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J. Compos. Sci., Volume 8, Issue 3 (March 2024) – 36 articles

Cover Story (view full-size image): This study describes the fabrication of hierarchical scaffolds aimed at mimicing the native osteochondral tissue architecture. A complex 3D bilayered structure was composed of two layers, (i) chitosan/β-TCP, which resembles bone, and (ii) silk fibroin, which resembles cartilage, whereas genipin was applied as a natural crosslinking agent to produce the composite architectures. The findings revealed that genipin crosslinking promoted a structural rearrangement in the scaffolds, enhancing the interaction between layers, and improved the composite scaffold properties. The biological outcomes corroborated that the developed hierarchical scaffolds show good ATDC5 and MC3T3 cell adherence and proliferation for 14 days. Overall, the physicochemical properties and biological data suggest that they may be potential candidates for osteochondral tissue strategies. View this paper
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36 pages, 7429 KiB  
Review
Structure, Properties, and Recent Developments in Polysaccharide- and Aliphatic Polyester-Based Packaging—A Review
by Wasana N. Marasinghe, K. G. L. R. Jayathunge, Rohan S. Dassanayake, Rumesh Liyanage, Pasan C. Bandara, Suranga M. Rajapaksha and Chamila Gunathilake
J. Compos. Sci. 2024, 8(3), 114; https://doi.org/10.3390/jcs8030114 - 21 Mar 2024
Viewed by 791
Abstract
Food packaging plays an imperative role in the food processing sector by safeguarding foods from their point of harvesting until the moment of consumption. In recent years, biopolymers have attracted the attention of the scientific community as an alternative to conventional packaging materials. [...] Read more.
Food packaging plays an imperative role in the food processing sector by safeguarding foods from their point of harvesting until the moment of consumption. In recent years, biopolymers have attracted the attention of the scientific community as an alternative to conventional packaging materials. Among the available biopolymer sources, a lot of the focus has been on polysaccharides due to their superior barrier properties against gases, oils, and odors and their processing versatility. Moreover, there is also a growing interest in aliphatic polyester as a potential replacement for petrochemical-based synthetic plastics. Both polysaccharides and aliphatic polyesters have gained popularity in sustainable food packaging due to their unique characteristics, including their low cost, availability, biodegradability, gas and moisture barrier properties, film-forming capabilities, excellent heat resistance, and ability to be processed into films, trays, and coatings. This review highlights the structural features, properties, and recent advancements of several vital polysaccharides, namely, starch, chitosan, cellulose, alginate, pectin, carrageenan, and aliphatic polyesters, including polylactic acid (PLA) and polyhydroxybutyrate (PHB) for developing packaging materials, and their applications in the food industry. Conventional packaging and future perspectives of biopolymer-based food packaging are also comprehensively covered in this review. Full article
(This article belongs to the Special Issue Progress in Polymer Composites, Volume III)
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3 pages, 191 KiB  
Editorial
Editorial for the Special Issue on Carbon Fiber Composites
by Jiadeng Zhu, Guoqing Li and Lixing Kang
J. Compos. Sci. 2024, 8(3), 113; https://doi.org/10.3390/jcs8030113 - 21 Mar 2024
Viewed by 514
Abstract
Carbon fibers (CFs) have received tremendous attention since their discovery in the 1860s due to their unique properties, including outstanding mechanical properties, low density, excellent chemical resistance, good thermal conductivity, etc [...] Full article
(This article belongs to the Special Issue Carbon Fiber Composites)
15 pages, 5015 KiB  
Article
Static and Dynamic Mechanical Behavior of Carbon Fiber Reinforced Plastic (CFRP) Single-Lap Shear Joints Joule-Bonded with Conductive Epoxy Nanocomposites
by Yuheng Huang, Ian A. Kinloch and Cristina Vallés
J. Compos. Sci. 2024, 8(3), 112; https://doi.org/10.3390/jcs8030112 - 21 Mar 2024
Viewed by 675
Abstract
The potential of electrically conductive graphene nanoplatelets (GNPs)/epoxy, multi-walled carbon nanotubes (MWNCTs)/epoxy and hybrid GNPs-MWCNTs/epoxy nanocomposites as adhesives for out-of-autoclave (OoA) and in-the-field CFRP repair via Joule heat curing was investigated. Scanning electron microscopy revealed a good dispersion of the nanoparticles in the [...] Read more.
The potential of electrically conductive graphene nanoplatelets (GNPs)/epoxy, multi-walled carbon nanotubes (MWNCTs)/epoxy and hybrid GNPs-MWCNTs/epoxy nanocomposites as adhesives for out-of-autoclave (OoA) and in-the-field CFRP repair via Joule heat curing was investigated. Scanning electron microscopy revealed a good dispersion of the nanoparticles in the matrix in all the nanocomposite adhesives above their percolation thresholds, which led to a homogeneous distribution of the heat generated during Joule CFRP repair. The joints bonded with neat epoxy and the nanocomposites showed similar lap shear strengths, with the addition of nanoparticles enhancing the fatigue performance of the adhesively bonded joints relative to when neat epoxy was used as an adhesive and oven-cured. The interfacial and cohesive failure mechanisms were found to coexist in all the cases, with an increasing dominance of the cohesive when nanofillers were embedded into the adhesive. No effect of the specific type of nanofiller incorporated into the epoxy as the conductive component was observed on the mechanical performance of the bonded joints, with the adhesives containing MWCNTs showing similar results to those filled with GNPs at considerably lower loadings due to their lower percolation thresholds. The independence of the properties regardless of the curing method highlights the promise of these Joule-cured adhesives for industrial applications. Full article
(This article belongs to the Special Issue Polymer Composites and Fibers, Volume II)
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13 pages, 6894 KiB  
Article
Fabrication and Characterization of Granulated β-Tricalcium Phosphate and Bioactive Glass Powders by Spray Drying
by Akihiro Nakanishi, Henni Setia Ningsih, Dwi Fortuna Anjusa Putra, Toshihiro Moriga and Shao-Ju Shih
J. Compos. Sci. 2024, 8(3), 111; https://doi.org/10.3390/jcs8030111 - 20 Mar 2024
Viewed by 754
Abstract
Biocomposite materials are widely implemented in various applications in clinical dentistry and orthopedics since it is possible to combine multiple materials by relying on their compatibility. Ceramic-based materials have osteogenic and osteoconductive features owing to their inorganic constituents with dental and bone tissue. [...] Read more.
Biocomposite materials are widely implemented in various applications in clinical dentistry and orthopedics since it is possible to combine multiple materials by relying on their compatibility. Ceramic-based materials have osteogenic and osteoconductive features owing to their inorganic constituents with dental and bone tissue. β-tricalcium phosphate (β-TCP) and bioactive glass have excellent biocompatibility, bioresorbability, and bioactivity. In this study, β-TCP and BG powders were fabricated by spray pyrolysis (SP) and spray drying (SD). These fabrication methods are suitable for the mass production and synthesis of spherical particles. At first, β-TCP and BG spherical particles were synthesized by SP and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electronic microscopy (SEM). After that, these powders were granulated with the different weight ratios of β-TCP/BG = 100/0, 75/25, 50/50, 25/75, and 0/100 by SD. The resulting granulation powders were characterized using XRD, FT-IR, and SEM to investigate phase compositions and microstructures. In addition, cytotoxicity was investigated using the MTT assay. Full article
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16 pages, 7064 KiB  
Article
Evaluation of Joint Strength for CFRPs and Aluminum Alloys by Friction Stir Spot Welding Using Multi-Stage Heating
by Kazuto Tanaka and Yusuke Aiba
J. Compos. Sci. 2024, 8(3), 110; https://doi.org/10.3390/jcs8030110 - 20 Mar 2024
Viewed by 574
Abstract
To reduce car body weight, multi-material structures with lightweight materials such as carbon-fiber-reinforced plastics (CFRPs) and aluminum alloys (Als) are used to replace parts of steel components, and joining technologies for such dissimilar materials are essential. Friction stir spot welding (FSSW) is one [...] Read more.
To reduce car body weight, multi-material structures with lightweight materials such as carbon-fiber-reinforced plastics (CFRPs) and aluminum alloys (Als) are used to replace parts of steel components, and joining technologies for such dissimilar materials are essential. Friction stir spot welding (FSSW) is one of the technologies used to rapidly and strongly join dissimilar materials. FSSW for carbon-fiber-reinforced thermosetting resin (CFRTS) and Als has been developed using composite laminates with integrally molded thermoplastic resin in the outermost layer. To suppress excessive heating under the tool, this study investigated whether multi-stage heating with a non-heating time during joining affects the heat distribution and strength properties of the joint. Due to heat diffusion in Al during the non-heating time, multi-stage heating can suppress excessive heating under the tool compared to continuous heating, resulting in up to 27% larger welded area, up to 37% smaller decomposed area, and up to 6% lower maximum temperature. The use of multi-stage heating results in up to 5% higher tensile shear strength and 210% longer fatigue life by reducing the thermal decomposition of CFRP matrix resin and PA12 resin. Full article
(This article belongs to the Special Issue Metal Composites, Volume II)
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19 pages, 2520 KiB  
Article
On the Multidisciplinary Design of a Hybrid Rocket Launcher with a Composite Overwrapped Pressure Vessel
by Alain Souza, Paulo Teixeira Gonçalves, Frederico Afonso, Fernando Lau, Nuno Rocha and Afzal Suleman
J. Compos. Sci. 2024, 8(3), 109; https://doi.org/10.3390/jcs8030109 - 19 Mar 2024
Viewed by 740
Abstract
A multidisciplinary design optimisation (MDO) study of a hybrid rocket launcher is presented, with a focus on quantifying the impact of using composite overwrapped pressure vessels (COPVs) as the oxidiser tank. The rocket hybrid propulsion system (RHPS) consists of a combination of solid [...] Read more.
A multidisciplinary design optimisation (MDO) study of a hybrid rocket launcher is presented, with a focus on quantifying the impact of using composite overwrapped pressure vessels (COPVs) as the oxidiser tank. The rocket hybrid propulsion system (RHPS) consists of a combination of solid fuel (paraffin) and liquid oxidiser (NOx). The oxidiser is conventionally stored in metallic vessels. Alternative design concepts involving composite-based pressure vessels are explored that could lead to significant improvements in the overall performance of the rocket. This design choice may potentially affect parameters such as total weight, thrust curve, and maximum altitude achieved. With this eventual impact in mind, structural considerations such as wall thickness for the COPV are integrated into an in-house MDO framework to conceptually optimise a hybrid rocket launcher. Full article
(This article belongs to the Special Issue Recent Progress in Hybrid Composites)
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13 pages, 5732 KiB  
Article
Fabrication and Ablation Properties of SiC Nanowires-Network Modified Carbon/Carbon–Ultrahigh Temperature Ceramics Composites
by Long Chen, Yuanting Wu, Wanting Wang, Xiaoxiao Yuan, Changqing Liu and Chengxin Li
J. Compos. Sci. 2024, 8(3), 108; https://doi.org/10.3390/jcs8030108 - 19 Mar 2024
Viewed by 632
Abstract
In order to address the anti-ablation of carbon/carbon (C/C) composites, SiC nanowires (SiCnws) network-modified C/C-ZrB2-ZrC-SiC composites were prepared through the one-step precursor conversion method. With an optimized B-Si-Zr sol-precursor, uniformly dispersed SiCnws and ceramic particles forming an interlocking structure were synchronous [...] Read more.
In order to address the anti-ablation of carbon/carbon (C/C) composites, SiC nanowires (SiCnws) network-modified C/C-ZrB2-ZrC-SiC composites were prepared through the one-step precursor conversion method. With an optimized B-Si-Zr sol-precursor, uniformly dispersed SiCnws and ceramic particles forming an interlocking structure were synchronous in situ grown in the C/C matrix. During ablation, the partially oxidized SiCnws networks with molten SiO2 surface can stabilize the oxide protecting layer and heal the microcracks efficiently in combination with the refractory ZrO2 particles, thus significantly improving the anti-ablation properties of the composites. This study lays the foundation for the high temperature and long-term anti-oxidation and anti-ablation application of C/C composites in the aerospace industry. Full article
(This article belongs to the Section Fiber Composites)
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20 pages, 12602 KiB  
Article
Ultrasonic Nondestructive Evaluation of Composite Bond Strength: Quantification through Bond Quality Index (BQI)
by Sourav Banerjee, Vahid Tavaf and Mustahseen M. Indaleeb
J. Compos. Sci. 2024, 8(3), 107; https://doi.org/10.3390/jcs8030107 - 18 Mar 2024
Viewed by 637
Abstract
This article presents a concept, materials, and methods to devise a Bond Quality Index (BQI) for assessing composite bond quality, approximately correlating to the respective bond strength. Interface bonding is the common mechanism to join two composite structural components. Ensuring the health and [...] Read more.
This article presents a concept, materials, and methods to devise a Bond Quality Index (BQI) for assessing composite bond quality, approximately correlating to the respective bond strength. Interface bonding is the common mechanism to join two composite structural components. Ensuring the health and quality of the bond line between two load-bearing composite structures is crucial. The article presents the classification and data-driven distinction between two types of bond lines between similar structural components. The interface bonds in composite plates were prepared using polyester peel ply and TX-1040 nylon peel ply. For all the plates, ultrasonic inspection through scanning acoustic microscopy (SAM) (>10 MHz) was performed before and after localized failure of the plate by impinging energy. Energy was impinged 0–10 J/cm2 of in the 16-ply plates, and 0–25 J/cm2 were impinged in 40-ply plates. Followed by bond failure and SAM, a new parameter called the Bond Quality Index (BQI) was formulated using ultrasonic scan data and energy data. The BQI was found to be 0.55 and 0.45, respectively, in plates with polyester peel ply and TX-1040 nylon peel ply bonds. Further, in 40-ply plates with polyester peel ply resulted in a BQI equivalent to 3.49 compared to 0.75 in plates with a TX-1040 nylon peel ply bond. Currently, the BQI is not normalized; however, this study could be used for AI-driven normalized BQIs for all types of bonds in the future. Full article
(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2023)
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19 pages, 5082 KiB  
Article
Plasma-Enhanced Alginate Pre-Treatment of Short Flax Fibers for Improved Thermo-Mechanical Properties of PLA Composites
by Ghane Moradkhani, Jacopo Profili, Alex Destrieux, Mathieu Robert, Gaétan Laroche, Saïd Elkoun, Frej Mighri and Pascal Y. Vuillaume
J. Compos. Sci. 2024, 8(3), 106; https://doi.org/10.3390/jcs8030106 - 18 Mar 2024
Viewed by 703
Abstract
This research centered on enhancing the mechanical properties of sustainable composite materials made from short flax fibers. Challenges associated with fiber–matrix adhesion and moisture absorption were systematically addressed. A water–alginate pre-treatment, combined with plasma modification, was employed to stabilize the fibers, ensuring their [...] Read more.
This research centered on enhancing the mechanical properties of sustainable composite materials made from short flax fibers. Challenges associated with fiber–matrix adhesion and moisture absorption were systematically addressed. A water–alginate pre-treatment, combined with plasma modification, was employed to stabilize the fibers, ensuring their optimal preparation and improved compatibility with biopolymers. A thorough investigation of the effect of the plasma modulation using a duty cycle (DC) was conducted, and extensive physicochemical and mechanical analyses were performed. These efforts revealed conditions that preserved fiber integrity while significantly improving surface characteristics. Techniques such as optical emission spectroscopy (OES), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and Dynamic Mechanical Analysis (DMA) were utilized, providing a comprehensive understanding of the transformations induced by the plasma treatment. The findings underscored the critical role of alginate and precise plasma settings in enhancing the mechanical properties of the composites. Ultimately, this study made a substantial contribution to the field of eco-friendly materials, showcasing the potential of short flax fibers in sustainable composite applications and setting the stage for future advancements in this area. Full article
(This article belongs to the Special Issue Sustainable Biocomposites, Volume II)
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21 pages, 7711 KiB  
Article
Evaluation of the Effect of the Composition of the Foam Glass Concrete on Its Flammability and Moisture Characteristics
by Jurga Šeputytė-Jucikė, Sigitas Vėjelis, Saulius Vaitkus, Agnė Kairytė and Arūnas Kremensas
J. Compos. Sci. 2024, 8(3), 105; https://doi.org/10.3390/jcs8030105 - 16 Mar 2024
Viewed by 581
Abstract
The purpose of this study was to evaluate the moisture and flammability characteristics of lightweight concrete with different aggregates and different amounts of cement according to different criteria. The moisture properties of the specimens were evaluated by the coefficient of water absorption due [...] Read more.
The purpose of this study was to evaluate the moisture and flammability characteristics of lightweight concrete with different aggregates and different amounts of cement according to different criteria. The moisture properties of the specimens were evaluated by the coefficient of water absorption due to capillary action, short-term water absorption, and water vapour permeability. Short-term water absorption correlated with the density of the specimens, and capillary absorption was evaluated depending on the soaking time, amount of cement, and type of lightweight aggregate. The values of the water vapour diffusion resistance factor were estimated based on the amount of cement, the type of lightweight aggregate, the density, and the porosity. The porosity correlated with the amount of cement and the type of lightweight aggregate. The flammability properties of concrete with lightweight aggregate were evaluated by several methods, such as the single flame source test, the single burning item test, and the non-combustibility test. After assessing the flammability characteristics, a structure analysis of the samples was specifically performed to assess the processes that occur during the combustion of lightweight concrete. It was found that short-term water absorption depended mainly on the density, capillary absorption on the amount of cement, and the water vapour diffusion resistance factor, flammability, and thermal stability of lightweight concrete on the type of granules. Full article
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13 pages, 4949 KiB  
Article
Antimicrobial Hydrophobic SiO2-TiO2-PDMS Films: Effect of Indirect Ultrasonic Irradiation on the Synthesis Process
by Alicia Rosales, Hugo Mandujano, José Antonio Cervantes-Chávez and Karen Esquivel
J. Compos. Sci. 2024, 8(3), 104; https://doi.org/10.3390/jcs8030104 - 16 Mar 2024
Viewed by 587
Abstract
Film applications’ recent advances in the alimentary industry mainly focus on extending product shelf life. Researchers have investigated the use of nanomaterials as active packaging to shield food product contents from the outside elements and prevent bacterial development. In this context, the use [...] Read more.
Film applications’ recent advances in the alimentary industry mainly focus on extending product shelf life. Researchers have investigated the use of nanomaterials as active packaging to shield food product contents from the outside elements and prevent bacterial development. In this context, the use of sonochemistry energy offers a friendly and efficient opportunity to obtain this kind of film. However, access to an ultrasonic homogenizer is limited because of the cost and accessories. In this work, a self-cleaning coating based on the SiO2-TiO2-PDMS composite was obtained by the sol–gel method coupled with indirect sonochemical energy. Two sonication reaction times were used to investigate its impact on the final composite’s chemical, morphological, and antibacterial properties. TEM and SEM techniques indicate an amorphous morphology and superficial cracks in SiO2-TiO2-PDMS films over aluminum foil. At the same time, AFM reveals a rise in rugosity with a value of Ra = 18.7 ± 2.47 nm, increasing the sonochemical reaction time. Non-significative changes by FTIR-ATR analysis were observed. The antibacterial evaluation was conducted, and the results indicate that both composites exhibited superior effectiveness. Specifically, the S40 film demonstrated a significant reduction in the growth of Gram-negative cells (E. coli, P. putida, and P. aeruginosa), with reductions ranging from 50% to 95%. In contrast, the reduction in Gram-positive cells (S. aureus) was less than 10%. These findings underscore the potential application of the SiO2-TiO2-PDMS film as active packaging. Full article
(This article belongs to the Section Polymer Composites)
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14 pages, 4887 KiB  
Article
Innovative Wedge Anchorage for CFRP Plates: Development and Testing
by Mustafa Alhusain and Adil Al-Mayah
J. Compos. Sci. 2024, 8(3), 103; https://doi.org/10.3390/jcs8030103 - 14 Mar 2024
Viewed by 738
Abstract
Gripping prestressed carbon fiber-reinforced polymers (CFRPs) in structural strengthening applications is challenging due to CFRPs’ susceptibility to lateral loading. This paper presents a reliable and reusable wedge anchorage for gripping CFRP plates that are 50 mm wide and 1.2 mm thick. The cylindrical [...] Read more.
Gripping prestressed carbon fiber-reinforced polymers (CFRPs) in structural strengthening applications is challenging due to CFRPs’ susceptibility to lateral loading. This paper presents a reliable and reusable wedge anchorage for gripping CFRP plates that are 50 mm wide and 1.2 mm thick. The cylindrical anchorage, which is 75 mm long and 76.2 mm in diameter, consists of an external steel barrel, two internal steel wedges, and two soft copper sleeves. The barrel-wedge interface is designed using an innovative arc–linear configuration, through which the desired stress distribution is attained, preventing stress concentration and the premature failure of the CFRP plate. The wedge anchorage was experimentally tested by applying a displacement-controlled tensile load of 0.6 mm/min until the complete fracture of the CFRP plate. The anchorage’s performance was examined under distinct installation conditions by applying different presetting levels: high (40–120 kN) and low (hammering) presetting. It was observed that the anchorage successfully prevented CFRP premature failure in all tests by achieving an average tensile loading of 172.3 (±5.7) kN, exceeding its reported tensile strength of 168 kN (2800 MPa). Minor CFRP displacements of 6.26 (±0.75) mm and 3.33 (±0.16) mm were recorded under low and high presetting levels, respectively. Similarly, the CFRP slippage relative to the wedges for the low and high presetting tests was only 1.18 (±0.75) mm and 0.33 (±0.15) mm, respectively. Also, only minor scratches were observed in the wedge–barrel interface, indicating the absence of extensive plastic deformation. Full article
(This article belongs to the Special Issue Carbon Fiber Composites, Volume III)
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13 pages, 3340 KiB  
Article
Promotive Effect of Non-Woven Polylactide/Natural Rubber Composites on Growth and Biochemical Constituents of Purple Basil (Ocimum basilicum L.)
by Yulia V. Tertyshnaya, Anastasia N. Skorokhodova, Anastasia Yu. Anpilova and Anatoliy A. Olkhov
J. Compos. Sci. 2024, 8(3), 102; https://doi.org/10.3390/jcs8030102 - 13 Mar 2024
Viewed by 735
Abstract
Presently, modern trends focused on eco-friendly “green” technologies are increasing the widespread use of biodegradable polymers and polymer composites in agricultural production. In this work, non-woven materials, polylactide/natural rubber (PLA/NR) composites with a different natural rubber content, were used as substrates for growing [...] Read more.
Presently, modern trends focused on eco-friendly “green” technologies are increasing the widespread use of biodegradable polymers and polymer composites in agricultural production. In this work, non-woven materials, polylactide/natural rubber (PLA/NR) composites with a different natural rubber content, were used as substrates for growing purple basil (Ocimum basilicum L.) in the multisoil compound in a phytochamber. It was shown that non-woven PLA/NR fabrics stimulate the growth and development of purple basil plants during the growing season. Compared to the control sample, the germination and biometric indicators of basil were higher when using PLA/NR substrates. The production of basil’s photosynthetic pigments also increased. While using PLA/NR fabrics with a rubber content of 10 and 15 wt.%, the number of chlorophyll a was enhanced by 1.8–2.2 times and chlorophyll b by 2.5–3.2 times. In the process of the hydrolytic and enzymatic degradation of the polymer matrix, organic compounds are formed that provide additional nutrition for basil plants. Non-woven PLA/NR composites became brittle after the experiment. The PLA/NR morphology, structure, and rheological properties changed, which indicates the course of biodegradation processes in the polymer matrix. Full article
(This article belongs to the Special Issue Polymer Composites and Fibers, Volume II)
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16 pages, 5413 KiB  
Article
Influence of Glass Microfibers on the Control of Autogenous Shrinkage in Very High Strength Self-Compacting Concretes (VHSSCC)
by Lucas Onghero, Marcelo Tramontin Souza, Daniel Cusson and Wellington Longuini Repette
J. Compos. Sci. 2024, 8(3), 101; https://doi.org/10.3390/jcs8030101 - 12 Mar 2024
Viewed by 843
Abstract
High-performance concrete (HPC) is widely used in infrastructure for its durability and sustainability benefits. However, it faces challenges like autogenous shrinkage, leading to potential cracking and reduced durability. Fiber reinforcement offers a solution by mitigating shrinkage-induced stresses and enhancing concrete durability. In this [...] Read more.
High-performance concrete (HPC) is widely used in infrastructure for its durability and sustainability benefits. However, it faces challenges like autogenous shrinkage, leading to potential cracking and reduced durability. Fiber reinforcement offers a solution by mitigating shrinkage-induced stresses and enhancing concrete durability. In this sense, this study investigates the use of glass microfibers to mitigate autogenous shrinkage and early-age cracking in high-strength self-compacting concrete. Samples were prepared with two water-to-binder ratios (w/b): 0.25 and 0.32; and three glass microfiber contents: 0.20%, 0.25%, and 0.30 vol.%. The concrete mixtures were characterized in the fresh state for slump flow and in the hardened state for compressive strength, static, and dynamic Young’s modulus. Unrestrained and restrained shrinkage tests were also conducted in the seven days-age. The findings revealed that glass microfibers reduced the workability in mixtures with lower slump flow values (w/b of 0.25), while less viscous mixtures (w/b of 0.32) exhibited a slight improvement. Compressive strength showed a proportional enhancement with increasing fiber contents in concretes with a w/b ratio of 0.32. A contrasting trend emerged in concretes with a w/b ratio of 0.25, wherein strength diminished as fiber additions increased. The modulus of elasticity improved with fiber additions only in the matrix with a w/b ratio of 0.25, showing no correlation with compressive strength results. In shrinkage tests, the addition of glass microfibers up to specific limits (0.20% for a w/b ratio of 0.25 and 0.25% for w/b of 0.32) demonstrated improvements in controlling concrete deformation in unrestrained shrinkage analyses. Concerning cracking reduction in restrained concrete specimens, the mixtures did not exhibit significant improvements in crack prevention. Full article
(This article belongs to the Special Issue Discontinuous Fiber Composites, Volume III)
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14 pages, 2853 KiB  
Article
The Effect of Epoxy Resin on the Infiltration of Porous Metal Parts Formed through Laser Powder Bed Fusion
by Jibing Chen, Yanfeng Liu, Yong She, Yang Yang, Xinyu Du, Junsheng Yang and Yiping Wu
J. Compos. Sci. 2024, 8(3), 99; https://doi.org/10.3390/jcs8030099 - 11 Mar 2024
Viewed by 711
Abstract
Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious [...] Read more.
Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious porous structure and insufficient mechanical properties, and few studies have been conducted studying this. In this paper, epoxy resin was used to impregnate the blank of porous metal parts formed by L-PBF with iron-based powder material at a certain temperature, and a cross-linked curing reaction was carried out with three kinds of phenolic resin in different proportions under the action of a curing agent, so as to fill the pores and achieve the desired mechanical properties. The characteristic peaks of each group of epoxy resin were characterized using Fourier transform infrared spectroscopy (FT-IR) and H-nuclear magnetic resonance (1H-NMR) spectrums. The microstructure, decomposition temperature, and residue of four epoxy resin dispersion systems were analyzed with a scanning electron microscope (SEM), a thermal gravimetric analyzer (TGA), and derivative thermogravimetry (DTG). The results show that the density of the porous metal parts was obviously improved, the heat resistance temperature of the parts could reach 350 °C, and the tensile strength of the sample after EP2-1 impregnation was increased by 4–6 times after curing at 160 °C for 6 h. Therefore, the use of an epoxy resin dispersion system can increase the porosity of L-PBF porous metal parts, but can also significantly improve their mechanical properties, which can help them to meet the requirements of applications as model materials, biological materials, and functional materials to provide a feasible solution. Full article
(This article belongs to the Section Metal Composites)
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20 pages, 2673 KiB  
Article
Carbon Sequestration via Bituminous Composites Containing Recycled High-Density Polyethylene
by Peyman Sadeghi, Ahmad Goli and Elham Fini
J. Compos. Sci. 2024, 8(3), 100; https://doi.org/10.3390/jcs8030100 - 11 Mar 2024
Viewed by 1025
Abstract
This paper presents an innovative bituminous composite containing recycled high-density polyethylene (HDPE) as a means of carbon sequestration. To prepare the composite, rejuvenators and recycled HDPE were introduced to reclaimed asphalt pavement (RAP), separately and in combination. To evaluate efficacy of rejuvenators, this [...] Read more.
This paper presents an innovative bituminous composite containing recycled high-density polyethylene (HDPE) as a means of carbon sequestration. To prepare the composite, rejuvenators and recycled HDPE were introduced to reclaimed asphalt pavement (RAP), separately and in combination. To evaluate efficacy of rejuvenators, this study used the following three rejuvenators: waste engine oil (WEO), oleic acid (OA), and vacuum bottom (VB). The performance of the bituminous composite containing HDPE and rejuvenators was evaluated using the indirect tensile fatigue test, the rutting resistance test, the resilient modulus test, and the semi-circular bending test. Results showed that applying a combination of rejuvenators and recycled HDPE improved the resistance to fatigue, rutting, and cracking. Particularly, in terms of improving resistance to cracking, OA proved to be the most effective rejuvenator, followed by WEO and VB. In all bituminous composites studied here, the hybrid application of HDPE and rejuvenator proved to be more effective than the rejuvenator or HDPE alone. Full article
(This article belongs to the Special Issue Recycled Polymer Composites: Futuristic Sustainable Material)
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20 pages, 31558 KiB  
Article
The Use of the Computer Tomography Method in the Analysis of the Microstructure of Materials Formed as a Result of Hydrothermal Treatment: Cellular Concretes
by Anna Stepien and Ryszard Dachowski
J. Compos. Sci. 2024, 8(3), 98; https://doi.org/10.3390/jcs8030098 - 08 Mar 2024
Viewed by 642
Abstract
The subject of this research is sustainable construction and energy saving, which is most reflected in the technological aspects of building construction. This article focuses on single-family buildings, and the subject of this research is hollow blocks (blocks) created as a result of [...] Read more.
The subject of this research is sustainable construction and energy saving, which is most reflected in the technological aspects of building construction. This article focuses on single-family buildings, and the subject of this research is hollow blocks (blocks) created as a result of hydrothermal treatment, in this case, autoclaved aerated concrete (AAC) and autoclaved cellular concrete (ACC), both traditional and modified plastics (HIPS). There are two types of materials resulting from hydrothermal treatment: autoclaved sand-lime bricks and autoclaved concrete. Both in the case of ACC and silicates bricks, the basic substrates used during their production are lime, sand and water (cement is also added to cellular concrete). This article presents the methodology of testing the porous structure of autoclaved materials with the use of computed tomography. Aerated concrete (light autoclaved concrete) has a compressive strength of 2–6 MPa. The tests included aerated concrete modified with high-impact polystyrene, commonly known as HIPS. HIPS high-impact polystyrene is a thermoplastic polymer that is obtained by block suspension polymerization of styrene with the addition of synthetic rubber. As a result of polymerization, small particles of polybutadiene remain in the polystyrene male, changing its physical and mechanical properties. The results from the content of air voids in the autoclaved concrete sample were, on average, 52.53%. Full article
(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2024)
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25 pages, 20956 KiB  
Article
Studies on the Mechanical, Strengthening Mechanisms and Tribological Characteristics of AA7150-Al2O3 Nano-Metal Matrix Composites
by K. Chinna Maddaiah, G. B. Veeresh Kumar and R. Pramod
J. Compos. Sci. 2024, 8(3), 97; https://doi.org/10.3390/jcs8030097 - 07 Mar 2024
Viewed by 987
Abstract
Stir-casting with ultrasonic cavitation produced nano-Al2O3-filled AA7150 matrix composites in this study. The SEM microstructure study shows that all composites include nano-Al2O3 particles with consistent particle sizes and homogenous distribution. EDS and XRD showed no secondary [...] Read more.
Stir-casting with ultrasonic cavitation produced nano-Al2O3-filled AA7150 matrix composites in this study. The SEM microstructure study shows that all composites include nano-Al2O3 particles with consistent particle sizes and homogenous distribution. EDS and XRD showed no secondary phases or impurities in the composite. Optical microscopy showed intense ultrasonic cavitation effects, and nano-Al2O3 particles caused grain refinement in the AA7150 matrix. The composite’s mechanical characteristics improved when the Al2O3 nanoparticle weight percentage (wt.%) increased. With only 2.0 wt.% nano-Al2O3 particles, the composites yielded 232 MPa, 97.52% higher than the sonicated AA7150 matrix alloy. Multiple models were used to characterize the strength of the AA7150 nano-Al2O3 composite. The findings showed that thermal incongruity, Orowan strengthening, the Hall–Petch mechanism, and load transfer effects contributed the most towards the increased strength of the composite. Increasing the nano-Al2O3 wt.% in the AA7150 matrix improved hardness by 95.08%, yield strength by 90.34%, and sliding wear resistance by 46.52%. This enhancement may be attributed to the combined effects of better grain refinement, enhanced dispersion with dislocation strengthening, and better load transfer between the matrix and reinforcement, which are assisted by the inclusion of reinforcements. This result was confirmed by optical studies. Full article
(This article belongs to the Special Issue Metal Composites, Volume II)
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21 pages, 6810 KiB  
Article
Machine Learning Approaches for Predicting the Ablation Performance of Ceramic Matrix Composites
by Jayanta Bhusan Deb, Jihua Gou, Haonan Song and Chiranjit Maiti
J. Compos. Sci. 2024, 8(3), 96; https://doi.org/10.3390/jcs8030096 - 05 Mar 2024
Viewed by 981
Abstract
Materials used in aircraft engines, gas turbines, nuclear reactors, re-entry vehicles, and hypersonic structures are subject to severe environmental conditions that present significant challenges. With their remarkable properties, such as high melting temperatures, strong resistance to oxidation, corrosion, and ablation, minimal creep, and [...] Read more.
Materials used in aircraft engines, gas turbines, nuclear reactors, re-entry vehicles, and hypersonic structures are subject to severe environmental conditions that present significant challenges. With their remarkable properties, such as high melting temperatures, strong resistance to oxidation, corrosion, and ablation, minimal creep, and advantageous thermal cycling behavior, ceramic matrix composites (CMCs) show great promise as a material to meet the strict requirements in these kinds of environments. Furthermore, the addition of boron nitride nanoparticles with continuous fibers to the CMCs can offer thermal resistivity in harsh conditions, which will improve the composites’ strength and fracture toughness. Therefore, in extreme situations, it is crucial to understand the thermal resistivity period of composite materials. To forecast the ablation performance of composites, we developed six machine learning regression methods in this study: decision tree, random forest, support vector machine, gradient boosting, extreme gradient boosting, and adaptive boosting. When evaluating model performance using metrics including R2 score, root mean square error, mean absolute error, and mean absolute percentage error, the gradient boosting and extreme gradient boosting machine learning regression models performed better than the others. The effectiveness of machine learning models as a useful tool for forecasting the ablation behavior of ceramic matrix composites was effectively explained by this study. Full article
(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2024)
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2 pages, 190 KiB  
Correction
Correction: Smirnov et al. Experimental and Statistical Modeling for Effect of Nozzle Diameter, Filling Pattern, and Layer Height of FDM-Printed Ceramic–Polymer Green Body on Biaxial Flexural Strength of Sintered Alumina Ceramic. J. Compos. Sci. 2023, 7, 381
by Anton Smirnov, Nikita Nikitin, Pavel Peretyagin, Roman Khmyrov, Ekaterina Kuznetsova and Nestor Washington Solis Pinargote
J. Compos. Sci. 2024, 8(3), 95; https://doi.org/10.3390/jcs8030095 - 04 Mar 2024
Viewed by 542
Abstract
The authors would like to highlight the following correction to their published paper [...] Full article
20 pages, 10216 KiB  
Article
Development of Sugarcane Bagasse Ash Blended Cementitious Composites Reinforced with Carbon Nanotubes and Polypropylene Fibers
by Muhammad Ayyan Iqbal, Umbreen Us Sahar, Alireza Bahrami, Noor Yaseen and Iffat Siddique
J. Compos. Sci. 2024, 8(3), 94; https://doi.org/10.3390/jcs8030094 - 04 Mar 2024
Viewed by 956
Abstract
Cement-based composites, as primary construction materials, have undergone significant advancements over the years, yet researchers still face challenges in terms of their durability and impact on the environment. The goal of this research is to develop environmentally friendly cementitious composites blended with sugarcane [...] Read more.
Cement-based composites, as primary construction materials, have undergone significant advancements over the years, yet researchers still face challenges in terms of their durability and impact on the environment. The goal of this research is to develop environmentally friendly cementitious composites blended with sugarcane bagasse ash (SCBA) and reinforce them with multi-walled carbon nanotubes and polypropylene (PP) fibers. Because of the high cost associated with carbon nanotubes (CNTs) and PP fibers, as well as CO2 emission, which affect the economic and environmental aspects of this field, an agricultural waste such as SCBA was introduced in the current study that is both economically and environmentally viable. For this purpose, five mixes were designed by varying the CNTs content whilst keeping the PP fibers and SCBA contents constant at 1.5% and 15% by weight of the binder (ordinary Portland cement + SCBA), respectively. The developed blends were tested for various mechanical and durability properties, i.e., compressive strength, flexural strength, impact strength, water absorption, and ultrasonic pulse velocity. Moreover, the microstructures of the newly developed low-carbon SCBA-based composites reinforced with PP fibers and CNTs were studied through scanning electron microscopy and energy dispersive spectroscopy. The results showed that the developed blends incorporating 15% SCBA, 1.5% PP fibers, and 0.08% CNTs, by weight of the binder, demonstrated the compressive, flexural, and impact strengths as 15.30 MPa, 0.98 MPa, and 0.11 MPa, respectively. The investigated blends proved to be cost-effective and environmentally beneficial, rendering them suitable for utilization in general construction and maintenance works. Full article
(This article belongs to the Special Issue Polymer Composites and Fibers, Volume II)
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13 pages, 4060 KiB  
Article
Optimization of a Tapered Specimen Geometry for Short-Term Dynamic Tensile Testing of Continuous Fiber Reinforced Thermoplastics
by Florian Mischo and Sebastian Schmeer
J. Compos. Sci. 2024, 8(3), 93; https://doi.org/10.3390/jcs8030093 - 03 Mar 2024
Viewed by 766
Abstract
Continuous fiber reinforced thermoplastics (cFRTP) are one of the most promising lightweight materials. For their use in structural components, reproducible and comparable material values have to be evaluated, especially at high strain rates. Due to their high stiffness and outstanding strength properties, the [...] Read more.
Continuous fiber reinforced thermoplastics (cFRTP) are one of the most promising lightweight materials. For their use in structural components, reproducible and comparable material values have to be evaluated, especially at high strain rates. Due to their high stiffness and outstanding strength properties, the evaluation of the material behavior at high strain rates is complex. In the presented work, a new tensile specimen geometry for strain rate testing is virtually optimized using a metamodel approach with an artificial neural network. The final specimen design is experimentally validated and compared with rectangular specimen results for a carbon fiber reinforced polycarbonate (CF-PC). The optimized specimen geometry leads to 100% valid test results in experimental validation of cross-ply laminates and reaches 9% higher tensile strength values than the rectangle geometry with applied end tabs at a strain rate of 40 s−1. Through the optimization, comparable material parameters can be efficiently generated for a successful cFRTP strain rate characterization. Full article
(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)
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23 pages, 12050 KiB  
Article
Stiffness Retention in Cyclic-Loaded CFRP Composites Produced via Novel Automatic Tape Laying
by Ashley Blythe, Bronwyn Fox, Mostafa Nikzad, Boris Eisenbart and Boon Xian Chai
J. Compos. Sci. 2024, 8(3), 92; https://doi.org/10.3390/jcs8030092 - 03 Mar 2024
Viewed by 712
Abstract
Sixteen-head automatic tape laying of non-crimped carbon-fibre-reinforced plastic is performed, and the fibre alignment is compared with that produced via hand laying. The effect of fibre alignment is tested via quasi-static and cyclic three-point bending tests. Using the Fill Multilayer (a 16-head tape-laying [...] Read more.
Sixteen-head automatic tape laying of non-crimped carbon-fibre-reinforced plastic is performed, and the fibre alignment is compared with that produced via hand laying. The effect of fibre alignment is tested via quasi-static and cyclic three-point bending tests. Using the Fill Multilayer (a 16-head tape-laying machine), precision fibre laying of unidirectional fabrics is performed with deliberate misalignment to examine the effect of fibre orientation and investigate the random effect on longitudinal misalignment. The automatic tape-layered coupons are compared with hand-layered carbon fibre tapes to investigate the relationship between the fibre alignment and the flexural strength. A 52% reduction in the fibre alignment scatter is achieved via the Fill Multilayer. Fibre orientation increases lead to a higher flexural strength of 16.08% for Fill Multilayer-made coupons compared with hand-layered samples. An investigation of the correlation between fibre alignment and flexural strength shows that shear-based failure increases exponentially as the alignment decreases. Fill Multilayer-made coupons have a higher void concentration due to ultrasonic welding, but also the highest modulus and flexural strength, as fibre misalignment is reduced to 1.68°, with a modulus degradation of 1.4%. Full article
(This article belongs to the Special Issue Carbon Fiber Composites, Volume III)
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12 pages, 1565 KiB  
Article
Modification of Talc and Mechanical Properties of Polypropylene-Modified Talc Composite Drawn Fibers
by Costas Tsioptsias, Konstantinos Leontiadis, Xanthi Ntampou and Ioannis Tsivintzelis
J. Compos. Sci. 2024, 8(3), 91; https://doi.org/10.3390/jcs8030091 - 03 Mar 2024
Viewed by 739
Abstract
A large amount of the polypropylene (PP) produced worldwide is used in the form of fibers. In this work, a new modification route for talc and PP is investigated, which is based on the in situ polymerization of a silane–siloxane monomer mixture on [...] Read more.
A large amount of the polypropylene (PP) produced worldwide is used in the form of fibers. In this work, a new modification route for talc and PP is investigated, which is based on the in situ polymerization of a silane–siloxane monomer mixture on the surface of talc particles or PP pellets, respectively. The obtained modified talc and PP samples were used for the development of PP-talc composite drawn fibers. Tensile tests, thermogravimetry (TGA), and X-ray diffraction (XRD) were used for the characterization of the materials. It was observed that such a modification procedure resulted in the exfoliation of some talc particles. Enhanced tensile strength was observed for composite drawn fibers of a low talc content (1% with respect to PP) and a low modifier content (2% with respect to talc), while co-aggregation of talc and silicone may occur at high silicone and talc contents, resulting in the inferior mechanical performance of the corresponding composites. It was concluded that the produced silicone polymer simultaneously acts as a modifier, antioxidant, and compatibilizer. The proposed modification route is promising and should be further optimized. Full article
(This article belongs to the Special Issue Polymer Composites and Fibers, Volume II)
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15 pages, 4233 KiB  
Article
An Investigation of the Thermal Properties of LM13- Quartz- Fly-Ash Hybrid Composites
by B. R. N. Murthy, Amar Murthy Ambekar and Anupama Hiremath
J. Compos. Sci. 2024, 8(3), 90; https://doi.org/10.3390/jcs8030090 - 01 Mar 2024
Viewed by 911
Abstract
In the present work, a metal–matrix composite was casted using the LM13 aluminum alloy, which is most widely used for casting automotive components. Such applications require materials to withstand high operating temperatures and perform reliably without compromising their properties. In this regard, particulate-reinforced [...] Read more.
In the present work, a metal–matrix composite was casted using the LM13 aluminum alloy, which is most widely used for casting automotive components. Such applications require materials to withstand high operating temperatures and perform reliably without compromising their properties. In this regard, particulate-reinforced composites have gained widespread adaptability. The particulate reinforcements used comprise of one of the widely available industrial by-products. which is fly ash, along with the abundantly available quartz. Hybrid composites are fabricated through the economical liquid route that is widely used in mass production. Though there are numerous published research articles investigating the mechanical properties of metal–matrix composites, very few investigated the thermal properties of the composites. In the present work, thermal properties such as thermal conductivity and thermal diffusivity of cast hybrid composites were evaluated. The particulate reinforcements were added in varied weight percentages to the molten LM13 alloy and were dispersed uniformly using a power-driven stirrer. The melt with the dispersed particulate reinforcements was then poured into a thoroughly dried sand mold, and the melt was allowed to solidify. The quality of the castings was ascertained through density evaluation followed by a microstructural examination. It was found that the composites with only the fly ash particles as a reinforcement were less dense in comparison to the composites cast with the quartz particulate reinforcement. However, the hybrid composite, with both particulate reinforcements were dense. The microstructure revealed a refined grain structure. The thermal diffusivity and thermal conductivity values were lower for the composites cast with only the fly ash reinforcement. On the other hand, the composites cast with only quartz as the particulate reinforcement exhibited higher thermal diffusivity and thermal conductivity. The specific heat capacity was found to be lower for the fly ash-reinforced composites and higher for the quartz-reinforced composites in comparison to the LM13 base matrix alloy. However, the highest value of thermal diffusivity and thermal conductivity were reported for the hybrid composites with a 10 wt.% inclusion of both fly ash and quartz particulate reinforcements. Full article
(This article belongs to the Special Issue Metal Composites, Volume II)
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18 pages, 5974 KiB  
Article
Hybrid Treatment and Natural Aging Behavior of Peak-Aged Eutectoid Steel Powder-Reinforced Al 7075 Matrix Composites
by Ananda Hegde, Karthik Birur Manjunathaiah, Sathyashankara Sharma, Gowrishankar Mandya Chennegowda, Gajanan Anne and Ramakrishna Vikas Sadanand
J. Compos. Sci. 2024, 8(3), 89; https://doi.org/10.3390/jcs8030089 - 29 Feb 2024
Viewed by 814
Abstract
The current work focuses on the natural aging phenomenon of a eutectoid steel powder-(0.8 wt.%) reinforced Al-Zn-Mg (Al 7075) alloy, which was subjected to a hybrid heat treatment. The hybrid treatment comprises the aging treatment of a matrix and the conventional treatment of [...] Read more.
The current work focuses on the natural aging phenomenon of a eutectoid steel powder-(0.8 wt.%) reinforced Al-Zn-Mg (Al 7075) alloy, which was subjected to a hybrid heat treatment. The hybrid treatment comprises the aging treatment of a matrix and the conventional treatment of a steel reinforcement in a single stretch on the stir cast composite. This material finds uses in space and transportation applications. The hybrid treatment consists of a conventional heat treatment cycle to obtain pearlite, bainite, and martensite phases in steel powder, followed by an age-hardening treatment for the Al 7075 matrix. This hybrid heat treatment resulted in improvements in the hardness and strength over the conventional aging treatment. The peak-aged hybrid specimens were subjected to natural aging in an open atmosphere for a continuous duration of 25 weeks to study the stability of the properties after peak aging. Tests of the mechanical properties such as the hardness and tensile strength along with microstructure analysis were carried out. During natural aging, the hardness of composites decreases irrespective of the quantity of the reinforcement in the composites and the type of reinforcement phase alteration during hybrid heat treatment. Also, the composites subjected to hybrid heat treatment show better resistance to natural aging compared to the conventionally aged samples. Within the group, the hybrid-treated martensite formed into a composite with 6 wt.% reinforcement showed only a 4% reduction in hardness during natural aging, which is an indication of a decent level of resistance to natural aging. Full article
(This article belongs to the Special Issue Metal Composites, Volume II)
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13 pages, 4628 KiB  
Article
Influence of Cu Addition on the Wear Behavior of a Eutectic Al–12.6Si Alloy Developed by the Spray Forming Method
by Dayanand M. Goudar, Julfikar Haider, K. Raju, Rajashekar V. Kurahatti and Deesy G. Pinto
J. Compos. Sci. 2024, 8(3), 88; https://doi.org/10.3390/jcs8030088 - 27 Feb 2024
Viewed by 840
Abstract
In the present study, the influence of the addition of copper (Cu) on the wear behavior of a Al-12.6Si eutectic alloy developed using the spray forming (SF) method was discussed, and the results were compared with those of as-cast (AC) alloys. The microstructural [...] Read more.
In the present study, the influence of the addition of copper (Cu) on the wear behavior of a Al-12.6Si eutectic alloy developed using the spray forming (SF) method was discussed, and the results were compared with those of as-cast (AC) alloys. The microstructural features of the alloys were examined using both optical and the scanning electron microscopy, and the chemical composition and phase identification were achieved by X-ray diffraction (XRD) analysis. The results revealed that the microstructure of binary the SF alloy consisted of fine primary and eutectic Si phases, evenly distributed in the equiaxed α-Al matrix, whereas the Cu-based SF ternary alloy consisted of uniformly distributed fine eutectic Si particulates and spherical-shaped θ-Al2Cu precipitates, uniformly distributed in α-Al matrix. In contrast, the AC ternary (Al-12.6Si-2Cu) alloy consisted of unevenly dispersed eutectic Si needles and the coarse intermetallic compound θ-Al2Cu in the α-Al matrix. The addition of Cu enhanced the micro hardness of the SF ternary alloy by 8, 34, and 41% compared to that of the SF binary, AC ternary, and binary alloys, respectively. The wear test was conducted using a pin-on-disc wear testing machine at different loads (10–40 N) and sliding velocities (1–3 ms−1). The wear tests revealed that SF alloys exhibited an improved wear behavior in the entire applied load and sliding velocity range in comparison to that of the AC alloys. At a load of 40 N and a sliding velocity of 1 ms−1, the wear rate of the SF2 alloy is 62, 47, and 23% lower than that of the AC1, AC2, and SF1 alloys, respectively. Similarly, at a sliding velocity of 3 ms−1, the wear rate of the SF2 alloy is 52%, 42%, and 21% lower than that of the AC1, AC2, and SF1 alloys, respectively. The low wear rate in the SF2 alloy was due to the microstructural modification during spray forming, the precipitation of fine Al2Cu intermetallic compounds, and increased solid solubility. The SF alloys show an increased transition from oxidative to abrasive wear, while the AC alloys demonstrate wear mechanisms that change from oxidative to abrasive, including delamination, with an increase in sliding velocity and load. Full article
(This article belongs to the Special Issue Metal Composites, Volume II)
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19 pages, 14336 KiB  
Article
Experimental Research on the Impact Resistance Mechanical Properties and Damage Mechanism of Rubberized Concrete under Freeze–Thaw Cycling
by Xiaowen Huang, Tengsheng Yue, Jun Zhang and Jinsong Zhang
J. Compos. Sci. 2024, 8(3), 87; https://doi.org/10.3390/jcs8030087 - 27 Feb 2024
Viewed by 827
Abstract
To improve the long-term performance of concrete engineering in high-altitude areas, waste tire rubber was added to a concrete mix, and freeze–thaw and impact tests were conducted. The effects of waste tire rubber with different particle sizes (10, 20, 30 mesh) and freeze–thaw [...] Read more.
To improve the long-term performance of concrete engineering in high-altitude areas, waste tire rubber was added to a concrete mix, and freeze–thaw and impact tests were conducted. The effects of waste tire rubber with different particle sizes (10, 20, 30 mesh) and freeze–thaw cycles (0, 25, 50, 75, 100, 125) on the dynamic mechanical properties of concrete materials were studied. The stress–strain curves, peak stress, and fracture morphology of the specimens were analyzed. The microstructure changes of the specimens were also analyzed using scanning electron microscopy (SEM). The results showed the following: (1) Both macroscopic and microscopic analysis results showed that the internal damage of rubber concrete specimens was smaller after freeze–thawing, and the integrity was better after impact, maintaining a loose but not scattered state. The addition of waste tire rubber significantly improved the material’s impact resistance to a certain extent. (2) As the impact pressure increased, the strain rate of the specimens increased linearly, and the dynamic peak stress was linearly positively correlated with the strain rate. (3) After 125 freeze–thaw cycles, the peak stress of the specimens with 30-mesh added rubber decreased significantly less than that of ordinary concrete under 0.3, 0.45, and 0.6 MPa impact pressure. The dynamic peak stress was higher than that of specimens with 10-mesh and 20-mesh added rubber, and the addition of 30-mesh rubber significantly improved the frost resistance and impact resistance of concrete materials. This study can provide new ideas for the engineering application of rubber concrete. Full article
(This article belongs to the Special Issue Composite Rock Mechanics and Engineering)
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14 pages, 9395 KiB  
Article
Development of Highly Ultraviolet-Protective Polypropylene/TiO2 Nonwoven Fiber
by Md. Abu Hanif, Hyokyeong Shin, Danbi Chun, Hong Gun Kim, Lee Ku Kwac, Sang-Won Han, Sung-Soo Kang and Young Soon Kim
J. Compos. Sci. 2024, 8(3), 86; https://doi.org/10.3390/jcs8030086 - 25 Feb 2024
Cited by 1 | Viewed by 906
Abstract
In recent decades, there has been a rise in public consciousness of the adverse effects of expanded skin contact with sunlight, particularly the ultraviolet (UV) spectrum. UV radiation causes serious health problems like skin cancer, early aging, erythema, pigmentation, etc., due to contact [...] Read more.
In recent decades, there has been a rise in public consciousness of the adverse effects of expanded skin contact with sunlight, particularly the ultraviolet (UV) spectrum. UV radiation causes serious health problems like skin cancer, early aging, erythema, pigmentation, etc., due to contact with the skin. Therefore, the highly efficient UV-protection materials were manufactured using polypropylene and TiO2 (PPTO) through cost-effective and easy methods. The designated 7.5 PPTO and 15 PPTO were prepared, varying the amount of TiO2, as well as without using TiO2 (PPNF), which was also manufactured as a control material. All the as-synthesized nonwoven fibers were carefully characterized employing a variety of microscopic and spectroscopic methods, such as X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, and contact angle measurements. In conclusion, 15 PPTO showed the highest UV-protection ability (87.5%) compared to 7.5 PPTO and PPNF. In addition, 15 PPTO exhibited 1.76 and 1.32 times higher protection than 7.5 PPTO and PPNF, respectively, when exposed to UB-B radiation. The enhanced activity may be due to the amount of TiO2 because TiO2 increased the product’s absorption and reflection capability. Overall, the PPTO nonwoven fibers can be applied to block harmful UV radiation. Full article
(This article belongs to the Special Issue Polymer Composites and Fibers, Volume II)
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20 pages, 4962 KiB  
Article
Chitosan-Based Hierarchical Scaffolds Crosslinked with Genipin
by Lya Piaia, Simone S. Silva, Emanuel M. Fernandes, Joana M. Gomes, Albina R. Franco, Isabel B. Leonor, Márcio C. Fredel, Gean V. Salmoria, Dachamir Hotza and Rui L. Reis
J. Compos. Sci. 2024, 8(3), 85; https://doi.org/10.3390/jcs8030085 - 24 Feb 2024
Viewed by 1109
Abstract
Osteochondral defects present significant challenges for effective tissue regeneration due to the complex composition of bone and cartilage. To address this challenge, this study presents the fabrication of hierarchical scaffolds combining chitosan/β-tricalcium phosphate (β-TCP) to simulate a bone-like layer, interconnected with a silk [...] Read more.
Osteochondral defects present significant challenges for effective tissue regeneration due to the complex composition of bone and cartilage. To address this challenge, this study presents the fabrication of hierarchical scaffolds combining chitosan/β-tricalcium phosphate (β-TCP) to simulate a bone-like layer, interconnected with a silk fibroin layer to mimic cartilage, thus replicating the cartilage-like layer to mimic the native osteochondral tissue architecture. The scaffolds were produced by freeze-drying and then crosslinking with genipin. They have a crosslinking degree of up to 24%, which promotes a structural rearrangement and improved connection between the different layers. Micro-CT analysis demonstrated that the structures have distinct porosity values on their top layer (up to 84%), interface (up to 65%), and bottom layer (up to 77%) and are dependent on the concentration of β-tricalcium phosphate used. Both layers were confirmed to be clearly defined by the distribution of the components throughout the constructs, showing adequate mechanical properties for biomedical use. The scaffolds exhibited lower weight loss (up to 7%, 15 days) after enzymatic degradation due to the combined effects of genipin crosslinking and β-TCP incorporation. In vitro studies showed that the constructs supported ATDC5 chondrocyte-like cells and MC3T3 osteoblast-like cells in duo culture conditions, providing a suitable environment for cell adhesion and proliferation for up to 14 days. Overall, the physicochemical properties and biological results of the developed chitosan/β-tricalcium phosphate/silk fibroin bilayered scaffolds suggest that they may be potential candidates for osteochondral tissue strategies. Full article
(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2023)
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