J. Compos. Sci., Volume 9, Issue 12 (December 2025) – 69 articles

In this study, the potential use of Epsom salt production waste as a supplementary cementitious material was investigated. This acidic waste was neutralized with lime milk and used to replace up to 25 wt.% of Portland cement. The following research methods were employed: XRD, XRF, SEM, DSC-TG, and isothermal calorimetry. The waste neutralization process was found to proceed consistently, producing a neutral material (pH = 7.5) composed of amorphous silicon compounds with a negligible impurity of crystalline antigorite. Consequently, this material exhibits very high pozzolanic activity. The neutralized Epsom salt production waste accelerates the early hydration of Portland cement and promotes an intense pozzolanic reaction. This new material is a highly effective supplementary cementitious material, capable of replacing up to 25 wt.% of Portland cement without reducing its strength class. Full article

The study investigates the influence of a hybrid filler system based on carbon black, silica (SiO₂) and shungite from the Bakyrchik deposit on the curing behavior of rubber compounds as well as on the physical–mechanical properties and thermal stability of vulcanizates based on a blend of butadiene-alpha-methylstyrene and isoprene rubbers. The morphology and elemental composition of shungite were examined using SEM-EDS analysis. Thermogravimetric analysis of shungite was also performed. The introduction of shungite led to a decrease in Mooney viscosity and an increase in scorch time. Rubber composites containing 10–20 phr (parts per hundred rubber) of shungite exhibited a satisfactory balance between the processing properties of the rubber compounds and the physical–mechanical properties of the vulcanizates (tensile strength, elongation at break, and rebound resiliency), which makes them promising for practical application. When 10 phr of shungite was added, the tensile strength of the rubber composites after thermal aging remained at the level of the control sample, while the changes in elongation at break, rebound resilience, and hardness were less pronounced than in the control. Full article

Granular copper oxide nanoparticles (CopOx NPs), synthesized via laser ablation (100 nm, ζ-potential +30 mV), were introduced into photolithographic polymethyl methacrylate (PMMA) resin at concentrations of 0.001–0.1%. The resulting composite material enables the fabrication of high-resolution (up to 50 μm) parts with a high degree of surface quality after polishing using the MSLA method. CopOx NPs increased the degree of resin polymerization (decrease by almost 4× in unpolymerized components at 0.1% CopOx NPs) and induced the in situ formation of self-organized periodic structures visible under a modulation interference microscope. The composite samples exhibit pronounced oxidative activity: they intensify the generation of hydrogen peroxide and hydroxyl radicals and cause the oxidative modification of biomolecules (formation of 8-oxoguanine in DNA and long-lived reactive forms of proteins). A key property of the materials is their selective biological activity. While lacking cytotoxicity for human fibroblasts, they exhibit a strong antibacterial effect against E. coli, leading to cell death within 24 h. Thus, the developed composite photolithographic resin combines improved technological characteristics (high printing resolution, degree of polymerization) with functional properties (selective antibacterial activity) and holds promise for application in biomedicine, as well as in the food and agricultural industries. Full article

This study evaluates the performance of ethylene propylene diene monomer (EPDM) composites for rubber sealing applications in a cable-based tsunami system. Rubber composites were prepared using EPDM rubber with varying monomer and filler content to determine the most suitable composite. Mechanical characterization reveals that the composition of EPDM and the amount of filler loading influence the mechanical properties. Dynamic mechanical analysis shows that ethylene and 5-ethylene-2-norbornene (ENB) content influence the glass transition and viscoelastic behavior of the composite. Thermal analysis of rubber composites using EPDM containing 70% ethylene and 5% ENB indicates no change in thermal stability due to prolonged immersion in seawater. Visual inspection using a microscope reveals no cracks on the surface of the rubber seal after the pressure chamber test for rubber composites utilizing EPDM with 70% ethylene and 5% ENB. It was shown that EPDM containing 70% ethylene and 5% ENB, with optimal reinforcement with 80 phr carbon black, exhibits the best performance for rubber sealing applications in subsea environments. Full article

This study investigates the Mode II fracture behavior of bamboo–coir–rubber (BCR) hybrid composite panels developed as sustainable alternatives for wood-based panels used in structural applications. The composites were fabricated using alternating bamboo and coir layers within a polypropylene (PP) thermoplastic matrix, with styrene–butadiene rubber (SBR) incorporated as an additive at 0–30 wt.% to enhance interlaminar toughness. Commercial structural plywood was tested as the benchmark. Mode II interlaminar fracture toughness (G_IIc) was evaluated using the ASTM D7905 End-Notched Flexure (ENF) test, supported by optical monitoring to study crack monitoring and Scanning Electron Microscopy (SEM) for microstructural interpretation. Results demonstrated a steady increase in G_IIc from 1.26 kJ/m² for unmodified laminates to a maximum of 1.98 kJ/m² at 30% SBR, representing a 60% improvement over the baseline and nearly double the toughness of plywood (0.7–0.9 kJ/m²). The optimum performance was obtained at 20–25 wt.% SBR, where the laminated retained approximately 85–90% of their initial flexural modulus while exhibiting enhanced energy absorption. Increasing the initial notch ratio (a₀/L) from 0.2 to 0.4 caused a reduction of 20% in G_IIc and a twofold rise in compliance, highlighting the geometric sensitivity of shear fracture to the remaining ligament. Analysis of Variance (ANOVA) confirmed that the increase in G_IIc for the 20–25% SBR laminates relative to plywood and the unmodified composite is significant at p < 0.05. SEM observations revealed rubber-particle cavitation, matrix shear yielding, and coir–fiber bridging as the dominant toughening mechanisms responsible for the transition from abrupt to stable delamination. The measured toughness levels (1.5–2.0 kJ/m²) position the BCR panels within the functional range required for reusable formwork, interior partitions, and transport flooring. The combination of renewable bamboo and coir with a thermoplastic PP matrix and rubber modification hence offers a formaldehyde-free alternative to conventional plywood for shear-dominated applications. Full article

Fiber-reinforced polymer composites, particularly carbon fiber and glass fiber reinforced composites, are widely used in cutting-edge industries due to their excellent properties, such as light weight and high strength. This review systematically compares and summarizes recent research advances in flame retardancy for carbon fiber-reinforced polymers and glass fiber-reinforced polymers. Focusing on various polymer matrices, including epoxy, polyamide, and polyetheretherketone, the mechanisms and synergistic effects of different flame-retardant modification strategies—such as additive flame retardants, nanocomposites, coating techniques, intrinsically flame-retardant polymers, and advanced manufacturing processes—are analyzed with emphasis on improving flame retardancy and suppressing the “wick effect.” The review critically examines the challenges in balancing flame retardancy, mechanical performance, and environmental friendliness in current approaches, highlighting the key role of interface engineering in mitigating the “wick effect.” Based on this analysis, four future research directions are proposed: implementing green design principles throughout the material life cycle; promoting the use of natural fibers, bio-based resins, and bio-derived flame retardants; developing intelligent responsive flame-retardant systems based on materials such as metal–organic frameworks; advancing interface engineering through biomimetic design and advanced characterization to fundamentally suppress the fiber “wick effect”; and incorporating materials genome and high-throughput preparation technologies to accelerate the development of high-performance flame-retardant composites. This review aims to provide systematic theoretical insights and clear technical pathways for developing the next generation of high-performance, safe, and sustainable fiber-reinforced composites. Full article

The characterization and biomedical modification of bentonite clays from the Kalzhat deposit (Kzh), which is situated in Kazakhstan’s Zhetysu region, are the main objectives of this work. In order to improve the raw material’s structural qualities, the montmorillonite fraction was enriched, and coarse impurities were eliminated using the Salo method. The presence of meso- and micropores that guarantee high dispersity and specific surface area, as well as the prevalence of montmorillonite and kaolinite, was all confirmed by physicochemical analysis. Particle size measurements indicated finely dispersed structures with a propensity to aggregate, whereas thermal analysis demonstrated resilience under heating. After effective functionalization with silver nanoparticles, a porous hybrid system with improved surface reactivity was produced. These enhancements demonstrate the modified bentonite’s usefulness as a multifunctional carrier for the immobilization and controlled release of pharmaceuticals, with potential uses in drug delivery systems, antimicrobial coatings, and wound-healing materials. The material has potential use in sorption and environmental protection technologies in addition to its biomedical application. Overall, Kzh’s structural and functional performance is greatly improved by the combination of purification and functionalization with silver nanoparticles, highlighting its promise as a useful element in the development of next-generation polymer–composite systems. Full article

This study develops and assesses a hydrophobized fly ash mineral powder as a filler for dense fine-graded asphalt mixtures in Kazakhstan. Fly ash from a local TPP was dry co-milled with a stearate-based modifier to yield a free-flowing, hydrophobic powder that meets the national limits for moisture, porosity, and gradation. SEM shows cenospheres and broken shells partially armored by adherent fines, suggesting an increased micro-roughness and potential sites for binder–filler bonding. Three mixes were produced: a carbonate reference and two fly ash variants, all designed at the same optimum binder content. Compared with the reference, fly ash fillers delivered a markedly higher compressive strength (up to about five times at 20 °C), improved adhesion, and high internal friction, while the mixture density rutting resistance was essentially unchanged. Water resistance indices remained high and stable despite only modest changes in water saturation, and crack resistance improved, especially for the dry ash mixture. The convergence of microstructural, physicochemical, and mechanical results shows that surface-engineered fly ash from a Kazakhstani TPP can technically replace natural carbonate filler while enhancing durability-critical performance and supporting the more resource-efficient use of industrial by-products in pavements. Full article

Magnetic soft manganese–zinc ferrite in a concentration scale ranging from 100 to 500 phr was incorporated into acrylonitrile-butadiene rubber. The work was focused on the investigation of manganese–zinc ferrite content on electromagnetic interference shielding effectiveness and mechanical properties of composites. The rubber-based products used in industrial practice should not only provide good utility and functional properties but should also exhibit good stability towards degradation factors, like oxygen and ozone. Therefore, the samples were exposed to the thermo-oxidative and ozone ageing conditions, and the influence of both factors on the composites’ properties was evaluated. The results demonstrated that the incorporation of ferrite into the rubber matrix resulted in the fabrication of composites with absorption-shielding performance. It was demonstrated that the higher the ferrite content, the lower the absorption-shielding ability. Electrical and thermal conductivity showed an increasing trend with increasing content of ferrite. On the other hand, the study of mechanical properties implied that ferrite acts as a non-reinforcing filler, leading to a decrease in tensile characteristics. Thermo-oxidative ageing tests revealed that ferrite, mainly in high amounts, could accelerate the degradation processes in composites. Though the absorption-shielding performance of composites after ageing corresponded to that of their equivalents before ageing, it can also be concluded that the higher the amount of ferrite in the rubber matrix, the lower the composites’ stability against ozone ageing. Full article

The use of food industry by-products in the production of construction materials is a great method to achieve sustainability and simultaneously reduce cement consumption. The present research analyzes the use of pomegranate seed cakes (untreated, oven-roasted, and microwave-treated), grape seeds, and black cumin seeds for 0–15% cement replacement. In addition, the focus is on the thermal pretreatment methods and their compatibility with the microstructure of the cement, especially microwave processing due to its rapid heating, low energy demand, and improved microstructural compatibility. The outcomes suggest that microwave-treated pomegranate seed cakes resulted in the highest workability stability, lowest slump loss, and most uniform distribution in the cement matrix in comparison to untreated and oven-roasted pomegranate seed cakes. Comprehensive mechanical tests (compressive, flexural, and splitting tensile strength) and microstructural analyses (SEM, EDS, FTIR, XRD, BET) were conducted on both raw additives and concrete specimens. Although mechanical performance decreases with increasing organic content, mixtures containing 3–5% bio-modifier provided a favorable balance between workability, strength retention, and microstructural development. Microwave pretreatment not only improved the surface morphology but also made the interface more reactive, and by consuming around 80–85% less energy than the oven roasting, it strengthened the sustainability feature of the process. In a nutshell, the research proves that low-energy thermal pretreatment of food-grade waste can result in functional, eco-efficient cementitious composites, and at the same time, the integration of food engineering principles into environmentally friendly construction material design will become inevitable. Full article

The rubber industry uses phthalates as plasticizers in technical rubber goods due to their excellent compatibility, low volatility and cost-effectiveness. Growing concerns over their environmental and health impact have driven the search for sustainable alternatives. Bio-based plasticizers offer a promising solution due to their renewable nature, non-toxicity and biodegradability. This study explores the feasibility of replacing a conventional petroleum-based Di-Iso-Nonyl Phthalate (DINP) with a bio-based phthalate-free plasticizer, Aurora PHFree, in Nitrile Butadiene Rubber (NBR) compounds filled with semi-reinforcing carbon black N660. Aurora PHFree achieves similar processing behavior, cure characteristics, and mechanical properties as well as aging performance by using only half of the amount by weight of DINP. This efficiency is attributed to the improved plasticizing effects, which enable polymer chain mobility, without altering the overall crosslink density, as well as the enhanced dispersion of the carbon black (CB) fillers of the rubber compounds. This research supports the development of more sustainable rubber materials and contributes to reducing the dependence on fossil-based materials while maintaining high-quality standards. Full article

Currently, in hydrotechnical engineering, such as oil and gas platform construction, floating docks, and other floating structures, the need to develop new lightweight composite building materials is becoming an important problem. Expanded clay concrete (ECC) is the most common lightweight concrete option for floating structures. The aim of this study is to develop effective composite ECC with improved properties and a coefficient of structural quality (CCQ). To improve the properties of ECC, the following formulation and technological techniques were additionally applied: reinforcement of lightweight expanded clay aggregate by pre-treatment in cement paste (CP-LECA) with the addition of microsilica (MS) and dispersed reinforcement with basalt fiber (BF). An experimental study examined the effect of the proposed formulation and technological techniques on the density and cone slump of fresh ECC and the density, compressive and flexural strength, and water absorption of hardened ECC. A SEM analysis was conducted. The optimal parameters for LECA pretreatment were determined. These parameters are achieved by treating LECA grains in a cement paste with 10% MS and using dispersed reinforcement parameters of 0.75% BF. The best combination of CP-LECA10MS-0.75BF provides increases in compressive and flexural strength of up to 50% and 61.7%, respectively, and a reduction in water absorption of up to 32.8%. The CCQ increases to 44.4%. If the ECC meets the design requirements, it can be used in hydraulic engineering for floating structures. Full article

Externally bonded carbon-fiber-reinforced polymer (CFRP) can increase the flexural capacity of steel beams, but the benefit is often limited by the performance of the adhesive interface. This study develops and validates a three-dimensional finite-element model (FEM) with an explicit cohesive-zone representation of the adhesive layer. It reproduced benchmark four-point bending tests in terms of peak load, corresponding mid-span deflection, and the transition from end/intermediate debonding to laminate rupture. A one-factor-at-a-time parametric analysis is carried out to examine the influence of (i) member geometry (beam depth; flange and web thickness), (ii) CFRP configuration (bonded length; laminate thickness), and (iii) bond quality (cohesive normal strength). Within the ranges studied, cohesive strength and bonded length are the primary variables controlling both capacity and failure mode: strengths below about 25 MPa and short plates lead to debonding-governed response. Increasing strength to around 27 MPa and bonded length to 650–700 mm delays debonding, promotes CFRP rupture, and produces the largest incremental gains in peak load, while further increases in length give smaller additional gains. Increasing laminate thickness and steel depth or flange/web thickness always raises peak load, but under baseline bond conditions failure remains debonding and the added material is only partially mobilized. When cohesive strength is increased above the threshold, additional CFRP thickness becomes more effective. A linear regression model is fitted to the FEM dataset to express peak load as a function of bonded length, cohesive strength, laminate thickness, and steel dimensions, and is complemented by a failure-mode map and a cost–capacity chart based on material quantities. Together, these results provide quantitative trends and simple relations that can support preliminary design of CFRP-strengthened steel beams for similar configurations. Full article

This study explores the potential of integrating thermoplastic surfaces into fiber-reinforced plastics (FRPs) to eliminate the need for extensive surface preparation prior to bonding. Traditional bonding techniques for FRPs, especially in aerospace applications, demand meticulous surface preparation to ensure adequate adhesion. As a potential alternative to conventional methods for generating adhesion, the formation of an interpenetrating polymer network (IPN) by diffusion of the epoxy monomers into a thermoplastic surface layer is investigated. The research involved manufacturing CFRP panels with thermoplastic surfaces, polyether sulfone (PES), and polyetherimide (PEI), followed by a bonding process with and without conventional surface preparation. The performance of the joints was tested by tensile shear and Mode-I fracture toughness tests and compared to reference samples without thermoplastic surfaces. The formation and characteristics of the IPNs were analyzed using optical microscopy, laser scanning microscopy, and energy-dispersive X-ray spectroscopy. The results demonstrate that PES surfaces, even without surface treatment, can provide high mechanical performance with shear strengths ranging from 18 MPa to 23 MPa. PEI surfaces led to a shear strength from 10 MPa up to 14 MPa, correlating to a less extensive IPN formation compared to PES. However, both thermoplastics significantly improved the bonding process performance without surface preparation. Full article

The study proposes a methodology that combines digital image correlation (DIC) with cluster analysis (CA) to investigate the damage evolution and localization behavior of basalt fiber foam concrete (BFFC) under tensile loading. This method can simultaneously conduct quantitative analysis of both the process of damage accumulation and the process of damage localization. Quasi-static tensile tests were performed on specimens with different matrix densities and basalt fiber content. The full-field and full-process deformation images of the specimens were recorded by a high-resolution CCD. Cluster analysis was performed on the precise deformation data obtained from the DIC method, and damage extent factors and damage localization coefficients were defined. Statistical analysis indicates that the incorporation of basalt fibers not only effectively delays the progression of damage in foam concrete materials but also significantly enhances their initial damage threshold load and inhibits the phenomenon of damage localization in foam concrete. Compared to specimens without basalt fibers, those incorporating basalt fibers exhibited increases in the damage localization coefficients at tensile failure of 0.4, 0.33 and 0.18, respectively, under three different matrix density conditions. Therefore, the proposed DIC-CA method, in conjunction with the defined damage extent factor and damage localization coefficient, can effectively and quantitatively capture the two key dimensions of damage (accumulation extent and spatial distribution characteristics) in fiber-reinforced foam concrete under tensile loading. This provides an efficient, intuitive, quantitative analysis method for characterizing the initiation, development and localization processes of damage in similar materials. Full article

Asymmetric and symmetric magnetoelectric (ME)-laminated composites with magnetostrictive layer FeNi and piezoelectric layer PZT are prepared. The longitudinal resonance ME voltage coefficient in the symmetric composite is approximately 1.57 times that in the asymmetric composite with same constituents due to the flexural deformation and asymmetric stress distribution in the asymmetric structure. By bonding an additional high-permeability FeSiB, combining FeSiB with FeNi forms magnetization-graded ferromagnetic materials. A stronger maximum ME voltage coefficient, a dual-peak phenomenon, and a self-bias ME effect are observed. The maximum ME voltage coefficients for asymmetric and symmetric composites reach 3.10 V/Oe and 5.67 V/Oe by adjusting the thickness of the FeCuNbSiB layer. The maximum zero-bias ME voltage coefficients for asymmetrical and symmetrical composite materials reach 2.19 V/Oe at 25 µm thickness of FeSiB and 2.87 V/Oe at 75 µm thickness of FeSiB. Such high performances enable the ME composites to possess ideal sensing and make them promising for self-bias current sensor applications. Full article

The growing demand for sustainable pavement materials has increased interest in using recycled concrete aggregate (RCA) as a substitute for natural aggregates. However, the mechanical, durability, and environmental performance of roller-compacted concrete pavement (RCCP) incorporating very high RCA contents (≥75%) remains poorly understood, particularly when combined with hybrid steel fiber reinforcement. This knowledge gap limits the practical adoption of high-RCA RCCP in infrastructure applications. To address this gap, this study investigates the eco-efficiency of RCCP produced with 75% RCA and different steel fiber systems, including industrial (ISF), recycled (RSF), and hybrid (HSF) combinations. Mechanical performance was evaluated through compressive, tensile, and flexural testing, while freeze–thaw durability was assessed under extended cyclic exposure. Environmental impacts were quantified through a cradle-to-gate life cycle assessment (LCA), and a multi-criteria decision analysis (MCDA) was applied to integrate mechanical, durability, and environmental indicators. The findings show that although high-RCA mixtures exhibit reduced mechanical performance due to weaker interfacial bonding, HSF reinforcement effectively mitigates these drawbacks, enhancing toughness and improving freeze–thaw resistance. The LCA results indicate that replacing natural aggregates and industrial fibers with RCA and RSF substantially reduces environmental burdens. MCDA rankings further identify HSF-reinforced high-RCA mixtures as the most balanced and eco-efficient configurations. Overall, the study demonstrates that hybrid steel fibers enable the development of durable, low-carbon, and high-RCA RCCP, providing a viable pathway toward circular and sustainable pavement construction. Full article

The investigation of the behavior of ZrB₂-SiC-based ultra-high temperature ceramic (UHTC) materials under high-velocity CO₂ plasma flow is of significant importance and relevance for evaluating their prospective use in the exploration of planets such as Venus or Mars. Accordingly, the degradation process of a ZrB₂-30 vol.% SiC ceramic composite, fabricated by hot-pressing at 1700 °C with a 15 vol.% Ti₂AlC sintering aid, was examined using a high-frequency induction plasmatron. It was found that the modification of the ceramic’s elemental and phase composition during consolidation, resulting from the interaction between ZrB₂ and Ti₂AlC, leads to the formation of an approximately 400 µm-thick multi-layered oxidation zone following 15 min stepwise thermochemical exposure at surface temperatures reaching up to 1970 °C. This area consists of a lower layer depleted of silicon carbide and an upper layer containing large pores (up to 160–200 µm), where ZrO₂ particles are distributed within a silicate melt. SEM analysis revealed that introduction of more refractory titanium and aluminum oxides into the melt upon oxidation, along with liquation within the melt, prevents the complete removal of this sealing melt from the sample surface. This effect remains even after 8 min exposure at an average temperature of ~1960–1970 °C. Full article

The growing demand for efficient hydrogen storage solutions highlights the need for reliable and safe composite overwrapped pressure vessels (COPVs). This study investigates the application of an inline monitoring system combining laser-based measurements and photogrammetric line photography to assess COPV quality during fabrication, including quantitative evaluation of liner concentricity and high-resolution line scanning of the composite surface to detect and measure fiber orientations. Fiber detection and angle measurement using the Hough Transform provide detailed assessment of local winding orientation, while global Fourier Transform analysis supports comparative evaluation across vessels or segments, allowing identification of dominant fiber directions and detection of micro-scale deviations. The integrated approach enables early detection of geometric inconsistencies and localized winding irregularities, providing robust performance-based criteria for accept-reject decisions, while filtering out minor noise and ensuring reliable quantitative evaluation. This framework enhances inline quality control, optimizes material usage, and supports the safe deployment of COPVs in hydrogen storage systems, contributing to efficient and reliable energy storage solutions. Full article

Aluminum alloys require improved surface performance to satisfy the demands of today’s aerospace, automotive, marine, and structural applications. This paper compares three key surface hardening methods: diffusion-assisted microalloying, thermomechanical deformation-based treatments, and composite/hybrid reinforcing procedures. Diffusion-assisted Zn/Mg enrichment allows for localized precipitation hardening but is limited by the native Al₂O₃ barrier, slow solute mobility, alloy-dependent solubility, and shallow hardened depths. In contrast, thermomechanical techniques such as shot peening, surface mechanical attrition treatment (SMAT), and laser shock peening produce ultrafine/nanocrystalline layers, high dislocation densities, and deep compressive residual stresses, allowing for predictable increases in hardness, fatigue resistance, and corrosion performance. Composite and hybrid reinforcement systems, such as SiC, B₄C, graphene, and graphite-based aluminum matrix composites (AMCs), use load transfer, Orowan looping, interfacial strengthening, and solid lubrication effects to enhance wear resistance and through-thickness strengthening. Comparative evaluations show that, while diffusion-assisted procedures are still labor-intensive and solute-sensitive, thermomechanical treatments are more industrially established and scalable. Composite and hybrid systems provide the best tribological and load-bearing performance but necessitate more sophisticated processing approaches. Recent corrosion studies show that interfacial chemistry, precipitate distribution, and galvanic coupling all have a significant impact on pitting and stress corrosion cracking (SCC). These findings highlight the importance of treating corrosion as a fundamental design variable in all surface hardening techniques. This work uses unified tables and drawings to provide a thorough examination of strengthening mechanisms, corrosion and fatigue behavior, hardening depth, alloy suitability, and industrial feasibility. Future research focuses on overcoming diffusion barriers, establishing next-generation gradient topologies and hybrid processing approaches, improving strength ductility corrosion trade-offs, and utilizing machine-learning-guided alloy design. This research presents the first comprehensive framework for selecting multifunctional aluminum surfaces in demanding aerospace, automotive, and marine applications by seeing composite reinforcements as supplements rather than strict alternatives to diffusion-assisted and thermomechanical approaches. Full article

This study focuses on improving the operational properties of a magnesium potassium phosphate (MPP) matrix MgKPO₄ × 6H₂O for the immobilization of radioactive waste (RW) by introducing detonation nanodiamonds (NDs). The study evaluates the impact of NDs on the phase composition of the resulting composite based on the MPP matrix (further referred to as MPP-ND composite), as well as its compressive and flexural strength, porosity, thermal conductivity, and leaching resistance to actinides (²³⁹Pu, ²³⁸U) and europium (as a lanthanide simulator). It was found that the optimal content of NDs in the composite is 1 wt%, along with 20 wt% of wollastonite as a reinforcing additive. This MPP-ND composite exhibited high compressive and flexural strengths of 24 and 4 MPa, respectively, a thermal conductivity coefficient of (0.5–1.0) W/(m∙K) in the interval of (47–510) °C, and a minimal open porosity of no more than 5%. An increase in hydrolytic stability to leaching of actinides and europium due to their prior sorption on NDs was observed. The leaching rates of ²³⁹Pu, ²³⁸U, and Eu from the MPP-ND composite on the 28th day of sample contact with water were 3.5 × 10⁻⁶, 1.5 × 10⁻⁴, and 4.0 × 10⁻⁶ g/(cm²·day), respectively. Thus, for the first time, data on the influence of NDs on the physicochemical properties and hydrolytic stability of MPP-ND composite demonstrating the practical applicability of this composite for RW immobilization have been obtained. Full article

Owing to their superior mechanical performance, strong adhesion, thermal resistance, and insulating properties, epoxy resins are commonly employed as protective coatings, electronic encapsulants, adhesives, and matrices in composites. The selection of the epoxy system components—the base resin and curing agent—along with the chosen curing protocol, directly determines the properties of the final cross-linked polymer. This study compares the influence of halogen substituents in 4,4′-methylenebis(2,6-diethylaniline) (MDEA), 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) and 4,4′-methylenebis(3-bromo-2,6-diethylaniline) (MBDEA). The results of mechanical tests on plastics and composites demonstrated an increase in the strength properties and elastic modulus of the matrix, improved adhesive interactions with carbon fiber, and showed a reduction in moisture saturation across the series MDEA → MCDEA → MBDEA. Notably, the improvement in properties exceeded the increase in the density of the compositions, indicating an enhancement in the specific characteristics of the matrix. Full article

Wide band gap (WBG) oxide and metal nanocomposites can possess bifunctionality from combining tightly coupled nanoobjects with different physicochemical properties. Adjusting synthesis conditions tunes these properties through modulating the process–morphology–function relationship. However, the controllable synthesis of such nanocomposites and their related applications are still underexplored. Here, we present a novel process flow to synthesize crystalline ZnO nanosheaves dotted with silver nanoparticles. The uniqueness of our strategy lies in the use of a silver mask for vertical growth of ZnO nanosheaves and thermal evaporating/dewetting Ag film to form a photocatalytic/plasmonic heterostructure. Upon combining a huge specific surface area and nanocrystallinity of ZnO nanosheaves, we enabled its surface-enhanced Raman scattering (SERS)-activity free of plasmonic components, yet their Ag modification resulted in improving detection limit in relation to Ellman’s reagent. Ag/ZnO nanosheaves showed dramatic photocatalytic activity to clean SERS-active surface. The systematic approach to synthesize Ag/ZnO heterostructure holds great promise in practical applications associated with interest in both photocatalytic and plasmonic properties. Full article

In-plane shear is the dominant deformation mode during thermoforming of fiber-reinforced composites, and accurate characterization of shear behavior is essential for reliable forming simulations. The present work investigates the shear response of a unidirectional cross-ply UHMWPE material system (DSM Dyneema^® HB210) using the picture-frame test, with emphasis on sample configuration, normalization methods, and shear rate effects. Three cruciform sample sizes were tested at 120 °C, along with a configuration in which cross-arm material was removed to isolate the gage region. Finite element analyses using LS-DYNA^® were performed to evaluate the shear rate distribution during forming and to validate the experimental characterization. To maintain a constant shear rate during testing, a decreasing crosshead speed profile was implemented in the test software. Results showed that normalizing by the full specimen area yielded consistent shear stiffness curves across sample sizes, indicating that the arm region contributes equally to the load. Samples with cross-arm material removed exhibited greater scatter than those specimens without cross-arm material removed, confirming that preparation of cross-arm removal complicates repeatability. Rate dependence was observed at room temperature but not at elevated processing temperatures, suggesting that rate-dependent shear models are unnecessary for forming simulations of this material system. These findings provide a practical methodology for shear characterization of UHMWPE cross-ply laminates suitable for thermoforming analyses. Full article

Radiation shielding in medical settings has traditionally relied on fixed structural models, with thicknesses and material composition determined by their shielding effect against direct X-rays. However, clinical practice increasingly demands lightweight and biocompatible shielding tools that can be locally applied to specific anatomical regions. Such tools should allow rapid installation and removal, skin protection, and disposable as well as continuous shielding. As a potential solution, this study aimed to improve the effectiveness of a cream-type material that directly coats the skin with shielding agents. A modeling pack was fabricated using bismuth oxide, an eco-friendly shielding material; zinc oxide, commonly utilized in cosmetics for ultraviolet protection; and alginate, which enhances skin adhesion by evaporating moisture. The effects of varying bismuth oxide and zinc oxide ratios on porosity and shielding performance were evaluated to establish assessment criteria for future commercialization. The experimental results demonstrated that higher proportions of bismuth oxide enhanced the shielding effect, while a linear change in shielding rate was observed at a thickness of 1.0 mm. Although pore structure variations were minimal, optimizing inter-particle arrangement may further improve skin adhesion. These findings suggest that cream-type radiation-shielding materials are highly promising for medical applications. Full article

Composite structures are generally more susceptible to impact damage than non-composite structures, and early identification of damage is the primary goal of structural health monitoring (SHM). If such damage remains undetected or reaches a critical size, it can lead to sudden collapse and catastrophic failure. Modern SHM methods aim to preserve the integrity of composite structures through continuous inspection, monitoring, and damage assessment, including detection, localization, quantification, classification, and prognosis. These methods use sensor-based technologies to assess vibration, extension, and acoustic and thermal emission. This paper provides a review of various computational methods including physics-based methods (signal processing techniques, modal analysis, and finite element model updating) and optimization methods (inverse problems, particle swarm optimization, topology optimization, genetic algorithms, time series analysis, and hybrid techniques), alongside machine learning methodologies employing neural networks as well as deep learning for damage identification in composite structures. These computational and learning-based techniques are widely applied in the development of algorithms, optimization strategies, and hybrid frameworks for SHM. The review further summarizes the applications, advantages, and limitations of each method according to structure type and damage characteristics. The key emphasis of this review is on integrating computational approaches, as well as machine learning, to enhance the efficiency of damage identification. The conclusion is drawn based on an overview of the literature, focusing on the contributions of different computational methods and machine learning for damage identification in composites. Full article

The recycling and reuse of thermoset composite materials present considerable challenges due to the cross-linked network formed during the curing process. The growing implementation of these materials in various industries, such as automotive and wind energy sectors, has generated significant research interest in this area. This paper presents a comprehensive review of different approaches for the recycling, focusing on two aspects: established methods with higher technological readiness levels (mechanical, thermal, and chemical) and emerging methods still under development (microwave-assisted recycling, enzymatic recycling, electrochemical recycling, superheated steam recycling and ultrasonic recycling). Furthermore, the reuse of thermoset composite materials by thermoforming, for example, is discussed, along with an overview of innovative resin systems specially designed for recyclability and reusability. Finally, the challenges and future prospects are briefly summarised. Full article

Background: Soft actuation relies on materials that are lightweight, flexible, and responsive to external stimuli. In biomedical applications, miniaturization and biocompatibility are key requirements for developing smart devices. Thermoplastic polyurethane (TPU) is particularly attractive due to its elasticity, processability, and biocompatibility; however, an improvement in its shape-recovery performance would significantly enhance its suitability for actuation systems. This study aims to develop TPU-based shape memory polymer (SMP) composites with improved functional behavior for biomedical applications. Methods: TPU was modified with aluminum nanoparticles (AlNPs) and multi-walled carbon nanotubes (MWCNTs), incorporated individually (1 wt.% and 3 wt.%) and in hybrid combinations (MWCNT:AlNP ratios of 2:1, 5:1, and 10:1). Samples were produced by compression molding and characterized through thermal, mechanical, electrical, and shape-recovery tests, supported by morphological analysis. Results: AlNPs moderately improved thermal conductivity, while MWCNTs significantly enhanced electrical conductivity and doubled the recovery force compared with neat TPU. Hybrid composites showed intermediate properties, with the 5:1 MWCNT:AlNP ratio offering the best balance between recovery force and activation speed. Conclusions: The synergistic combination of MWCNTs and AlNPs effectively enhances TPU’s multifunctional behavior, demonstrating strong potential for soft actuation in biomedical devices. Full article

Poly(ethylene terephthalate) (PET) is a widely used polymer that accumulates in the environment due to its low degradability, requiring efficient recycling strategies. In this study, CaO filler derived from calcium carbide slag (CS) waste was used for the first time as a catalyst for PET depolymerization. PET/CaO composites were prepared via hot extrusion of PET with the finely dispersed CaO filler. The resulting composite demonstrated consistently higher PET conversion (≥95%) and the yields of dimethyl and dibutyl terephthalates (80 and 84%, respectively). Kinetic studies of glycolysis demonstrated that embedding 1 wt% of CaO in the PET matrix doubled the bis(2-hydroxyethyl) terephthalate (BHET) formation rate relative to an externally added CaO catalyst, which resulted in BHET yields of 84.7% and 41.1% after 40 min. SEM and EDX investigations demonstrated good adhesion between the polymer matrix and the filler. The recovered BHET was successfully re-polymerized to produce recycled PET (r-PET). The maximum rate of weight loss of r-PET samples (at T_max = 438.7–444.7 °C) was comparable to the original materials (at T_max = 455.3–457.7 °C). In fact, the direct incorporation of CaO catalyst derived from waste into the polymer matrix during additive manufacturing enabled the implementation of an efficient and scalable closed-loop recycling strategy. Full article

This preliminary study investigates a direct, non-delaminated route to valorize multilayer pharmaceutical sachet offcuts (comprising paper/plastic/aluminum) as partial substitutes for wood fiber in wood-based panels. Milled offcuts were incorporated at 10, 20, and 30 wt% (control: wood only). Laboratory mats were hot-pressed at 170 °C for 9 min under a staged pressure regime. Sampling and three-point bending were performed according to EN 326-1 and EN 310, respectively, with the density held essentially constant by controlling the mat mass and press stops. Bending stiffness (MOE) was maintained at 10–20 wt% (within experimental uncertainty of the reference), while 30 wt% showed a consistent downward trend (approximately 10%). Bending strength (MOR) peaked at 10 wt% (approximately 8% higher than the reference), then declined at 20% and 30%. Representative stress–strain curves corroborated these outcomes, indicating auxiliary bonding and crack-bridging effects at low waste loadings. Hygroscopic performance improved monotonically: 24 h water absorption and thickness swelling decreased progressively with increasing substitution, attributable to the hydrophobic polymer layers and aluminum fragments interrupting capillary pathways. Process observations identified opportunities to improve press-cycle efficiency at higher waste contents, and the dispersed foil imparted a subtle decorative sheen. Overall, the results establish the technical feasibility and a practical utilization window of approximately 10–20 wt% for furniture-grade applications. Limitations include the laboratory scale, a single resin/press schedule, and the absence of internal bond, density profile, emissions, and long-term durability tests—topics prioritized for future work (including TGA/DSC, EN 317 extensions, and scale-up). Full article