J. Compos. Sci., Volume 8, Issue 7 (July 2024) – 53 articles

Switching elements are crucial components in electrical and electronic systems that undergo severe degradation due to the electrical arc that is generated during breaking. Understanding the behavior of the electrical arc and modifying its characteristics via proper electrode design can significantly improve durability while also promoting optimal performance, reliability, and safety in circuit breakers. This work evaluates the feasibility of carbon nanotube (CNT)-reinforced silver and copper metal matrix composites (MMCs) as switching electrodes and the influence of CNT concentration on the characteristics of the arcs generated. Accordingly, three different concentrations per MMC were manufactured via powder metallurgy. The MMCs and reference materials were subjected to a single break operation and the electrical arcs generated using 100 W and 200 W resistive loads were analyzed. The proposed MMCs displayed promising results for application in low-voltage switches. The addition of CNTs improved performance by maintaining the arc’s energy in the silver MMCs and reducing the arc’s energy in the copper MMCs. Moreover, a CNT concentration of at least 2 wt.% is required to prevent unstable arcs in both metallic matrices. Increased CNT content further promotes the splitting of the electrical arc due to a more complex phase distribution, thereby reducing the arc’s spatial energy density. Full article

This article presents the results of research on the development of chemically resistant polymer–mineral casting composites based on industrial waste. The aim of this work is to develop a technological basis for obtaining effective inorganic fillers and highly filled composites for use in chlorine-containing environments. On the basis of theoretical data, mineral fillers and a polymer binder for filling composites were selected, optimal quantities of input hardeners and an appropriate thermal curing mode were determined, and the influence of the filling degree on the properties of composites was studied. The influence of various factors on the properties of the obtained composites was also studied, and the possibility of using local raw materials to obtain special-purpose composites was investigated. Ash from a thermal power plant (TPP) was used as an acid-resistant filler in composites. Two components were chosen as binders: phenol formaldehyde resin and mineral filler (TPP ash). As the third component, hydrolytically active fillers—anhydrite, phosphogypsum and phosphate slag—were used. The degree of filling has a significant influence on the properties of composites, including the compressive strength, chemical resistance and degree of curing, the values of which were elucidated across a wide range of composite variations based on the degree of filling. The conducted research allowed us to establish the limit of admissible anhydrite content, which should not exceed 15 mas.%. To optimize the chemical resistance and durability of the composites of the investigated substances, the method of mathematical planning was used. According to the results of this study, the optimal compositions of composites, in terms of anhydrite, phosphogypsum and phosphorus slag contents, were selected. At the maximum possible degree of filling, these composites exhibit high target characteristics. Full article

In this study, active coatings based on carboxymethylcellulose (CMC) were prepared using liposomes filled with an aqueous extract of Melissa officinalis retained in high acyl gellan gum (HAG), low acyl gellan gum (LAG), and their mixture (HAG/LAG). The objective was to investigate the effect of these coatings on postharvest preservation of tomato (Solanum lycopersicum) fruits. The tomato fruits were divided into four groups: (i) coating with HAG-based liposomes (WL-HAG), (ii) coating with LAG-based liposomes (WL-LAG), (iii) coating with HAG/LAG-based liposomes (WL-HAG/LAG), and (iv) control group treated with sterile water. Over a period of 10 days, various quality attributes, such as respiration rate, soluble solids, titratable acidity, luminosity, weight loss, malondialdehyde (MDA) content, hydrogen peroxide, total phenols, and DPPH scavenging ability, were studied. The results indicated that the WL-HAG coatings significantly (p < 0.05) decreased the respiration rate, hydrogen peroxide, and MDA content compared to the control fruits and other coatings. Therefore, WL-HAG could be considered a promising option to enhance postharvest preservation of tomato fruits in the Colombian fruit and vegetable industry. Full article

A simple approach was used to create Fe₃O₄-methylcellulose (MC) nanocomposites, which were then analyzed using XRD, FTIR, and FE-SEM to determine their structure. The effective factors for enhancing the ratio of magnetite NPs in the samples were investigated using RTFM and optical absorbance. Fe₃O₄ was synthesized utilizing the reverse co-precipitation technique and magnetic characteristics. Fe₃O₄/MC nanocomposites with magnetite/MC weight ratios of 0, 0.07, 0.15, and 0.25 have been developed. The diffraction pattern of magnetite is well indexed in accordance with the spinal reference pattern of Fe₃O₄ (space group: R¯3m), as confirmed by the Rietveld analysis of XRD data of magnetite NPs with an average crystallite size of 50 nm. Magnetite’s insertion into the MC network causes a red shift in the band gap energy (E_g) as the weight percentage of magnetite nanoparticles in the samples rises. The MC, MC-7, MC-15, and MC-25 samples have E_g values of 5.51, 5.05, 2.84, and 2.20 eV, respectively. Full article

Recent studies show that zinc oxide (ZnO) nanostructures have promising potential as an absorbing material. In order to improve the optoelectronic properties of the initial system, this paper considers the process of adsorbing multilayer graphene-like ZnO onto a Si (111) surface. The density of electron states for two- and three-layer graphene-like zinc oxide on the Si (111) surface was obtained using the Vienna ab-initio simulation package by the DFT method. A computer model of graphene-like Zinc oxide on a Si (111)-surface was created using the DFT+U approach. One-, two- and three-plane-thick graphene-zinc oxide were deposited on the substrate. An isolated cluster of Zn₃O₃ was also considered. The compatibility of g-ZnO with the S (100) substrate was tested, and the energetics of deposition were calculated. This study demonstrates that, regardless of the possible configuration of the adsorbing layers, the Si/ZnO structure remains stable at the interface. Calculations indicate that, in combination with lower formation energies, wurtzite-type structures turn out to be more stable and, compared to sphalerite-type structures, wurtzite-type structures form longer interlayers and shorter interplanar distances. It has been shown that during the deposition of the third layer, the growth of a wurtzite-type structure becomes exothermic. Thus, these findings suggest a predictable relationship between the application method and the number of layers, implying that the synthesis process can be modified. Consequently, we believe that such interfaces can be obtained through experimental synthesis. Full article

Fibres in different textile forms (woven, knitted, stitched, and non-crimp) are used to reinforce composites for multifaced applications, including automotive, aerospace, marine, rail, energy, construction, and defence sectors. Textile fabric-based fibre reinforcements for composites possess some outstanding features, such as good dimensional stability, subtle conformability, deep draw moldability/processability, lightweightness, high strength and stiffness, and low cost. The greatest advantage of textile fibre-reinforced composites is the freedom to tailor their strength and stiffness properties for specific applications. Therefore, the design of composites involves defining the fabric geometry, stacking sequence, and orientation of fibres to optimise the system. Compared to knitted, stitched, and non-crimp fabrics, woven fabric-based fibre-reinforced composites are widely used in the industry. The properties of woven fabric-reinforced composites depend on several factors, such as types of fibre, compositions, polymeric matrices, and fibre/matrix interfacial strength. Some of the advantages are reduced preforming process steps, good impact and delamination resistance, and thermo-mechanical properties. This review has been written to provide detailed information and discussions, including the fabrication processes, relationship between fabric structure and composite properties, and morphological characteristics encompassing the current state-of-the-art in woven fabrics for composite reinforcement. Full article

Ag-nanoparticle-reinforced polymethyl methacrylate (AgNP/PMMA) composites are widely used in healthcare, electronics, construction, transportation and many other fields. As the service temperature fluctuates easily, it is necessary to study the temperature effect on the properties of AgNP/PMMA composites. In this work, a preparation method of mixing and hot-pressing was used to fabricate multifunctional AgNP/PMMA composites that are suitable for large-scale industrial production. AgNPs are found to disperse homogeneously in the PMMA matrix. The thermal conductivity of the composite with 15 vol% AgNPs is 116.19% higher than that of PMMA and decreases as the temperature rises. Flexural strength increases first and then decreases with the rising of AgNP content and service temperature, while the flexural modulus decreases gradually. The minimum electrical resistivity of the composite achieves 1.37 × 10⁻³ Ω·m, with a low percolation threshold of 5 vol%, an improvement of nine orders of magnitude over PMMA. The results demonstrate that the service temperature has a significant effect on the comprehensive properties of AgNP/PMMA composites. Full article

The rotor blades of wind turbines are becoming increasingly longer, which increases the diameter at the blade connection. Transport problems are the result, as the rotor blades no longer fit under highway bridges, for example. The increase in diameter can be prevented by increasing the bearing strength of the laminate using fiber metal laminates (FMLs). Individual layers of fiber material are replaced by metal foils in FMLs. This work is focused on the infusion of thick-walled FMLs, with infiltration experiments being carried out in-plane and out-of-plane. For the out-of-plane infusion tests, the metal foils are perforated and it is investigated whether the holes should be arranged alternately or aligned in the metal foils. It has been shown that greater laminate thicknesses can be realized with aligned holes. For the determination of voids and dry-spots, the metal foils are treated with a release agent before infusion and after curing the laminate can be demolded ply by ply. The samples made of glass fiber-reinforced plastic (GFRP) and steel/aluminum measure 500 mm by 800 mm by 20 mm. Full article

Nowadays, powder-based manufacturing processes are recognized as cost-efficient methods frequently employed for producing parts with intricate shapes and tight tolerances in large quantities. However, like any manufacturing method, powder-based technologies also have several disadvantages. One of the most significant issues lies in the degree of porosity. By modifying the morphology of the gas-atomized spherical 17-4PH stainless steel powder via prior ball milling and then raising both the pressure of cold compaction (1.6 GPa) and sintering temperature (1275 °C), the porosity could be reduced considerably. In our novel powder metallurgical (PM) experimental process, an exceptionally high green density of 92% could be reached by employing die wall lubrication instead of internal lubrication and utilizing induction heating for rapid sintering. After sintering (at temperatures of 1200, 1250, and 1275 °C), the samples aged in the H900 condition were then mechanically tested (Charpy impact, HV hardness, and tensile tests) as a function of porosity. Sintering at 1275 °C for one hour enabled porosity reduction to below 4%, resulting in 1200 MPa yield strength and 1350 MPa ultimate tensile strength with significant (16%) fracture strain. These values are comparable to those of the same alloy products fabricated via ingot metallurgy (IM) or additive manufacturing (AM). Full article

The competitive sailing boat industry uses carbon fibre for high-performance purposes. Nevertheless, this material is known to cause environmental issues during its manufacturing. We can currently observe, based on the literature, difficulty integrating a reliable, justified, and transparent inventory of carbon-fibre production for LCA applications of high-performance composite materials. The current study aims to gain a better understanding of carbon fibre’s environmental impacts by suggesting a justified, reliable, and transparent inventory, based on the life-cycle assessment methodology. It also aims at providing a LCA of high-performance composites. An EcoInvent flows inventory is suggested, based on the literature presenting primary inventories. It is then discussed in terms of data quality, flows under study, and indicators calculated. Eventually, the inventory is used to assess the environmental impact of carbon fibre-reinforced composites applied to an industrial example representative of the competitive sailing boat industry: a hydrofoil mould. Regarding results on carbon fibres’ scale and impacts, indicators commonly highlighted by the literature, were calculated in this study (GWP = 72 kgCO₂eq and CED = 1176 MJ), as well as other indicators. These indicators are two to five times higher than the inventories suggested in the literature, due to high heat-production value, production scales, or the quality of the fibre under study. The composite scale results show a major contribution from carbon fibre compared to other flows under study, highlighting the need to suggest a reliable inventory of carbon-fibre production. Full article

Composite laminates were produced by RTM using similar glass and flax fabrics and both vitrimer epoxy and aerospace-grade epoxy, both formulated for liquid molding. Tensile and flexural properties were measured and compared, revealing that the vitrimer composites exhibited equivalent performance in flexural strength and tensile modulus, but slightly lower performance in tensile strength relative to reference epoxy composites. In general, glass–fiber composites outperformed flax–fiber composites in tension. However, both glass and flax–fiber composites yielded roughly equivalent flexural strength and tensile modulus-to-weight ratios. Flax fabrics were recovered from composites by matrix dissolution, and a second-life laminate showed full retention of the mechanical properties relative to those produced from fresh flax. Finally, a demonstration of re-forming was undertaken, showing that simple press-forming can be used to modify the composite shape. However, re-forming to a flat configuration resulted in local fiber damage and a decrease in mechanical properties. An alternative forming method was demonstrated that resulted in less fiber damage, indicating that further refinements might lead to a viable forming and re-forming process. Full article

Friction-type bolted joints are widely used in both the civil and aerospace industries. Uncontrolled excessive bolt clamping force can cause damage to the laminated fiber-reinforced polymeric (FRP) composite through the thickness and damage the joint before applying the service loads. The effect of the friction coefficient (between 0 and 0.3), bolt clearance, joint type, and other parameters on failure modes and the maximum bolt clamping force of the carbon FRP lapped joint is studied. A three-dimensional finite element (FE) model consisting of a bolt, a washer, a laminate FRP composite plate, and steel plates was developed for the simulation of the double- (3DD) and single (3DS)-lapped bolted joint. The FE model was validated by using experimental results and was able to predict the experimental results by a difference of between 2.2 and 6.7%. The joint capacity of the clamping force was found to be greatly increased by adopting the double lap technique, which involves placing an FRP composite plate between two steel plates. Also, it was recommended to use an internal washer diameter less than or equal to the FRP composite plate hole diameter since a larger washer clearance can produce higher contact pressure and reduce the resistance by 22%. In addition, reducing the bolt head diameter can lead to a 65% reduction in the 3DS joint clamping strength. Full article

The incorporation of fiber reinforcements into polymer matrices has emerged as an effective strategy to enhance the mechanical properties of composites. This study investigated the tensile and fracture behavior of 3D-printed polylactic acid (PLA) composites reinforced with chopped carbon fibers (CCFs) through experimental characterization and finite element analysis (FEA). Composite samples with varying CCF orientations (0°, 0°/90°, +45°/−45°, and 0°/+45°/−45°/90°) were fabricated via fused filament fabrication (FFF) and subjected to tensile and single-edge notched bend (SENB) tests. The experimental results revealed a significant improvement in tensile strength, elastic modulus, and fracture toughness compared to unreinforced PLA. The 0°/+45°/90° orientation exhibited a 3.6% increase in tensile strength, while the +45°/−45° orientation displayed a 29.9% enhancement in elastic modulus and a 29.9% improvement in fracture toughness (259.12 MPa) relative to neat PLA (199.34 MPa√m). An inverse correlation between tensile strength and fracture toughness was observed, attributed to mechanisms such as crack deflection, fiber bridging, and fiber pull-out facilitated by multi-directional fiber orientations. FEA simulations incorporating a transversely isotropic material model and the J-integral approach were conducted using Abaqus, accurately predicting fracture toughness trends with a maximum discrepancy of 8% compared to experimental data. Fractographic analysis elucidated the strengthening mechanisms, highlighting the potential of tailoring CCF orientation to optimize mechanical performance for structural applications. Full article

Additively manufactured polymer structures often exhibit strong anisotropies due to their layered composition. Although existing methods in additive manufacturing (AM) for improving the mechanical properties are available, they usually do not eliminate the high degree of structural anisotropy. Existing methods for continuous fiber (cF) reinforcement in AM can significantly increase the mechanical properties in the strand direction, but often do not improve the interlaminar strength between the layers. In addition, it is mostly not possible to deposit cFs three-dimensionally and curved (variable–axial) and, thus, in a path that is suitable for the load case requirements. There is a need for AM methods and design approaches that enable cF reinforcements in a variable–axial way, independently of the AM mounting direction. Therefore, a novel two-stage method is proposed in which the process steps of AM and cF integration are decoupled from each other. This study presents the development and validation of the method. It was first investigated at the specimen level, where a significant improvement in the mechanical properties was achieved compared to unreinforced polymer structures. The Young’s modulus and tensile strength were increased by factors of 9.1 and 2.7, respectively. In addition, the design guidelines were derived based on sample structures, and the feasibility of the method was demonstrated on complex cantilevers. Full article

Several traditional methods for producing polymer microparticle adsorbents for metal ions exist, such as bulk polymerization followed by milling and crushing the material to micron-size particles, precipitation from organic solvents, and suspension polymerization utilizing surfactants. Alternative methods that are easily scalable and are environmentally friendly are in high demand. This study employs Pickering Emulsion Polymerization Technology (PEmPTech) to synthesize nanostructured polymer microspheres that incorporate Schiff-base ligands, which can be utilized for metal ion adsorption, and specifically Cu(II) ions. Our innovative approach makes use of nanoparticle-stabilized, surfactant-free emulsions/suspensions, enabling the straightforward production of ligand-bearing microspheres while allowing for the precise modulation of the polymer matrix chemistry to maximize adsorption capacities. Through this method, we demonstrate notable enhancements in Cu(II) ion adsorption, which correlates with both the polarity of the monomers used and the concentration of Schiff-base ligands within the microspheres. Notably, our results offer insights into the structure–activity relationships essential for designing tailored adsorbents. This work provides a scalable method to produce high-performance adsorbents and also contributes to sustainable methodologies by excluding harmful surfactants and solvents. Full article

Alternative fuel sources are necessary in today’s economic and environmental climate. Hydrogen fuel arises as an environmentally friendly and energy dense option; however, the volatility of hydrogen gas makes it dangerous to store and utilize. The evolution of hydrogen from hydrogen feedstock materials may prove to overcome this safety barrier, but a catalyst for this reaction is necessary to optimize production. In this work, a composite catalyst comprised of palladium nanoparticles embedded on mesoporous carbon materials (Pd-MCM) was synthesized and characterized by Transmission Electron Microscope (TEM), Powder X-Ray diffraction (P-XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscope (EDS). Various reaction conditions such as concentration of reactant, temperature, and pH were applied in measuring the catalytic activity of Pd-MCM. Results show the catalytic activity of the Pd-MCM composite catalysts increased with increasing concentrations of sodium borohydride, increasing temperature, and lower pH. The reaction involving the Pd-MCM composite had an activation energy of 27.9 kJ mol⁻¹. Reusability trials showed the Pd-MCM composite remained stable for up to five consecutive trials. Full article

This review explores the design, fabrication, and biomedical applications of nanofibrous scaffolds, emphasizing their impact on tissue engineering and regenerative medicine. Advanced techniques like electrospinning and 3D printing have enabled precise control over scaffold architecture, crucial for mimicking native tissue structures. Integrating bioactive materials has significantly enhanced cellular interactions, mechanical properties, and the controlled release of therapeutic agents. Applications span bone, cardiovascular, soft tissue, neural regeneration, wound healing, and advanced drug delivery. Despite these advancements, challenges such as scalability, biocompatibility, and long-term stability remain barriers to clinical translation. Future research should focus on developing smart scaffolds and utilizing AI-enhanced manufacturing for more personalized and effective regenerative therapies. Full article

The flame-retardant performance of carbon fiber-reinforced composites is crucial for ensuring structural stability. Traditional additive flame-retardant methods often struggle to balance structural integrity with fire resistance. Herein, Ni(OH)₂ and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were used as flame-retardant agents and mixed with glass fibers to construct the flame-retardant functional fiber veil which was used as the skin layer on the composite surface for fire protection. The structure performance and flame retardancy of composites were characterized via Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and a cone calorimeter test. The results confirmed that a flame-retardant glass fiber mat could effectively improve the flame-retardant and smoke-suppressive properties of the composite material. Due to the synergistic flame-retardant mechanism of Ni(OH)₂ and DOPO, the C-N3-D2 composite with the highest LOI value of 32.3% has shown significant reduction in peak heat release rate (PHRR) and total smoke production (TSP) by 31.3% and 19.5%, respectively. In addition, due to flame-retardant agents only being employed in the skin layer of the composite, the core layer of a carbon fiber-reinforced structure could be protected without structure disruption. This approach maintained consistent interlayer shear strength, highlighting the effectiveness of using a flame-retardant fiber veil as a protective skin layer. This strategy could offer a viable solution for safeguarding high-performance composite materials from fire hazards without compromising their structural integrity. Full article

There is a wide variety of superconducting materials, but only a few of them are suitable for practical industrial use, and one of the most promising superconductors is MgB₂. Its main advantages are a critical temperature close to 40 K, which allows for operation in a cryogenic environment, low cost of precursors, and the ease of manufacture. In this paper, we attempted to obtain superconducting materials based on magnesium diboride in a new way by using a high-temperature centrifuge and then investigated how centrifugal acceleration could affect the superconducting characteristics of the materials in a greater way during combustion synthesis. As a brief result of this research, it was found that the value of centrifugal acceleration affected the critical current density (J_c = 1.4 A/cm²) of the MgB₂ composites, although it did not considerably impact the critical transition temperature of the MgB₂ materials (remained at around 37.5–38 K). Full article

As one of the most common fossil derivatives, plastics are widely used for their exceptional chemical stability, low density, and ease of processing. In recent years, there has been a significant increase in the production of waste plastics, coupled with a low recycling rate, resulting in serious environmental pollution. To enhance the use of waste plastics, this research synthesized flame-retardant materials from hypercrosslinked polystyrene with different molar fractions of flame retardants. Waste polystyrene foam was used as the raw material, while aniline, triphenylphosphine, and melamine were employed as flame-retardant additives. The flame-retardant additives were successfully doped into the porous skeleton structure of hypercrosslinked polystyrene through a chemical reaction or physical mixing to achieve in situ flame retardancy, and the materials were shaped by a phenolic resin prepolymer. Then, the samples were characterized in detail, and the results indicate that the addition of a flame retardant enhances the flame retardancy of the material. In addition, the material has excellent thermal insulation performance, with a minimum thermal conductivity of 0.04176 W/(m·K). Full article

This study investigates the mechanical properties of tiled laminates, frequently used in FRP bridges, and a completely new class of composites for which currently no experimental literature is available. In this paper, first a microscopic examination of laminates extracted from bridge deck flanges is performed, revealing complex multi-ply structures and tiled laminates in the transverse direction of the bridge deck. The subsequent fabrication of tiled laminates in the transverse (i.e., weak) and longitudinal (i.e., strong) span direction explores stiffness and strength characteristics depending on the stacking angle. It is observed that the stiffness in both directions is only slightly reduced with increasing stacking angles, reaching a maximum decrease of 10%, while the failure strength is significantly reduced, particularly with longitudinal tiling, dropping by approximately 70% for a 2° stacking angle. Transverse tiling demonstrates a more moderate 45% strength reduction due to the presence of some 90° plies. Given the small reduction in the stiffness and the fact that in many applications the design is mainly governed by serviceability (i.e., stiffness) requirements than strength, this strength reduction may be acceptable, considering other advantages of the concept. Additionally, this research sheds light on failure mechanisms, emphasizing the role of ply assembly in stress distribution and highlighting the importance of gradual ply ends in reducing strain concentrations. These findings provide valuable insights for optimizing tiled laminates in structural applications, ensuring their effective and reliable use. Full article

A sophisticated characterisation of a porous material structure has been challenging in material science. Three-dimensional (3D) structure analysis allows the evaluation of a material’s homogeneity, pore size distribution and pore wall properties. Micro-computed tomography (micro-CT) offers a non-destructive test method for material evaluation. This paper characterises a novel ternary binder’s porous structure using micro-CT. Gypsum–cement–pozzolan (GCP) ternary binders are low-carbon footprint binders. Both natural and industrial gypsum were evaluated as a major components of GCP binders. Porous GCP binder was obtained by a foaming admixture, and the bulk density of the material characterised ranged from 387 to 700 kg/m³. Micro-CT results indicate that pores in the range from 0.017 to 3.0 mm can be effectively detected and described for porous GCP binders. The GCP binder structure proved to be dominant by 0.1 to 0.2 mm micropores. For GCP binders produced with natural gypsum, macropores from 2.2 to 2.9 mm are formed, while GCP binders with phosphogypsum possess pores from 0.2 to 0.6 mm. Micro-CT proved to be an effective instrument for characterising the homogeneity and hierarchical pore structure of porous ternary binders. Full article

Diverse industries are witnessing an increase in demand for hybrid structures of metals and carbon-fiber-reinforced thermoplastic composites (CFRTPs). Welding is an essential technique in the manufacture of metal–CFRTP hybrid structures. However, achieving high-strength metal–CFRTP welded joints faces serious challenges due to the considerable disparities in material characteristics. As an effective method to strengthen metal–CFRTP joints, surface texturing on metal is gaining significant attention. This study introduces an emerging surface texturing approach, electrochemical jet machining (EJM) using a film electrolyte jet, for enhancing the performance of AA6061-CF/PA66 hot-pressure-welded (HPW) joints. Parametric effects on surface morphology and roughness in the EJM of AA6061 are investigated. The results show that a rough surface with multiscale pores can be generated on AA6061 by EJM, and that surface morphology can be modulated by adjusting the applied current density and jet translational speed. Subsequently, the effects of different EJM-textured surface morphologies on the performance of HPW joints are examined. Surface textures created by EJM are demonstrated to significantly enhance the mechanical interlocking effect at the bonding interface between AA6061 and CF/PA66, resulting in a substantial increase in joint strength. The maximum joint strength attained in the present work with EJM texturing is raised by 45.29% compared to the joints without surface texturing. Additionally, the joint strength slightly improves as the roughness of EJM-textured surfaces rises, with the exception of rough surfaces that are textured with a combination of low current density and rapid translational speed. Overall, these findings suggest that EJM texturing using a film jet prior to welding is a potential approach for the manufacture of high-performance metal–CFRTP hybrid structures. Full article

The quest for a smooth transition from fossil fuels to clean and sustainable energy has warranted studies on alternative energy materials. Herein, we report on an experimental and theoretical study focused on hydrogen generation through the hydrolysis of microcrystalline cellulose (MCC) treated in different media (deionized water, sodium hydroxide) and MCC functionalized with magnesium (MCC-Mg), titanium (MCC-Ti), and niobium (MCC-Nb). The XRD results reveal the decreased crystallinity of MCC due to ball milling along with the formation of metal oxide composites between MCC and various metals (magnesium, titanium, and niobium). Theoretical studies using NVT molecular dynamic simulations with the NH chain thermostat implemented in the Dmol3 provides further support to the experimental results reported herein. The results from the experimental and theoretical studies revealed that ball milling and composite formation with metal species enhanced the kinetics of the hydrolysis of MCC and, consequently, hydrogen generation, while the addition of NaOH and urea inhibited the hydrogen yield. Full article

Ionizing radiation in therapeutic doses alters the composition and properties of dentin and resin composites. This may influence the adhesion of restorative materials to irradiated dentin and compromise the success of the restorative treatment. The objective of this study was to evaluate the effect of ionizing radiation on the shear bond strength (SBS) of bulk-fill composite materials to dentin. Coronal dentin slabs (N = 90) were embedded in acrylate and randomly assigned to six groups (N = 15) depending on the time of radiation (70 Gy) and material (SDR Plus Bulk Fill Flowable and Tetric EvoFlow Bulk Fill (TET)): (1) control group (CG) SDR; (2) CG TET; (3) radiation + SDR; (4) radiation + TET; (5) SDR + radiation; and (6) TET + radiation. Composite cylinders were bonded to the dentin slabs using Scotchbond Universal Plus Adhesive. The specimens were stored in distilled water and fractured in shear mode after 7 weeks. Radiation before and after restoration resulted in an SBS decrease. The SBS was statistically significantly lower in groups 5 and 6 (p < 0.05). The difference between the bulk-fill composites was not significant (p > 0.05). In the CGs, adhesive fractures prevailed. In groups 3 and 4, cohesive fractures in the dentin were more frequent, and in groups 5 and 6, cohesive fractures in the material. Radiotherapy affects the SBS of bulk-fill composites to dentin. Immediate radiation after restoration resulted in the lowest SBS in both bulk-fill composite materials. Full article

This research presents a comprehensive dynamic finite element analysis (FEA) of a cryogenic fuel tank made from an innovative aluminium/lithium–graphene nano-composite material, assessing its suitability for aerospace launch vehicles carrying cryogenic hydrogen and oxygen. The study focuses on the effects of lightweighting, utilizing 0.5 wt.% reinforced graphene in the Al 2195 matrix, a material poised to revolutionize the aerospace industry. Objectives include developing a digital twin of the fuel tank, CAD modeling to aerospace standards, and conducting ANSYS simulations under launch conditions to evaluate stress, strain, and deformation. Numerical results reveal a significant weight reduction of approximately 19,420 kg and a notable maximum stress reduction of 1.3% compared to traditional Al 2195 alloy tanks. The novelty of this research lies in its pioneering analysis of aluminium/lithium–graphene composites for lightweighting in cryogenic fuel tanks under space launch conditions. Conclusions affirm the composite’s viability, advocating for the development of lighter yet robust aerospace structures and fostering innovation in spacecraft design and materials science. Full article

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) offer an alternative to traditional reinforced concrete columns for new construction applications due to their high strength, ductility, and corrosion resistance properties. Despite their popularity, there is a lack of accurate analytical models for the cyclic/seismic performance of CFFT columns. This is due to the absence of precise stress–strain models for FRP tubes and confined concrete under cyclic loading. Previous experiments on CFFT columns suggest that even minimal reinforcement (≤1%) provides essential energy dissipation for extreme events. However, existing stress–strain models for FRP-confined concrete often neglect the contribution of longitudinal and transverse steel reinforcement. While some researchers have proposed material models to address this issue, the analytical modeling of confinement effects from both steel reinforcement and FRP tubes, especially under lateral cyclic loading, continues to pose a significant challenge. This study aims to use previously collected experimental data to evaluate current analytical modeling approaches in OpenSeesPy3.5.1.12 to simulate the lateral cyclic behavior of CFFT columns with ±55° glass fiber-reinforced polymer (GFRP) fiber orientation. Both the lumped inelasticity and the distributed inelasticity modeling approaches are applied. The performance of various FRP confinement models is compared. The effect of plastic hinge length is also considered in the lumped plasticity approach. The findings suggest that integrating a fiber element section into the plastic hinge zone enhances the efficiency of the distributed inelasticity approach. This method accurately captures the non-linear behavior in the critical region and precisely predicts the shape of the hysteretic curve, all while reducing computational costs. Conversely, the lumped inelasticity modeling approach effectively forecasts energy dissipation and peak load values across the entire cyclic hysteresis curve, offering significant computational savings. Finally, a generalized modeling methodology for predicting the response of CFFTs under cyclic lateral load is proposed and subsequently validated using experimental results found in the existing literature. Full article

A multiscale model is developed for vertically aligned carbon nanotube (CNT)-based membranes that are made for water purification or gas separation. As a consequence of driving fluids through the membranes, they carry stress waves along the fiber direction. Hence, a continuum mixture theory is established for a representative volume element to characterize guided waves propagating in a periodically CNT-reinforced matrix material. The obtained coupled governing equations for the CNT-based composite are found to retain the integrity of the wave propagation phenomenon in each constituent, while allowing them to coexist under analytically derived multiscale interaction parameters. The influence of the mesoscale characteristics on the continuum behavior of the composite is demonstrated by dispersion curves of harmonic wave propagation. Analytically established continuum mixture theory for the CNT-based composite is strengthened by numerical simulations conducted in COMSOL for visualizing mode shapes and wave propagation patterns. Full article

The possibility of producing cement clinker using low-energy, resource-saving technologies is studied. The composition of industrial waste for low-energy-intensive production of Portland cement clinker at factories in Southern Kazakhstan is analyzed. The possibility of replacing the deficient iron-containing corrective additive with “Waelz clinker for zinc ores” is shown. “Waeltz clinker from zinc ores” as part of the raw material charge performs several tasks: it is a ferrous corrective additive, works as a mineralizer for clinker formation processes, introduces coal into the charge and allows one to reduce the consumption of natural fuel. The processes of burning raw mixtures, wholly or partially consisting of industrial waste, are completed at 1350 °C. This reduces the consumption of main burner fuel for clinker burning and reduces CO₂ emissions into the atmosphere. High-quality cement clinker is obtained based on raw material mixtures with Waeltz clinker from zinc ores from the Achisai Metallurgical Plant, phosphorus slag, coal mining waste from Lenger mines and sodium fluoride. The phase composition and microstructure of low-energy clinkers are revealed. Involving industrial waste in raw material circulation will reduce environmental pollution and improve the environment. Full article

Fiberglass is a waste generated in the construction materials industry, which is not dangerous for the environment, but long-term and very long-term storage is expensive. Finding a method of reuse as in creating a useful composite material led to the research work in this study. The impact of waste fiberglass and furnace slag on the characteristics of novel composite materials was examined in this study. The density and mechanical properties of the composite samples were examined to determine the impact of waste fiberglass (WFG) concentration in it. Washed river aggregates were replaced with WFG in various ratios in our laboratory tests. Concrete class C16/20 was utilized, having 0.35–0.7 w. % WFG and 2–10% slag. The obtained material was evaluated for density, workability, and compressive strength. The experiments were carried out in an accredited concrete station laboratory. The density of the resulting materials decreased as the WFG content was increased. The densities were higher than the witness sample, ranging from 2358 to 2405 kg/m³. The findings show that adding WFG and slag to concrete has a positive impact on its characteristics. With the addition of WFG, the mixture became more non-homogenous, but these characteristics can be optimized in future. Because of the differential in density between WFG and natural coarse aggregates, the fresh density of obtained composites dropped as the percentage of WFG increased; this could be an advantage, as the newly obtained material became lighter. The findings show that adding waste to concrete has a detrimental impact on its qualities. The introduction of blast furnace slag up to 5% does not modify the compressive strength, compared to the reference samples, but 10% slag causes a decrease in compressive strength of 4.2%. A proportion of 0.25% WFG causes a slight increase in mechanical strength; therefore, 0.25% WFG and 5% slag increased the compressive strength, the maximum value being obtained for a composite with 0.25% WFG, 5% slag, 5% sand and aggregates. Capitalization of WFG and slag resulted in significant economic and environmental benefits by reducing waste storage costs and production costs, and advantages resulted from the new material. Full article