parameters related to the binding of SDDS with HEC have been assessed. The aggregation number (Nagg) of SDDS micelles in the presence of non-ionic HEC polymer has been measured by the steady-state fluorescence method. The hydrodynamic diameter (Dh) and zeta potential (ζ) of the polymer-surfactant aggregate have been measured by the dynamic light scattering method. The interaction study has further been amplified by detecting the change in the surface morphology of the polymer due to surfactant binding using Field Emission Scanning Electron Microscopy (FESEM) and high resolution transmission electron microscopy (HR-TEM) imaging in solvent-free state, as well as visualization of the HEC-SDDS micelle in the solution phase using fluorescence microscopy technique. Significant findingsFrom a physicochemical point of view, hydrophobic synergism seems to be important for understanding the interaction pattern of HEC-SDDS combination. In each scenario, the CMC of SDDS decreases with an increase in weight percentage of HEC. The aggregation number (Nagg) of SDDS micelles is also found to decrease with an increase in weight percentage of HEC in the medium. The hydrodynamic diameter (Dh) and zeta potential (ζ) of the polymer-surfactant aggregate, these two parameters have been found to be strongly dependent on the amphiphile concentration. Finally, investigations of the surface morphologies by taking Field Emission Scanning Electron Microscopy (FESEM), high resolution transmission electron microscopy (HR-TEM) and fluorescence microscopy techniques assist the experimental data.

Microstructure and mechanical properties of AZ91D/Si3N4 composites using squeeze casting method

The material utilized in the aerospace and automotive industries must be capable of withstanding significant loads while maintaining a minimal structural weight. In pursuit of novel lightweight materials for industrial applications, magnesium is quickly displacing aluminum-based alloys. In this study, a magnesium (AZ91D) matrix composite reinforced with nano ceramic silicon nitride (Si3N4) of varying weight proportion (2 wt%,4 wt% and 6 wt%) was synthesized using vacuum stir casting method. The microstructural study of uniform distribution of nano Si3N4 particles are revealed by an optical microscope. Micro hardness (26.8%) and tensile strength (32.12%) increased with increasing weight percentages of Si3N4 particles in a magnesium alloy matrix, whereas percentage of elongation decreased (6.52%). With an increase in weight% of Si3N4 particles in the magnesium matrix, the porosity of composites decreased (1.02%) and density of composites increased to minimum (0.06%). The corrosion characteristics were examined using B117 salt spray test. The test illustrated that an increase in percentage of reinforcement accelerates corrosion resistance (17.52%) due to induced segregation, dislocation, and micro crevice formation. Based on the results, it can be concluded that the manufactured composite can be employed in a variety of industrial applications where lighter structural materials are required.