Journal of Composites Science

23 pages, 3977 KB

Open AccessArticle

Mechanical Performance of Pultruded and Compression-Molded CFRTP Laminates: A Comparative Study

by James C. Haller, Jr., Jacob C. Clark and James T. Gayton

J. Compos. Sci. 2025, 9(10), 572; https://doi.org/10.3390/jcs9100572 - 17 Oct 2025

In this work, the mechanical performance of unidirectional thermoplastic laminates produced via a proprietary non-reactive thermoplastic pultrusion system known as the continuous forming machine (CFM) was compared to the mechanical performance of similar laminates produced via compression-molding in a heated platen press. Using [...] Read more.

In this work, the mechanical performance of unidirectional thermoplastic laminates produced via a proprietary non-reactive thermoplastic pultrusion system known as the continuous forming machine (CFM) was compared to the mechanical performance of similar laminates produced via compression-molding in a heated platen press. Using commercially available pre-impregnated unidirectional thermoplastic tapes as the material feedstock for both production methods, a comparison of mechanical performance was executed for six separate material systems ranging from commodity-grade (e.g., polypropylene) to aerospace-grade (e.g., low-melt polyaryletherketone) polymer systems. Mechanical performance was evaluated and compared through tensile testing, compression testing, and short beam strength testing in a universal testing machine. The continuous fiber-reinforced thermoplastic (CFRTP) laminates were composed solely of unidirectional plies and were tested in the longitudinal material orientation. Through testing, it was found that the laminates produced on the proprietary thermoplastic pultrusion platform exhibited mechanical performance characteristics equivalent with those of the laminates produced using heated compression-molding. Furthermore, comparisons to values found in the literature were performed, demonstrating the viability of the CFM’s novel manufacturing process to pultrude thermoplastic parts for axially loaded applications. Full article

(This article belongs to the Special Issue Advances in Continuous Fiber Reinforced Thermoplastic Composites)

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25 pages, 1795 KB

Open AccessReview

Environmentally Friendly PLA-Based Conductive Composites: Electrical and Mechanical Performance

by Nassima Naboulsi, Fatima Majid and Mohamed Louzazni

J. Compos. Sci. 2025, 9(10), 571; https://doi.org/10.3390/jcs9100571 - 16 Oct 2025

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Abstract

This review investigates recent progress in the field of PLA-based conductive composites for 3D printing. First, it introduces PLA as a biodegradable thermoplastic polymer, describing its processing and recycling methods and highlighting its environmental advantages over conventional polymers. In order to evaluate its [...] Read more.

This review investigates recent progress in the field of PLA-based conductive composites for 3D printing. First, it introduces PLA as a biodegradable thermoplastic polymer, describing its processing and recycling methods and highlighting its environmental advantages over conventional polymers. In order to evaluate its printability, PLA is briefly compared to other commonly used thermoplastics in additive manufacturing. The review then examines the incorporation of conductive fillers such as carbon black, carbon nanotubes, graphene, and metal particles into the PLA matrix, with a particular focus on the percolation threshold and its effect on conductivity. Critical challenges such as filler dispersion, agglomeration, and conductivity anisotropy are also highlighted. Recent results are summarized to identify promising formulations that combine improved electrical performance with acceptable mechanical integrity, while also emphasizing the structural and morphological characteristics that govern these properties. Finally, potential applications in the fields of electronics, biomedicine, energy, and electromagnetic shielding are discussed. From an overall perspective, the review highlights that while PLA-based conductive composites show great potential for sustainable functional materials, further progress is needed to improve reproducibility, optimize processing parameters, and ensure reliable large-scale applications. Full article

(This article belongs to the Section Composites Applications)

15 pages, 2931 KB

Open AccessArticle

Low Poisson’s Ratio Measurement on Composites Based on DIC and Frequency Analysis on Tensile Tests

by Luis Felipe-Sesé, Andreas Kenf, Sebastian Schmeer, Elías López-Alba and Francisco Alberto Díaz

J. Compos. Sci. 2025, 9(10), 570; https://doi.org/10.3390/jcs9100570 - 16 Oct 2025

Viewed by 191

Abstract

Accurate determination of elastic properties, especially Poisson’s ratio, is crucial for the design and modeling of composite materials. Traditional methods often struggle with low strain measurements and non-uniform strain distributions inherent in these anisotropic materials. This research work introduces a novel methodology that [...] Read more.

Accurate determination of elastic properties, especially Poisson’s ratio, is crucial for the design and modeling of composite materials. Traditional methods often struggle with low strain measurements and non-uniform strain distributions inherent in these anisotropic materials. This research work introduces a novel methodology that integrates Digital Image Correlation (DIC) with frequency analysis techniques to improve the precision of Poisson’s ratio determination during tensile tests, particularly at low strain ranges. The focus is on the evaluation of two distinct frequency-based approaches: Phase-Based Motion Magnification (PBMM) and Lock-in filtering. DIC + PBMM, while promising for motion amplification, encountered specific challenges in this application, particularly at very low strain amplitudes, leading to increased variability and computational demands. In contrast, the DIC + Lock-in filtering method proved highly effective. It provided stable, filtered strain distributions, significantly reducing measurement uncertainty compared to traditional DIC and other conventional methods like strain gauges and Video Extensometers. This study demonstrates the robust potential of Lock-in filtering for characterizing subtle periodic mechanical behaviors leading to a reduction of approximately 70% in the standard deviation of the measurement. This work lays a strong foundation for more precise and reliable material characterization, crucial for advancing composite design and engineering applications. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Modeling and Simulation of Composite Materials)

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23 pages, 3276 KB

Open AccessArticle

The Effect of Calcium Stearate Additives in Concrete on Mass Transfer When Exposed to Aspergillus niger Fungi

by Viktoriya S. Konovalova, Konstantin B. Strokin, Aleksey A. Galtsev and Denis G. Novikov

J. Compos. Sci. 2025, 9(10), 569; https://doi.org/10.3390/jcs9100569 - 15 Oct 2025

Viewed by 259

Abstract

Understanding and predicting the damage to concrete caused by microorganisms in aquatic environments is challenging, highlighting the need for effective, simple, and inexpensive preventative methods. This paper presents the results of a study on the effect of calcium stearate addition on the kinetics [...] Read more.

Understanding and predicting the damage to concrete caused by microorganisms in aquatic environments is challenging, highlighting the need for effective, simple, and inexpensive preventative methods. This paper presents the results of a study on the effect of calcium stearate addition on the kinetics of mass transfer processes occurring in cement stone exposed to Aspergillus niger fungi under humid conditions. Calcium stearate was added into the cement mix during sample preparation at concentrations of 0.5% and 1% by cement weight. After curing, the cement stone surfaces were inoculated with Aspergillus niger. To investigate mass transfer processes during biodegradation, the samples were immersed in water. Calcium leaching from the cement stone was quantified using complexometric titration of the water, while the calcium content within the cement stone was determined by derivatographic analysis. The quantitative indicators of calcium leaching in water from cement stone with calcium stearate additives were 2.5 times lower. The profiles of calcium concentrations in the thickness of cement samples demonstrated an increase in the intensity of mass transfer under the influence of fungi and a significant decrease in the processes in hydrophobic cement stone. The values of the mass conductivity coefficients for fungal-infected samples in water differed by two orders of magnitude from 10⁻⁹ and 10⁻¹¹ [m²/s] for conventional and hydrophobic concrete. The mass transfer parameters (flow density, mass conductivity coefficients, and mass transfer coefficients) revealed a 3-fold slowdown in mass transfer processes during fungal exposure in cement stone with a hydrophobic additive compared with control samples. A mathematical model of concrete biocorrosion was used to predict the durability of concrete under humid conditions with fungal exposure. The predicted maintenance-free service life of concrete without additives is 15 years, whereas for hydrophobic concrete, it is 25 to 30 years. The research results are used in the design of concrete structures in conditions of high humidity, in the development of new compositions of hydrophobic concretes, to predict the service life of concrete structures, and in the creation of methods for preventing biological damage to concrete structures. Full article

(This article belongs to the Special Issue Structural Design, Health Monitoring and Performance Evaluation of Composite Materials)

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23 pages, 16775 KB

Open AccessArticle

Development of Carbide-Reinforced Al-7075 Multi-Layered Composites via Friction Stir Additive Manufacturing

by Adeel Hassan, Khurram Altaf, Mokhtar Che Ismail, Srinivasa Rao Pedapati, Roshan Vijay Marode, Imtiaz Ali Soomro and Naveed Ahmed

J. Compos. Sci. 2025, 9(10), 568; https://doi.org/10.3390/jcs9100568 - 15 Oct 2025

Viewed by 238

Abstract

Friction stir additive manufacturing (FSAM) is a promising solid-state technique for fabricating high-strength aluminum alloys, such as Al-7075, which are difficult to process using conventional melting-based additive manufacturing (AM) methods. This study investigates the mechanical properties and tool wear behavior of seven-layered Al-7075 [...] Read more.

Friction stir additive manufacturing (FSAM) is a promising solid-state technique for fabricating high-strength aluminum alloys, such as Al-7075, which are difficult to process using conventional melting-based additive manufacturing (AM) methods. This study investigates the mechanical properties and tool wear behavior of seven-layered Al-7075 multi-layered composites reinforced with silicon carbide (SiC) and titanium carbide (TiC) fabricated via FSAM. Microstructural analysis confirmed defect-free multi-layered composites with a homogeneous distribution of SiC and TiC reinforcements in the nugget zone (NZ), although particle agglomeration was observed at the bottom of the pin-driven zone (PDZ). The TiC-reinforced composite exhibited finer grains than the SiC-reinforced composite in both as-welded and post-weld heat-treated (PWHT) conditions, achieving a minimum grain size of 1.25 µm, corresponding to a 95% reduction compared to the base metal. The TiC-reinforced multi-layered composite demonstrated superior mechanical properties, attaining a microhardness of 93.7 HV and a UTS of 263.02 MPa in the as-welded condition, compared to 88.6 HV and 236.34 MPa for the SiC-reinforced composite. After PWHT, the TiC-reinforced composite further improved to 159.12 HV and 313.46 MPa UTS, along with a higher elongation of 11.14% compared to 7.5% for the SiC-reinforced composite. Tool wear analysis revealed that SiC reinforcement led to greater tool degradation, resulting in a 1.17% weight loss. These findings highlight the advantages of TiC reinforcement in FSAM, offering enhanced mechanical performance with reduced tool wear in multi-layered Al-7075 composites. Full article

(This article belongs to the Special Issue Effect of Processing Techniques on the Characterization of Alloys Composites and Hybrids)

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18 pages, 4222 KB

Open AccessArticle

Analytical and Numerical Investigation of Vibration Characteristics in Shear-Deformable FGM Beams

by Murat Çelik, Erol Demirkan and Ahmet Feyzi Yıldırım

J. Compos. Sci. 2025, 9(10), 567; https://doi.org/10.3390/jcs9100567 - 15 Oct 2025

Viewed by 212

Abstract

In this study, the free vibration characteristics of a functionally graded (FG) shear-deformable Timoshenko beam were investigated both analytically and numerically. The work is notable for its significant contribution to the literature, particularly in addressing analytically challenging problems related to complex FGM structures [...] Read more.

In this study, the free vibration characteristics of a functionally graded (FG) shear-deformable Timoshenko beam were investigated both analytically and numerically. The work is notable for its significant contribution to the literature, particularly in addressing analytically challenging problems related to complex FGM structures using advanced computer-aided finite element methods. For the analytical approach, the governing equations and associated boundary conditions were derived using Hamilton’s principle of minimum potential energy. These equations were then solved using the Navier solution method to determine the natural frequencies of the beam. In the numerical analysis, a 3D FG beam model was developed in the ABAQUS finite element software (2023, Dassault Systèmes, Providence, RI, USA)using the second-order hexahedral (HEX20/C3D20) and 1D three-node quadratic beam (B32) elements. The material gradation was defined layer-by-layer along the thickness direction in accordance with the rule of mixtures. Modal analysis was subsequently performed to extract the natural frequency values. The results show a high level of agreement between the analytical and numerical solutions. and were consistent with previously published studies in the literature. Full article

(This article belongs to the Special Issue Composite Materials for Civil Engineering Applications)

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11 pages, 6009 KB

Open AccessArticle

Performance and Preparation of Styrene-Butadiene Copolymer Modified Polypropylene Matte Films

by Kang Yang, Yu-Long Ma, Jin-Long Lv, Zhang Yi, Shu Zeng, Ju-Heng Wang and Xiao-Xiao Huang

J. Compos. Sci. 2025, 9(10), 566; https://doi.org/10.3390/jcs9100566 - 15 Oct 2025

Viewed by 197

Abstract

The demand for high-performance polypropylene (PP) films in high-end packaging applications has been growing rapidly. However, Traditional polypropylene (PP) films are limited in application by their inadequate mechanical strength, heat-sealing performance, and matte properties. Hence, in this study, styrene-butadiene copolymer-modified polypropylene (PP) matte [...] Read more.

The demand for high-performance polypropylene (PP) films in high-end packaging applications has been growing rapidly. However, Traditional polypropylene (PP) films are limited in application by their inadequate mechanical strength, heat-sealing performance, and matte properties. Hence, in this study, styrene-butadiene copolymer-modified polypropylene (PP) matte films using styrene-butadiene copolymer (SB) as a modifier were successfully prepared. A comprehensive characterization of the films’ optical, mechanical, thermal, and processing properties was conducted using specialized instrumentation. Capillary rheometry revealed that the melt viscosity of the PP/SB blends decreased with increasing shear rate, demonstrating typical pseudoplastic behavior. Differential scanning calorimetry (DSC) showed single melting and crystallization peaks, indicating excellent compatibility between PP and SB. The optimal performance was achieved with 7.00 wt% SB, resulting in a film with a light transmittance of 92.08%, a haze of 66.40%, and a gloss of 3.63 GU. This formulation also yielded more uniform tensile strength and elongation in both longitudinal and transverse directions, and reduced the heat-sealing temperature to 101 °C, significantly lower than the 111 °C required for pure PP. Overall, the SB-modified PP films exhibited excellent mechanical strength, enhanced heat sealability, and superior matte properties, highlighting their significant potential for high-end packaging applications. Full article

(This article belongs to the Section Polymer Composites)

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32 pages, 6187 KB

Open AccessArticle

Sustainable Reprocessing of Thermoset Composite Waste into Thermoplastics: A Polymer Blend Approach for Circular Material Design

by Hasan Kasim, Yu-Chao Shih, Selvum Pillay and Haibin Ning

J. Compos. Sci. 2025, 9(10), 565; https://doi.org/10.3390/jcs9100565 - 14 Oct 2025

Viewed by 187

Abstract

Thermoset composites provide excellent strength but pose major recycling challenges due to their crosslinked structure. In this study, epoxy–polyurethane–glass fiber (EPG) wastes were mechanically recycled into low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polyamide-6 (PA6) matrices to produce second-generation thermoplastic composites (STCs). Fillers [...] Read more.

Thermoset composites provide excellent strength but pose major recycling challenges due to their crosslinked structure. In this study, epoxy–polyurethane–glass fiber (EPG) wastes were mechanically recycled into low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polyamide-6 (PA6) matrices to produce second-generation thermoplastic composites (STCs). Fillers at 10–50 wt% were processed by single-screw extrusion and compression molding, and the resulting composites were comprehensively characterized. For LDPE, the tensile modulus increased by ~286–589% and tensile strength increased by 40–47% at 20–30 wt% loading, though ductility decreased at higher levels. HDPE composites showed a ~347% rise in modulus and ~24% increase in strength, but performance declined with more than 40 wt% filler. PA6 offered the most balanced outcome, retaining ~70% of its neat tensile strength while achieving an ~300% modulus improvement at 40 wt% loading. Thermal stability was strongly enhanced, with char residue at 700 °C rising from 0.4% to 38.7% in PA6 and from ~2.5% to 33–46% in polyolefins. In contrast, crystallinity decreased (e.g., LDPE 62.2% → 23.7%), and impact strength dropped at a loading above 30 wt%. Overall, the results demonstrate that EPG wastes can be reprocessed into functional composites without compatibilizers, with PA6 providing the most robust property retention at high filler contents. Full article

(This article belongs to the Special Issue Advances in Continuous Fiber Reinforced Thermoplastic Composites)

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30 pages, 4851 KB

Open AccessArticle

Scalable Production of Boron Nitride-Coated Carbon Fiber Fabrics for Improved Oxidation Resistance

by Cennet Yıldırım Elçin, Muhammet Nasuh Arık, Kaan Örs, Uğur Nakaş, Zeliha Bengisu Yakışık Özgüle, Özden Acar, Salim Aslanlar, Özkan Altay, Erdal Çelik and Korhan Şahin

J. Compos. Sci. 2025, 9(10), 564; https://doi.org/10.3390/jcs9100564 - 14 Oct 2025

Viewed by 378

Abstract

This study aimed to develop an industrially scalable coating route for enhancing the oxidation resistance of carbon fiber fabrics, a critical requirement for next-generation aerospace and high-temperature composite structures. To achieve this goal, synthesis of hexagonal boron nitride (h-BN) layers was achieved via [...] Read more.

This study aimed to develop an industrially scalable coating route for enhancing the oxidation resistance of carbon fiber fabrics, a critical requirement for next-generation aerospace and high-temperature composite structures. To achieve this goal, synthesis of hexagonal boron nitride (h-BN) layers was achieved via a single wet step in which the fabric was impregnated with an ammonia–borane/THF solution and subsequently nitrided for 2 h at 1000–1500 °C in flowing nitrogen. Thermogravimetric analysis coupled with X-ray diffraction revealed that amorphous BN formed below ≈1200 °C and crystallized completely into (002)-textured h-BN (with lattice parameters a ≈ 2.50 Å and c ≈ 6.7 Å) once the dwell temperature reached ≥1300 °C. Complementary XPS, FTIR and Raman spectroscopy confirmed a near-stoichiometric B:N ≈ 1:1 composition and the elimination of O–H/N–H residues as crystallinity improved. Low-magnification SEM (100×) confirmed the uniform and large-area coverage of the BN layer on the carbon fiber tows, while high-magnification SEM revealed a progressive densification of the coating from discrete nanospheres to a continuous nanosheet barrier on the fibers. Oxidation tests in flowing air shifted the onset of mass loss from 685 °C for uncoated fibers to 828 °C for the coating produced at 1400 °C; concurrently, the peak oxidation rate moved ≈200 °C higher and declined by ~40%. Treatment at 1500 °C conferred no additional benefit, indicating that 1400 °C provides the optimal balance between full crystallinity and limited grain coarsening. The resulting dense h-BN film, aided by an in situ self-healing B₂O₃ glaze above ~800 °C, delayed carbon fiber oxidation by ≈140 °C. Overall, the process offers a cost-effective, large-area alternative to vapor-phase deposition techniques, positioning BN-coated carbon fiber fabrics for robust service in extreme oxidative environments. Full article

(This article belongs to the Section Fiber Composites)

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14 pages, 2654 KB

Open AccessArticle

Microstructure and Hydrogen Storage Properties of Composites Derived from Oxidized Alloy Glass in the System of Zr-Pd-Pt

by Masakuni Ozawa, Naoya Katsuragawa, Masatomo Hattori and Hidemi Kato

J. Compos. Sci. 2025, 9(10), 563; https://doi.org/10.3390/jcs9100563 - 13 Oct 2025

Viewed by 282

Abstract

A study on the hydrogen storage of composite materials derived from alloy glass in the system of Zr-Pd-Pt was conducted through the integration of multiple methodologies. The alloy following heat treatment in air at temperatures ranging from 280 °C to 800 °C showed [...] Read more.

A study on the hydrogen storage of composite materials derived from alloy glass in the system of Zr-Pd-Pt was conducted through the integration of multiple methodologies. The alloy following heat treatment in air at temperatures ranging from 280 °C to 800 °C showed a precipitated structure comprising metallic Pd-Pt particles and a ZrO₂ matrix. In the sample treated at 280 °C, the spillover phenomenon of absorbed hydrogen was suggested. The plateau region of the hydrogen pressure–concentration (PCT) isotherm showed the gradient profiles for the samples oxidized at 400 °C, 600 °C, and 800 °C. In the equilibrium absorption process, the ΔH° of approximately 38 kJ/mol was proposed, and the highest storage of hydrogen was H/Pd = 0.61 by the sample oxidized in air at 600 °C. The temperature programmed reduction (TPR) results exhibited rapid hydrogen release behavior at temperatures ranging from 50 °C to 65 °C. The findings offer novel insights into the microstructure, fabrication process, and overall hydrogen absorption/desorption properties of the composites prepared from a Zr-Pd-Pt alloy glass. Full article

(This article belongs to the Special Issue Composite Materials for Hydrogen Storage)

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17 pages, 9120 KB

Open AccessArticle

Processing of Steelmaking Slags into Artificial Granular Aggregate for Concrete by Forced Carbonation

by Tamara Bakhtina, Nikolay Lyubomirskiy, Alexey Gusev, Aleksandr Bakhtin, Ivan Tyunyukov, Valentina Volchenkova and Wolfgang Linert

J. Compos. Sci. 2025, 9(10), 562; https://doi.org/10.3390/jcs9100562 - 13 Oct 2025

Viewed by 285

Abstract

This article presents the results of experimental studies to determine the possibility of processing steelmaking slags into an artificial granulated filler for concrete by the method of forced carbonization and the stabilization of the obtained filler in the concrete matrix over time. The [...] Read more.

This article presents the results of experimental studies to determine the possibility of processing steelmaking slags into an artificial granulated filler for concrete by the method of forced carbonization and the stabilization of the obtained filler in the concrete matrix over time. The utilization of metallurgical waste and technogenic CO₂ is a global problem. In this work, the method of the granulation of finely ground converter (BOF) and electric steelmaking (EAF) slags was used to obtain artificial granules and their subsequent forced carbonization in the developed laboratory carbonization chamber. Within the framework of this study, the quantitative binding of CO₂ by granules based on BOF and EAF slags was established, which amounted to 5.2 and 7.8% by weight, respectively. It was determined that the mass loss during crushability testing, indirectly characterizing the actual compressive strength of the granule material, depending on the type of slag and grain size, ranges from 13.6 to 42.3%, which is quite sufficient for using this artificial filler in concrete production. Based on the developed batches of fillers, concretes were obtained that have a compressive strength of 30.7 to 37.8 MPa in 28 days of hardening, which generally corresponds to concrete class B25. The preliminary studies and the results obtained indicate the prospects of processing steel slags into artificial granulated fillers by forced carbonization and using this product in concrete production. Full article

(This article belongs to the Special Issue Novel Cement and Concrete Materials)

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14 pages, 6606 KB

Open AccessArticle

Bio-Derived Porous Carbon/Nickel Oxide Composite for High-Performance Energy Storage Applications

by Aigerim R. Seitkazinova, Meruyert Nazhipkyzy, Kenes Kudaibergenov, Almagul Issanbekova, Nurgul S. Bergeneva, Alisher Abdisattar and Meiramgul Kyzgarina

J. Compos. Sci. 2025, 9(10), 561; https://doi.org/10.3390/jcs9100561 - 13 Oct 2025

Viewed by 215

Abstract

The development of bio-derived composites represents a sustainable and cost-effective strategy for advanced energy storage applications. In this work, a porous carbon/nickel oxide (NiO) composite was synthesized from orange peel via carbonization at 500 °C followed by KOH activation at 700 °C and [...] Read more.

The development of bio-derived composites represents a sustainable and cost-effective strategy for advanced energy storage applications. In this work, a porous carbon/nickel oxide (NiO) composite was synthesized from orange peel via carbonization at 500 °C followed by KOH activation at 700 °C and subsequent hydrothermal NiO modification. The resulting material exhibited a hierarchical porous structure with a high specific surface area (2120 m² g⁻¹ for OP_500_700 and 1968 m² g⁻¹ for NiO-modified OP_500_700_0.1M), with both values being significantly higher than that of the non-activated OP_500 (3.40–18.12 m² g⁻¹). Electrochemical evaluation revealed that the NiO-functionalized composite achieved a specific capacitance of 306.0 F g⁻¹ at 5 mV s⁻¹ and 281.5 F g⁻¹ at 2 A g⁻¹, surpassing the pristine activated carbon (281.9 F g⁻¹ and 259.6 F g⁻¹, respectively). In addition, both electrodes demonstrated excellent cycling stability, retaining more than 80% capacitance after 5000 charge–discharge cycles at a high current density of 20 A g⁻¹, while the NiO-modified electrode further benefited from a self-activation effect leading to >100% retention. These findings emphasize the synergistic effects of hierarchical porosity and NiO pseudocapacitance, establishing orange peel-derived carbon/NiO composites as scalable and sustainable electrode materials for next-generation supercapacitors. Full article

(This article belongs to the Section Composites Applications)

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21 pages, 3777 KB

Open AccessArticle

Optical and Thermal Studies, Isothermal Crystallization Kinetics and Mechanical Properties of Poly(lactic acid) Nanocomposites Based on Hybrid Lignin/MWCNT Nanomaterial

by Andreas Pitsavas, Rafail O. Ioannidis, Sofia Makri, Stefania Koutsourea, Alexios Grigoropoulos, Ioanna Deligkiozi, Alexandros Zoikis-Karathanasis, Eleftheria Xanthopoulou and Dimitrios N. Bikiaris

J. Compos. Sci. 2025, 9(10), 560; https://doi.org/10.3390/jcs9100560 - 13 Oct 2025

Viewed by 255

Abstract

A depth study of optical, isothermal crystallization and mechanical properties was conducted on a series of poly(lactic acid) (PLA) nanocomposites based on lignin/multi-walled carbon nanotubes (MWCNTs) hybrid nanomaterial. The preparation was performed via solution casting followed by melt mixing. For comparison reasons, a [...] Read more.

A depth study of optical, isothermal crystallization and mechanical properties was conducted on a series of poly(lactic acid) (PLA) nanocomposites based on lignin/multi-walled carbon nanotubes (MWCNTs) hybrid nanomaterial. The preparation was performed via solution casting followed by melt mixing. For comparison reasons, a group of PLA/lignin polymeric materials were prepared. Infrared spectroscopy (FTIR) did not reveal any significant impact on the main peaks of the nanocomposites by the incorporation of the additives. The optical properties were strongly affected by the content of the additive, as long as the thermal transitions parameters as evaluated from the differential scanning calorimetry (DSC) show important differences between cold and melt crystallization. X-ray diffraction (XRD) showed the semicrystalline behavior of the materials, while during isothermal crystallization experiments, the hybrid conductive nanomaterial acted as nucleation agent by promoting crystallization. Under evaluation of the mechanical properties, Young’s modulus tensile parameter increased significantly while the content of the hybrid nanomaterial increased, and the bending experiments of the materials with low content of the additives did not break. Thus, these substrates could be promising candidates for engineering applications, such as printed electronics. Full article

(This article belongs to the Section Nanocomposites)

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40 pages, 7197 KB

Open AccessReview

Pultrusion and Vitrimer Composites: Emerging Pathways for Sustainable Structural Materials

by Vishal Kumar, Khaled W. Shahwan, Wenbin Kuang, Kevin L. Simmons, Philip Taynton and Emily R. Cieslinski

J. Compos. Sci. 2025, 9(10), 559; https://doi.org/10.3390/jcs9100559 - 13 Oct 2025

Viewed by 522

Abstract

Pultrusion is a manufacturing process used to produce fiber-reinforced polymer composites with excellent mechanical, thermal, and chemical properties. The resulting materials are lightweight, durable, and corrosion-resistant, making them valuable in aerospace, automotive, construction, and energy sectors. However, conventional thermoset composites remain difficult to [...] Read more.

Pultrusion is a manufacturing process used to produce fiber-reinforced polymer composites with excellent mechanical, thermal, and chemical properties. The resulting materials are lightweight, durable, and corrosion-resistant, making them valuable in aerospace, automotive, construction, and energy sectors. However, conventional thermoset composites remain difficult to recycle due to their infusible and insoluble cross-linked structure. This review explores integrating vitrimer technology a novel class of recyclable thermosets with dynamic covalent adaptive networks into the pultrusion process. As only limited studies have directly reported vitrimer pultrusion to date, this review provides a forward-looking perspective, highlighting fundamental principles, challenges, and opportunities that can guide future development of recyclable high-performance composites. Vitrimers combine the mechanical strength (tensile strength and modulus) of thermosets with the reprocessability and reshaping of thermoplastics through dynamic bond exchange mechanisms. These polymers offer high-temperature reprocessability, self-healing, and closed-loop recyclability, where recycling efficiency can be evaluated by the recovery yield retention of mechanical properties and reuse cycles meeting the demand for sustainable manufacturing. Key aspects discussed include resin formulation, fiber impregnation, curing cycles, and die design for vitrimer systems. The temperature-dependent bond exchange reactions present challenges in achieving optimal curing and strong fiber–matrix adhesion. Recent studies indicate that vitrimer-based composites can maintain structural integrity while enabling recycling and repair, with mechanical performance such as flexural and tensile strength comparable to conventional composites. Incorporating vitrimer materials into pultrusion could enable high-performance, lightweight products for a circular economy. The remaining challenges include optimizing curing kinetics, improving interfacial adhesion, and scaling production for widespread industrial adoption. Full article

(This article belongs to the Section Polymer Composites)

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22 pages, 4230 KB

Open AccessArticle

The Effect of Lubricant and Nanofiller Additives on Drilling Temperature in GFRP Composites

by Mohamed Slamani, Jean-François Chatelain and Siwar Jammel

J. Compos. Sci. 2025, 9(10), 558; https://doi.org/10.3390/jcs9100558 - 12 Oct 2025

Viewed by 294

Abstract

Glass fiber-reinforced polymer (GFRP) composites are highly susceptible to thermal damage during machining, which can compromise their structural integrity and final quality. This study examines the efficacy of graphene and wax additives in reducing drilling temperatures in GFRP composites. Nine unique samples were [...] Read more.

Glass fiber-reinforced polymer (GFRP) composites are highly susceptible to thermal damage during machining, which can compromise their structural integrity and final quality. This study examines the efficacy of graphene and wax additives in reducing drilling temperatures in GFRP composites. Nine unique samples were manufactured with varying weight percentages of wax (0%, 1%, 2%) and graphene (0%, 0.25%, 2%). Drilling experiments were performed on a CNC milling center under a range of cutting parameters, with temperature monitoring carried out using an infrared thermal camera. A hierarchical cubic response surface model was employed to analyze thermal behavior. The results indicate that cutting speed is the dominant factor, accounting for 67.28% of temperature generation. The formulation containing 2% wax and 0% graphene achieved the lowest average drilling temperature (64.64 °C), underscoring wax’s superior performance as both a lubricant and heat sink. Although graphene alone slightly elevated median temperatures, it substantially reduced thermal variability. The optimal condition for minimizing thermal damage was identified as 2% wax combined with a high cutting speed (200 mm/min), providing actionable insights for industrial process optimization. Full article

(This article belongs to the Special Issue Polymer Composites and Fibers, 3rd Edition)

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16 pages, 1619 KB

Open AccessArticle

Effect of Mixing Time on the Thermal Stability and Activation Energies of NiO/PMMA Nanocomposites

by Aytekin Ulutaş

J. Compos. Sci. 2025, 9(10), 557; https://doi.org/10.3390/jcs9100557 - 11 Oct 2025

Viewed by 305

Abstract

In this study, NiO nanoparticle–reinforced PMMA nanocomposites were fabricated by melt blending, and the influence of extrusion mixing time on structural and thermal properties was examined. Mixing durations of 6 and 12 min were applied, and the materials were characterized by X-ray diffraction [...] Read more.

In this study, NiO nanoparticle–reinforced PMMA nanocomposites were fabricated by melt blending, and the influence of extrusion mixing time on structural and thermal properties was examined. Mixing durations of 6 and 12 min were applied, and the materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). These analyses confirmed the presence of NiO within the PMMA matrix and indicated that prolonged mixing promoted particle agglomeration. Thermal behavior was assessed by thermogravimetric analysis (TGA) at heating rates of 5, 10, 15, and 20 K·min⁻¹, and activation energies of decomposition were calculated using the Kissinger, Takhor, and Augis–Bennett methods. The results showed that extended mixing reduced composite homogeneity and adversely affected thermal stability. Incorporation of NiO nanoparticles decreased both the onset decomposition temperature and the activation energy compared to pure PMMA, facilitating earlier degradation. At 620 K, pure PMMA exhibited ~8% mass loss, whereas the 12 min blend showed ~12% loss. These findings highlight the importance of nanoparticle dispersion and processing parameters in governing the degradation behavior of PMMA/NiO nanocomposites. Full article

(This article belongs to the Section Polymer Composites)

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13 pages, 2897 KB

Open AccessArticle

Thermal Performance of Silica-Coated Wood Particles

by Elif Yurttaş, Mariem Zouari, Silvo Hribernik and Matthew Schwarzkopf

J. Compos. Sci. 2025, 9(10), 556; https://doi.org/10.3390/jcs9100556 - 10 Oct 2025

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Abstract

Wood is one of the most widely used sustainable lignocellulosic materials, with numerous applications in consumer goods and the construction sector. Despite its positive properties, such as a high strength-to-weight ratio, thermal insulation, and low density, wood’s natural thermal degradation can limit its [...] Read more.

Wood is one of the most widely used sustainable lignocellulosic materials, with numerous applications in consumer goods and the construction sector. Despite its positive properties, such as a high strength-to-weight ratio, thermal insulation, and low density, wood’s natural thermal degradation can limit its potential applications. In composite applications like wood–plastic composites, the particle morphology and surface topography must be preserved to support intimate polymer–wood contact and mechanical interlocking. This study investigated the efficacy of a thin silica coating for thermal protection, which was applied via an in situ sol–gel method using the precursor tetraethoxysilane (TEOS). The wood particles and treatments were characterized using particle size analysis, physisorption, FTIR, SEM, XRD, and TGA analyses. After treatment, the specific and microporous surface area of wood particles increased by 118% and 97%, respectively, an effect of the porosity of silica itself. FTIR spectra of the silica-treated wood displayed peaks corresponding to Si stretching, and SEM micrographs confirmed a successful silica coating formation. TGA showed that the silica coating increased the temperatures needed to degrade the underlying hemicellulose and cellulose by 16 °C for all treatment levels. This particle-scale coating provided a promising method for producing thermally protected, functionalizable wood fillers for composites that maintain the filler geometry and potential mechanical interlocking, offering an attractive upcycling pathway for wood residues. Full article

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

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13 pages, 660 KB

Open AccessArticle

Design of Experiments (DoE) Approach for Optimizing the Processing and Manufacturing Parameters of SnO₂ Thin Films via Ultrasonic Pyrolytic Deposition

by Aldo Enrique Mariño-Gámez, Maria Eugenia Juarez-Huitron, Josúe Amilcar Aguilar-Martínez, Luis Felipe-Verdeja, Linda Viviana García-Quiñonez and Cristian Gómez-Rodríguez

J. Compos. Sci. 2025, 9(10), 555; https://doi.org/10.3390/jcs9100555 - 10 Oct 2025

Viewed by 237

Abstract

This work employed a design-of-experiments (DoE) strategy, specifically a 2³ full factorial design, to assess how suspension concentration (0.001–0.002 g/mL), substrate temperature (60–80 °C), and deposition height (10–15 cm) influence tin dioxide (SnO₂) thin films produced by ultrasonic spray pyrolysis [...] Read more.

This work employed a design-of-experiments (DoE) strategy, specifically a 2³ full factorial design, to assess how suspension concentration (0.001–0.002 g/mL), substrate temperature (60–80 °C), and deposition height (10–15 cm) influence tin dioxide (SnO₂) thin films produced by ultrasonic spray pyrolysis (USP). The response variable was the net intensity of the principal diffraction peak, used as an operational metric for detecting the deposited phase. All patterns matched the SnO₂ phase cassiterite reference without impurity peaks. Statistical analyses (ANOVA, Pareto and half-normal plots, and response surface methodology, RSM) identified suspension concentration as the most influential factor, followed by significant two- and three-factor interactions. The model exhibited a high coefficient of determination (R² = 0.9908) and low standard deviation (12.53), validating its predictive capability. The optimal deposition process was achieved at the highest suspension concentration (0.002 g/mL), lowest substrate temperature (60 °C), and shortest deposition height (10 cm). These results demonstrate the utility of full factorial DoE for quantifying and controlling deposition outcomes in USP and provide a robust statistical framework to guide the synthesis of SnO₂ thin films. Full article

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

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22 pages, 2698 KB

Open AccessArticle

Shear Capacity of Fiber-Reinforced Polymer (FRP)–Reinforced Concrete (RC) Beams Without Stirrups: Comparative Modeling with FRP Modulus, Longitudinal Ratio, and Shear Span-to-Depth

by Mereen Hassan Fahmi Rasheed, Bahman Omar Taha, Ayad Zaki Saber Agha, Mohamed M. Arbili and Payam Ismael Abdulrahman

J. Compos. Sci. 2025, 9(10), 554; https://doi.org/10.3390/jcs9100554 - 10 Oct 2025

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Abstract

This study develops data-driven models for predicting the shear capacity of reinforced concrete (RC) beams longitudinally reinforced with fiber-reinforced polymer (FRP) bars and lacking transverse reinforcement. Owing to the comparatively low elastic modulus and linear–elastic–brittle behavior of FRP bars, reliable shear prediction remains [...] Read more.

This study develops data-driven models for predicting the shear capacity of reinforced concrete (RC) beams longitudinally reinforced with fiber-reinforced polymer (FRP) bars and lacking transverse reinforcement. Owing to the comparatively low elastic modulus and linear–elastic–brittle behavior of FRP bars, reliable shear prediction remains a design challenge. A curated database of 402 tests was compiled from the literature, spanning wide ranges of beam size (width b, effective depth d), concrete compressive strength (f′c), FRP elastic modulus (Ef), longitudinal reinforcement ratio (ρf), and shear span-to-depth ratio (a/d). Multiple multivariate regression formulations—both linear and nonlinear—were developed using combinations of these variables, including a mechanics-informed reinforcement index (ρf·Ef). Model predictions were benchmarked against 15 existing expressions drawn from design codes, standards, and prior studies. Across the full database, the proposed models demonstrated consistently stronger agreement with experimental results than the existing predictors, yielding higher correlation and lower prediction error. The resulting closed-form equations are transparent and straightforward to implement, offering improved accuracy for the preliminary design and assessment of FRP-RC beams without stirrups while highlighting the influential roles of Ef, ρf, and a/d within the observed parameter ranges. Full article

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

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12 pages, 883 KB

Open AccessArticle

Optimizing Post-Processing Parameters of 3D-Printed Resin for Surgical Guides

by Maria Gabriela Packaeser, Alexander Christiaan Santana, Amanda Maria de Oliveira Dal Piva, Cornelis Johannes Kleverlaan and João Paulo Mendes Tribst

J. Compos. Sci. 2025, 9(10), 553; https://doi.org/10.3390/jcs9100553 - 10 Oct 2025

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Abstract

This study evaluated post-processing protocols for 3D-printed implant surgical guides, aiming to determine the ideal timing after printing and post-curing durations that do not compromise residual monomer release and leachable components or mechanical properties. Specimens made of a surgical guide resin were 3D-printed [...] Read more.

This study evaluated post-processing protocols for 3D-printed implant surgical guides, aiming to determine the ideal timing after printing and post-curing durations that do not compromise residual monomer release and leachable components or mechanical properties. Specimens made of a surgical guide resin were 3D-printed (Formlabs Form 2) into bars (14 × 1 × 1 mm; n = 10) and square-shaped samples (10 × 10 × 1 mm; n = 1). They were grouped based on the time elapsed after printing (immediate, 24 h, and 72 h) and underwent washing in 99% isopropyl alcohol. Post-curing was performed for 5, 10, 20, or 30 min using a UV-light curing unit (NextDent LC-3DPrint Box). Residual monomer and components levels were assessed through solvent dissolution tests (n = 5), while mechanical properties were evaluated via flexural strength (n = 10) and hardness (n = 10). Statistical analysis with one-way ANOVA and Tukey’s post hoc test showed no significant differences in flexural strength across curing times or storage periods (p > 0.05), with values ranging from 42.93 MPa to 59.43 MPa. Monomers and leachable components were significantly higher immediately after printing (0.84 ± 0.36 mm³) compared to other groups (p < 0.05). For Vickers hardness, a 10 min curing protocol produced values comparable to longer durations (20.26 HV at 20 min/24 h), while the lowest hardness was 14.59 HV in the 5 min groups (p < 0.001). These findings suggest that delaying post-processing up to 72 h and reducing curing time to 10 min do not compromise mechanical properties, released monomers, and leachable components. Full article

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

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19 pages, 4640 KB

Open AccessArticle

Preparation of Aluminum Matrix Composites Reinforced with Hybrid MAX–MXene Particles for Enhancing Mechanical Properties and Tribological Performance

by Zipeng Li, Qinghua Li, Junda You, Fuguo Li, Guo Yu, Wen Zhang and Zikun Liang

J. Compos. Sci. 2025, 9(10), 552; https://doi.org/10.3390/jcs9100552 - 10 Oct 2025

Viewed by 372

Abstract

This study presents a novel methodology for the fabrication of aluminum matrix composites (AMCs) reinforced with a hybrid of MAX phase (Ti₃AlC₂) and MXene (Ti₃C₂T_x) particles via vacuum hot-pressing sintering, aiming to enhance [...] Read more.

This study presents a novel methodology for the fabrication of aluminum matrix composites (AMCs) reinforced with a hybrid of MAX phase (Ti₃AlC₂) and MXene (Ti₃C₂T_x) particles via vacuum hot-pressing sintering, aiming to enhance the mechanical properties and tribological performance of aluminum matrix composites. The hybrid-reinforced aluminum matrix composites were fabricated with Ti₃AlC₂/Ti₃C₂T_x reinforcements at a 1:1 mass ratio, incorporating reinforcement contents of 5 wt.%, 15 wt.%, and 25 wt.%, respectively. The optimized vacuum hot press sintering process was as follows: firstly, a cold press pressure of 20 MPa was applied to the composite powder, and then hot press sintering was carried out by means of segmental pressurization with a sintering pressure of 20 MPa, a temperature of 500 °C, and a heat preservation of 1 h before cooling in the furnace. It was found by micro-morphological characterization and mechanical property testing that with the increase of Ti₃AlC₂/Ti₃C₂T_x reinforcement content (5 wt.%→15 wt.%), the micro-hardness of the composites (31.9→76.1 HV_0.2), compressive strength (41.7→151.9 MPa), and tribological properties (friction coefficient 0.68→0.50) were significantly improved; however, when the content of reinforcement exceeded 15 wt.%, the deterioration of properties triggered by the increase in pore defects and particle agglomeration leads instead to a decrease in compressive strength (by 12.3%), apparent modulus of elasticity (specimen’s compressive specific stiffness, by 9.8%) and frictional stability (coefficient of friction recovered to 0.62). The 15 wt.% hybrid reinforcement composites demonstrated optimal strength-toughness synergies, exhibiting a 361.6% increase in yield strength and a 597.1% increase in apparent modulus of elasticity compared to pure aluminum. Furthermore, the friction coefficient exhibited a 26.47% reduction in comparison to pure aluminum, thereby substantiating enhanced tribological performance. The observed enhancements are attributed to the synergistic effects of the MAX and MXene phases, where MXene improves interfacial wettability and densification, while MAX particles enhance overall strength through diffusion reinforcement. Full article

(This article belongs to the Section Metal Composites)

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24 pages, 3909 KB

Open AccessArticle

Investigations on Repeated Overheating by Hot Air of Aromatic Epoxy-Based Carbon Fiber-Reinforced Plastics with and Without Thermoplastic Toughening

by Sebastian Eibl and Lara Greiner

J. Compos. Sci. 2025, 9(10), 551; https://doi.org/10.3390/jcs9100551 - 8 Oct 2025

Viewed by 286

Abstract

This work provides a comparison of two commercial carbon fiber reinforced plastic (CFRP) materials: HexPly^® M18 1/G939 and RTM6/G939. Differences due to the additional thermoplastic in one CFRP are investigated for the two otherwise nearly identical, aromatic epoxy-based composites with respect to [...] Read more.

This work provides a comparison of two commercial carbon fiber reinforced plastic (CFRP) materials: HexPly^® M18 1/G939 and RTM6/G939. Differences due to the additional thermoplastic in one CFRP are investigated for the two otherwise nearly identical, aromatic epoxy-based composites with respect to thermal degradation. The scenario chosen for testing is based on real incidents of repeated overheating by hot gases between roughly 200 and 320 °C, leading to moderate thermal damage. A special test setup is designed to continuously and alternately load CFRP with hot air in a rapid change. Post-mortem analysis is performed by mass loss, ultrasonic, and mechanical testing. Polymer degradation is analyzed by infrared spectroscopy. Even if the temperature-resistant thermoplastic polyetherimide (PEI) in the M18-1 matrix is enriched between the plies and a compensation of thermal strain during rapid temperature changes is expected, only a weak improvement is observed for residual strength in the presence of PEI, for continuous as well as alternating thermal loading. Thermally induced delaminations are even more pronounced in M18-1/G939. Deep insight is gained into degradation after repeated overheating of CFRP within the chosen scenario. Multivariate data analyses based on infrared spectroscopy allow for the determination of thermal history and residual strength, valuable for failure analysis. Full article

(This article belongs to the Special Issue Advances in Continuous Fiber Reinforced Thermoplastic Composites)

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14 pages, 293 KB

Open AccessReview

Tooth Allografts as Natural Biocomposite Bone Grafts: Can They Revolutionize Regenerative Dentistry?

by Ishita Singhal, Gianluca Martino Tartaglia, Sourav Panda, Seyda Herguner Siso, Angelo Michele Inchingolo, Massimo Del Fabbro and Funda Goker

J. Compos. Sci. 2025, 9(10), 550; https://doi.org/10.3390/jcs9100550 - 7 Oct 2025

Viewed by 572

Abstract

For decades, regeneration of alveolar bone defects has depended on traditional grafting options, such as autogenous/allogenic grafts or allografts. Recently, extracted teeth was introduced as an alternative graft source. Tooth autografts are being used and have gained significant attention due to their biocompatibility, [...] Read more.

For decades, regeneration of alveolar bone defects has depended on traditional grafting options, such as autogenous/allogenic grafts or allografts. Recently, extracted teeth was introduced as an alternative graft source. Tooth autografts are being used and have gained significant attention due to their biocompatibility, osteoconductivity, osteoinductivity, and osteogenic properties. Furthermore, tooth allografts have potential to act as natural biocomposites for oral regeneration procedures and might be advantageous options in near future. Recent advances in tooth banking, including cryopreservation, can serve to maintain bioactivity and to improve the safety, viability, and regenerative potential of teeth. They might be revolutionary in oral surgery, offering a more sustainable solution to the growing demand for bone regeneration procedures. Nevertheless, challenges such as immunogenic responses, ethical issues, and regulatory constraints persist. Ongoing research and technological innovation continue to address these problems. To date, the success rates of tooth autografts are promising, and they are regarded as a reliable option in clinical practice, with predictable outcomes in alveolar ridge preservation, sinus augmentation, periodontal regeneration, guided bone regeneration (GBR), and endodontic surgery by providing natural scaffolds for cell integration and bone remodeling. However, the scientific literature on tooth allografts is lacking. Therefore, this review aimed to comprehensively evaluate the scientific literature for comparing the properties of tooth grafts with other grafting options, in terms of processing techniques, and various clinical applications, positioning them as versatile biocomposites for the future, bridging material science and regenerative dentistry. Furthermore, possible applications of allogenic tooth grafts and overcoming current limitations are also discussed. Full article

(This article belongs to the Special Issue Advances in Biocomposite Materials for Regenerative Medicine and Biomedical Applications)

15 pages, 7140 KB

Open AccessArticle

Tuning the Carbonation Resistance of Metakaolin–Fly Ash-Based Geopolymers: The Dual Role of Reactive MgO in Microstructure and Degradation Mechanisms

by Shuai Li and Dongyu Ji

J. Compos. Sci. 2025, 9(10), 549; https://doi.org/10.3390/jcs9100549 - 7 Oct 2025

Viewed by 494

Abstract

Geopolymers, as a novel class of low-carbon and eco-friendly cementitious material, exhibit outstanding durability and promote the resource utilization of industrial solid wastes. However, as a promising alternative to ordinary Portland cement, its susceptibility to carbonation-induced degradation may limit its widespread application. To [...] Read more.

Geopolymers, as a novel class of low-carbon and eco-friendly cementitious material, exhibit outstanding durability and promote the resource utilization of industrial solid wastes. However, as a promising alternative to ordinary Portland cement, its susceptibility to carbonation-induced degradation may limit its widespread application. To address this challenge, this study systematically examined the effects of magnesium oxide (MgO) content and the metakaolin-to-fly ash ratio on the carbonation performance, mechanical properties, pH value, and microstructures of metakaolin–fly ash-based (MF-based) geopolymer pastes. The findings revealed that an increase in the fly ash ratio correlated with a decline in the compressive strength of MF-based geopolymer pastes. Conversely, the incorporation of MgO significantly enhanced the compressive strength, with higher fly ash ratios leading to more substantial improvements in strength. Furthermore, the addition of MgO and fly ash effectively mitigated the penetration of carbonation and the associated decrease in the pH value of the MF-based geopolymer pastes. Specifically, compared to the control group without MgO (M8F2-0%), MF-based geopolymer pastes with 4% and 8% MgO additions exhibited reductions in carbonation depth of 69.4% and 80.4%, respectively, after 28 days of carbonation, while pH values were observed to be 1.22 and 1.15 units higher, respectively. Additionally, microscopic structural analysis revealed that the inclusion of MgO resulted in a reduction in pore size, porosity, and mean pore diameter within the geopolymer pastes. This improvement was mainly attributed to the promotion of hydration processes by MgO, leading to the formation of fine Mg(OH)₂ crystals within the high-alkalinity pore solution, which enhances microstructural densification. In conclusion, the incorporation of MgO significantly improves the carbonation resistance and mechanical performance of MF-based geopolymers. It is recommended that future studies explore the long-term performance under combined environmental actions and evaluate the economic and environmental benefits of MgO-modified geopolymers for large-scale applications. Full article

(This article belongs to the Special Issue Composite Materials for Civil Engineering Applications)

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20 pages, 2587 KB

Open AccessArticle

Load-Dedicated Fiber Reinforcement of Additively Manufactured Lightweight Structures

by Sven Meißner, Daniel Kalisch, Rezo Aliyev, Sebastian Scholz, Henning Zeidler, Sascha Müller, Axel Spickenheuer and Lothar Kroll

J. Compos. Sci. 2025, 9(10), 548; https://doi.org/10.3390/jcs9100548 - 6 Oct 2025

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Abstract

This study focuses on a novel lightweight technology for manufacturing variable-axial fiber-reinforced polymer components. In the presented approach, channels following the load flow are implemented in an additively manufactured basic structure and impregnated continuous fiber bundles are pulled through these component-integrated cavities. Improved [...] Read more.

This study focuses on a novel lightweight technology for manufacturing variable-axial fiber-reinforced polymer components. In the presented approach, channels following the load flow are implemented in an additively manufactured basic structure and impregnated continuous fiber bundles are pulled through these component-integrated cavities. Improved channel cross-section geometries to enhance the mechanical performance are proposed and evaluated. The hypothesis posits that increasing the surface area of the internal channels significantly reduces shear stresses between the polymer basic structure and the integrated continuous fiber composite. A series of experiments, including analytical, numerical, and microscopic analyses, were conducted to evaluate the mechanical properties of the composites formed, focusing on Young’s modulus and tensile strength. In addition, an important insight into the failure mechanism of the novel fiber composite is provided. The results demonstrate a clear correlation between the channel geometry and mechanical performance, indicating that optimized designs can effectively reduce shear stress, thus improving load-bearing capacities. The findings reveal that while fiber volume content influences the impregnation quality, an optimal balance must be achieved to enhance mechanical properties. This research contributes to the advancement of production technologies for lightweight components through additive manufacturing and the development of new types of composite materials applicable in various engineering fields. Full article

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

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23 pages, 4001 KB

Open AccessArticle

Analysis of Elastic-Stage Mechanical Behavior of PBL Shear Connector in UHPC

by Lin Xiao, Yawen He, Hongjuan Wang, Xing Wei, Xuan Liao, Yingliang Wang and Xiaochun Dai

J. Compos. Sci. 2025, 9(10), 547; https://doi.org/10.3390/jcs9100547 - 5 Oct 2025

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Abstract

This paper investigates the mechanical behavior of PBL shear connectors in UHPC during the elastic stage, utilizing push-out experiments and numerical simulation. This study simplifies the mechanical behavior of PBL shear connectors in UHPC under normal service conditions as a plane strain problem [...] Read more.

This paper investigates the mechanical behavior of PBL shear connectors in UHPC during the elastic stage, utilizing push-out experiments and numerical simulation. This study simplifies the mechanical behavior of PBL shear connectors in UHPC under normal service conditions as a plane strain problem for the UHPC dowel and a Winkler’s Elastic foundation beam theory for the transverse reinforcement. The UHPC dowel is a thick-walled cylindrical shell subjected to non-axisymmetric loads inside and outside simultaneously in the plane-strain state. The stress solution is derived by assuming the contact stress distribution function and using the Airy stress function. The displacement solution is subsequently determined from the stresses by differentiating between elastic and rigid body displacements. By modeling the transverse reinforcement as an infinitely long elastic foundation beam, its displacement solution and stress solution are obtained. We obtain the load–slip curve calculation method by superimposing the displacement of UHPC with the transverse reinforcement in the direction of shear action. The proposed analytical solutions for stress and slip, as well as the method for calculating load–slip, are shown to be reliable by comparing them to the numerical simulation analysis results. Full article

(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)

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21 pages, 12738 KB

Open AccessArticle

Determining the Properties of a Layered Composite Plate Made of Twill-Weave Glass Fibre Fabric Using Non-Destructive Testing Methods

by Andrejs Kovalovs, Vitalijs Kuzmickis and Vladimir Kulakov

J. Compos. Sci. 2025, 9(10), 546; https://doi.org/10.3390/jcs9100546 - 5 Oct 2025

Viewed by 320

Abstract

A non-destructive method for determining the properties of laminated composite materials made of twill-weave glass fibre fabric is considered. To determine the elastic characteristics of the composite monolayer, a combined numerical–experimental method is used. The method combines the results of experimental tests and [...] Read more.

A non-destructive method for determining the properties of laminated composite materials made of twill-weave glass fibre fabric is considered. To determine the elastic characteristics of the composite monolayer, a combined numerical–experimental method is used. The method combines the results of experimental tests and numerical modelling methods using optimization techniques. Firstly, the method for determining the properties is tested in a virtual experiment to determine the influence of the elastic characteristics of the material that do not affect the frequency response. The adequacy of the approximation equations and the influence of elastic constants on frequency response are evaluated using Analysis of Variance (ANOVA). Using the results obtained, the properties of the elastic characteristics of layered composite plates made of twill-weave glass fibre fabric using vacuum infusion are determined. To compare the properties obtained from the dynamic calculation, a series of static measurements of tensile samples were carried out. The results showed that the elastic modulus from the static test and the flexural test do not coincide by 4% and 23%, respectively. The technique demonstrates high accuracy and applicability for the non-destructive determination of dynamic material properties in engineering practice. Full article

(This article belongs to the Special Issue Characterization and Modeling of Composites, 4th Edition)

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25 pages, 3901 KB

Open AccessArticle

Influence of Steel Fiber and Rebar Ratio on the Flexural Performance of UHPC T-Beams

by Huiqing Xue, Shichun Mao, Liyang Wang and Zongcai Deng

J. Compos. Sci. 2025, 9(10), 545; https://doi.org/10.3390/jcs9100545 - 4 Oct 2025

Viewed by 290

Abstract

To address the bottleneck issues of traditional concrete T-beams, such as excessive self-weight, susceptibility to cracking, and insufficient durability, this study investigates the flexural performance of Ultra-High-Performance Concrete (UHPC) T-beams. Through systematic experiments, the combined effects of three UHPC material ratios and three [...] Read more.

To address the bottleneck issues of traditional concrete T-beams, such as excessive self-weight, susceptibility to cracking, and insufficient durability, this study investigates the flexural performance of Ultra-High-Performance Concrete (UHPC) T-beams. Through systematic experiments, the combined effects of three UHPC material ratios and three rebar schemes were analyzed. Six UHPC T-beam specimens were designed, and flexural performance tests were conducted using a staged loading approach, focusing on crack propagation, failure modes, and load-deflection curves to reveal their mechanical behavior and failure mechanisms. The results indicate that steel fibers significantly enhance UHPC toughness. At a fiber content of 1.5%, the specimens exhibited a yield load of 395–418 kN, with an ultimate load increase of 93% compared to the fiber-free specimens. The failure mode transitioned from brittle shear to ductile flexural. Increasing the rebar ratio improved load-bearing capacity, with a 4.58% rebar ratio yielding an ultimate load of 543 kN (51% higher than B1-02), but reduced ductility by 36%. Steel fibers restricted crack widths to 0.1 mm via crack-bridging effects, raising the cracking load by 53% and the shear capacity by 2.8 times. UHPC mix ratio adjustments had a limited impact on beam performance at the same fiber content. Overall, UHPC T-beams exhibited a compressive concrete crushing-dominated failure mode, with load-deflection curves showing a 42% gentler slope than conventional concrete. The ductility coefficient ranged from 3.8 to 5.2. For engineering applications, it is recommended to maintain a steel fiber content of at least 1.5% and a rebar ratio of 2.5–4.0% to strike a balance between strength and ductility. Full article

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

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3 pages, 157 KB

Open AccessEditorial

Editorial for the Special Issue on Carbon Fiber Composites III

by Jiadeng Zhu

J. Compos. Sci. 2025, 9(10), 544; https://doi.org/10.3390/jcs9100544 - 4 Oct 2025

Viewed by 371

Abstract

Composites, which combine two or more components to produce a product with properties superior to those of their individual parts, have played a critical role in modern materials science and engineering [...] Full article

(This article belongs to the Special Issue Carbon Fiber Composites, Volume III)

17 pages, 3617 KB

Open AccessArticle

Sol–Gel Synthesis of Carbon-Containing Na₃V₂(PO₄)₃: Influence of the NASICON Crystal Structure on Cathode Material Properties

by Oleg O. Shichalin, Zlata E. Priimak, Alina Seroshtan, Polina A. Marmaza, Nikita P. Ivanov, Anton V. Shurygin, Danil K. Tsygankov, Roman I. Korneikov, Vadim V. Efremov, Alexey V. Ognev and Eugeniy K. Papynov

J. Compos. Sci. 2025, 9(10), 543; https://doi.org/10.3390/jcs9100543 - 3 Oct 2025

Viewed by 518

Abstract

With the rapid advancement of energy storage technologies, there is a growing demand for affordable, efficient, and environmentally benign battery systems. Sodium-ion batteries (SIBs) present a promising alternative to lithium-ion systems due to sodium’s high abundance and similar electrochemical properties. Particular attention is [...] Read more.

With the rapid advancement of energy storage technologies, there is a growing demand for affordable, efficient, and environmentally benign battery systems. Sodium-ion batteries (SIBs) present a promising alternative to lithium-ion systems due to sodium’s high abundance and similar electrochemical properties. Particular attention is given to developing NASICON -sodium (Na) super ionic conductor, type cathode materials, especially Na3V2(PO4)3, which exhibits high thermal and structural stability. This study focuses on the sol–gel synthesis of Na₃V₂(PO₄)₃ using citric acid and ethylene glycol, as well as investigating the effect of annealing temperature (400–1000 °C) on its structural and electrochemical properties. Phase composition, morphology, textural characteristics, and electrochemical performance were systematically analyzed. Above 700 °C, a highly crystalline NASICON phase free of secondary impurities was formed, as confirmed by X-ray diffraction (XRD). Microstructural evolution revealed a transition from a loose amorphous structure to a dense granular morphology, accompanied by changes in specific surface area and porosity. The highest surface area (67.40 m²/g) was achieved at 700 °C, while increasing the temperature to 1000 °C caused pore collapse due to sintering. X-ray photoelectron spectroscopy (XPS) confirmed the predominant presence of V³⁺ ions and the formation of V⁴⁺ at the highest temperature. The optimal balance of high crystallinity, uniform elemental distribution, and stable texture was achieved at 900 °C. Electrochemical testing in a Na/NVP half-cell configuration delivered an initial capacity of 70 mAh/g, which decayed to 55 mAh/g by the 100th cycle, attributed to solid-electrolyte interphase (SEI) formation and irreversible Na⁺ trapping. These results demonstrate that the proposed approach yields high-quality Na₃V₂(PO₄)₃ cathode materials with promising potential for sodium-ion battery applications. Full article

(This article belongs to the Special Issue Composite Materials for Energy Management, Storage or Transportation)

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J. Compos. Sci., Volume 9, Issue 10 (October 2025) – 61 articles

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