Journal of Composites Science

15 pages, 24620 KB

Open AccessArticle

In Situ UV-Assisted Direct Ink Writing of High-Resolution Silver Inks for Fine-Line Sensor Applications

by Guo-Xiang Zhou, Heng Pang, Xing-Ping Zhou, Chang Kong, Kuang Zhang, Zhi-Hua Yang, De-Chang Jia and Yu Zhou

J. Compos. Sci. 2026, 10(9), 447; https://doi.org/10.3390/jcs10090447 - 24 Aug 2026

Abstract

Direct ink writing (DIW) is a promising additive manufacturing technique for flexible electronics; however, lateral spreading of conventional silver inks often limits printing resolution and geometric fidelity. To address this limitation, an in situ UV-assisted DIW strategy using photocurable silver inks was developed [...] Read more.

Direct ink writing (DIW) is a promising additive manufacturing technique for flexible electronics; however, lateral spreading of conventional silver inks often limits printing resolution and geometric fidelity. To address this limitation, an in situ UV-assisted DIW strategy using photocurable silver inks was developed for the fabrication of high-resolution conductive features. The effects of Ag loading, TPO photoinitiator concentration, and dispersant type on the rheological behavior, photocuring response, and stability of the inks were systematically investigated. Excessive TPO concentrations were found to induce rheological instability, whereas an optimized formulation enabled a stable photocuring response. Among the dispersants investigated, AH100 provided the most favorable balance between ink flowability and controlled substrate wetting, thereby suppressing excessive lateral spreading. During printing, in situ UV irradiation rapidly promoted crosslinking of the resin matrix, increasing the structural rigidity of the deposited filament and restricting capillary-driven spreading. Using the optimized printing conditions and a photocurable silver ink with a Ag powder-to-photosensitive resin mass ratio of 4:1, the post-sintering line width was reduced from 269.8 to 72.57 μm, corresponding to a reduction of approximately 73%. After sintering at 800 °C, the printed tracks exhibited an electrical conductivity on the order of 10⁷ S/m, demonstrating that the substantial improvement in printing resolution was achieved without significantly compromising electrical performance. This in situ UV-assisted DIW strategy therefore provides an effective route for fabricating fine conductive features with improved dimensional fidelity and competitive electrical performance, showing promise for high-resolution flexible electronics and sensor applications. Full article

(This article belongs to the Section Composites Applications)

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17 pages, 5265 KB

Open AccessArticle

Fabrication and Characterization of Electrospun Polyacrylonitrile/Polyaniline–Graphene Oxide Nanoscroll Nanofiber Composite for Potential Glucose Sensing Applications

by Abdullah Bin Bashir and Dilip Depan

J. Compos. Sci. 2026, 10(9), 446; https://doi.org/10.3390/jcs10090446 - 24 Aug 2026

Abstract

Wearable sweat biosensors require electrode materials with high surface area, conductivity and mechanical compliance, yet chemically polymerized polyaniline forms dense, low-surface-area films with limited flexibility. In this work, flexible free-standing nanofiber mats were fabricated by coaxial electrospinning, using a sulfuric-acid-doped polyacrylonitrile/polyaniline (PAN/PANI) core [...] Read more.

Wearable sweat biosensors require electrode materials with high surface area, conductivity and mechanical compliance, yet chemically polymerized polyaniline forms dense, low-surface-area films with limited flexibility. In this work, flexible free-standing nanofiber mats were fabricated by coaxial electrospinning, using a sulfuric-acid-doped polyacrylonitrile/polyaniline (PAN/PANI) core and a shell containing graphene oxide nanoscrolls (GONS) at 1 and 3 wt%, followed by gold nanoparticle and ferrocene incorporation, glucose oxidase (GOx) immobilization and a Nafion coating. Scanning electron microscopy showed uniform bead-free fibers with an interconnected pore network and an apparent image-derived porosity of approximately 40%. Energy-dispersive X-ray spectroscopy confirmed the uniform distribution of carbon, oxygen, nitrogen and sulfur across the matrix. Fourier-transform infrared spectroscopy retained the nitrile band at 2243 cm⁻¹ and the quinoid and benzenoid bands at 1547 and 1476 cm⁻¹, while amide bands at 1730 and 1641 cm⁻¹ confirmed retention of protein from enzymes. X-ray diffraction gave crystallinities of 76.6% for GONS and 60% for the pure PANI. Four-point probe measurements showed conductivity increasing from 0.0481 S/cm to 1 wt% GONS to 0.0595 S/cm for the 3 wt% mat with additives. These material and structural characterizations establish a promising foundation for future electrochemical validation and sensor development. Full article

(This article belongs to the Section Polymer Composites)

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24 pages, 54040 KB

Open AccessArticle

Mechanical Properties of AZ91D Magnesium Alloy with Short Carbon Fibers Under Heat Treatment and Equal-Channel Angular Pressing

by Song-Jeng Huang, Jun Yi Lin, William Li, Chuan Li and Sathiyalingam Kannaiyan

J. Compos. Sci. 2026, 10(9), 445; https://doi.org/10.3390/jcs10090445 - 23 Aug 2026

Abstract

AZ91D is a lightweight, representative commercial magnesium alloy known for its excellent castability and specific strength. However, the mechanical properties of as-cast AZ91D remain limited by inherent brittleness, relatively low strength, and microstructural inhomogeneity caused by enrichment of secondary phases at grain boundaries. [...] Read more.

AZ91D is a lightweight, representative commercial magnesium alloy known for its excellent castability and specific strength. However, the mechanical properties of as-cast AZ91D remain limited by inherent brittleness, relatively low strength, and microstructural inhomogeneity caused by enrichment of secondary phases at grain boundaries. In this study, AZ91D/Csf (short carbon fiber at 0, 2.5, and 5 wt.%) composites were prepared by gravity casting with mechanical stirring, followed by post-casting T4 heat treatment and equal-channel angular pressing (ECAP). Material characterization included optical microscopy (OM), field-emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), uniaxial tensile testing, and microhardness tests. The results demonstrate that T4 treatment reduced intermetallic β-Mg₁₇Al₁₂ segregation and homogenized the microstructure, whereas one-pass ECAP further refined the grains. Mechanically, these two processes enable the (AZ91D/5 wt.% Csf) composite to achieve higher ultimate tensile strength (280.7 MPa by T4/280.2 MPa by T4 + one-pass ECAP), larger maximum strain (12.1% by T4/5.4% by T4 + one-pass ECAP), and higher microhardness (63.9 HV by T4/78.1 HV by T4 + one-pass ECAP). Compared to as-cast AZ91D, these findings demonstrate that T4 treatment provides a better strength–ductility balance via solid solution, whereas one-pass ECAP preferentially enhances surface microhardness by plastic deformation. This study highlights the performance of AZ91D/Csf composites and their potential for lightweight, high-strength-demand applications. Full article

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

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22 pages, 2546 KB

Open AccessArticle

Study on Concrete Confined Effectiveness with FRP Bars

by Yung-Chih Wang, Ming-Gin Lee, Wei-Chien Wang, Chia-Yuan Liang and Yu-Sung Chen

J. Compos. Sci. 2026, 10(9), 444; https://doi.org/10.3390/jcs10090444 - 23 Aug 2026

Abstract

Corrosion of steel reinforcement is a major cause of deterioration in reinforced concrete (RC) structures exposed to aggressive environments. Although fiber-reinforced polymer (FRP) reinforcement provides excellent corrosion resistance, its confinement effectiveness in RC columns has not been fully understood. This study experimentally investigated [...] Read more.

Corrosion of steel reinforcement is a major cause of deterioration in reinforced concrete (RC) structures exposed to aggressive environments. Although fiber-reinforced polymer (FRP) reinforcement provides excellent corrosion resistance, its confinement effectiveness in RC columns has not been fully understood. This study experimentally investigated the axial compressive behavior of rectangular RC short columns reinforced with steel, carbon fiber-reinforced polymer (CFRP), and glass fiber-reinforced polymer (GFRP) bars. Ten specimens with different reinforcement types and stirrup configurations were tested under monotonic axial compression to evaluate compressive strength, axial strain response, deformation behavior, failure mechanisms, and confinement performance. The results indicated that the contribution of FRP reinforcement depended on the reinforcement configuration and confinement mechanism. Specimens reinforced with CFRP longitudinal bars exhibited higher axial capacity than the steel-reinforced control specimen within the tested configurations; however, the influence of the longitudinal reinforcement ratio should also be considered. GFRP stirrups exhibited confinement behavior comparable to CFRP stirrups, whereas CFRP stirrups experienced premature fracture at bent corner regions, which reduced their confinement effectiveness and deformation capacity. Reducing stirrup spacing from 150 mm to 75 mm provided limited improvement in compressive strength because of premature stirrup failure and insufficient development of confinement effects. Existing confinement models tended to overestimate the post-peak response of FRP-reinforced columns. These preliminary findings provide experimental insights into the confinement behavior of FRP-reinforced concrete columns and contribute to the development of improved analytical models. Full article

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

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24 pages, 23593 KB

Open AccessArticle

Physical and Elevated-Temperature Tensile Characterization of Surface-Modified BFRP/Al FMLs

by Cesar Alfonso Cortes-Tejada, Honorio Ortiz-Hernández, Marco Antonio García-Bernal, Gabriela Lourdes Rueda-Morales, Alexander Morales-Gómez, Hilario Hernández-Moreno, David Hernández-Silva and Antonio Mosqueda-Sánchez

J. Compos. Sci. 2026, 10(9), 443; https://doi.org/10.3390/jcs10090443 - 22 Aug 2026

Abstract

Out-of-autoclave (OoA) manufacturing of Fiber Metal Laminates (FMLs) remains challenging because their mechanical performance and failure mechanisms are sensitive to processing-induced variations in phase distribution and interfacial bonding quality. Three FML-2/1 configurations (FML/Al-20, FML/Al-40, and FML/Al-60), where the numerical values indicate the exposure [...] Read more.

Out-of-autoclave (OoA) manufacturing of Fiber Metal Laminates (FMLs) remains challenging because their mechanical performance and failure mechanisms are sensitive to processing-induced variations in phase distribution and interfacial bonding quality. Three FML-2/1 configurations (FML/Al-20, FML/Al-40, and FML/Al-60), where the numerical values indicate the exposure time (minutes) of 3003-H14 aluminum to NaOH alkaline etching, were physically characterized after bonding to a basalt fiber-reinforced polymer (BFRP) core to quantify constituent and void volumetric fractions. Based on previously reported differences in interlaminar strength, FML/Al-40 was selected to evaluate tensile behavior at room temperature and high temperature. The average density across all FML configurations was about 2.15 g/cm³, corresponding to a 21% reduction relative to aluminum. Compositional analysis revealed significant differences among configurations in both the complete FML and the renormalized matrix–fiber–void composition of the BFRP core, indicating that surface treatment is associated with changes in internal phase distribution beyond the metallic contribution. At room temperature, FML/Al-40 exhibited an ultimate tensile strength of 262.7 MPa. Relative to this value, tensile strength was retained at 83%, 54%, and 31% at 100, 150, and 200 °C, respectively, demonstrating a progressive reduction in strength with increasing temperature and a corresponding change in the thermomechanical response associated with evolving failure mechanisms. Full article

(This article belongs to the Special Issue Hybrid Composites—from Fundamental Studies to Intelligent and Sustainable Solutions)

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34 pages, 2186 KB

Open AccessReview

Sustainable and Recyclable Composites for Electric Aviation and UAVs: Component-Specific Evidence, Qualification Pathways, and Circular Design

by Abdallah M. Almomani, Mohammed A. Almomani, Muath A. Bani-Hani and Mahmoud A. Hayajnh

J. Compos. Sci. 2026, 10(9), 442; https://doi.org/10.3390/jcs10090442 - 22 Aug 2026

Abstract

Electric aviation and unmanned aerial vehicles (UAVs) depend on lightweight composites to preserve payload and range, yet mass reduction, recycled content, or bio-based content alone does not establish component suitability. Candidate systems must also satisfy coupled structural, thermal, fire, electrical, manufacturing, durability, repair, [...] Read more.

Electric aviation and unmanned aerial vehicles (UAVs) depend on lightweight composites to preserve payload and range, yet mass reduction, recycled content, or bio-based content alone does not establish component suitability. Candidate systems must also satisfy coupled structural, thermal, fire, electrical, manufacturing, durability, repair, and circularity requirements. This structured critical narrative review evaluates thermoplastic carbon-fibre-reinforced polymer (CFRP) systems, recycled-carbon-fibre composites, natural-fibre systems, bio-based and recyclable matrices, hybrid architectures, and multifunctional composites using a component-specific framework based on source role, evidence maturity, test comparability, and failure consequence. The framework links processing and chemistry to defects, retained performance, repair and recovery, and the evidence required for defined aircraft and UAV components. Thermoplastic CFRP provides the strongest near-term pathway for secondary and semi-structural components, although weld durability, impact tolerance, fire response, and process conformity remain system specific. Recycled-carbon-fibre and natural-fibre systems are most defensible for lower-consequence covers, fairings, housings, interiors, and UAV parts when feedstock variability, moisture, porosity, and fire performance are controlled. Battery enclosures, primary structures, rotor-support members, and structural-battery systems require representative coupled-hazard and component-scale evidence. The resulting adoption pathways are bounded by component and operating conditions, with manufacturing, durability, repair, recovery, and qualification evidence specified for each application. Full article

(This article belongs to the Topic Advances in Sustainable Composite Materials)

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13 pages, 53503 KB

Open AccessArticle

Features and Mechanism of Low-Cycle Fatigue of Al–Ca–Ti Composite Alloys with Different Eutectic Fractions

by Stanislav Rogachev, Evgeniya Naumova and Mikhail Zadorozhnyy

J. Compos. Sci. 2026, 10(9), 441; https://doi.org/10.3390/jcs10090441 - 22 Aug 2026

Abstract

Finely dispersed Al–Ca–Ti composite alloys with a set of remarkable properties can be considered as new promising structural materials. For wider use of these alloys, data on their fatigue behavior are needed. In this work the comparative study of the low-cycle fatigue strength [...] Read more.

Finely dispersed Al–Ca–Ti composite alloys with a set of remarkable properties can be considered as new promising structural materials. For wider use of these alloys, data on their fatigue behavior are needed. In this work the comparative study of the low-cycle fatigue strength of hot-rolled Al–xCa–0.2Ti alloys with different eutectic fractions determined by different calcium contents was conducted. The fatigue tests were carried out according to a single-plane bending scheme using a dynamic mechanical analyzer. A symmetrical loading cycle (asymmetry coefficient R = −1) with a constant stress amplitude was used. The maximum number of cycles was 20,000. It was found that increasing the eutectic fraction from 40% to 80% led to a 75% increase in the fatigue limit—from 80 to 140 MPa—which directly correlated with the alloy’s yield strength. The fatigue crack propagation occurred with the formation of a scaly fracture surface, whereas final static rupture was associated with a ductile dimple fracture. The microstructural mechanisms of alloy fatigue failure were discussed. It was found that increasing the total length of the eutectic particles/aluminum matrix interphase boundaries changed the failure mechanism to a more brittle one. Full article

(This article belongs to the Section Metal Composites)

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17 pages, 18351 KB

Open AccessArticle

A Comparative Experimental Investigation of the Static Flexural Behavior of Five Typical Bio-Inspired Composite Structures

by Zhiquan Wei, Xinlan Hu, Xinran Hu and Yaozhe Yu

J. Compos. Sci. 2026, 10(8), 440; https://doi.org/10.3390/jcs10080440 - 21 Aug 2026

Abstract

Natural biological materials achieve synergistic strengthening and toughening through soft–stiff dual-phase architectures, inspiring artificial composites. Despite extensive studies on individual bio-inspired designs, systematic comparative investigations under fully unified experimental conditions remain limited. Here, five representative bio-inspired composite structures (brick–mud, cross-lamellar, interlock, overlap, and [...] Read more.

Natural biological materials achieve synergistic strengthening and toughening through soft–stiff dual-phase architectures, inspiring artificial composites. Despite extensive studies on individual bio-inspired designs, systematic comparative investigations under fully unified experimental conditions remain limited. Here, five representative bio-inspired composite structures (brick–mud, cross-lamellar, interlock, overlap, and concentric) are fabricated via 3D printing and compared under quasi-static three-point bending. Key mechanical parameters—including flexural modulus, flexural strength, crack-initiation displacement, effective fracture displacement, total energy absorption, and post-peak energy dissipation ratio—are derived from force–displacement curves, complemented by high-resolution imaging of crack paths, crack front morphologies, and fracture surfaces. The concentric structure exhibits the highest flexural modulus and flexural strength, yet fails catastrophically with only a 9.95% post-peak energy dissipation ratio. The brick–mud and cross-lamellar structures achieve the highest post-peak energy dissipation ratios (27.69% and 27.42%, respectively), which may be attributed to crack deflection and interfacial debonding, yet at the cost of low flexural strength. The interlock structure, apparently lacking effective deflecting interfaces, shows straight-through propagation and brittle behavior. In contrast, the overlap structure appears to benefit from sustained crack deflection along inclined interfaces, thereby providing a balanced combination of high flexural strength, large deformability, and moderate energy absorption, demonstrating the best overall mechanical performance. Full article

(This article belongs to the Section Polymer Composites)

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31 pages, 2358 KB

Open AccessReview

Triply Periodic Minimal Surface (TPMS) Cellular Structures: Modeling, Manufacturing, and Application Perspectives—A Review

by Martin Koroľ, Monika Töröková and Jozef Tkáč

J. Compos. Sci. 2026, 10(8), 439; https://doi.org/10.3390/jcs10080439 - 20 Aug 2026

Abstract

Triply Periodic Minimal Surfaces (TPMSs) represent a progressive class of cellular materials with high potential for high-tech applications. This review provides a comprehensive analysis of TPMS architectures, linking their mathematical underpinnings and advanced CAD modeling in PTC Creo Parametric 12 with technological aspects [...] Read more.

Triply Periodic Minimal Surfaces (TPMSs) represent a progressive class of cellular materials with high potential for high-tech applications. This review provides a comprehensive analysis of TPMS architectures, linking their mathematical underpinnings and advanced CAD modeling in PTC Creo Parametric 12 with technological aspects of additive manufacturing and macroscopic mechanical response. The work critically compares dominant topologies such as Schoen Gyroid, Schwarz Diamond, and Schwarz Primitive, focusing on the differences between uniform and functionally graded (FG-TPMS) structures. From a production perspective, this study identifies key process limitations of PBF-LB/M and SLA additive technologies, in particular the issues of unsintered powder accumulation, geometric deviations, and the negative impact of surface roughness (satellite particles) on fatigue life. Analysis of mechanical behavior confirms the superiority of sheet-based modifications in kinetic energy absorption, where specifically tailored FG-TPMS topologies exhibit stable deformation plateaus and controlled, progressive failure modes under compression. The conclusion of the work summarizes established applications in biomedical engineering for the elimination of stress shielding, as well as emerging trends in the field of 4D printing and acoustic metamaterials. This review serves as a comprehensive engineering guide for the optimization and implementation of next-generation porous structures. Full article

(This article belongs to the Section Polymer Composites)

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18 pages, 1875 KB

Open AccessArticle

Structural Performance of Glulam Beams Improved by Composing the Cross-Section with Lamellae of Different Strength Classes

by Leonardo Carriel Kurowski, Julio Soriano, Douglas Lamounier Faria and José Benedito Guimarães Junior

J. Compos. Sci. 2026, 10(8), 438; https://doi.org/10.3390/jcs10080438 - 19 Aug 2026

Abstract

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 [...] Read more.

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. Full article

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

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25 pages, 1394 KB

Open AccessArticle

Assessment of the Dissipative Properties of Viscoelastic Hollow Cylindrical Bodies with Filler During the Propagation of Natural Waves

by Tulkin Ruziyev, Ismoil Safarov, Mukhsin Teshayev, Zafar Boltayev, Nuriddin Esanov, Botir Usmanov, Zamira Ismailova, Sanobar Karimova, Bekzod Zaripov, Anora Jumayeva, Yerlan Tleukeyev, Abdurakhim Marasulov and Utkir Urolov

J. Compos. Sci. 2026, 10(8), 437; https://doi.org/10.3390/jcs10080437 - 18 Aug 2026

Abstract

Searching by numerical simulation for structures with optimal damping properties among viscoelastic hollow cylindrical bodies with a filler is usually associated with a large amount of computation. Formulating the mechanical problem as one of natural vibrations and natural wave propagation makes it possible [...] Read more.

Searching by numerical simulation for structures with optimal damping properties among viscoelastic hollow cylindrical bodies with a filler is usually associated with a large amount of computation. Formulating the mechanical problem as one of natural vibrations and natural wave propagation makes it possible to evaluate the dissipative properties of such a structure independently of external force and kinematic actions, and thereby to reduce the computational cost substantially. The solution of the natural vibration problem for a piecewise homogeneous viscoelastic hollow cylindrical body with a filler yields complex natural frequencies, the real part of which represents the vibration frequency and the imaginary part the damping factor (attenuation rate). The mechanical behavior of the viscoelastic material is described by the linear Boltzmann–Volterra hereditary theory with a three-parameter Koltunov–Rzhanitsyn relaxation kernel, within which the material characteristics are represented by complex dynamic moduli—the shear modulus and the bulk modulus—that, as a rule, depend on frequency. In the natural vibration problem these moduli become functions of the real part of the sought complex natural frequency alone, which makes the standard eigenvalue procedures of commercial finite-element codes inapplicable. The paper presents an algorithm that removes this difficulty. The dispersion relation of the piecewise homogeneous cylinder is obtained analytically in the form of a complex determinant of order 12 for a two-layer and 18 for a three-layer configuration, the elements of which are Bessel and Neumann functions of complex argument; the global stiffness and mass matrices needed for the general configuration can be assembled automatically in a general-purpose finite-element code such as ABAQUS; the resulting complex characteristic equation is solved by Muller’s method—every iteration of which evaluates the determinant by Gaussian elimination with partial pivoting, so that no expansion of the determinant is required. The efficiency of the algorithm is demonstrated for a two-layer viscoelastic hollow cylindrical body with a filler, the outer load-carrying layer being made of Kh12 steel and the inner layer (the filler) of 30 L steel. The real and imaginary parts of the complex natural frequencies, of the phase velocities and of the attenuation are obtained as functions of the dimensionless wave number, of Poisson’s ratio, of the ratio of the layer radii and of the ratio of the instantaneous elastic moduli of the layers. Full article

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

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15 pages, 9686 KB

Open AccessArticle

Effect of Omani Limestone Waste as a Reinforcing Agent on the Mechanical Properties of Scrap-Based Aluminum Matrix Composites

by Mutlag Shafi Alaythee, Saadoon Isaoglu, Alreem Aldaoudi, Gheed Almukhaini, Mryam Alareimi, Mehad Albahri, Maeen Alghusaini and Hawraa Alrawahi

J. Compos. Sci. 2026, 10(8), 436; https://doi.org/10.3390/jcs10080436 - 18 Aug 2026

Abstract

This study utilizes Omani limestone waste powder (CaCO₃) sourced from the mountain ranges of the Sultanate of Oman as an economical natural reinforcement for scrap-based aluminum matrix composites (AMCs) using stir casting. The recycling of aluminum alloy from end-of-life automotive engine [...] Read more.

This study utilizes Omani limestone waste powder (CaCO₃) sourced from the mountain ranges of the Sultanate of Oman as an economical natural reinforcement for scrap-based aluminum matrix composites (AMCs) using stir casting. The recycling of aluminum alloy from end-of-life automotive engine cylinder blocks was strengthened with limestone at volume fractions of 2.5%, 5.0%, and 7.5%. Mechanical characterization was conducted in accordance with ASTM standards (E8/E8M, E18, E23). Statistical significance (p < 0.05) was calculated using one-way ANOVA. The optimum 5.0 vol.% reinforcing fraction showed tensile strength, Rockwell hardness and Charpy impact energy of 130.9 MPa (+16.9%), 91 HRF (+19.7%) and 7.2 J (+28.6%) compared to the unreinforced scrap alloy (112.0 MPa, 76 HRF, 5.6 J). The results of Scanning Electron Microscopy (SEM) research showed that the composite of 5.0 vol.% had a uniform distribution of CaCO₃ particles and very low porosity, while the composite of 7.5 vol.% had a significant porosity (2–8 μm), interconnected microcracks and particle agglomeration. The porosity was increased with the increase of the content of the reinforcement as shown by the density experiments based on Archimedes’ principle. The maximum deviation of the experimental density from the predicted one was at 7.5 vol. % reinforcement. X-ray diffraction (XRD) confirmed the stability of the aluminum matrix structure as well as stable CaCO₃ phases without any evidence of harmful interfacial reaction products (Al₄C₃ or CaAl₂O₄). The findings confirm the optimal reinforcement ratio of 5.0 vol.% of Omani limestone, tackling both the environmental load of limestone quarrying waste and the expensive synthetic reinforcements, in accordance with the circular economy goals of Oman Vision 2040. Full article

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

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19 pages, 12747 KB

Open AccessArticle

Evaluation of the Self-Healing Behaviour of Structural Polyamide 6 (PA6)/Poly(butylene-adipate-terephthalate) (PBAT) Blends

by Laura Simonini, Giuseppe Fuoli, Alessandro Sorze, Alessandro Pegoretti and Andrea Dorigato

J. Compos. Sci. 2026, 10(8), 435; https://doi.org/10.3390/jcs10080435 - 18 Aug 2026

Abstract

In this study, polyamide 6/poly(butylene-adipate-terephthalate) (PA6/PBAT) blends, potentially applied as novel self-healing matrices for structural composites, were developed and characterized. The blends were melt-compounded at different PBAT amounts (from 20 up to 50%vol) and hot pressed. Rheological analysis showed a decreased in the [...] Read more.

In this study, polyamide 6/poly(butylene-adipate-terephthalate) (PA6/PBAT) blends, potentially applied as novel self-healing matrices for structural composites, were developed and characterized. The blends were melt-compounded at different PBAT amounts (from 20 up to 50%vol) and hot pressed. Rheological analysis showed a decreased in the storage and loss moduli of PA6 with PBAT, maintaining viscosity levels suitable for conventional melt-processing operations. FT-IR and FESEM observations demonstrated the formation of blends with immiscible morphology and uniformly dispersed PBAT domains. Quasi-static tensile tests showed a progressive decrease in tensile modulus and strength with PBAT, but a strong improvement in the elongation at break. The blend containing 30%vol PBAT showed satisfactory stiffness (2.2 GPa), strength (42 MPa) and elongation at break (10.5%) compared to PA6 (3.4 GPa, 62 MPa and 5.2%), thus this formulation was selected for self-healing assessment. Its repair efficiency was quantified as recovery of the fracture toughness (K_IC) after a thermal treatment at 150 °C for 30–120 min under pressure from 1–3 MPa. The highest healing efficiency (28%) was obtained after 120 min under 1 MPa, conditions at which the PBAT reduced its viscosity and flowed across the crack interface. Therefore, the blend with 30%vol PBAT will be considered in future for the preparation of multifunctional composites with thermal self-healing capability. Full article

(This article belongs to the Section Polymer Composites)

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15 pages, 5599 KB

Open AccessArticle

The Electron-Providing Effect of a Schiff Base Copper(II) Complex Mediator and Lignin for Laccase

by Reon Aihara, Daisuke Nakane, Abul Monsur Showkot Hossain, Kholnazarov Bakhodir Azamovich, Sayantan Pradhan and Takashiro Akitsu

J. Compos. Sci. 2026, 10(8), 434; https://doi.org/10.3390/jcs10080434 - 17 Aug 2026

Abstract

In biofuel cells using laccase, the electron supply to the type 1 (T1) site is inefficient, constituting a major bottleneck for the overall reaction. To solve this problem, the use of mediator molecules that mediate electron transfer is being studied. Furthermore, lignin is [...] Read more.

In biofuel cells using laccase, the electron supply to the type 1 (T1) site is inefficient, constituting a major bottleneck for the overall reaction. To solve this problem, the use of mediator molecules that mediate electron transfer is being studied. Furthermore, lignin is known to be oxidized by laccase and can donate electrons, which indicates the potential application of this reaction in biofuel cells. Therefore, in this study, docking calculations were performed to clarify the interactions between a copper(II) complex mediator and laccase. At the same time, a copper complex mediator was selected, and cyclic voltammetry (CV) measurements were performed to evaluate its electrochemical properties. In the CV measurements, the differences in current responses with and without the mediator and lignin (an oxidized substrate of laccase) were compared. As a result, based on the docking calculations, it was proposed that the synthesized copper complex mediator binds relatively strongly to laccase. Moreover, CV measurements confirmed that the current tended to increase upon the addition of the mediator and/or lignin. This current enhancement explicitly demonstrates the efficient electron-providing effect of the mediator and lignin to the laccase-based system. Full article

(This article belongs to the Section Biocomposites)

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18 pages, 3134 KB

Open AccessArticle

Valorisation of Vegetal Biomass Residues in the Development of Sustainable Composites: An Alternative for Biodegradable Packaging

by Rodrigo Ortega-Toro, Candelaria Tejada-Tovar, Nicole Yances-Guette, Joaquín Hernández-Fernández and Ángel Villabona-Ortiz

J. Compos. Sci. 2026, 10(8), 433; https://doi.org/10.3390/jcs10080433 - 17 Aug 2026

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Based Composites: Innovations and Application)

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16 pages, 6398 KB

Open AccessArticle

Development of TPMS Lattice Substrates for Catalytic Cracking Applications via Fused Filament Fabrication

by Rubén Dorado-Vicente, Eloísa Torres-Jiménez, Laura Robles-Lorite and Fernando Cruz-Peragón

J. Compos. Sci. 2026, 10(8), 432; https://doi.org/10.3390/jcs10080432 - 16 Aug 2026

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Lattice Structures)

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26 pages, 9070 KB

Open AccessArticle

Numerical Fatigue Analysis of CFRP Tension Elements in Cable Supported Bridges Under Multiaxial State of Stress

by Prathamesh Khorgade, Nicolas Schoeneweiß, Arndt Goldack and Mike Schlaich

J. Compos. Sci. 2026, 10(8), 431; https://doi.org/10.3390/jcs10080431 - 15 Aug 2026

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Fiber Composites)

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46 pages, 7786 KB

Open AccessReview

Functional Chitosan Nanocomposites for Enhanced Electrochemical Sensing: A Comprehensive Review

by Ratiba Wali, Yosra Hadjkacem, Ramzi Maalej, Mourad Arous and Ahmed Koubaa

J. Compos. Sci. 2026, 10(8), 430; https://doi.org/10.3390/jcs10080430 - 14 Aug 2026

Abstract

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, [...] Read more.

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. Full article

(This article belongs to the Special Issue Sustainable Biocomposites, 3rd Edition)

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28 pages, 8373 KB

Open AccessArticle

Structural Response of Thin-Web Beams to Various Web Opening Retrofit Techniques

by Oday A. Salih, Kaythar A. Ibrahim, Mohammed H. Shukur, Suhaib Y. K. Al-Darzi and Sofyan Y. Ahmed

J. Compos. Sci. 2026, 10(8), 429; https://doi.org/10.3390/jcs10080429 - 14 Aug 2026

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Composites Applications)

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