Journal of Composites Science

29 pages, 9034 KB

Open AccessArticle

Optimization of Higher-Order Harmonic Surface Tessellations for Additively Manufactured Air-to-Air Heat Exchangers: A Numerical Study

by Patrick Adegbaye, Aigbe E. Awenlimobor, Justin An and Jiajun Xu

J. Compos. Sci. 2026, 10(9), 503; https://doi.org/10.3390/jcs10090503 (registering DOI) - 20 Sep 2026

Abstract

Air-to-air heat exchangers are vital for energy recovery and thermal management but often suffer from reduced effectiveness, high pressure losses, and increased pumping power in conventional designs. Advances in additive manufacturing have enabled nature-inspired geometries, such as lattice and triply periodic minimal surface [...] Read more.

Air-to-air heat exchangers are vital for energy recovery and thermal management but often suffer from reduced effectiveness, high pressure losses, and increased pumping power in conventional designs. Advances in additive manufacturing have enabled nature-inspired geometries, such as lattice and triply periodic minimal surface (TPMS) structures, which enhance heat transfer through complex first-order surfaces but are frequently associated with excessive pressure drops. This study proposes an optimized higher-order harmonic heat transfer surface tessellation developed through an optimization framework integrating analytical and numerical methods. The goal is to improve the overall thermal–hydraulic performance of the heat exchanger over a range of operating conditions. Results of the sensitivity analysis show that secondary surface modification of this type can yield a significant increase in effectiveness reaching up to 14%, although with an associated increase in the pressure drop. Additionally, we show that the optimized second-order harmonic-type structure achieved relatively higher effectiveness for comparable but slightly lower pressure drop than the gyroid structure across the flow regimes considered. While the gyroid structure outperformed the optimized harmonic-type structure in terms of the fin geometry heat transfer efficiency assessed based on the London goodness factor, j/f^1/3 by a factor of 1.9, the optimized harmonic-type structure had relatively higher energy efficiency than that of the gyroid structure across the entire spectrum of operating conditions reaching up to a factor of about 1.6 in the laminar flow regime. The findings from this study demonstrate a balanced pathway for additively manufacturable, high-performance air-to-air heat exchangers, offering compact, energy-efficient solutions for applications in building ventilation, aerospace, and electronics cooling. Full article

(This article belongs to the Special Issue Lattice Structures, 2nd Edition)

19 pages, 11307 KB

Open AccessArticle

Processing, Characterization, and Thermomechanical Performance of YSZ/SiCN Ceramic Matrix Composites Under Hydrogen Combustion

by Christopher Varela, Luis Longas, Fahim Faysal, Jayanta Bhusan Deb, Yiting Wang, Chiranjit Maiti, Kareem Ahmed and Jihua Gou

J. Compos. Sci. 2026, 10(9), 502; https://doi.org/10.3390/jcs10090502 (registering DOI) - 19 Sep 2026

Abstract

Ceramic matrix composites (CMCs) are promising thermal-protection materials for hydrogen-fueled gas turbines, where components are exposed to high temperatures, steam-rich combustion products, and pressure-driven heat transfer. This study investigates yttria-stabilized zirconia (YSZ) fiber-reinforced polymer-derived ceramic composites fabricated by polymer infiltration and pyrolysis (PIP) [...] Read more.

Ceramic matrix composites (CMCs) are promising thermal-protection materials for hydrogen-fueled gas turbines, where components are exposed to high temperatures, steam-rich combustion products, and pressure-driven heat transfer. This study investigates yttria-stabilized zirconia (YSZ) fiber-reinforced polymer-derived ceramic composites fabricated by polymer infiltration and pyrolysis (PIP) using Durazane-1800 as the preceramic precursor. Eight-layer YSZ preforms were rigidized, vacuum-infiltrated, cured, and pyrolyzed at 950 °C in nitrogen; repeated PIP cycles were used to increase matrix densification. Under hydrogen torch exposure at a heat flux of 180–190 W/cm², the front-face temperature of the CMC coupon reached approximately 1400 °C while the back-face temperature stabilized near 600 °C during a 10 min test, with no observed delamination or burn-through. Post-test SEM/EDS and XRD characterization indicated oxidation of the SiCN matrix and the deposition of a silica-rich substance on the material surface. In a hydrogen-combustion rig, the CMC liner reduced the external wall temperature relative to the unlined wall by approximately 32 °C at 1 atm and 17 °C at 5 atm. Transient thermal simulations reproduced the measured temperature trends with differences of approximately 3.8–7.8% for selected temperatures at 1 atm and 6.2% for the liner back-face temperature at 5 atm. Increasing the number of PIP cycles from two to seven increased fracture strength from 7.87 to 19.77 MPa and flexural modulus from 4.05 to 24.34 GPa. These results demonstrate the potential of YSZ-reinforced polymer-derived CMCs as thermal barriers for hydrogen-combustion environments and identify porosity control as a key requirement for improved high-pressure performance. Full article

(This article belongs to the Section Composites Applications)

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29 pages, 31090 KB

Open AccessArticle

Geopolymer-Derived Aluminosilicate Matrix Composites Reinforced with Continuous Inconel 601 Fibers: Tensile Properties and Thermo-Oxidative Behavior

by Michal Jasiczek, Marcelina Bobrowska and Arnold Jedral

J. Compos. Sci. 2026, 10(9), 501; https://doi.org/10.3390/jcs10090501 (registering DOI) - 19 Sep 2026

Abstract

Continuous-fiber composite laminates based on Inconel 601 reinforcement and a geopolymer-derived aluminosilicate matrix were fabricated using a slurry-impregnation/prepreg processing route followed by low-temperature consolidation and post-curing. The objective of this study was to evaluate the flexural and tensile properties, as well as the [...] Read more.

Continuous-fiber composite laminates based on Inconel 601 reinforcement and a geopolymer-derived aluminosilicate matrix were fabricated using a slurry-impregnation/prepreg processing route followed by low-temperature consolidation and post-curing. The objective of this study was to evaluate the flexural and tensile properties, as well as the thermo-oxidative behavior, of this composite system. The as-fabricated laminates exhibited a bulk density of 4.05 ± 0.08 g/cm³ and an apparent porosity of 24.88 ± 0.62%. Tensile testing showed measurable mechanical properties for both unidirectional and balanced laminate architectures. The [0]₈ laminates exhibited tensile strengths of approximately 327–365 MPa from room temperature to 538 °C, while the [0/90]_2S laminates showed a decrease in room-temperature tensile strength, consistent with the lower fraction of load-bearing 0° fibers. Thermo-oxidative exposure in air at 538 °C for 336 h produced no measurable reduction in room-temperature flexural strength; accordingly, accelerated oxidation tests were conducted at higher temperatures to promote observable degradation. These tests indicated a transition from limited oxidation at 538 °C to more uniform oxidation at intermediate temperatures and to more aggressive, localized fiber attack at 816 °C. These results suggest that the material system, although still in its developmental stage, is a candidate for further development toward intermediate-temperature applications (approximately 300–600 °C). Full article

(This article belongs to the Topic Advances in Fiber-Reinforced Composites)

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22 pages, 4043 KB

Open AccessArticle

Influence of Refining Parameters on Fiber Granulometry, Surface Quality, and Mechanical Properties of Embossed MDF Door Panels

by Johanna Gaitán-Álvarez, Rosilei Garcia, Véronic Landry and Alain Cloutier

J. Compos. Sci. 2026, 10(9), 500; https://doi.org/10.3390/jcs10090500 (registering DOI) - 19 Sep 2026

Abstract

Medium-density fiberboard (MDF) is widely used for embossed door panels. The fiber refining process is crucial for determining both surface quality and mechanical performance of these panels. This study investigated how different refining conditions affect fiber granulometry, surface quality, and mechanical properties of [...] Read more.

Medium-density fiberboard (MDF) is widely used for embossed door panels. The fiber refining process is crucial for determining both surface quality and mechanical performance of these panels. This study investigated how different refining conditions affect fiber granulometry, surface quality, and mechanical properties of embossed MDF door panels. Three key refining parameters were investigated: digester steam pressure (0.8 and 0.9 MPa), refiner specific energy (70 and 80 kWh/t), and refiner differential pressure (24, 35, and 50 kPa). Panel properties were evaluated in terms of vertical density profile, surface roughness, bending properties, and cleavage strength. Statistical analysis revealed that refining parameters significantly affected fiber granulometry, as well as the average and surface density of the panels. Surface roughness, however, showed minimal variation under the refining conditions considered. In contrast, the bending properties—modulus of rupture (MOR) and modulus of elasticity (MOE)—were significantly improved, with MOR and MOE increasing by up to 12% relative to the control (48.0 vs. 42.7 MPa and 4.6 vs. 4.1 GPa, respectively). Cleavage strength also varied with refining conditions but remained comparable to the control across all treatments. Overall, the results indicate that optimized refining conditions can enhance MDF door panel performance, particularly bending properties, without compromising surface quality or cleavage strength. Full article

(This article belongs to the Section Composites Manufacturing and Processing)

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14 pages, 14942 KB

Open AccessArticle

Digital Image Correlation and Static Structural Analysis of Mechanical Behavior of Unidirectional Helicteres isora Fiber-Reinforced PLA Biocomposites

by Prashantha Acharya, Dayananda Pai, Chethan K N and G. T. Mahesha

J. Compos. Sci. 2026, 10(9), 499; https://doi.org/10.3390/jcs10090499 (registering DOI) - 18 Sep 2026

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Abstract

Natural fiber-reinforced composites have attracted considerable interest because of their eco-friendly nature and impressive mechanical properties. Numerical models of composites are helpful to predict the behavior of materials before actual testing or application. In the current study, chemically modified Helicteres isora fiber-reinforced Polylactic [...] Read more.

Natural fiber-reinforced composites have attracted considerable interest because of their eco-friendly nature and impressive mechanical properties. Numerical models of composites are helpful to predict the behavior of materials before actual testing or application. In the current study, chemically modified Helicteres isora fiber-reinforced Polylactic acid composites were evaluated to determine the Poisson’s ratio using Digital Image Correlation analysis and static structural simulation of the laminated composites to predict the tensile and flexural behavior of the composites. The modeling of Laminated composites for static structural simulation was done using ANSYS ACP (PrepPost). The properties of the fiber mat and matrix material, as per the experimental study, were considered for the simulation input parameters. The layers of the laminated composite specimens in experimental work were replicated in ANSYS ACP. The static structural analysis was accomplished to find the maximum equivalent stress, maximum deflection, and stress distribution patterns in tensile and flexural models. The deviation in the results of the simulation from the experimentally obtained results was 2.70% and 1.80% in tensile and flexural stress, and 4.48% and 5.03% in tensile and flexural deformation, respectively. Full article

(This article belongs to the Special Issue Advances in Fiber-Reinforced Composite Structures: From Design to Applications)

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40 pages, 13982 KB

Open AccessReview

Energy-Efficient MOF–PCM Composites: A Review of Integrated Porous Architectures for Multifunctional Thermal and Hygrothermal Energy Storage

by M. M. Nour, Maha A. Tony and Hossam A. Nabwey

J. Compos. Sci. 2026, 10(9), 498; https://doi.org/10.3390/jcs10090498 (registering DOI) - 18 Sep 2026

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Abstract

The growing demand for sustainable and energy-efficient systems has accelerated the development of multifunctional materials capable of simultaneously storing, regulating, and conserving thermal energy. Metal–organic framework (MOF)–based phase change material (PCM) composites have emerged as promising candidates for thermal and hygrothermal energy storage [...] Read more.

The growing demand for sustainable and energy-efficient systems has accelerated the development of multifunctional materials capable of simultaneously storing, regulating, and conserving thermal energy. Metal–organic framework (MOF)–based phase change material (PCM) composites have emerged as promising candidates for thermal and hygrothermal energy storage because of their tunable porosity, surface chemistry, and structural adaptability. This review critically examines the relationships among MOF architecture, PCM confinement, interfacial interactions, heat and moisture transport, cycling stability, and application-specific performance. Particular emphasis is placed on the multidimensional trade-offs governing composite design. Increasing PCM loading can improve latent-heat capacity but reduce the pore accessibility required for moisture buffering, whereas the incorporation of conductive fillers can enhance heat transfer at the expense of gravimetric energy-storage density. Likewise, highly hydrophilic frameworks favor moisture regulation but may exhibit lower hydrothermal stability, while mechanically robust and scalable formulations may require compromises in porosity, PCM loading, or interfacial performance. Comparative assessment across building, solar-thermal, electronic, textile, and environmental applications further shows that no single MOF–PCM configuration can simultaneously maximize latent-heat storage, thermal conductivity, humidity control, mechanical integrity, durability, and manufacturability. Accordingly, rational MOF–PCM development should follow a multi-objective, application-specific design strategy that balances structure, interface, performance, stability, and scalability rather than optimizing a single property. These insights provide practical guidance for the development of next-generation multifunctional thermal and hygrothermal energy-storage materials. Full article

(This article belongs to the Section Composites Applications)

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27 pages, 3716 KB

Open AccessReview

Copper Separation and Recovery from Solutions: Conventional and Membrane-Based Methods

by Kaster Kamunur, Zarina Shnali, Aibek Makan, Lyazzat Mussapyrova, Sandugash Tanyrbergenova, Nurzhamal Zhylybayeva, Dana Assylkhanova and Meiram Atamanov

J. Compos. Sci. 2026, 10(9), 497; https://doi.org/10.3390/jcs10090497 (registering DOI) - 18 Sep 2026

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Abstract

Cu is central to electrification and low-carbon technologies, while declining ore grades and environmental pressures increase interest in recovery from secondary liquid resources. This review critically evaluates copper separation from mine-affected waters, copper-smelting waste acids, electroplating wastewaters, and secondary-material leachates. Cu is the [...] Read more.

Cu is central to electrification and low-carbon technologies, while declining ore grades and environmental pressures increase interest in recovery from secondary liquid resources. This review critically evaluates copper separation from mine-affected waters, copper-smelting waste acids, electroplating wastewaters, and secondary-material leachates. Cu is the principal target; co-occurring metals are treated as competitors or sequential recovery targets. Feed origin, Cu concentration and speciation, pH/free acidity, ionic strength, ligands, and polymetallic composition are related to process performance and product form. Conventional precipitation, solvent extraction, ion exchange, and electrowinning are compared with microfiltration, ultrafiltration, nanofiltration, reverse osmosis, electrodialysis, supported liquid membranes, emulsion liquid membranes, and polymer inclusion membranes. High Cu removal or rejection does not by itself demonstrate Cu-selective recovery. MF and UF require conversion of dissolved Cu into retainable species; NF and RO mainly recover water and preconcentrate metals; ED becomes more selective with speciation control; and carrier-mediated membranes can fractionate metals but face stability constraints. Most membrane processes generate a Cu-rich retentate, concentrate, or stripping solution rather than metallic Cu and therefore require downstream crystallisation or electrowinning. Key gaps are long-term operation with variable industrial feeds, fouling and scaling control, mass balances and product-purity reporting, membrane/carrier durability, and consistent techno-economic validation. Full article

(This article belongs to the Section Composites Applications)

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18 pages, 1907 KB

Open AccessArticle

A Luminescent Tb-MOF/Pistachio Shell Bio-Composite for Rapid Adsorption and Fluorescence Detection of Methyl Parathion in Water

by Helen Paola Toledo Jaldín, Oscar Roberto Montes-Moreno, Alien Blanco Flores, Delia Monserrat Ávila-Márquez, Josué Valdés-García, Alejandro Dorazco-González and Martha Stephanie Pérez Mendoza

J. Compos. Sci. 2026, 10(9), 496; https://doi.org/10.3390/jcs10090496 (registering DOI) - 18 Sep 2026

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Abstract

Methyl parathion (MP) is an organic pesticide used on crops to control pest populations. However, its indiscriminate use contaminates soil and water, necessitating the development of cost-effective solutions for its removal and detection. In this work, a novel luminescent composite (Pi@Tb-MOF) [...] Read more.

Methyl parathion (MP) is an organic pesticide used on crops to control pest populations. However, its indiscriminate use contaminates soil and water, necessitating the development of cost-effective solutions for its removal and detection. In this work, a novel luminescent composite (Pi@Tb-MOF) was successfully synthesized via the in situ growth of a terbium-based metal–organic framework on pistachio shell biomass. The successful formation of the Pi@Tb-MOF composite was confirmed by XRD, SEM-EDS, FTIR, and TGA analyses. The composite was evaluated for the removal and detection of MP in aqueous media. Kinetic data were best described by the second-order and Avrami models, which indicate heterogeneous surface reactions and progressive activation of adsorption sites. Isotherm analysis revealed that the Hill model provided the best fit (K_H = 0.6644), suggesting cooperative adsorption and strong adsorbate–adsorbate interactions on the composite surface. Although the maximum adsorption capacity predicted by the Langmuir model was 1.47 mg/g, the material exhibited a remarkable luminescence response to MP. The Tb-MOF characteristic emission bands decreased progressively upon pesticide adsorption, enabling fluorescence-based detection with a limit of detection of 0.1 µM. The quenching process followed a linear Stern–Volmer relationship at low concentrations (R² = 0.99), demonstrating the composite’s potential as a sensing platform. The fluorescence quenching is attributed to electron transfer interactions between the MOF ligand and the nitroaromatic group of MP combined with adsorption on the pistachio matrix. These results demonstrate that Pi@Tb-MOF is a sustainable composite capable of simultaneously removing and detecting methyl parathion, highlighting its potential as an environmentally friendly material for monitoring pesticide contamination in water. This work reports, for the first time, a novel Pi@Tb-MOF composite based on pistachio shell biomass and a luminescent Tb-MOF, which has not been previously described in the literature and enables the simultaneous adsorption and optical sensing of methyl parathion. Full article

(This article belongs to the Special Issue From Waste to Advance Composite Materials, 2nd Edition)

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23 pages, 43127 KB

Open AccessArticle

Processing–Structure Relationships in Epoxy Nanocomposites Filled with GNP, GO, and MoS₂: Contact-Sensitive Impedance and Raman Mapping

by Stefano Bellucci

J. Compos. Sci. 2026, 10(9), 495; https://doi.org/10.3390/jcs10090495 - 17 Sep 2026

Viewed by 144

Abstract

This study examines how filler-specific processing and the resulting spatial organization govern the structural response and measured electrical behaviour of epoxy nanocomposites containing graphene nanoplatelets (GNP), graphene oxide (GO), or molybdenum disulfide (MoS₂). Bulk specimens and spin-coated films containing 0.25–5 wt% [...] Read more.

This study examines how filler-specific processing and the resulting spatial organization govern the structural response and measured electrical behaviour of epoxy nanocomposites containing graphene nanoplatelets (GNP), graphene oxide (GO), or molybdenum disulfide (MoS₂). Bulk specimens and spin-coated films containing 0.25–5 wt% nominal filler were prepared with 22 wt% and 8 wt% A1 amine hardener, respectively. GNP and MoS₂ formulations required pulsed sonication followed by planetary mixing, whereas GO was processed by planetary mixing alone; temporary isopropanol was additionally required for the nominal 5 wt% GNP formulation. Film thickness, low-frequency impedance, diamond-ATR FTIR spectra, Raman spectra, and planar and cross-sectional Raman maps were evaluated. Films from the higher nominal GNP-loading formulation showed the clearest increase in mean thickness, consistent with concentration-dependent rheology and platelet interactions during spin coating. The impedance response was strongly contact-sensitive. Under identical embedded-contact conditions, the specimen prepared from the nominal 5 wt% GNP formulation exhibited substantially lower impedance than neat epoxy across the common frequency range, with a median |Z_GNP|/|Z_epoxy| ratio of approximately 0.16. The persistence of this difference across the common frequency interval provides a clear same-fixture electrical distinction between the two tested specimens. Because one specimen was examined per condition, this result is reported at the specimen level and is not used to assign bulk conductivity, a unique conduction mechanism, or a numerical percolation threshold. ATR-FTIR showed preservation of the epoxy fingerprint together with the oxygen-rich GO contribution, while Raman spectroscopy retained the characteristic carbon and MoS₂ signatures. Raman mapping showed isolated filler-rich domains at nominal 0.25 wt% and broader, more spatially continuous domains at nominal 5 wt% for the matched GNP and GO datasets, while cross-sectional mapping confirmed subsurface filler signatures for all three systems. Together, the results establish a processing–structure–measurement framework for these three 2D-filler/epoxy systems and identify the experimental controls needed for reliable interpretation of functional response. Full article

(This article belongs to the Section Nanocomposites)

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29 pages, 3122 KB

Open AccessArticle

Architecture-Dependent Reinforcement of FFF-Printed PLA Nanocomposites by Functionalized Multi-Walled Carbon Nanotubes

by Dorivane Cohen Farias, Diogo Monteiro Porfírio, Miriane Alexandrino Pinheiro, Mário Edson Santos de Sousa, Alessandro José Gomes dos Santos, Douglas Santos Silva, Raí Felipe Pereira Junio, Sergio Neves Monteiro and Marcos Allan Leite dos Reis

J. Compos. Sci. 2026, 10(9), 494; https://doi.org/10.3390/jcs10090494 - 17 Sep 2026

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Abstract

This study investigates the combined influence of multi-walled carbon nanotube (MWCNT) concentration and structural architecture on the compressive behavior of fused filament fabrication (FFF)-printed PLA components. Neat PLA and PLA reinforced with 1.0 and 2.0 wt% carboxyl-functionalized MWCNTs were characterized by Raman spectroscopy, [...] Read more.

This study investigates the combined influence of multi-walled carbon nanotube (MWCNT) concentration and structural architecture on the compressive behavior of fused filament fabrication (FFF)-printed PLA components. Neat PLA and PLA reinforced with 1.0 and 2.0 wt% carboxyl-functionalized MWCNTs were characterized by Raman spectroscopy, DSC, TGA, compression testing, statistical analysis, and scanning electron microscopy. Thermal characterization showed that MWCNT incorporation caused only minor changes in PLA thermal degradation while altering its crystallization behavior. For nearly solid specimens (90% infill), compressive strength increased from 53.4 MPa for neat PLA to 73.6 MPa at 2.0 wt% MWCNTs, although differences among MWCNT concentrations were not statistically significant. Honeycomb structures exhibited the highest mechanical performance at 1.0 wt% MWCNTs, reaching a compressive strength of 33.3 MPa, approximately 59% higher than that of neat PLA, with significant improvements in both compressive strength and elastic modulus. Two-way ANOVA revealed significant interactions between structural architecture and MWCNT concentration for both compressive strength and elastic modulus, demonstrating an architecture-dependent reinforcement response. SEM provided complementary morphological evidence consistent with the observed mechanical trends. These findings demonstrate that the most effective MWCNT concentration depends on structural architecture, highlighting the importance of simultaneously optimizing material composition and geometry in FFF-manufactured polymer nanocomposites. Full article

(This article belongs to the Special Issue Manufacturing and Machining of Composites)

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16 pages, 1862 KB

Open AccessArticle

Modification of Bitumen with Graphene Oxide-like Material from Lemon Peel Biochar via a Modified Hummers Method

by Aliya Kenzhegaliyeva and Yerdos Ongarbayev

J. Compos. Sci. 2026, 10(9), 493; https://doi.org/10.3390/jcs10090493 - 16 Sep 2026

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Abstract

This study examined the effect of a graphene oxide-like (GO-like) carbon material obtained from lemon peel biochar on road bitumen. Pyrolysis of the raw material was conducted at 500, 550 and 600 °C. The graphene oxide-like carbon material was synthesized using a modified [...] Read more.

This study examined the effect of a graphene oxide-like (GO-like) carbon material obtained from lemon peel biochar on road bitumen. Pyrolysis of the raw material was conducted at 500, 550 and 600 °C. The graphene oxide-like carbon material was synthesized using a modified Hummers method. Among the investigated pyrolysis temperatures, 550 °C produced the most favorable structural characteristics, including a higher contribution of oxygen-containing groups and a more uniform structure. Adding a selected dosage of 3 wt.% graphene oxide-like carbon material increased shear stress by 20–25 kPa, ultimate strain from 13 to 17%, and fatigue life by 36–109%. The results confirm the potential of using lemon peel biochar to produce a road bitumen modifier. Full article

(This article belongs to the Section Composites Applications)

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24 pages, 4654 KB

Open AccessArticle

Parametric Seismic Analysis of FRP-Strengthening Length at Beam and Column Ends of Existing RC Frames

by Pengfei Ma, Shuming Jia and Shangke Yuan

J. Compos. Sci. 2026, 10(9), 492; https://doi.org/10.3390/jcs10090492 - 16 Sep 2026

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Abstract

In view of the seismic performance deficiencies commonly observed in existing reinforced concrete (RC) frame structures, the application of fiber-reinforced polymer (FRP) composites for seismic strengthening has become a key technical approach to enhance the safety reserve of such structures. However, most existing [...] Read more.

In view of the seismic performance deficiencies commonly observed in existing reinforced concrete (RC) frame structures, the application of fiber-reinforced polymer (FRP) composites for seismic strengthening has become a key technical approach to enhance the safety reserve of such structures. However, most existing studies primarily focus on the overall effectiveness of strengthening schemes, while systematic investigations on key geometric parameters, such as strengthening location and length, remain insufficient. In this paper, based on the ABAQUS finite element software and calibrated against a quasi-static test of a 1/2-scale two-story two-bay RC plane frame, refined numerical models of both unstrengthened and FRP-strengthened frames were established. Adopting a “control-variable parametric analysis” strategy and using cross-sectional dimensions as the reference, nine strengthening cases were designed with column-end FRP lengths of 0.5b, 1.5b, and 2.5b and beam-end FRP lengths of 1h, 2h, and 3h. The differential effects of FRP-strengthening lengths at beam and column ends on the seismic performance of the frame structure were revealed. The results indicate that FRP strengthening can effectively enhance the load-bearing capacity and improve the hysteretic performance of members. Nevertheless, the underlying mechanisms by which beam-end and column-end strengthening lengths affect mechanical behavior are fundamentally different: column-end FRP strengthening primarily governs the initial stiffness and load-bearing capacity, with a maximum increase in peak load of 40.7%; beam-end FRP strengthening mainly controls the post-yield stiffness degradation rate and energy dissipation capacity, achieving a peak load increase of up to 53.2%, although the marginal benefit tends to diminish with increasing length. Beam-end strengthening is the critical factor governing the transition of failure mode (from brittle joint shear failure to ductile beam-end flexural failure), while column-end strengthening plays a supplementary role in restraining the formation of column hinges and maintaining the desirable “strong column-weak beam” failure hierarchy. This study reveals the influence of FRP strengthening length on the seismic performance of structures, and to some extent addresses the deficiency of existing studies in systematic parametric analysis. Full article

(This article belongs to the Special Issue Concrete Composites in Hybrid Structures)

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28 pages, 4994 KB

Open AccessArticle

Mechanical and Structural Characterization of MWCNT-Reinforced NR/BR Rubber Composites for Mud Pump Pistons and Sealing Applications

by Suadad Noori Ghani, Haithem Abdulla Moftin, Raghad Azeez Neamah and Abbas Ali Diwan

J. Compos. Sci. 2026, 10(9), 491; https://doi.org/10.3390/jcs10090491 (registering DOI) - 15 Sep 2026

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Abstract

This study was conducted to discover nanocomposite materials with high stiffness and toughness to meet industrial requirements, particularly for applications that demand high durability and abrasion resistance, such as mud pump pistons and sealing components. A nanocomposite constructed of natural rubber/polybutadiene rubber at [...] Read more.

This study was conducted to discover nanocomposite materials with high stiffness and toughness to meet industrial requirements, particularly for applications that demand high durability and abrasion resistance, such as mud pump pistons and sealing components. A nanocomposite constructed of natural rubber/polybutadiene rubber at a 90/10 ratio was combined with 48 phr black carbon and multi-walled carbon nanotubes (MWCNTs) at different proportions: 0, 0.96,1.28 and 1.6 phr, reduced from 48 phr. The maximum tensile strength was observed for rubber with a nanocarbon content of 1.28 phr, representing an increase of 111% compared to that of neat rubber. The elongation at break was 3.2 in rubber with 1.28 phr of MWCNT, an increase of 53.5% compared to that of neat rubber. The minimum weight loss was 0.07 g in the abrasion resistance test in rubber with 1.28 phr of MWCNT. This represents a decrease in weight loss of 22.22% compared to the results for neat rubber. Full article

(This article belongs to the Section Composites Modelling and Characterization)

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14 pages, 2506 KB

Open AccessArticle

Atmospheric-Pressure Plasma-Induced Surface Modification of Recycled Carbon Fibers for Improved Interfacial Properties in Epoxy Composites

by Seong-Hyun Kang, Se-Hun Kim, Kwan-Woo Kim and Byung-Joo Kim

J. Compos. Sci. 2026, 10(9), 490; https://doi.org/10.3390/jcs10090490 - 15 Sep 2026

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Abstract

The recycling of carbon fiber-reinforced polymer (CFRP) is essential for reducing environmental pollution and improving resource efficiency. However, carbon fibers recovered during the recycling process are typically obtained in the form of short fibers, and the removal of sizing leaves the fiber surface [...] Read more.

The recycling of carbon fiber-reinforced polymer (CFRP) is essential for reducing environmental pollution and improving resource efficiency. However, carbon fibers recovered during the recycling process are typically obtained in the form of short fibers, and the removal of sizing leaves the fiber surface unsized, resulting in deteriorated interfacial properties. In this study, an atmospheric-pressure plasma (APP) treatment applicable to continuous processing was employed to modify the surface characteristics of recycled carbon fiber (rCF) and promote more favorable interactions with an epoxy matrix. The surface characteristics of plasma-treated rCF were analyzed using temperature-programmed desorption, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and single-fiber contact angle measurements. Furthermore, the mechanical performance of recycled carbon fiber-reinforced epoxy composites, hereafter denoted as rCFRP, fabricated with the treated fibers was evaluated through tensile and flexural testing. APP treatment increased the content of oxygen-containing groups on the rCF surface, with the O1s/C1s ratio increasing from 0.15 to 0.39 and the polar component of the surface free energy increasing from 14% to 32% which may have contributed to more favorable interactions with the epoxy matrix. The tensile and flexural strengths of the rCFRP composites increased by up to 59% and 58%, respectively, compared with those of the untreated rCFRP composites. This study demonstrates that APP treatment is an effective approach for surface modification of rCF and suggests its potential applicability to the continuous manufacturing of rCFRP composites. Full article

(This article belongs to the Section Carbon Composites)

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25 pages, 13221 KB

Open AccessArticle

Pseudomorphic Transformation of a Magnesium Citrate Precursor to Shape-Memory MgO Nanorods: A Facet-Specific Interaction with Graphene Oxide

by Wafa Shamsan Al-Arjan, Lamia A. Ismail, W. Christopher Boyd and Islam Gomaa

J. Compos. Sci. 2026, 10(9), 489; https://doi.org/10.3390/jcs10090489 - 14 Sep 2026

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Abstract

The precise control of one-dimensional (1D) nanoscale architecture and facet-specific interfaces in alkaline earth metal oxides remains a critical challenge for developing advanced, multifunctional nanocomposites. Herein, we report the template- and surfactant-free mechanochemical synthesis of polyhedral magnesium oxide (MgO) nanorods via the pseudomorphic [...] Read more.

The precise control of one-dimensional (1D) nanoscale architecture and facet-specific interfaces in alkaline earth metal oxides remains a critical challenge for developing advanced, multifunctional nanocomposites. Herein, we report the template- and surfactant-free mechanochemical synthesis of polyhedral magnesium oxide (MgO) nanorods via the pseudomorphic transformation of a magnesium citrate precursor (Mg-P), followed by systematic integration with graphene oxide (GO). Controlled thermal decomposition of the multiphase 1D coordination precursor yields phase-pure, shape-memory periclase nanorods that retain the precursor’s anisotropic <100> growth axis without undergoing structural collapse. Comprehensive structural and thermogravimetric analyses of the resulting MgO-GO nanocomposites (10, 30, and 50 wt.% GO) suggest a non-covalent, facet-specific interaction mechanism. GO nanosheets are shown to preferentially adhere to the {100} prismatic facets of the MgO nanorods, inducing anisotropic compressive strain, impeding lateral crystallite coarsening, and elevating the autocatalytic deoxygenation temperature of GO by over 145 °C. Furthermore, electrokinetic, and hydrodynamic assessments demonstrate an anomalous, composition-dependent colloidal evolution. While initial GO loadings mask the basic MgO surface to trigger massive hydrodynamic expansion, reaching an equimass 50 wt.% loading forces a profound electrokinetic inversion (+33.5 mV) and volumetric compaction, as the highly basic MgO interfaces re-establish dominance over the hydrodynamic shear plane. The data support a pseudomorphic route under the current conditions for the shape-directed synthesis of 1D metal oxides from coordination precursors and unravel the primitive interfacial dynamics governing the structural and colloidal stability of metal oxide–graphene hybrids. Full article

(This article belongs to the Section Nanocomposites)

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33 pages, 15633 KB

Open AccessArticle

Numerical Simulation of Heat-and-Aerodynamic Cycles in a Multilayer Composite Wall Ventilated Façade System Using ANSYS Software Under Hot Climate Conditions

by Nurlan Zhangabay, Akmaral Utelbayeva, Bolat Duissenbekov, Svetlana Buganova and Timur Tursunkululy

J. Compos. Sci. 2026, 10(9), 488; https://doi.org/10.3390/jcs10090488 - 10 Sep 2026

Viewed by 329

Abstract

This article investigates the numerical simulation of heat-and-aerodynamic cycles in the ventilated air gap of a multilayer composite wall façade system in a hot climate using ANSYS 19/2 Fluent. Standard normative techniques rely on averaged, stationary boundary conditions and account for neither the [...] Read more.

This article investigates the numerical simulation of heat-and-aerodynamic cycles in the ventilated air gap of a multilayer composite wall façade system in a hot climate using ANSYS 19/2 Fluent. Standard normative techniques rely on averaged, stationary boundary conditions and account for neither the height-wise inequality of solar exposure nor the dependence of air density and viscosity on barometric pressure and temperature, resulting in significant errors in predicting the actual heating of such structures. The model was calibrated on the authors’ own full-scale, in situ measurements of temperature, air speed and solar exposure in the ventilated gap of a nine-storey building, from which linear height-dependent surface-temperature relations were derived and used as boundary conditions for 3D models of façades 25 and 60 m tall. Thirty-two finite-volume experiments were performed under free convection (Boussinesq approximation), varying gap width (5 and 10 cm), inlet width (20 and 40 cm), barometric pressure (690 and 770 mmHg) and external air temperature (20 and 40 °C). Façade height proved the dominant factor (air speed up to 1.8 times higher, temperature 3–12.1 °C higher), followed by gap width (speed lower by 1.7 times, temperature by 3–5 °C), whereas pressure and inlet width altered the results by no more than 6%. Discrepancies with the standard calculation reached 10 °C in temperature and a two-fold difference in flow speed, confirming the need for verified CFD simulation when designing ventilated composite wall façades in hot climates. Full article

(This article belongs to the Section Composites Modelling and Characterization)

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24 pages, 4053 KB

Open AccessArticle

High-Temperature Rheological Evolution of Recovered Asphalt Composite Binders Under Laboratory Long-Term Aging Protocols

by Ahmed Hemida, Louay N. Mohammad and Samuel B. Cooper III

J. Compos. Sci. 2026, 10(9), 487; https://doi.org/10.3390/jcs10090487 - 10 Sep 2026

Viewed by 385

Abstract

Asphalt mixtures are heterogeneous composite materials primarily composed of mineral aggregates and asphalt binder; depending on the mixture design, they may also incorporate reclaimed asphalt pavement (RAP) and polymer-modified binders. Their long-term performance is governed by the rheological evolution of the asphalt binder [...] Read more.

Asphalt mixtures are heterogeneous composite materials primarily composed of mineral aggregates and asphalt binder; depending on the mixture design, they may also incorporate reclaimed asphalt pavement (RAP) and polymer-modified binders. Their long-term performance is governed by the rheological evolution of the asphalt binder and its interactions with surrounding composite constituents during aging. Existing laboratory long-term aging (LTA) protocols have been developed primarily to evaluate mixture cracking resistance; however, their ability to reproduce the high-temperature rheological evolution of recovered asphalt binders remains insufficiently understood. This study evaluated the fidelity of accelerated LTA protocols by comparing the high-temperature rheological response of binders recovered from plant-produced asphalt mixtures with the conventional benchmark of 85 °C for 5 days. Five mixtures, including one containing an unmodified PG 67-22 binder with RAP and four containing SBS-modified PG 76-22 binders with varying RAP contents, were characterized using continuous high-temperature performance grade (PG-HT), dynamic shear rheometer rutting parameter (|G*|/sinδ), zero-shear viscosity, multiple stress creep recovery, and interrupted shear flow. Among the investigated protocols, loose-mixture aging at 135 °C for 6 h showed the closest agreement with the benchmark rheological response, whereas 135 °C for 8 h and 120 °C for 20 h produced greater rheological stiffening relative to the benchmark. The unmodified PG 67-22 binder exhibited the greatest aging sensitivity, while SBS-modified binders showed closer agreement overall. Full article

(This article belongs to the Section Composites Applications)

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25 pages, 8796 KB

Open AccessArticle

Numerical Investigation of the Earthquake Response of Rearing Jib Tower Crane Made of Composite Materials with the Adoption of Joint Dampers

by Ivan Tomasi, Luigi Solazzi and Xiangwei Liu

J. Compos. Sci. 2026, 10(9), 486; https://doi.org/10.3390/jcs10090486 - 9 Sep 2026

Viewed by 242

Abstract

Tower cranes are highly vulnerable to seismic excitation owing to their slender geometry and pronounced dynamic behaviour. Although carbon fibre reinforced polymer (CFRP) materials offer significant lightweight potential, and damping devices are widely adopted for seismic protection, their combined application to tower cranes [...] Read more.

Tower cranes are highly vulnerable to seismic excitation owing to their slender geometry and pronounced dynamic behaviour. Although carbon fibre reinforced polymer (CFRP) materials offer significant lightweight potential, and damping devices are widely adopted for seismic protection, their combined application to tower cranes has received limited attention. This study numerically investigates the seismic response of a rearing jib tower crane equipped with a CFRP jib and base joint dampers. A finite element model was developed and analysed under four critical operating configurations through static structural, modal and response spectrum analyses in accordance with the Italian Building Code (NTC 2018). The performance of the CFRP solution was compared with that of a conventional steel crane, while two damper configurations with different stiffness values were also assessed. The proposed lightweight design reduced the total crane mass by 34% and the jib weight by 77%. Compared with the steel configuration, the CFRP solution decreased static displacements by 38–56% and equivalent stresses by 22–44%. Under seismic loading, the adoption of joint dampers reduced the maximum equivalent stress by up to 35%, while increasing structural displacements by 5–19% because of the lower support stiffness. The results demonstrate that combining CFRP lightweight design with seismic damping devices effectively improves the earthquake performance of tower cranes while maintaining structural safety. Full article

(This article belongs to the Section Composites Modelling and Characterization)

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22 pages, 15490 KB

Open AccessArticle

Valorization of Sugarcane Bagasse Ash and Jackfruit Leaf Ash in Sustainable Geopolymer Binders: Performance and Microstructural Characteristics

by Saathvika Sivanandam and Parthiban Kathirvel

J. Compos. Sci. 2026, 10(9), 485; https://doi.org/10.3390/jcs10090485 - 9 Sep 2026

Viewed by 282

Abstract

The mounting requirement for sustainable construction materials has augmented the development of geopolymer binders incorporating agricultural wastes. Unlike the previous studies on individual agricultural ashes, this study investigates the viability of combined use of sugarcane bagasse ash (SCBA) and jackfruit leaf ash (JLA) [...] Read more.

The mounting requirement for sustainable construction materials has augmented the development of geopolymer binders incorporating agricultural wastes. Unlike the previous studies on individual agricultural ashes, this study investigates the viability of combined use of sugarcane bagasse ash (SCBA) and jackfruit leaf ash (JLA) in fly ash-ground granulated blast furnace slag (GGBFS)-based geopolymer binders under ambient curing conditions. Five mixtures with varying proportions of SCBA and JLA were evaluated for their fresh (flow, setting time, fresh density and rise in temperature), hardened (compressive strength and flexural strength) and microstructural characteristics (FESEM-EDS, XRD, FTIR and TG/DTG analyses). The incorporation of 10% SCBA and 10% JLA of the total binder (M3 mixture) was found to produce best performing performance, resulting in a maximum 28-day compressive strength of 64.83 MPa and flexural strength of 7.25 MPa, corresponding to increments of 36.5% and 73.0%, respectively, over the control mix. The formation of a dense reaction matrix along with enhanced geopolymerization and thermal characteristics were also observed for the best performing mixture through microstructural studies. The outcome of this investigation reveals that the utilization of agricultural ashes (SCBA and JLA) can be an efficient supplementary aluminosilicate precursor to develop high-performance geopolymer binders. Full article

(This article belongs to the Section Composites Applications)

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42 pages, 1532 KB

Open AccessReview

Weathering-Induced Aging of Polyethylene-Based Lignocellulosic Composites in the Context of the Circular Economy

by Lumirca Del Valle Espinoza León, Leila Lea Yuan Visconte, Ana Lúcia Nazareth da Silva, Ana Maria Furtado de Sousa and Elen Beatriz Acordi Vasques Pacheco

J. Compos. Sci. 2026, 10(9), 484; https://doi.org/10.3390/jcs10090484 - 8 Sep 2026

Viewed by 446

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Research on Recycling Methods or Reuse of Composite Materials)

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24 pages, 48703 KB

Open AccessArticle

Eco-Efficient Mortars Incorporating Phase Change Material-Impregnated Recycled Clay Brick Aggregates for Thermal Energy Storage

by Nelson Andrés Guerrero Jimenez, York Antony Calvache Tabarez, Manuel Alejandro Rojas Manzano and Mónica Villaquiran Caicedo

J. Compos. Sci. 2026, 10(9), 483; https://doi.org/10.3390/jcs10090483 - 8 Sep 2026

Viewed by 378

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue High-Performance Cementitious Composites: Materials Development, Smart Technologies, and Engineering Applications)

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38 pages, 12402 KB

Open AccessArticle

Green Cement Innovations: Use of Pillared Clays to Increase the Environmental Friendliness and Durability of Cement Materials

by Ekaterina Smolskaya, Ekaterina Potapova, Ivan Korchunov, Tatiana Guseva and Viktor Guryanov

J. Compos. Sci. 2026, 10(9), 482; https://doi.org/10.3390/jcs10090482 - 7 Sep 2026

Viewed by 298

Abstract

Cement production is associated with substantial carbon dioxide (CO₂) emissions due to the high material and energy intensity of Portland clinker manufacture. Partial clinker replacement with supplementary cementitious materials is one of the most promising strategies for reducing the carbon footprint [...] Read more.

Cement production is associated with substantial carbon dioxide (CO₂) emissions due to the high material and energy intensity of Portland clinker manufacture. Partial clinker replacement with supplementary cementitious materials is one of the most promising strategies for reducing the carbon footprint of cement; however, the thermal activation of aluminosilicate raw materials does not always yield highly reactive products. In this study, a pillaring approach is proposed as a controlled method for modifying the structure of clays and unlocking their latent reactivity. Different clay types—namely, kaolinitic, montmorillonitic, and illite–chlorite clays—were sequentially treated with an aluminum sulfate solution and calcined at 650 °C. Their phase composition and microstructure were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), while specific surface area was determined by BET analysis and pozzolanic activity. The results showed that pillaring doubled the specific surface area of montmorillonitic (2:1) and illite–chlorite (2:1:1) clays. Replacing 30% of clinker with pillared clays and limestone increased the compressive strength to 86.5 MPa and the flexural strength to 34.6 MPa. The developed low-carbon composite cements also exhibited high durability: the density of the hardened cement mortar increased to 2.410 g/cm³, the strength loss after 200 freeze–thaw cycles decreased to ≤5.5%, and the sulfate resistance coefficient (Ks) increased to 0.98 (with minimal expansion of the samples <0.02%). The proposed approach makes it possible to reduce the carbon footprint of cement by 25–30% while enabling the use of locally available raw materials for the production of competitive low-carbon green cements. Reported reductions of this order are broadly consistent with the known effect of lowering clinker content through supplementary cementitious materials in blended cement systems. Full article

(This article belongs to the Special Issue Sustainable Cementitious Composites)

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14 pages, 12275 KB

Open AccessArticle

Experimental Characterization of Cure-State-Dependent Tool–Prepreg Friction in a Carbon Fiber/Bismaleimide System

by Zhiwei Nie, Chun Li, Zinan Liu, Xing Lu, Yuhan Ma, Helezi Zhou and Huamin Zhou

J. Compos. Sci. 2026, 10(9), 481; https://doi.org/10.3390/jcs10090481 - 7 Sep 2026

Viewed by 421

Abstract

Tool–prepreg friction contributes to process-induced residual stress and distortion in thermoset composite manufacturing, but its variation with the resin cure state remains insufficiently characterized. This study experimentally characterizes the friction response of untreated and post-gel pretreated T800/bismaleimide prepregs using a pull-out apparatus. The [...] Read more.

Tool–prepreg friction contributes to process-induced residual stress and distortion in thermoset composite manufacturing, but its variation with the resin cure state remains insufficiently characterized. This study experimentally characterizes the friction response of untreated and post-gel pretreated T800/bismaleimide prepregs using a pull-out apparatus. The effects of slip velocity, temperature, and normal pressure are evaluated, and the measured trends are interpreted using Coulomb-type contact, viscous film shearing, and mixed-lubrication concepts. The friction coefficient of the untreated prepreg increases with the slip velocity and decreases with temperature and pressure, indicating a substantial contribution from viscous resin-film shearing. In contrast, the post-gel pretreated prepreg is nearly insensitive to the slip velocity and pressure, while its friction coefficient increases with temperature, consistent with a predominantly solid-like interfacial response. During a cure cycle, the friction increases slowly at low cure levels and more rapidly during the later stages of curing. The results provide experimental friction data for a high-temperature bismaleimide prepreg system and suggest that the gelation state may serve as a useful reference for distinguishing early- and later-stage interfacial behavior. Full article

(This article belongs to the Section Composites Manufacturing and Processing)

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19 pages, 10298 KB

Open AccessArticle

Fabrication of SiC/Al-Mg Composites via Binder Jetting 3D Printing and Infiltration: Effects of Mg Content and Infiltration Temperature

by Fahim Khan, Evgenia Dimitriou, Miloš Dujović, Md Shakil Arman, Miladin Radovic, Zhijian Pei and Stephen Kachur

J. Compos. Sci. 2026, 10(9), 480; https://doi.org/10.3390/jcs10090480 - 7 Sep 2026

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Abstract

This study systematically investigates the effects of infiltration temperature (800 and 1000 °C) and magnesium (Mg) content (0, 5, and 10 wt.%) on the density, morphology, and chemical composition of silicon carbide/aluminum-magnesium (SiC/Al–Mg) composites. Poor wettability between molten Al and SiC can restrict [...] Read more.

This study systematically investigates the effects of infiltration temperature (800 and 1000 °C) and magnesium (Mg) content (0, 5, and 10 wt.%) on the density, morphology, and chemical composition of silicon carbide/aluminum-magnesium (SiC/Al–Mg) composites. Poor wettability between molten Al and SiC can restrict the infiltration of porous SiC preforms. Although Mg is commonly used to improve wettability, the combined effects of Mg content and infiltration temperature have not been investigated for composites produced from binder-jetted SiC preforms. Porous SiC preforms were first fabricated by binder jetting of SiC powder and then air-assisted oxidation bonded at 1200 °C for 2 h. The oxidation-bonded preforms were subsequently spontaneously melt infiltrated under an inert atmosphere using either pure Al powder or Al–Mg powder mixtures containing 5 or 10 wt.% Mg. The results showed that composite density increased consistently with increasing Mg content. At 800 °C, the density increased from 1.73 to 2.63 g/cm³ as Mg content increased from 0 to 10 wt.%. Similarly, at 1000 °C, the density increased from 1.80 to 2.73 g/cm³. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to evaluate phase formation and microstructural features. The results confirmed effective infiltration in Mg-containing samples, while samples without Mg showed limited infiltration at both temperatures. A two-way ANOVA showed that Mg content was the primary factor controlling post-infiltration density, while infiltration temperature had a smaller but statistically significant effect. These findings provide practical guidance for selecting Mg content and infiltration temperature during the fabrication of binder-jetted SiC/Al–Mg composites. Overall, this study highlights the importance of Mg-assisted infiltration for fabricating binder-jetted SiC/Al–Mg composites and provides processing insights relevant to their potential use in aerospace, automotive, and defense applications, subject to further evaluation of their mechanical and functional properties. Full article

(This article belongs to the Section Composites Manufacturing and Processing)

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21 pages, 23113 KB

Open AccessArticle

The Role of Cement–Water Interaction on Chloride Ingress in Sustainable Cement-Based Systems

by Ahmed A. Ahmed, Mahmoud Shakouri and Naga Pavan Vaddey

J. Compos. Sci. 2026, 10(9), 479; https://doi.org/10.3390/jcs10090479 - 5 Sep 2026

Viewed by 560

Abstract

The durability of concrete structures exposed to chlorides is critically governed by chloride ingress, which induces reinforcement corrosion. While ordinary Portland cement (OPC) has been extensively studied, alternative binders such as calcium aluminate cement (CAC) and calcium sulfoaluminate (CSA) cement offer distinct microstructures [...] Read more.

The durability of concrete structures exposed to chlorides is critically governed by chloride ingress, which induces reinforcement corrosion. While ordinary Portland cement (OPC) has been extensively studied, alternative binders such as calcium aluminate cement (CAC) and calcium sulfoaluminate (CSA) cement offer distinct microstructures that may enhance chloride resistance. Understanding how cement type and the water-to-cementitious material ratio (w/cm) influence the apparent chloride diffusion coefficient (D_a) is paramount for designing durable infrastructure. This study systematically quantifies the influence of cement type (OPC, CAC, CSA) and w/cm ratio (0.45, 0.55, 0.65) on D_a using a full-factorial experimental design and bulk diffusion testing. The results reveal a significant interaction between cement type and w/cm (p < 0.001). OPC exhibits predictable porosity-driven degradation, with D_a increasing exponentially from 8.42 × 10⁻¹² to 1.46 × 10⁻¹⁰ m²/s as w/cm increases from 0.45 to 0.65. CAC shows a non-linear response, with optimal performance at w/cm = 0.55 (D_a = 2.90 × 10⁻¹¹ m²/s) due to microstructural refinement from hydrate conversion but suffers severe degradation at w/cm = 0.65. CSA cement is extremely water-sensitive, with D_a increasing by an order of magnitude (from ~4 × 10⁻¹¹ to 3.37 × 10⁻¹⁰ m²/s) at w/cm = 0.65, marking a critical failure threshold. Model fit quality (R²) serves as a leading indicator of microstructural instability, which is corroborated by XRD phase analysis. This study concludes that CSA presents a high risk for field applications with poor w/cm control, while OPC offers more predictable performance, advocating for cement-specific, performance-based specifications beyond traditional OPC-centric limits. Full article

(This article belongs to the Special Issue Sustainable Composite Construction Materials, 3rd Edition)

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18 pages, 20460 KB

Open AccessArticle

Influence of Processing Parameters on the Mechanical Properties of 3D Printed Borosilicate Particulate Reinforced Polymer Composites

by Lucian Alexander-Roy, Meelad Ranaiefar, Mrityunjay Singh and Michael C. Halbig

J. Compos. Sci. 2026, 10(9), 478; https://doi.org/10.3390/jcs10090478 - 5 Sep 2026

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Abstract

Emerging composite materials are expanding the potential of additive manufacturing and enabling applications previously restricted by traditional manufacturing methods through their multi-phase nature and complex internal geometry. Additionally, these materials can be pyrolyzed to create dense metal, ceramic, and glass parts with geometries [...] Read more.

Emerging composite materials are expanding the potential of additive manufacturing and enabling applications previously restricted by traditional manufacturing methods through their multi-phase nature and complex internal geometry. Additionally, these materials can be pyrolyzed to create dense metal, ceramic, and glass parts with geometries typically not achievable by traditional processes. Additive manufacturing of borosilicate glass composites can enable new applications in nuclear engineering, astronomy, and bone regrowth therapy. To elucidate the process–parameter relationship of borosilicate–polylactic acid (PLA) composites, mechanical test specimens were fabricated by fused-filament fabrication and compared with a pure PLA baseline. Optical and scanning electron microscopy were conducted to observe the specimen microstructure before and after testing. From the stress–strain curves, the highest compressive yield strength for the composite was 28.22 MPa, and the highest compressive yield strength for PLA was 49.30 MPa. Print orientation was found to benefit the composite material but have a detrimental effect on the pure matrix material. Borosilicate–PLA with 100% infill, 1 shell wall, and layer lines parallel to compression axis had an elastic modulus of 2.66 GPa. Microscopy revealed that lower-modulus composite specimens had the particulates re-distributed within the matrix. Tensile testing was done according to a polymer testing standard, which caused difficulties obtaining consistent fracture within the gauge length. Full article

(This article belongs to the Special Issue 3D Printing and Additive Manufacturing of Composites, 2nd Edition)

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21 pages, 1818 KB

Open AccessArticle

Structure–Property–Durability Relationships in Grape-Derived Pectin/Kraft Lignin Films Before and After Accelerated UV Aging

by Amanda Marcely Reis, Camila Monteiro Cholant, Lincoln Audrew Cordeiro, Patricia Oliveira Schmitt, Everton Granemann Souza, Chiara das Dores do Nascimento, Ivandra Ignês de Santi, Darci Alberto Gatto, Alexandre Ferreira Galio, Caio Gomide Otoni and André Luiz Missio

J. Compos. Sci. 2026, 10(9), 477; https://doi.org/10.3390/jcs10090477 - 4 Sep 2026

Viewed by 487

Abstract

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 [...] Read more.

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/Lig_0.1 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. Full article

(This article belongs to the Special Issue Polymer Composites: Technology and Sustainability)

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15 pages, 31084 KB

Open AccessArticle

Shear Strengthening of Reinforced Concrete Beams Using Hybrid System of CFRP Composites Inside and over Groove

by Ahmed H. Al-Abdwais, Adil K. Al-Tamimi and Maher Al-Hamad

J. Compos. Sci. 2026, 10(9), 476; https://doi.org/10.3390/jcs10090476 - 4 Sep 2026

Viewed by 291

Abstract

Fiber-reinforced polymers (FRPs) are increasingly adopted in structural rehabilitation due to their high strength-to-weight ratio, corrosion resistance, and ease of installation, making them suitable for extending the service life of reinforced concrete (RC) infrastructure. Studies on shear strengthening with CFRP was early focused [...] Read more.

Fiber-reinforced polymers (FRPs) are increasingly adopted in structural rehabilitation due to their high strength-to-weight ratio, corrosion resistance, and ease of installation, making them suitable for extending the service life of reinforced concrete (RC) infrastructure. Studies on shear strengthening with CFRP was early focused on externally boning (EB) showed premature delamination between fiber and concrete which limits the bonding strength. Hence, this study experimentally evaluates the shear strengthening behavior of RC beams retrofitted using inside-groove bonded CFRP and hybrid techniques. A total of seven beam specimens with identical geometry, internal reinforcement layout, and concrete strength were fabricated and tested under four-point bending to generate a well-defined shear-critical region. The experimental program focused on directly comparing bonding configurations while also examining the influence of groove depth (10 mm and 15 mm) and steel anchorage for concrete cover on structural response and failure mechanisms. The strengthened specimens achieved ultimate load increases ranging from approximately 10% to 23% relative to the control beam. Variation in groove depth within the investigated range did not significantly influence shear capacity, indicating that moderate groove penetration is sufficient to develop effective mechanical interlock. Steel anchors were introduced to restrain concrete cover separation and improve confinement of the bonded region and substantially increase peak load, it successfully mitigated premature cover delamination near stirrup locations and altered the governing failure mode. Full article

(This article belongs to the Special Issue Concrete Composites in Hybrid Structures)

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21 pages, 7162 KB

Open AccessArticle

Mechanical and Thermal Properties of Cu-Alloyed AZ91 Magnesium Alloy Subjected to T4 and T6 Heat Treatments

by Song-Jeng Huang, Cheng-Yen Yang and Sathiyalingam Kannaiyan

J. Compos. Sci. 2026, 10(9), 475; https://doi.org/10.3390/jcs10090475 - 3 Sep 2026

Viewed by 423

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Composites Manufacturing and Processing)

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27 pages, 5815 KB

Open AccessArticle

Enhancing Safety and Crashworthiness of Vehicles Using Composite Metal Foam

by Aman Kaushik and Afsaneh Rabiei

J. Compos. Sci. 2026, 10(9), 474; https://doi.org/10.3390/jcs10090474 - 3 Sep 2026

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Abstract

Novel steel composite metal foams (CMFs) are lightweight materials made from stainless-steel hollow spheres, with entrapped air suspended within the stainless-steel matrix. In this work, the performance of CMF-core front rails, containing steel CMF within an aluminum 6061 alloy double tube, is compared [...] Read more.

Novel steel composite metal foams (CMFs) are lightweight materials made from stainless-steel hollow spheres, with entrapped air suspended within the stainless-steel matrix. In this work, the performance of CMF-core front rails, containing steel CMF within an aluminum 6061 alloy double tube, is compared against rectangular high-strength low-alloy (HSLA) 350 steel and double-octagon aluminum 6061 alloy front rails of equivalent masses and lengths. Explicit finite element models of different front rails are subjected to frontal impact with entrapped air within the CMF core modeled using the pneumatic fluid cavity technique. The inclusion of a steel CMF-core within the double-tube structure results in plateauing vehicle deceleration instead of pulsating behavior observed during the buckling of tube-only structures. CMFs containing pressurized air and core–tube interactions enhance the compressive resistance of front rails to prevent localized bucking. The CMF-core front rail increases the accident velocity required to exceed the critical accident severity and head injury criterion (HIC) by 33.73% and 39.50%, respectively, when compared to an equivalent double-octagon front rail and by 31.93% and 48.24%, respectively, when compared to an equivalent rectangular front rail. The research demonstrates that utilizing novel energy-absorbing steel CMFs within automotive front rail structures helps improve occupant safety for crashworthiness applications. Full article

(This article belongs to the Section Composites Modelling and Characterization)

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J. Compos. Sci., Volume 10, Issue 9 (September 2026) – 63 articles

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