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J. Compos. Sci.
Volume 8
Issue 9
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J. Compos. Sci., Volume 8, Issue 9 (September 2024) – 49 articles

Cover Story (view full-size image): Polyurethane foams are widely used but are brittle in tension and bending. This study explores the mechanical properties of fibre-reinforced polyurethane (FRPU) foams with natural henequen fibres. Pull-out tests identified an optimal foam density of 100 kg/m3 with a 10 mm fibre length. FRPU foams with this density and fibre contents of 1, 2, and 3 wt% were tested. Compression tests showed increased elastic modulus and yield stress, with a maximum 71% increase in the compressive yield stress for 2% fibre content. The FRPU foams also absorbed more energy than the unreinforced PU foam. Flexural tests revealed a 40% increase in flexural strength for 1% fibre content. These findings highlight the potential of FRPU foams with henequen fibres as sustainable materials with enhanced mechanical properties. View this paper
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14 pages, 15296 KiB  
Article
Optimization of Al6061 Nanocomposites Production Reinforced with Multiwalled Carbon Nanotubes
by Beatriz Monteiro and Sónia Simões
J. Compos. Sci. 2024, 8(9), 381; https://doi.org/10.3390/jcs8090381 - 23 Sep 2024
Abstract
This study investigates the impact of multi-walled carbon nanotubes (MWCNTs) on the microstructure and mechanical properties of Al6061 nanocomposites. The MWCNTs were uniformly dispersed in the aluminum alloy matrix using ultrasonication following cold pressing and sintering in a vacuum. The effect of the [...] Read more.
This study investigates the impact of multi-walled carbon nanotubes (MWCNTs) on the microstructure and mechanical properties of Al6061 nanocomposites. The MWCNTs were uniformly dispersed in the aluminum alloy matrix using ultrasonication following cold pressing and sintering in a vacuum. The effect of the sintered temperature on the microstructure and mechanical properties of the nanocomposites was evaluated. The addition of MWCNTs resulted in grain refinement, with the nanocomposites exhibiting smaller and more uniformly distributed grains than the pure Al6061 matrix, particularly at lower sintering temperatures of 580 and 600 °C. The nanocomposites also demonstrated an increase in hardness, with peak values observed at 580 °C, primarily due to the effective dispersion of MWCNTs, which restrict dislocation movement and reinforce grain boundaries. While higher sintering temperatures led to significant grain growth and less uniform hardness distribution, lower temperatures favored finer grain structures and more homogeneous hardness profiles. The results suggest that the optimal sintering temperature for achieving the best balance between microstructure and mechanical properties is 580 °C. However, the study also highlights the need for optimized dispersion techniques to achieve a more uniform distribution of MWCNTs. 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, 1565 KiB  
Article
Design of an Overhead Crane in Steel, Aluminium and Composite Material Using the Prestress Method
by Luigi Solazzi and Ivan Tomasi
J. Compos. Sci. 2024, 8(9), 380; https://doi.org/10.3390/jcs8090380 - 23 Sep 2024
Abstract
The present research describes a design of an overhead crane using different materials with a prestress method, which corresponds to an external compression force with the aim of reducing the displacement of the beam due to the external load. This study concerns a [...] Read more.
The present research describes a design of an overhead crane using different materials with a prestress method, which corresponds to an external compression force with the aim of reducing the displacement of the beam due to the external load. This study concerns a bridge crane with a span length of 10 m, with a payload equal to 20,000 N and an estimated fatigue life of 50,000 cycles. Three different materials are studied: steel S355JR, aluminium alloy 6061-T6 and carbon fibre-reinforced polymer (CFRP). These materials are analysed with and without the contribution of the prestress method. In reference to the prestressed steel solution (which has a weight equal to 79% of the non-prestressed configuration), this study designed an aluminium solution that is 50.7% of the weight of the steel one and a composite solution that is always 20.3% of the steel configuration. In combining the methods, i.e., the materials and prestress, compared to the non-prestressed steel solution with a weight evaluated to be 758 kg, the weight of the aluminium configuration is equal to 40% of the traditional one, and the composite value is reduced to 16%, with a weight of 121 kg. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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17 pages, 8517 KiB  
Article
Evaluation of Different ZX Tensile Coupon Designs in Additive Manufacturing of Amorphous and Semi-Crystalline Polymer Composites
by Raviteja Rayaprolu, Ajay Kumar Kadiyala and Joseph G. Lawrence
J. Compos. Sci. 2024, 8(9), 379; https://doi.org/10.3390/jcs8090379 - 22 Sep 2024
Abstract
The layer-by-layer deposition of molten polymer filament in fused deposition modeling (FDM) has evolved as a disruptive technology for building complex parts. This technology has drawbacks such as the anisotropic property of the printed parts resulting in lower strength for parts printed in [...] Read more.
The layer-by-layer deposition of molten polymer filament in fused deposition modeling (FDM) has evolved as a disruptive technology for building complex parts. This technology has drawbacks such as the anisotropic property of the printed parts resulting in lower strength for parts printed in the vertical Z direction compared with the other two planes. In this manuscript, we attempt to address these challenges as well as the lack of standardization in sample preparation and mechanical testing of the printed parts. The paper focuses on process parameters and design optimization of the ZX build orientation. Type I tensile bars in ZX orientation were printed as per the ASTM D638 standard using two (2B) and four (4B) tensile bar designs. The proposed design reduces material loss and post-processing to extract the test coupons. Printing a type I tensile bar in the ZX orientation is more challenging than type IV and type V due to the increased length of the specimen and changes in additional heat buildup during layer-by-layer deposition. Three different polymer composite systems were studied: fast-crystallizing nanofiller-based high-temperature nylon (HTN), slow-crystallizing nanofiller-based polycyclohexylene diethylene terephthalate glycol-modified (PCTG), and amorphous carbon fiber-filled polyetherimide (PEI-CF). For all the polymer composite systems, the 2B showed the highest strength properties due to the shorter layer time aiding the diffusion in the interlayers. Further, rheological studies and SEM imaging were carried out to understand the influence of the two designs on fracture mechanics and interlayer bonding, providing valuable insights for the field of additive manufacturing and material science. Full article
(This article belongs to the Special Issue Application of Composite Materials in Additive Manufacturing)
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16 pages, 2454 KiB  
Article
EIS Behavior of Polyethylene + Graphite Composite Considered as an Approximation to an Ensemble of Microelectrodes
by Javier Navarro-Laboulais, José Juan García-Jareño, Jerónimo Agrisuelas and Francisco Vicente
J. Compos. Sci. 2024, 8(9), 378; https://doi.org/10.3390/jcs8090378 - 22 Sep 2024
Abstract
The electrical percolation of alternating current through two-phase polyethylene/graphite composite electrodes with different contents of graphite microparticles immersed in aqueous KCl solutions has been studied. Above the graphite content of the first percolation threshold, the electrochemical impedance response of this electrode is associated [...] Read more.
The electrical percolation of alternating current through two-phase polyethylene/graphite composite electrodes with different contents of graphite microparticles immersed in aqueous KCl solutions has been studied. Above the graphite content of the first percolation threshold, the electrochemical impedance response of this electrode is associated with an equivalent circuit of resistance Ru in series with a constant phase element (CPE). An insulator material + conducting filler model is proposed in which the electroactive surface is considered as the intersection of the percolation cluster through the solid and the cluster associated with the interfacial region. CPE is analyzed assuming a distribution of microcapacitors of the graphite particles in contact with the dielectric solution and inside the dielectric polymeric phase. Full article
(This article belongs to the Section Composites Applications)
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13 pages, 3743 KiB  
Article
Evaluating the Hybridization and Treatment Effects on the Mechanical Properties of Enset and Sisal Hybrid Composites
by Abera Endesha Bekele and Hirpa G. Lemu
J. Compos. Sci. 2024, 8(9), 377; https://doi.org/10.3390/jcs8090377 - 21 Sep 2024
Abstract
Natural fibers are among the most employed reinforcements in the manufacturing process of innovative fiber-based composite materials. As with any composite materials, the properties of composites depend on the type and properties of the fiber, fiber structure, composition (hybridization), and treatment. In this [...] Read more.
Natural fibers are among the most employed reinforcements in the manufacturing process of innovative fiber-based composite materials. As with any composite materials, the properties of composites depend on the type and properties of the fiber, fiber structure, composition (hybridization), and treatment. In this study, the composite was fabricated by using hand lay-up with 100/0, 75/25, 50/50, 25/75, and 0/100 Enset/Sisal (E/S) hybridization ratio. Three cases, i.e., untreated, 5%, and 10% NaOH treatment were considered. The effects of hybridization and treatment on the mechanical and water absorption properties of woven and unidirectional orientation of E/S hybrid composite were evaluated by using a two-factors analysis of variance. The fiber–matrix interfacial fractured surface was characterized by scanning electron microscopy. The treated (5% NaOH) and woven fiber orientation exhibited better mechanical properties than untreated and unidirectional hybrid composites. The flexural and tensile strength of the woven composite was improved by 5% and 9%, respectively, when compared with woven untreated 50/50 volume ratio of composites. In both samples and orientations, the hybridization effects show a higher percentage contribution to the mechanical properties. But, in both orientations of composite samples, the treatment effects show a higher percentage contribution for water absorption properties. Full article
(This article belongs to the Special Issue Recent Progress in Hybrid Composites)
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14 pages, 4500 KiB  
Article
Lithium-Containing Sorbents Based on Rice Waste for High-Temperature Carbon Dioxide Capture
by Gaukhar Yergaziyeva, Manshuk Mambetova, Nursaya Makayeva, Banu Diyarova and Nurbol Appazov
J. Compos. Sci. 2024, 8(9), 376; https://doi.org/10.3390/jcs8090376 - 21 Sep 2024
Abstract
This article studies the influence of the nature of the carrier from rice wastes on the sorption properties of lithium-containing sorbents, and also considers the impact of the modifying additive (K2CO3) and adsorption temperature on their characteristics. It has [...] Read more.
This article studies the influence of the nature of the carrier from rice wastes on the sorption properties of lithium-containing sorbents, and also considers the impact of the modifying additive (K2CO3) and adsorption temperature on their characteristics. It has been shown that the sorption capacity of 11LiK/SiO2 at 500 °C reached 36%, which is associated with the formation of lithium orthosilicate in the sorbent composition, as well as with an increase in the specific surface area of the sorbent. After 12 cycles of sorption–desorption, it was found that the sorption capacity of 11LiK/SiO2 for CO2 decreased by only 8%. Rice waste-based sorbents have a high sorption capacity for CO2 at high temperatures, which allows them to be used for carbon dioxide capture. The results of this study indicate the prospects of using agricultural residues to create effective adsorbents that contribute to reducing environmental pollution and combating global warming. Full article
(This article belongs to the Section Composites Applications)
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11 pages, 4513 KiB  
Article
Nanostructured C@CuS Core–Shell Framework with High Lithium-Ion Storage Performance
by Changqing Jin, Zaidong Peng, Yongxing Wei, Ruihua Nan, Zhong Yang, Zengyun Jian and Qingping Ding
J. Compos. Sci. 2024, 8(9), 375; https://doi.org/10.3390/jcs8090375 - 21 Sep 2024
Abstract
In this study, we have synthesized a nanostructured core–shell framework of carbon-coated copper sulfide (C@CuS) through a one-step precipitation technique. The carbon sphere template facilitated the nucleation of CuS nanostructures. The synthesized nanocomposites have demonstrated remarkable lithium-ion storage capabilities when utilized as an [...] Read more.
In this study, we have synthesized a nanostructured core–shell framework of carbon-coated copper sulfide (C@CuS) through a one-step precipitation technique. The carbon sphere template facilitated the nucleation of CuS nanostructures. The synthesized nanocomposites have demonstrated remarkable lithium-ion storage capabilities when utilized as an anode in lithium-ion batteries. Notably, they exhibit an impressive rate capability of 314 mAh g−1 at a high current density of 5000 mA g−1, along with excellent long-term cycle stability, maintaining 463 mAh g−1 at 1000 mA g−1 after 800 cycles. This superior performance is due to the core–shell architecture of the composite, where the carbon core enhances the conductivity of CuS nanoparticles and mitigates volume expansion, thus preventing capacity loss. Our study not only elucidates the significance of carbon in the construction of nano-heterojunctions or composite electrodes but also presents a practical approach to significantly boost the electrochemical performance of CuS and other metal sulfides. Full article
(This article belongs to the Special Issue Advancements in Composite Materials for Energy Storage Applications)
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28 pages, 3366 KiB  
Review
Towpreg—An Advanced Composite Material with a Potential for Pressurized Hydrogen Storage Vessels
by Anka Trajkovska Petkoska, Blagoja Samakoski, Bisera Samardjioska Azmanoska and Viktorija Velkovska
J. Compos. Sci. 2024, 8(9), 374; https://doi.org/10.3390/jcs8090374 - 21 Sep 2024
Abstract
Hydrogen is one of the critical components to address global challenges such as climate change, environmental pollution and global warming. It is a renewable source of energy that has many advantages compared to other renewables. Even though it may not be a “silver [...] Read more.
Hydrogen is one of the critical components to address global challenges such as climate change, environmental pollution and global warming. It is a renewable source of energy that has many advantages compared to other renewables. Even though it may not be a “silver bullet” solution for the polluted world, there is still a big expectation that it can solve some of the energy crisis and challenges in the transportation, domestic and industry sectors. This study reviews the latest advancements in materials science, especially in the composite materials used for energy storage/transportation tanks. Special attention is given to towpreg material structures as the most promising ones for hydrogen storage. Various types of storage vessels are reviewed with emphasis on the most advanced type IV and type V vessels for energy (hydrogen) storage. The manufacturing processes, mainly filament winding (FW) and automatic fiber placement (AFP), are reviewed with their pros and cons. The sustainability aspects for the most promising hydrogen technologies, limitations and future challenges are also discussed. Full article
(This article belongs to the Special Issue Composite Materials for Energy Management, Storage or Transportation)
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14 pages, 5484 KiB  
Article
Core–Shell Inorganic/Organic Composites Composed of Polypyrrole Nanoglobules or Nanotubes Deposited on MnZn Ferrite Microparticles: Electrical and Magnetic Properties
by Marek Jurča, Lenka Munteanu, Jarmila Vilčáková, Jaroslav Stejskal, Miroslava Trchová, Jan Prokeš and Ivo Křivka
J. Compos. Sci. 2024, 8(9), 373; https://doi.org/10.3390/jcs8090373 - 21 Sep 2024
Abstract
Core–shell inorganic/organic composites have often been applied as fillers in electromagnetic interference shielding. Those composed of conducting polymers and ferrites are of particular interests with respect to their electrical and magnetic properties. Pyrrole was oxidized in aqueous medium in the presence of manganese-zinc [...] Read more.
Core–shell inorganic/organic composites have often been applied as fillers in electromagnetic interference shielding. Those composed of conducting polymers and ferrites are of particular interests with respect to their electrical and magnetic properties. Pyrrole was oxidized in aqueous medium in the presence of manganese-zinc ferrite microparticles with ammonium peroxydisulfate or iron(III) chloride to yield polypyrrole-coated, core–shell microstructures. The effect of methyl orange dye on the conversion of globular polypyrrole to nanotubes has been demonstrated by electron microscopy when iron(III) chloride was used as an oxidant. The formation of polypyrrole was proved by FTIR spectroscopy. The completeness of ferrite coating was confirmed by Raman spectroscopy. The resistivity of composite powders was determined by four-point van der Pauw method as a function of pressure applied up to 10 MPa. The conductivity of composite powders was determined by a polypyrrole matrix and only moderately decreased with increasing content of ferrite. The highest conductivity of composites, 13–25 S cm−1, was achieved after the deposition of polypyrrole nanotubes. Magnetic properties of composites have not been affected by the polypyrrole moiety, and the magnetization of composites was proportional to the ferrite content. Full article
(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2024)
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15 pages, 4416 KiB  
Article
Polymer Boron-Containing Composite for Protecting Astronauts of Manned Orbital Stations from Secondary Neutron Radiation
by Roman Nikolaevich Yastrebinsky, Anna Viktorovna Yastrebinskaya, Andrey Ivanovich Gorodov and Anastasia Vladislavovna Akimenko
J. Compos. Sci. 2024, 8(9), 372; https://doi.org/10.3390/jcs8090372 - 21 Sep 2024
Abstract
This article considers the prospects of using heat-resistant polyimide boron-containing composites to protect astronauts of manned orbital stations from secondary neutron radiation. Variant calculations are performed regarding neutron and gamma-quanta flux distributions in a polyimide composite material with different boron content used to [...] Read more.
This article considers the prospects of using heat-resistant polyimide boron-containing composites to protect astronauts of manned orbital stations from secondary neutron radiation. Variant calculations are performed regarding neutron and gamma-quanta flux distributions in a polyimide composite material with different boron content used to reduce capture radiation. The dependences of spatial distributions of thermal neutron flux density and the gamma-quanta dose rate in a polyimide composite layer with a boron content of 0 to 5% are obtained. An experimental assessment of the energy distribution of neutron and gamma radiation behind the protective polyimide composite is carried out. The introduction of boron atoms in an amount of 3.0 wt.% shows the absence of bursts of secondary gamma radiation energy in the composite, which is due to the high cross-section of thermal neutron absorption by boron atoms. As a result, with a material layer thickness of 3–10 cm, the gamma-quanta dose rate decreases by 2–3 times. The differential thermal analysis method showed that the upper limit of the working temperature of the polyimide composite is 500 °C. The polyimide matrix filled with boron atoms can find effective application in the development of new radiation-protective polymer materials used in manned orbital stations. Full article
(This article belongs to the Section Polymer Composites)
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13 pages, 5562 KiB  
Article
Advancing Thermochromic Glass Durability: Reinforcing Thermosensitive Hydrogels with Enhanced Adhesion Techniques
by Dewei Qian, Suili Peng, Tao Zhang, Liang Qin and Weijia Wen
J. Compos. Sci. 2024, 8(9), 371; https://doi.org/10.3390/jcs8090371 - 20 Sep 2024
Abstract
The growing use of glass in architecture has driven research into reducing its energy consumption. Thermochromic (TC) glass technology shows promise for enhancing building energy efficiency by regulating solar heat dynamically. Although TC glass helps reduce heat radiation, additional solutions like Low-E or [...] Read more.
The growing use of glass in architecture has driven research into reducing its energy consumption. Thermochromic (TC) glass technology shows promise for enhancing building energy efficiency by regulating solar heat dynamically. Although TC glass helps reduce heat radiation, additional solutions like Low-E or vacuum glass are needed to control heat convection and conduction. Low-E glass, while effective in lowering heat transfer, may increase surface temperature. Thermo-sensitive hydrogels, known for their light-scattering properties at high temperatures, have been explored to complement TC glass. However, their stability at elevated temperatures remains a challenge, especially for applications requiring durability under varying weather conditions. This study proposes enhancing the adhesion between hydrogel and glass by introducing silica–oxygen bonds. As a result, TC glass demonstrates stable performance over 100 cycles within temperature ranges from 85 °C to 30 °C in summer and 40 °C to −20 °C in winter. Furthermore, by incorporating ethylene glycol, the freezing point of TC glass is reduced to −26 °C, rendering it suitable for use in colder regions. The implementation of TC glass effectively addresses the dual requirements of summer shading and winter heating in areas with both cold winters and hot summers, significantly reducing building energy consumption. This study contributes substantially to developing advanced intelligent building materials, paving the way for more sustainable architectural designs. Full article
(This article belongs to the Special Issue Composites: A Sustainable Material Solution)
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18 pages, 12689 KiB  
Article
Ballistic Performance of Raffia Fiber Fabric Reinforcing Epoxy Composites as Standalone Targets
by Douglas Santos Silva, Raí Felipe Pereira Junio, Marcelo Henrique Prado da Silva and Sergio Neves Monteiro
J. Compos. Sci. 2024, 8(9), 370; https://doi.org/10.3390/jcs8090370 - 20 Sep 2024
Abstract
Reliable ballistic armor systems are crucial to ensure the safety of humans and vehicles. Typically, these systems are constructed from various materials like fiber-reinforced polymer composites, which are utilized for a favorable weight to ballistic protection ratio. In particular, there has been a [...] Read more.
Reliable ballistic armor systems are crucial to ensure the safety of humans and vehicles. Typically, these systems are constructed from various materials like fiber-reinforced polymer composites, which are utilized for a favorable weight to ballistic protection ratio. In particular, there has been a quest for eco-friendly materials that offer both strong mechanical properties and sustainable advantages. The present work conducted a ballistic analysis of epoxy matrix composites using raffia (Raphia vinifera) fibers from the Amazon region as reinforcement. The experiments investigated the limit and residual velocities of composites with 10, 20, and 30 vol% of raffia. The experimental density of the composites was lower than that of the epoxy. Fractured surfaces were examined by scanning electron microscopy (SEM) to reveal the failure mechanism. The results showed that composites with 10 vol% raffia fiber fabric had the highest ballistic energy absorption (168.91 J) and limit velocity (201.43 m/s). The ones with 30 vol% displayed a higher level of physical integrity. The SEM micrographs demonstrated the failure mechanisms were associated with delamination and fiber breakage. There was a small variation in residual velocity between the composites reinforced with 10, 20, and 30 vol% of raffia, with 826.66, 829.75, and 820.44 m/s, respectively. Full article
(This article belongs to the Section Fiber Composites)
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10 pages, 2393 KiB  
Article
The Effects of Different Blending Methods on the Thermal, Mechanical, and Optical Properties of PMMA/SiO2 Composites
by Chi-Kai Lin, Jia-Wei Xie, Ping-Jui Tsai, Hao-Yu Wang, Zhi-Wei Lu, Tung-Yi Lin and Chih-Yu Kuo
J. Compos. Sci. 2024, 8(9), 369; https://doi.org/10.3390/jcs8090369 - 20 Sep 2024
Abstract
In this study, PMMA/SiO2 composites were fabricated with monodispersed SiO2 and PMMA using four distinct methods—physical blending, in situ polymerization, random copolymerization, and block copolymerization—to investigate the composites’ thermal, mechanical, and optical properties. In the physical blending approach, SiO2 nanoparticles [...] Read more.
In this study, PMMA/SiO2 composites were fabricated with monodispersed SiO2 and PMMA using four distinct methods—physical blending, in situ polymerization, random copolymerization, and block copolymerization—to investigate the composites’ thermal, mechanical, and optical properties. In the physical blending approach, SiO2 nanoparticles were dispersed in a PMMA solution, while during in situ polymerization, silica nanoparticles were incorporated during the synthesis of PMMA/SiO2 composites. 3-methacryloxypropyltrimethoxysilane (MPS) was modified on the SiO2 surface to introduce the reactive double bonds. The MPS@SiO2 was either random- or block-copolymerized with PMMA through RAFT polymerization. The PMMA/SiO2 composites prepared via these different methods were characterized using FTIR, TGA, and DSC to determine their chemical structures, thermal degradation temperatures, and glass transition temperatures, respectively. Scanning electron microscopy (SEM) was employed to observe the microstructures and dispersion of the composites. This comprehensive analysis revealed that the PMMA/SiO2 composites prepared via block copolymerization exhibited thermal stability at temperatures between 200 and 300 °C. Additionally, they demonstrated excellent transparency (86%) and scratch resistance (≥6H) while maintaining mechanical strength, suggesting their potential application in thermal insulation materials. Full article
(This article belongs to the Special Issue Progress in Polymer Composites, Volume III)
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16 pages, 2201 KiB  
Article
Hydrogen Generation by Nickel Electrodes Coated with Linear Patterns of PTFE
by Alion Alushi, Atheer Al-Musawi, Kyuman Kim, Chong-Yong Lee, Klaudia Wagner and Gerhard F. Swiegers
J. Compos. Sci. 2024, 8(9), 368; https://doi.org/10.3390/jcs8090368 - 19 Sep 2024
Abstract
Previous studies have shown that partially coating electrode surfaces with patterns of ‘islands’ of hydrophobic tetrafluoroethylene (PTFE; Teflon) may lead to more energy efficient gas generation. This occurred because the gas bubbles formed preferentially on the PTFE, thereby freeing up the catalytically active [...] Read more.
Previous studies have shown that partially coating electrode surfaces with patterns of ‘islands’ of hydrophobic tetrafluoroethylene (PTFE; Teflon) may lead to more energy efficient gas generation. This occurred because the gas bubbles formed preferentially on the PTFE, thereby freeing up the catalytically active metallic surfaces to produce the gas more efficiently. This work examined electrochemically induced hydrogen bubble formation on a nickel electrode surface that had been coated with linear patterns of PTFE. The impact of the PTFE line size (width) and degree of coverage was examined and analyzed. No improvement in electrical energy efficiency was observed up to 15 mA/cm2 when comparing the PTFE-coated electrodes with the control bare uncoated electrode. However, increasing PTFE coverage up to 15% generally improved electrolysis performance. Moreover, samples with 50% wider lines performed better (at the equivalent PTFE coverage), yielding an overpotential decline of up to 3.9% depending on the PTFE coverage. A ‘bubble-scavenging’ phenomenon was also observed, wherein bubbles present on the PTFE lines rapidly shrunk until they disappeared. Full article
(This article belongs to the Special Issue Advancements in Composite Materials for Energy Storage Applications)
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11 pages, 1013 KiB  
Article
Preliminary Removal of Mercury from Depleted Coal Sorbents by Thermal Vacuum Method with Associated Extraction of Precious Metal Composite
by Bagdaulet Kenzhaliyev, Sergey Trebukhov, Valeriy Volodin, Alina Nitsenko, Yerkebulan Kilibayev, Olga Kolesnikova and Xeniya Linnik
J. Compos. Sci. 2024, 8(9), 367; https://doi.org/10.3390/jcs8090367 - 18 Sep 2024
Abstract
This paper presents the results of laboratory studies for the distillation of mercury from depleted coal sorbents produced in gold recovery factories using CIP technology. The mercury content in these materials is more than 1%. The developed technology was tested in a large-scale [...] Read more.
This paper presents the results of laboratory studies for the distillation of mercury from depleted coal sorbents produced in gold recovery factories using CIP technology. The mercury content in these materials is more than 1%. The developed technology was tested in a large-scale laboratory on a pilot vacuum sublimation electric furnace with the rheological movement of dispersed material. The use of this equipment makes it possible to demercurize various materials with fairly high moisture (up to 20%). It eliminates the use of an additional technological operation—drying the material in a vacuum drying oven. It has been shown that a high degree of mercury distillation is achieved (more than 99.8%) at 350–400 °C in the reaction space and residual pressure in the system of less than 1.33 kPa, with residual mercury content in the material of less than 0.001% (10 mg/kg), which complies with the European environmental standards. Mercury-free coal sorbents are sent for combustion for the additional extraction of precious metal composites. The proposed vacuum technology is characterized by its environmental safety because the process is performed in sealed equipment, eliminating toxic emissions of mercury vapor into the atmosphere. The proposed vacuum technology equipment is characterized by reliability and ease of use. Full article
(This article belongs to the Section Metal Composites)
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19 pages, 6257 KiB  
Article
In Situ Microscopy of Fatigue-Loaded Embedded Transverse Layers of Cross-Ply Laminates: The Role of an Inhomogeneous Fiber Distribution
by Andreas Baumann, Miro Duhovic and Joachim Hausmann
J. Compos. Sci. 2024, 8(9), 366; https://doi.org/10.3390/jcs8090366 - 18 Sep 2024
Abstract
Composites with continuous fiber reinforcement offer excellent fatigue properties but are tedious to characterize due to anisotropy and the interplay of fatigue properties, processing conditions, and the constituents. The global fiber volume content can affect both monotonic and fatigue strength. This dependence can [...] Read more.
Composites with continuous fiber reinforcement offer excellent fatigue properties but are tedious to characterize due to anisotropy and the interplay of fatigue properties, processing conditions, and the constituents. The global fiber volume content can affect both monotonic and fatigue strength. This dependence can increase the necessary testing effort even when processing conditions and constituents remain identical. This work presents an in situ edge observation method, enabling light microscopy during loading. As a result, digital image correlation can be employed to study local strains at cracking sites on the scale of fiber bundles. The geometric influence on fatigue damage is examined in non-crimp fabrics of glass and carbon fibers. Two epoxy resins (one modified by irradiation) are investigated to verify the geometric influence under changed polymer properties. The microscopy-based image correlation revealed that damage forms at very low global strains of only 0.2–0.3% in glass fiber-reinforced epoxy laminates. For carbon fiber-reinforced epoxy, laminate cracking was found to emanate mainly from regions containing stitching fibers. Across both reinforcements, irradiation treatment led to delayed cracks, emanating from interfaces. This detailed analysis of the damage formation is used as a basis for proposed applications of the in situ strain information. Full article
(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2024)
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19 pages, 2705 KiB  
Article
Natural Rubber Latex Wastes from Balloon Production as Valuable Source of Raw Material: Processing, Physico-Mechanical Properties, and Structure
by Jacek Kędzia, Józef Haponiuk and Krzysztof Formela
J. Compos. Sci. 2024, 8(9), 365; https://doi.org/10.3390/jcs8090365 - 18 Sep 2024
Abstract
This study explores the potential for recycling natural rubber (NR) latex waste from balloon production through the devulcanization and revulcanization processes. The mechanical devulcanization of colored latex balloon waste was conducted, followed by revulcanization using a sulfur-based system. The reclaimed rubber’s properties, including [...] Read more.
This study explores the potential for recycling natural rubber (NR) latex waste from balloon production through the devulcanization and revulcanization processes. The mechanical devulcanization of colored latex balloon waste was conducted, followed by revulcanization using a sulfur-based system. The reclaimed rubber’s properties, including crosslink density, tensile strength, and abrasion resistance, were compared with those of virgin NR. The results demonstrate that the reclaimed rubber maintains a crosslink density close to that of virgin NR. Hardness and abrasion resistance were comparable, indicating successful material recovery. Structural analyses, including FTIR and SEM microscopy, revealed that the devulcanization process effectively allowed for successful revulcanization. This study concludes that NR latex waste can be effectively recycled and reused in rubber composite formulations, offering a sustainable approach to waste management in the rubber industry and contributing to developing eco-friendly materials. In the context of this research, integrating advanced chemical and physical methods, such as solubility parameter calculations and enhanced devulcanization techniques, could further optimize the devulcanization process. These methods quantitatively enhance the efficiency of material recovery, offering a path to more sustainable recycling practices. The findings suggest that combining such advanced methodologies could significantly improve recycled NR latex’s overall performance and applicability in industrial applications. Full article
(This article belongs to the Special Issue Advanced Composite Materials from Natural and Synthetic Sources: Fabrication, Characterization and Practical Application, Volume II)
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22 pages, 15194 KiB  
Article
Effect of High Fiber Content on Properties and Performance of CFRTP Composites
by Saeed Ziaee, Eric Kerr-Anderson, Aaron Johnson, David Eastep and Beckry Abdel-Magid
J. Compos. Sci. 2024, 8(9), 364; https://doi.org/10.3390/jcs8090364 - 17 Sep 2024
Abstract
Continuously reinforced thermoplastic composites are widely used in structural applications due to their toughness, light weight, and shorter process cycle. Moreover, they provide flexibility in design and material selection. Unlike thermoset composites, continuous fiber content to maximize mechanical properties in thermoplastic composites has [...] Read more.
Continuously reinforced thermoplastic composites are widely used in structural applications due to their toughness, light weight, and shorter process cycle. Moreover, they provide flexibility in design and material selection. Unlike thermoset composites, continuous fiber content to maximize mechanical properties in thermoplastic composites has not been well investigated. In this paper, three thermoplastic systems are investigated to study the optimum content of continuous fiber reinforcement. These systems include carbon fiber/polyphenylene sulfide (PPS), glass fiber/PPS, and glass fiber/high-density polyethylene (HDPE). Tapes were made at several fiber contents, and samples were compression molded and tested using thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile, 3-point flexure, and short-beam shear tests. Results revealed that higher fiber content led to an increase in the glass transition and melt transition temperatures of the polymer. Some mechanical properties increased with fiber content and then began to decrease upon further addition of fibers, while other properties, such as ductility and interfacial bond strength, decreased with more reinforcement. Furthermore, the optimum fiber contents to maximize mechanical properties are different for different properties and different materials. Full article
(This article belongs to the Special Issue Advances in Continuous Fiber Reinforced Thermoplastic Composites)
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15 pages, 3717 KiB  
Article
Bio-Based Polyurethane Composites from Macauba Kernel Oil: Part 1, Matrix Synthesis from Glycerol-Based Polyol
by Rodolfo Andrade Breves, Daniel Ajiola, Roseany de Vasconcelos Vieira Lopes, Rafael L. Quirino, Baptiste Colin, Anelie Petrissans, Mathieu Petrissans and Maria José Araújo Sales
J. Compos. Sci. 2024, 8(9), 363; https://doi.org/10.3390/jcs8090363 - 17 Sep 2024
Abstract
Polyurethanes are the result of a reaction between an isocyanate and a polyol. The large variety of possible reagents creates many possible polyurethanes to be made, such as soft foams, rigid foams, coatings, and adhesives. This polymer is one of the most produced [...] Read more.
Polyurethanes are the result of a reaction between an isocyanate and a polyol. The large variety of possible reagents creates many possible polyurethanes to be made, such as soft foams, rigid foams, coatings, and adhesives. This polymer is one of the most produced and consumed polymers in the world with an ever-increasing demand. Despite its usual petrochemical nature, research on bio-based polyurethanes flourishes due to the ease in creating bio-based polyols. This work covers the synthesis of a novel macauba kernel oil polyol by the epoxidation of the oil, followed by a ring-opening reaction of the epoxide with glycerol, used for the preparation of polyurethane foams using different NCO/OH ratios. The FTIR and H1 results confirm the formation of the epoxide and polyol, and the polymers in all NCO/OH ratios were confirmed by FTIR, showing great similarities between the samples, especially PU 1.0 and PU 1.2. Despite the TGs showing close behaviors for the three samples, their DTGs showed great difference between the samples, with PU 1.0 presenting a regular PU DTG profile with three degradation peaks while the other two sample presented five degradation peaks, indicating a higher crosslinking density in them. Full article
(This article belongs to the Special Issue Progress in Polymer Composites, Volume III)
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13 pages, 6192 KiB  
Article
Investigation of Injection Repair Technique for Non-Visible Damages in Automotive Composites
by Ilaria Papa, Antonio Langella and Maria Rosaria Ricciardi
J. Compos. Sci. 2024, 8(9), 362; https://doi.org/10.3390/jcs8090362 - 17 Sep 2024
Abstract
In recent decades, composite materials have been widely used in several fields. The challenge in recent years has been to find an effective and automatable repair technique for these materials. Low-speed impact tests were carried out on panels made from prepregs in carbon [...] Read more.
In recent decades, composite materials have been widely used in several fields. The challenge in recent years has been to find an effective and automatable repair technique for these materials. Low-speed impact tests were carried out on panels made from prepregs in carbon fibre and epoxy resin. An innovative repair technique has been tested by injecting resin into the delamination due to the impact event. After the first impact, some panels were repaired and re-impacted, while others were impacted twice consecutively. The data analysis and damage detection by an ultrasound technique demonstrate that the absorbed energy of the twice-impacted panels is lower than that of the repaired ones, demonstrating a configuration similar to that of the panels impacted only once. The results of this research have demonstrated the effectiveness of the repairs. Full article
(This article belongs to the Section Composites Manufacturing and Processing)
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23 pages, 12241 KiB  
Article
Bridging Behavior of Palm Fiber in Cementitious Composite
by Selamawit Fthanegest Abrha, Helen Negash Shiferaw and Toshiyuki Kanakubo
J. Compos. Sci. 2024, 8(9), 361; https://doi.org/10.3390/jcs8090361 - 16 Sep 2024
Abstract
This study addresses the growing need for sustainable construction materials by investigating the mechanical properties and behavior of palm fiber-reinforced cementitious composite (FRCC), a potential eco-friendly alternative to synthetic fiber reinforcements. Despite the promise of natural fibers in enhancing the mechanical performance of [...] Read more.
This study addresses the growing need for sustainable construction materials by investigating the mechanical properties and behavior of palm fiber-reinforced cementitious composite (FRCC), a potential eco-friendly alternative to synthetic fiber reinforcements. Despite the promise of natural fibers in enhancing the mechanical performance of composites, challenges remain in optimizing fiber distribution, fiber–composite bonding mechanism, and its balance to matrix strength. To address these challenges, this study conducted extensive experimental programs using palm fiber as reinforcement, focusing on understanding the fiber–matrix interaction, determining the pullout load–slip relationship, and modeling fiber bridging behavior. The experimental program included density calculations and scanning electron microscope (SEM) analysis to examine the surface morphology and diameter of the fibers. Single fiber pullout tests were performed under varying conditions to assess the pullout load, slip behavior, and failure modes of the palm fiber, and a relationship between the pullout load and slip with the embedded length of the palm fiber was constructed. A trilinear model was developed to describe the pullout load–slip behavior of single fibers, and a corresponding palm-FRCC bridging model was constructed using the results from these tests. Section analysis was conducted to assess the adaptability of the modeled bridging law calculations, and the analysis result of the bending moment–curvature relationship shows a good agreement with the experimental results obtained from the four-point bending test of palm-FRCC. These findings demonstrate the potential of palm fibers in improving the mechanical performance of FRCC and contribute to the broader understanding of natural fiber reinforcement in cementitious composites. Full article
(This article belongs to the Special Issue Composites: A Sustainable Material Solution)
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21 pages, 15598 KiB  
Article
Optimising Additive Manufacturing to Produce PLA Sandwich Structures by Varying Cell Type and Infill: Effect on Flexural Properties
by Gabriele Marabello, Mohamed Chairi and Guido Di Bella
J. Compos. Sci. 2024, 8(9), 360; https://doi.org/10.3390/jcs8090360 - 14 Sep 2024
Abstract
The objective of this research is to optimize additive manufacturing processes, specifically Fused Filament Fabrication (FFF) techniques, to produce sandwich structures. Mono-material specimens made of polylactic acid (PLA) were produced, where both the skin and core were fabricated in a single print. To [...] Read more.
The objective of this research is to optimize additive manufacturing processes, specifically Fused Filament Fabrication (FFF) techniques, to produce sandwich structures. Mono-material specimens made of polylactic acid (PLA) were produced, where both the skin and core were fabricated in a single print. To optimize the process, variations were made in both the base cell geometry of the core (Tri-Hexagon and Gyroid) and the core infill (5%, 25%, 50%, and 75%), evaluating their effects on static three-point bending behavior. Optical microscopy was employed to assess both the structure generated by additive manufacturing and the fracture modes. The findings reveal that increasing the infill, and thus the core density, enhances the mechanical properties of the structure, although the improvement is such that samples with 50% infill already demonstrate excellent performance. The difference between hexagonal and Gyroid structures is not significant. Based on microscopic analyses, it is believed that the evolution of 3D printers, from open to closed chamber designs, could significantly improve the deposition of the various layers. Full article
(This article belongs to the Special Issue Additive Manufacturing of Advanced Composites)
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15 pages, 5282 KiB  
Article
Composite Building Materials Prepared from Bioresources: Use of Rice Husk for Autoclaved Lightweight Concrete Production
by Shao-Lin Peng, Ying-Liang Chen and Yu-Sheng Dai
J. Compos. Sci. 2024, 8(9), 359; https://doi.org/10.3390/jcs8090359 - 13 Sep 2024
Abstract
Rice husk (RH) and straw are common agricultural wastes in Asian countries, and they are potential bioresources for building materials. RH contains a large amount of SiO2, and many studies have burnt RH to ash and then used it as a [...] Read more.
Rice husk (RH) and straw are common agricultural wastes in Asian countries, and they are potential bioresources for building materials. RH contains a large amount of SiO2, and many studies have burnt RH to ash and then used it as a silica supplement in cement and concrete. However, the combustion of RH has an additional cost and exacerbates CO2 emissions and air pollution. RH inherently has a low bulk density and porous structure; therefore, it should be possible to directly use RH as a lightweight additive in concrete. The purposes of this study were to use RH in the production of autoclaved lightweight concrete (ALC) and to examine the effects of RH on ALC properties. Four RHs with different particle sizes, i.e., >1.2 mm, 0.6–1.2 mm, 0.3–0.6 mm, and <0.3 mm, were used as lightweight additives, and the ALC specimens were prepared with 0–20 wt.% RHs by autoclaving at 189 °C for 12 h. The >0.3 mm RH was applicable to prepare the ALC specimens, and the decomposition effect of <0.3 mm RH was significant. Both the bulk density and the compressive strength of the ALC specimens decreased with increasing RH size. RH with a particle size larger than 1.2 mm seems more appropriate for ALC production than RH with a smaller particle size because of the lower bulk density and higher compressive strength. The Ca/Si ratio decreased with increasing RH size, which affected the formation of tobermorite and thus reduced the compressive strength of the ALC specimens. With a suitable water-to-solid (W/S) ratio, the use of RHs as lightweight additives can yield ALC specimens that meet the requirements of commercial products. Full article
(This article belongs to the Special Issue Novel Cement and Concrete Materials)
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14 pages, 4452 KiB  
Article
Hollow Concrete Block Based on High-Strength Concrete as a Tool for Reducing the Carbon Footprint in Construction
by Mikhail Elistratkin, Alena Salnikova, Nataliya Alfimova, Natalia Kozhukhova and Elena Pospelova
J. Compos. Sci. 2024, 8(9), 358; https://doi.org/10.3390/jcs8090358 - 13 Sep 2024
Abstract
The production and servicing of cement-based building materials is a source of large amounts of carbon dioxide emissions globally. One of the ways to reduce its negative impact, is to reduce concrete consumption per cubic meter of building structure through the introduction of [...] Read more.
The production and servicing of cement-based building materials is a source of large amounts of carbon dioxide emissions globally. One of the ways to reduce its negative impact, is to reduce concrete consumption per cubic meter of building structure through the introduction of hollow concrete products. At the same time, to maintain the load-bearing capacity of the building structure, it is necessary to significantly increase the strength of the concrete used. However, an increase in strength should be achieved not by increasing cement consumption, but by increasing the efficiency of its use. This research is focused on the development of technology for the production of thin-walled hollow concrete blocks based on high-strength, self-compacting, dispersed, micro-reinforced, fine-grained concrete. The use of this concrete provides 2–2.5 times higher strength in the amount of Portland cement consumed in comparison with ordinary concrete. The formation of external contours and partitions of thin-walled hollow blocks is ensured through the use of disposable formwork or cores used as void formers obtained by FDM 3D printing. This design solution makes it possible to obtain products based on high-strength concrete with higher structural and thermal insulation properties compared to now existing lightweight concrete-based blocks. Another area of application of this technology could be the production of wall structures of free configuration and cross-section due to their division, at the digital modeling stage, into individual element-blocks, manufactured in a factory environment. Full article
(This article belongs to the Special Issue Research on Sustainable Cement-Based Composites)
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20 pages, 10364 KiB  
Article
Synergistic Effect in MoS2 Nanosheets–Biochar Nanocomposites with Enhanced Surface Area and Electrical Conductivity for Energy Storage Applications
by Thangaraj Pandiselvi, Chithiraiselvan Praveena, Venkatachalam Sridevi, Balu Alagar Venmathi Maran and Masanari Kimura
J. Compos. Sci. 2024, 8(9), 357; https://doi.org/10.3390/jcs8090357 - 12 Sep 2024
Abstract
Layered molybdenum disulfide (MoS2), a transition metal dichalcogenide, shows distinct optical, electrical, and physical properties at a few-layer thickness. MoS2 nanosheets (NSs) widely explored for energy and environmental applications but have limitations with respect to their electrical conductivity and charge [...] Read more.
Layered molybdenum disulfide (MoS2), a transition metal dichalcogenide, shows distinct optical, electrical, and physical properties at a few-layer thickness. MoS2 nanosheets (NSs) widely explored for energy and environmental applications but have limitations with respect to their electrical conductivity and charge transfer characteristics due to their low surface area. These limitations can be overcome by combining MoS2 NSs with carbon-based materials like graphene, carbon nanotubes, and biochar, which can enhance the properties in a synergistic way. In this study, biochar (BC), a carbon-rich material prepared from vegetable biomass through low-temperature pyrolysis has been combined with bulk MoS2 in various ratios using an aqueous phase exfoliation method to form MoS2 NSs–biochar nanocomposites. The spectroscopic, structural, and morphological studies confirmed the synergistic interaction between MoS2 and BC, which is well reflected in the facile exfoliation process and the formation of few layered MoS2 NSs on the surface of the BC without any agglomeration. The electrochemical studies prove that incorporating biochar into MoS2 enhances the capacitive behavior and reduces the charge transfer resistance compared to pristine MoS2 NSs and pristine biochar. This study provides ample scope for the composite to be explored for energy storage applications, especially towards the development of electrode materials due to the synergistic effect between MoS2 NSs and biochar. Full article
(This article belongs to the Special Issue Advancements in Composite Materials for Energy Storage Applications)
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38 pages, 2644 KiB  
Review
Conventional Machining of Metal Matrix Composites towards Sustainable Manufacturing—Present Scenario and Future Prospects
by Endalkachew Mosisa Gutema and Hirpa G. Lemu
J. Compos. Sci. 2024, 8(9), 356; https://doi.org/10.3390/jcs8090356 - 12 Sep 2024
Abstract
Metal matrix composites (MMCs) epitomize a promising class of resources in modern manufacturing, offering an enhanced strength-to-weight ratio and high-temperature performance which make them ideal for applications demanding over conventional metals. However, their machining presents significant challenges due to their inherent material properties. [...] Read more.
Metal matrix composites (MMCs) epitomize a promising class of resources in modern manufacturing, offering an enhanced strength-to-weight ratio and high-temperature performance which make them ideal for applications demanding over conventional metals. However, their machining presents significant challenges due to their inherent material properties. The conventional machining methods including turning, milling, drilling, shaping, and the grinding of MMCs pose several challenges, facing limitations in terms of sustainability and efficiency. This paper explores the current perspective and prospects of the conventional machining techniques applied to MMCs, emphasizing sustainable manufacturing practices. Key aspects include the challenges posed by MMCs’ inherent heterogeneity, the MMC materials used, the MMC manufacturing process, the cutting constraints employed, tool wear, surface unevenness, surface integrity, and high energy consumption throughout machining. The study also explores promising advancements in tooling materials, cutting parameters’ optimization, innovative machining techniques aimed at minimizing the environmental impact and maximizing material utilization, and the strategies developed to overcome these challenges. The paper concludes by highlighting optimizing tools, and processes, and adopting emerging optimization techniques and opportunities for further research aimed at the industry, allowing it to move towards more efficient, eco-friendly production methods. Full article
(This article belongs to the Special Issue Metal Composites, Volume II)
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17 pages, 4548 KiB  
Article
Fracture Behavior of Crack-Damaged Concrete Beams Reinforced with Ultra-High-Performance Concrete Layers
by Zenghui Guo, Xuejun Tao, Zhengwei Xiao, Hui Chen, Xixi Li and Jianlin Luo
J. Compos. Sci. 2024, 8(9), 355; https://doi.org/10.3390/jcs8090355 - 10 Sep 2024
Abstract
Reinforcing crack-damaged concrete structures with ultra-high-performance concrete (UHPC) proves to be more time-, labor-, and cost-efficient than demolishing and rebuilding under the dual-carbon strategy. In this study, the extended finite element method (XFEM) in ABAQUS was first employed to develop a numerical model [...] Read more.
Reinforcing crack-damaged concrete structures with ultra-high-performance concrete (UHPC) proves to be more time-, labor-, and cost-efficient than demolishing and rebuilding under the dual-carbon strategy. In this study, the extended finite element method (XFEM) in ABAQUS was first employed to develop a numerical model of UHPC-reinforced single-notched concrete (U+SNC) beams, analyze their crack extension behavior, and obtain the parameters necessary for calculating fracture toughness. Subsequently, the fracture toughness and instability toughness of U+SNC were calculated using the improved double K fracture criterion. The effects of varying crack height ratios (a/h) of SNC, layer thicknesses (d) of UHPC reinforcement, and fiber contents in UHPC (VSF) on the fracture properties of U+SNC beams were comprehensively investigated. The results indicate that (1) the UHPC reinforcement layer significantly enhances the load-carrying capacity and crack resistance of the U+SNC beams. Crack extension in the reinforced beams occurs more slowly than in the unreinforced beams; |(2) the fracture performance of the U+BNC beams increases exponentially with d. Considering both the reinforcement effect benefit and beam deadweight, the optimal cost-effective performance is achieved when d is 20 mm; (3) with constant d, increasing a/h favors the reinforcement effect of UHPC on the beams; (4) as VSF increases, the crack extension stage in the U+BNC beam becomes more gradual, with higher toughness and flexural properties; therefore, the best mechanical properties are achieved at a VSF of 3%. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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14 pages, 5290 KiB  
Article
Influence of Solid-Phase and Melt-Quenching Na3Fe2(PO4)3 Polycrystal Production Technology on Their Structure and Ionic Conductivity
by A. S. Nogai, A. A. Nogai, D. E. Uskenbaev, E. A. Nogai, A. B. Utegulov, P. A. Dunayev, A. S. Tolegenova, Bazarbek Assyl-Dastan Bazarbekuly and A. A. Abikenova
J. Compos. Sci. 2024, 8(9), 354; https://doi.org/10.3390/jcs8090354 - 9 Sep 2024
Abstract
This article studies the influence of solid-phase (type 1 samples) and melt-quenching (type 2 samples) technological modes of obtaining Na3Fe2(PO4)3 polycrystals on their structures and ion-conducting properties. α-Na3Fe2(PO4)3 polycrystals [...] Read more.
This article studies the influence of solid-phase (type 1 samples) and melt-quenching (type 2 samples) technological modes of obtaining Na3Fe2(PO4)3 polycrystals on their structures and ion-conducting properties. α-Na3Fe2(PO4)3 polycrystals of the 1st type are formed predominantly under an isothermal firing regime, and the synthesis of the 2nd type is carried out under sharp temperature gradient conditions, contributing to the formation of glassy precursors possessing a reactive and deformed structure, in which the crystallization of crystallites occurs faster than in precursors obtained under isothermal firing. The elemental composition of α-Na3Fe2(PO4)3 type 2 polycrystals is maintained within the normal range despite the sharp non-equilibrium thermodynamic conditions of synthesis. The microstructure of the type 1 Na3Fe2(PO4)3 polycrystals is dominated by chaotically arranged crystallites of medium (7–10 μm) and large (15–35 μm) sizes, while the polycrystals of type 2 are characterized by the preferential formation of small (3–4 μm) and medium (7–10 μm) crystallites, causing uniaxial deformations in their structure, which contribute to a partial increase in their symmetry. The advantage of type 2 polycrystals is that they have higher density and conductivity and are synthesized faster than type 1 samples by a factor of 4. The article also considers the issues of crystallization in a solid-phase precursor from the classical point of view, i.e., the process of the formation of small solid-phase nuclei in the metastable phase and their growth to large particles due to association with small crystallites using phase transitions. Possible variants and models of crystallite growth in Na3Fe2(PO4)3 polycrystals, as well as distinctive features of crystallization between two types of samples, are discussed. Full article
(This article belongs to the Section Composites Manufacturing and Processing)
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11 pages, 692 KiB  
Article
Composite Coatings of Gellan Gum and Inulin with Lactobacillus casei: Enhancing the Post-Harvest Quality of Guava
by Rafael Emilio González-Cuello, Leidy Mendoza-Nova, Virginia Consuelo Rodriguez-Rodriguez, Joaquín Hernández-Fernández and Rodrigo Ortega-Toro
J. Compos. Sci. 2024, 8(9), 353; https://doi.org/10.3390/jcs8090353 - 9 Sep 2024
Abstract
Guava is a highly sought-after tropical fruit in the market due to its high content of vitamins, minerals, antioxidants, and other phenolic compounds. However, due to its climacteric nature, it has a short post-harvest shelf life. The aim of this study was to [...] Read more.
Guava is a highly sought-after tropical fruit in the market due to its high content of vitamins, minerals, antioxidants, and other phenolic compounds. However, due to its climacteric nature, it has a short post-harvest shelf life. The aim of this study was to develop coatings based on gellan gum (GG) and inulin (IN) incorporating Lactobacillus casei, which were tested for their potential ability to extend the post-harvest shelf life of whole guava fruit. The coatings were prepared using the following formulations: 0.5 GG/1.0 IN (w/v), 0.8 GG/5.0 IN (w/v), 0.5 GG/1.0 IN(w/v), and 0.8 GG/5.0 IN (w/v). The coated and uncoated (control) fruits were stored at 25 °C for 12 days, and various quality attributes were evaluated (including respiration rate, soluble solids, titratable acidity, weight loss, total phenol content, and color). The results indicated that the application of the coatings reduced weight loss, color change, and respiration rate in the fruits. However, the 0.8 GG/5.0 IN (w/v) formulation provided the best maintenance of post-harvest quality for the fruit evaluated. The coatings with a higher inulin content showed the highest growth of L. casei, which could enhance the antimicrobial effect of the coating. Therefore, the combined application of L. casei and inulin in coatings based on gellan gum can be considered an effective treatment to extend the shelf life and preserve the quality of guava fruits. Full article
(This article belongs to the Special Issue Advanced Composite Materials from Natural and Synthetic Sources: Fabrication, Characterization and Practical Application, Volume II)
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25 pages, 1413 KiB  
Review
An Overview of Nanotechnology in Dental Medicine
by Carmen-Larisa Nicolae, Diana-Cristina Pîrvulescu, Adelina-Gabriela Niculescu, Marius Rădulescu, Alexandru Mihai Grumezescu and George-Alexandru Croitoru
J. Compos. Sci. 2024, 8(9), 352; https://doi.org/10.3390/jcs8090352 - 7 Sep 2024
Abstract
The dentistry industry has been modernized by nanotechnology, as this emerging field has opened up new doors for dental treatment, restoration, and tissue regeneration. The potential applications of nanomaterials in dentistry are reviewed in this paper, ranging from advanced restorative materials to targeted [...] Read more.
The dentistry industry has been modernized by nanotechnology, as this emerging field has opened up new doors for dental treatment, restoration, and tissue regeneration. The potential applications of nanomaterials in dentistry are reviewed in this paper, ranging from advanced restorative materials to targeted drug delivery systems. Due to their unique characteristics (e.g., high surface area-to-volume ratios and tunable physicochemical properties), nanomaterials allow for the precise control of material behavior at the nanoscale. The ability of nanostructured materials to promote tissue regeneration offers the prospect of developing new approaches in bone and periodontal regeneration. Therefore, this review thoroughly analyzes nanomaterials’ characteristics and biomedical applications, highlighting how they can aid in overcoming challenges in dental care and create possibilities for more individualized and less-invasive dental treatments. Full article
(This article belongs to the Special Issue Advanced Composite Materials from Natural and Synthetic Sources: Fabrication, Characterization and Practical Application, Volume II)
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