The use of phase change materials (PCMs) in cementitious mortars is a promising strategy for passive thermal regulation and thermal energy storage (TES) in buildings, but its practical implementation remains constrained by PCM leakage and its effects on physical and mechanical performance. This study investigates the use of recycled clay brick waste as a dual-function component in eco-efficient mortars, serving as a partial replacement for fine aggregate and as a porous carrier for paraffin-based PCM. The experimental program comprised three stages: selection of an eco-efficient reference mortar, impregnation of recycled ceramic aggregates using thermal and vacuum-assisted procedures, and evaluation of PCM-modified mortars through fresh-state, physical, mechanical, thermophysical, direct thermal exposure, thermoregulation, and infrared thermography tests. Thermal impregnation at 15 wt% PCM provided the most favorable balance between PCM incorporation and stability against surface accumulation and mass loss and was selected for mortar production. Compared with REFeco, PCM incorporation reduced water absorption by approximately 10% and caused compressive and flexural strength losses below 10%. PCM15 exhibited the most favorable thermophysical balance, increasing volumetric specific heat by 14.9% and thermal inertia by 8.5%, while reducing thermal diffusivity by 10.8%. Under direct flame exposure, PCM25 produced the greatest thermal buffering effect, delaying the attainment of 200 °C on the rear face by approximately 4 min and reducing maximum estimated heat flux by approximately 16% relative to REFeco. Overall, recycled clay brick waste demonstrated potential as a PCM carrier for eco-efficient cementitious mortars with thermal energy storage functionality.
Polyethylene (PE)-based composites reinforced with lignocellulosic fillers undergo a gradual decline in performance under weathering conditions. This review combines a bibliometric analysis using VOSviewer 1.6.20 with a critical assessment of the literature to examine the weathering behavior of these composites and discuss its implications for the circular economy, particularly with respect to extending service life. The literature shows that mechanical property retention depends primarily on the lignocellulosic filler content (below 50 wt%), fiber-matrix interfacial adhesion, composite microstructure, and environmental exposure conditions. Because lignocellulosic fibers are inherently hydrophilic, water uptake and subsequent microcrack formation can compromise the structural integrity of the composite. Conversely, lignin present in the lignocellulosic reinforcement, coupling agents such as maleic anhydride-grafted polyethylene (PE-g-MA), and ultraviolet (UV) stabilizers such as zinc oxide enhance fiber–matrix adhesion, mitigate photo-oxidative degradation and improve the retention of mechanical properties during weathering. Although the relationship between weathering and the circular economy has rarely been explicitly addressed, the available evidence identifies the material compositions and exposure conditions that favor property retention, thereby supporting longer service life and increasing the potential for circular use of PE-based lignocellulosic composites.
In this study, AZ91 magnesium alloy was used as the matrix material, and Cu powder was added at contents of 1 and 2 wt.% as an alloying addition. The AZ91–Cu alloys were fabricated by gravity casting combined with mechanical stirring. Subsequently, T4 solution treatment and T6 artificial aging treatment were conducted to investigate the effects of Cu content and heat treatment conditions on the microstructure, mechanical properties, and thermal conductivity. The results showed that Cu addition promoted the formation of Al4Cu9 intermetallic compounds. After T4 treatment, part of the β-Mg17Al12 phase dissolved into the α-Mg matrix, resulting in a more homogeneous microstructure. After T6 treatment, fine second phases re-precipitated, leading to a precipitation strengthening effect. In terms of mechanical properties, the T6-treated AZ91-2Cu alloy exhibited the highest hardness, yield strength, and ultimate tensile strength, reaching 83.73 HV, 117.94 MPa, and 173.82 MPa, respectively. In contrast, the highest thermal conductivity of 64.74 W/(m·K) was obtained for the as-cast AZ91-2Cu alloy. Therefore, although T6 aging maximized the mechanical strength, it did not simultaneously maximize thermal conductivity, demonstrating a trade-off between mechanical strengthening and thermal transport performance.
Pectin films are promising renewable materials for biodegradable coatings; however, their high hydrophilicity and limited resistance to ultraviolet (UV) radiation restrict practical applications. This work investigated the influence of kraft lignin (0–5 wt%) on the structure–property relationships of grape-derived pectin films before and after accelerated UV exposure. Structural organization (XRD and FTIR), photostability (CIELAB colorimetry and CIE chromaticity), wettability, water-vapor absorption, surface morphology, soil-burial disintegration, and integrated multifunctional performance were evaluated. Lignin improved resistance to UV-induced structural changes, reducing the relative loss of apparent crystallinity from 52.76% for neat pectin to less than 7% for films containing at least 0.1 wt% lignin, while substantially decreasing UV-induced color changes. Increasing lignin content also reduced surface wettability, water-vapor uptake, and soil-burial mass loss; nevertheless, all formulations exhibited more than 50% mass loss after 120 h of soil burial. Exploratory CRITIC–TOPSIS analysis identified Pec/Lig1 as the highest-performing formulation, whereas Pec/Lig0.1 provided the most compositionally efficient balance among photostability, moisture resistance, structural stability, soil-burial disintegration, and lignin consumption. These findings demonstrate that lignin governs the trade-offs among structural stability, photostability, moisture resistance, soil-burial disintegration, and additive consumption, establishing composition–structure–property–durability relationships that provide practical design guidance for candidate functional coatings for cellulose- and paper-based substrates.
Additive manufacturing enables the fabrication of cellular structures with complex geometries and tunable mechanical response. This study evaluates auxetic-inspired cellular metamaterials manufactured by fused deposition modeling using polylactic acid (PLA) and polyethylene terephthalate glycol (PETG). Standard specimens and three cellular architectures, namely conventional honeycomb, re-entrant honeycomb, and EigenModes, were investigated under tensile, flexural, and compressive loading. Results are reported as the mean ± standard deviation from three specimens per condition. In standard tensile specimens, PLA reached its highest failure load at 60% infill (1034.7 ± 5.8 N), whereas PETG increased with infill density, reaching 919.0 ± 16.5 N at 100% infill. Under flexural loading, the highest standard-specimen values were 38.7 ± 1.2 N for PLA and 20.0 ± 1.0 N for PETG, both at 90% infill. In compression, PLA standard specimens reached 98,645 ± 448 N at 100% infill, while PETG reached 47,292 ± 16,139 N. For cellular compression specimens manufactured at 90% infill, PLA showed higher failure load values than PETG in all evaluated geometries, with re-entrant honeycomb and EigenModes reaching 9424 ± 1327 N and 9172 ± 157 N, respectively. Scanning electron microscopy indicated brittle fracture and interlayer microcracking in PLA, while PETG showed greater deformation tolerance around voids and local discontinuities. Overall, the mechanical response depended on polymer behavior, loading mode, infill density, and cellular topology. Since Poisson’s ratio was not directly measured, auxetic-inspired metamaterial refers to architectures commonly associated with auxetic behavior in the literature.
A multiscale computational framework is presented to assess the effect of voids that may arise from a scarf repair and its influence on the post-repair lifetime of wind turbine blades. The approach links a full scale blade model with a detailed repair region model and a microscale representation of polymer adhesives containing voids. Boundary conditions from the global blade model are transferred to the scarf repair model, which subsequently provides input to a microscale representative volume element (RVE) of the adhesive containing voids using the submodelling technique. This RVE is combined with a continuum damage mechanics formulation to simulate high-cycle fatigue and estimate the lifetime for different void contents. The effect of void content resulting from scarf repair is evaluated under both quasi-static and high-cycle fatigue loading, enabling lifetime predictions. In the simulations, it was demonstrated that the lifetime of repaired blade is 4 times lower for the repair with 4% void content as compared with the repair with 1% void content.
An acylation reaction was performed on the crystalline surface of cellulose in a composite consisting of microfibrillated cellulose (MFC) and hydroxyapatite (HAP) with an inorganic weight fraction of 68%. The composite was acylated using acetic anhydride, propanoic anhydride, and butanoic anhydride in pyridine in the presence of potassium carbonate at 120 °C for 1 h. The formation of ester linkages was confirmed by infrared spectroscopy, and X-ray diffraction analysis showed that the crystalline structure of cellulose was retained after acylation. From the intensity of the carbonyl stretching vibration in the infrared spectra, the degree of substitution of the acetylated sample was estimated to be approximately 0.2. The acylated MFC–HAP composites were uniaxially hot-pressed at 120 °C and 300 MPa, and the resulting molded specimens were subjected to three-point bending tests. A yield point appeared at a bending strain of 1.1–1.4%, followed by plastic deformation and final fracture, indicating that they exhibited ductile fracture. The elastic moduli were 5.9 GPa (acetyl), 7.6 GPa (propanoyl), 7.4 GPa (butanoyl), 3.6 GPa (hexanoyl), and 7.1 GPa (before acylation), indicating that acyl groups with medium chain lengths did not reduce the rigidity of the composites. When the molded specimens were immersed in water at room temperature for 24 h, the water absorption ratios were 29% (acetyl), 24% (propanoyl), 17% (butanoyl), and 18% (hexanoyl), demonstrating that water resistance improved with increasing acyl chain length. In summary, propanoylation and butanoylation improved the water resistance of the composites without compromising their rigidity in the dry state.
Honey–gelatin–water composite membranes containing silver microparticles (SmPs) are investigated as soft pressure-responsive materials with potential applications in low-pressure sensing, including biomedical monitoring, and in tunable capacitive components. Three compositions, with nominal volumes of loose SmP powder of up to 3cm3, are prepared to determine how silver loading affects their electrical and apparent compressive response. The membranes are characterized by optical microscopy, XRD, and SEM and are placed between electrodes in a parallel-plate configuration. Capacitance and parallel resistance are measured at 1kHz under applied pressures up to 2.25kPa, and the corresponding admittance components and apparent compressive parameters are calculated from these measurements. It is shown that SmP loading increases the capacitance and reduces the resistance. Between the SmP-free and most highly loaded membranes, the zero-pressure capacitance increases by more than four orders of magnitude, whereas the resistance decreases by approximately a factor of 40. Applied pressure further increases the capacitance and decreases the parallel resistance of all membranes. The apparent strain increases approximately linearly with pressure and is greater in the SmP-loaded membranes, whereas the apparent modulus decreases as the SmP content is increased. The structural and electrical results show that SmP content and the associated heterogeneous microstructure influence both the electrical and apparent compressive response.
Tungsten trioxide (WO3) and molybdenum trioxide (MoO3) are redox-active Group VI transition-metal oxides widely used in functional thin-film technologies. Many studies have examined single-phase WO3 and MoO3 films. However, WO3/MoO3 nanocomposite thin films and heterostructures have not yet been comprehensively reviewed as interface-engineered platforms for smart and sustainable technologies. This review addresses this gap by analyzing WO3/MoO3 thin-film nanocomposites through the concept of interfacial synergy. Particular attention is paid to the structural complementarity of WO3 and α-MoO3, oxygen nonstoichiometry, mixed W6+/W5+/W4+ and Mo6+/Mo5+/Mo4+ valence states, crystallographic-shear suboxides, W–O–Mo interfaces, and fabrication routes for mixed, graded, and multilayer films. The functional advantages of these systems do not arise from simply combining the two oxides. Instead, they result from charge and oxygen-vacancy redistribution, shortened ion–electron transport pathways, phase stabilization, and the formation of new active sites at interface boundaries. The review also emphasizes the need to distinguish genuine interfacial synergy from apparent improvements caused by surface area, film thickness, porosity, hydration, or measurement conditions. Finally, the review links structural features, defect chemistry, and interface-controlled properties to device-level functionality. This framework highlights promising directions for WO3/MoO3 nanocomposite films in a wide range of smart and sustainable technologies.
Glued laminated timber (glulam) is a high-performance structural wood product. However, means are still being researched to increase efficiency in challenges with a large scale of complexity, either owing to the diversity of the lamella’s material properties or through the development of computational models to better represent the real behavior of the material. This study aimed to determine a more efficient combined glulam beam in terms of the lamella’s proportion. The beams with a 12,000 mm span and a 150 × 600 mm cross-section were modeled using solid finite elements and a linear-elastic isotropic model. Two homogeneous and four combined glulam cross-sectional compositions were established based on the physical and mechanical properties of two strength classes (35 and 50 MPa), and their deflections and bending stresses were evaluated. Compared with that of homogeneous glulam beams with lamellae of the strength class 35 MPa, for softwood and hardwood lamellas, the combined cross-section with 33.3% of the lamellas of class strength 50 MPa, the load corresponding to the deflection limit increased by 17% and 12.4%, respectively. This composition had a higher self-weight only in relation to homogeneous glulam. It can be concluded that the combined glulam with a proportion of 33.3% was more efficient, considering the behavior of the beam under a load corresponding to the deflection limit, and that the lower self-weight affects the production and transportation processes.
Chitosan has emerged as a multifunctional biopolymer widely exploited in electrochemical sensing due to its unique physicochemical properties, including biocompatibility, film-forming capacity, protonated amino groups, and strong affinity for metal ions and biomolecules. These intrinsic characteristics enable efficient electrode modification, enhanced analyte adsorption, and immobilization of enzymes, nanoparticles, and 2D materials. In recent years, integrating chitosan with conductive nanostructures, such as carbon nanomaterials, metal oxides, metallic nanoparticles, and layered 2D materials, has significantly enhanced sensor performance, providing high sensitivity, selectivity, stability, and low detection limits across a broad range of analytes. This review presents an updated overview of chitosan’s roles in electrochemical sensing, including its functionalization techniques, electron transfer mechanism, and analyte identification. Key applications, such as biomolecule detection, heavy-metal monitoring, environmental pollutant analysis, pharmaceuticals, and emerging wearable sensing platforms, are discussed. Finally, current challenges and future research directions are highlighted to support the development of next-generation chitosan-based electrochemical sensors.
The advancement of catalytic substrates through Additive Manufacturing (AM) offers notable benefits over conventional techniques, particularly for producing intricate three-dimensional forms that enable precise control over pore dimensions and surface characteristics. These attributes play a vital role in improving catalytic efficiency, which is evaluated by measuring pressure drop and mass transfer. This research focuses on the design and manufacture of a monolithic ceramic filter for catalytic cracking. The monoliths under study have a Triply Periodic Minimal Surface (TPMS) lattice. A macroporosity of about 65% is the criterion used to model the structures, and the TPMS unit cell length is the design parameter to achieve that porosity. Adapting a conventional Fused Filament Fabrication (FFF) desktop to use alumina filament, we produced samples based on three TPMS types: Schwar-Primitive (SP), Schoen Gyroid (SG), and Schwarz-Diamond (SD), which, after a plastic debinding process and subsequent sintering, resulted in meso-scale porous structures. The samples showed relative dimensional errors below 5% and a real total porosity of around 70%, with a maximum difference of 4% among the TPMS types. Because the printed SP lattices have the lowest unit cell length and real porosity, their pressure drop measurements were higher than those of the SG and SD. The opposite occurred with the estimated permeability. Although yielding similar pressure drop results, printed SG lattices had greater permeability than SD; therefore, in terms of monolith fluid dynamics, the SG lattice is the preferred geometry.
Due to their high strength-to-weight ratio and corrosion resistance, carbon fiber-reinforced polymers (CFRPs) are increasingly used as tension elements in bridge engineering. Their pronounced anisotropy, resulting from stiff carbon fibers and a weaker polymer matrix, is critical for fatigue behavior under multiaxial dynamic stress states, such as those occurring in stay cables over saddles of extradosed bridges or at clamps of suspension-bridge hangers. This multiaxial loading can cause progressive damage accumulation in the contact regions and lead to premature failure. To study this efficiently, an energy-based progressive damage analysis (PDA) model for CFRP tension elements under multiaxial fatigue loading was implemented as a vectorized user material in ABAQUS® 6.14 (VUMAT in FORTRAN) and validated against tension-tension fatigue tests on pin-loaded CFRP straps. The model was then applied to two representative bridge applications, viz. a clamped CFRP rod and a CFRP cable bent over a saddle, where parameters such as clamping pressure, maximum stress level, and friction coefficient were varied to quantify their influence on fatigue life and to assess suitability in line with fib recommendations. The results indicate that clamping pressures inducing transverse compressive stresses above roughly 85% of the CFRP’s transversal compressive strength significantly reduce fatigue life, whereas keeping the maximum fatigue stress below about 40% of the mean longitudinal tensile strength, the stress amplitude below 200 MPa, and the friction coefficient near 0.2 yields fatigue lives exceeding 2 × 106 load cycles, which is satisfactory under fib criteria.
This study investigated the development of biopolymer films from bitter cassava starch (Manihot esculenta) and coconut mesocarp cellulose as a promising alternative for biodegradable packaging. The biopolymer film was prepared using the casting method, with glycerol as a plasticiser and Tween 80 as an emulsifier. Different formulations were developed by varying the cellulose concentration to 6%, 8% and 10% to determine how this influences their physical and optical properties. FTIR analysis confirmed the presence of characteristic –OH, C–H, C=O, C–O–C and OH groups in the structure of the cellulose and starch, demonstrating their purity and chemical structure. It was found that the variation in cellulose within the starch polymer matrix significantly influences the microstructural organisation of the material, yielding film thicknesses of between 0.49 and 0.56 mm, with a moisture content ranging from 6.46% to 8.01% and a water absorption percentage between 67.7% and 109.5%; highlighting that the cellulose concentration of 0.4 g (8%) yielded the best results. This research contributes to bridging the existing gap in the utilisation of agricultural waste from bitter cassava and coconut mesocarp, integrating them to form biodegradable composites with potential use in biodegradable packaging, thereby strengthening environmental sustainability through the circular economy.
This study investigates the evolution of microstructural, mechanical, and transport properties in AZ31 magnesium alloy surface composites reinforced with Ti2AlC MAX-phase particles at volume fractions of 6, 9, and 12 vol.%, which were fabricated by solid-state friction stir processing (FSP). In contrast to conventional brittle ceramics, Ti2AlC MAX-phase mitigates interfacial reactivity and thermal mismatch. FSP successfully fabricated a highly consolidated, macroscopically defect-free, dynamically recrystallized fine-grained stirred zone with homogeneous particle distribution and metallurgically clean interfaces. Mechanically, the addition of 12 vol.% Ti2AlC significantly improved the elastic response, increasing the Young’s modulus from 51 GPa to 67 GPa. The microhardness of the stirred zone reached 60.14 HV, a 53.4% increase over the base metal. The controlled electron and phonon scattering, enabled by the introduction of heterogeneous Mg/Ti2AlC interfaces, decreased the electrical and thermal conductivities from initial values of 1.15 × 107 S/m and 86.0 W/m·K for the unreinforced matrix down to 7.8 × 106 S/m and 76.0 W/m·K, respectively, and caused a significant reduction in the coefficient of thermal expansion. Theoretical analysis, utilizing the Wiedemann–Franz law and Maxwell–Eucken approximations, provided a supportive baseline indicating the dominance of electronic thermal transport and interfacial scattering mechanisms. These results outline a viable route for developing lightweight magnesium-based composites with tailored mechanical and thermal characteristics for advanced structural applications.
Accidental web openings caused by impact, corrosion, or conflict-related damage can substantially reduce the strength, stiffness, and stability of steel bridge girders. Although numerous studies have examined beams containing intentionally designed web openings, limited experimental research has systematically compared practical rehabilitation methods for accidental openings in slender-web plate girders. This study experimentally and numerically evaluates several rehabilitation configurations incorporating welded patch plates and transverse stiffeners. Ten slender-web steel girder specimens, each 1800 mm long, 800 mm deep, and 300 mm wide, were tested under monotonic concentrated loading at mid-span. Nonlinear finite element models were also developed to qualitatively examine the principal deformation and instability trends. Relative to the control specimen, the untreated web opening reduced the ultimate load by approximately 43% and exhibited approximately 10% greater deflection at its respective ultimate load. One-sided and two-sided welded patch plates increased the ultimate load of the damaged specimen by approximately 22% and 26%, respectively. Transverse stiffeners increased the ultimate load by approximately 73% while exhibiting substantially lower ultimate-load deflections. The combined use of patch plates and transverse stiffeners provided the greatest improvement, increasing the ultimate load by approximately 101–123% relative to the untreated damaged specimen and substantially reducing lateral instability. The findings demonstrate that effective rehabilitation of slender-web girders requires not only restoration of the interrupted load path but also restraint of web instability.
The rising prevalence of chronic kidney disease (CKD) has intensified the demand for innovative blood filtration therapies. Hemoperfusion, which integrates membrane filtration with adsorbent technologies to sequester circulating uremic toxins, represents a promising therapeutic alternative. In this study, polyethersulfone (PES)-powdered activated carbon (PAC) composite membranes were fabricated via nonsolvent-induced phase separation (NIPS), and the molecular weight of polyethylene glycol (PEG) was optimized as a hydrophilic pore-forming agent. Dope solutions were formulated with 15 wt.% PES, 1 wt.% PAC, and 10 wt.% PEG at varying molecular weights (200, 400, 600, and 1000 Da). Comprehensive characterization revealed that PEG molecular weight significantly dictates the structural and functional performance of the resulting composites. The PEG 600 Da variant achieved an optimal balance of properties, characterized by homogeneous PAC dispersion, a peak water flux of 420.88 LMH/Bar, a water contact angle of 37.11°, and a porosity of 74.74%, while maintaining a high Bovine Serum Albumin (BSA) rejection of 90.87%. While increasing PEG molecular weight generally enhanced permeability through the formation of an open pore architecture, a performance trade-off was observed beyond the 600 Da threshold due to increased dope viscosity and altered phase inversion kinetics. These findings suggest that PEG 600-optimized PES-PAC membranes offer a high-performance, affordable platform for advanced hemoperfusion applications.
Acute and chronic wounds remain a major clinical burden, motivating the design of multilayer biomedical composite systems capable of combining structural support, antimicrobial protection, and controlled release of therapeutic agents within a single device. These architectures integrate natural and synthetic biomaterials, hydrogels, electrospun membranes, bioactive nanoparticles, and 3D-printed scaffolds to reproduce the multifunctionality of the native extracellular matrix. This review examines how layer-by-layer design and biomaterial selection govern mechanical strength, as well as bioactivity, and how these parameters can be tuned to the distinct phases of wound repair. Particular emphasis is placed on strategies for incorporating growth factors, antimicrobial agents, metal/metal-oxide nanoparticles to enhance re-epithelialization, angiogenesis, and infection control; emerging gene-based delivery strategies are also discussed. The main technologies and biomaterial combinations reported to date are compared, alongside a critical overview of their in vitro and in vivo performance. Reproducibility, scalability, and regulatory standardization remain the main barriers to clinical translation. We conclude by outlining priority research directions to advance multilayer composites from bench-scale prototypes toward approved wound-care products.
Satellite droplets and macroscopic distortions, induced by the non-Newtonian rheological behavior of ceramic inks, severely compromise the 3D inkjet printing of multilayer ceramics. To address these issues, we establish a two-phase fluid dynamics model coupling the Level Set method with the Carreau fluid model. The synergistic regulation mechanisms of the piezoelectric driving waveform, initial jet velocity, and pulse width under a high-shear field are elucidated. The results demonstrate that under the excitation of a rectangular pulse with an initial jet velocity of 6 m/s and a pulse width of 10–30 µs, the inertial force, surface tension, and internal non-Newtonian viscous dissipation of the fluid reach an optimal dynamic balance. This facilitates the on-demand ejection of spherical droplets while mitigating the formation of satellite droplets. Based on this, a 10 mm × 10 mm × 2 mm multilayer alumina ceramic packaging substrate was successfully fabricated, with the maximum relative dimensional error reduced from 2.6% to 1.4%. This study provides new insights into improving the 3D inkjet printing accuracy of ceramic devices.
The Lorenz number is a critical parameter for separating the electronic and lattice contributions to thermal conductivity in thermoelectric materials through the Wiedemann–Franz law. However, the classical Sommerfeld approximation often fails to accurately represent the temperature-dependent transport behavior of BiSbTe-based thermoelectric materials. This study presents a systematic analysis of the temperature dependence of the Lorenz number using experimental data compiled from eleven independent studies. A unified database was established through literature review, data extraction, normalization, and statistical analysis. Linear, exponential, and quadratic regression models were evaluated to identify the mathematical representation that best describes the reported behavior, and a Processing Complexity Index (PCI) was introduced to examine potential relationships between fabrication-route complexity and the degree of nonlinearity. The compiled datasets consistently exhibited an overall increase in the Lorenz number with temperature, although noticeable variability in magnitude and curvature was observed among studies, reflecting differences in material composition, processing routes, and experimental conditions. While the quadratic model generally achieved the best statistical performance, linear and exponential models provided comparable fits for some datasets, indicating that no single functional form is universally optimal. The proposed correlations provide a statistically representative framework for improving thermal conductivity decomposition and thermoelectric characterization within the investigated temperature range (300–500 K). Nevertheless, the correlations are constrained by the scope of the literature-derived database and should not be interpreted as universally applicable predictive models.
