Journal of Composites Science

15 pages, 4190 KiB

Open AccessArticle

The Influence of Different Solvents on the Physical Properties of ZnO Thin Films

by Alejandra López-Suárez and Dwight R. Acosta

J. Compos. Sci. 2024, 8(8), 332; https://doi.org/10.3390/jcs8080332 - 22 Aug 2024

Cited by 1 | Viewed by 1039

Polycrystalline zinc oxide (ZnO) thin films were deposited on soda-lime glass substrates using the chemical spray pyrolysis method at three different substrate temperatures: 400, 450, and 500 °C. The solvents used in the precursor solution consisted of either ethanol or methanol. The effects [...] Read more.

Polycrystalline zinc oxide (ZnO) thin films were deposited on soda-lime glass substrates using the chemical spray pyrolysis method at three different substrate temperatures: 400, 450, and 500 °C. The solvents used in the precursor solution consisted of either ethanol or methanol. The effects of these solvents on the compositional, structural, morphological, electrical, and optical properties were studied with different techniques, including Rutherford Backscattering Spectrometry (RBS), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), four-point method, and Ultraviolet and Visible Spectroscopy (Uv-Vis). The results show that both temperature and the type of solvent modify the properties of the materials. An essential outcome of the study was that at 500 °C, the ZnO thin films prepared with either ethanol or methanol exhibited almost the same high-quality crystallinity, stoichiometry, average crystallite size, energy band gap, and resistivity. These findings contribute to our understanding of the properties of these materials and their potential applications. Full article

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

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17 pages, 27352 KiB

Open AccessArticle

Geometry and Hybridization Effect on the Crashworthiness Performances of Carbon and Flax/Epoxy Composites

by Valentina Giammaria, Giulia Del Bianco, Monica Capretti, Simonetta Boria, Lorenzo Vigna, Andrea Calzolari and Vincenzo Castorani

J. Compos. Sci. 2024, 8(8), 331; https://doi.org/10.3390/jcs8080331 - 21 Aug 2024

Cited by 1 | Viewed by 1204

Abstract

Recent pressure on scientists and industries to use renewable resources, as well as the need to produce environmentally friendly materials, has led researchers and manufacturers to use natural fibres as possible reinforcements for their composites. Although they seem to be “ideal” due to [...] Read more.

Recent pressure on scientists and industries to use renewable resources, as well as the need to produce environmentally friendly materials, has led researchers and manufacturers to use natural fibres as possible reinforcements for their composites. Although they seem to be “ideal” due to their low cost, light weight and interesting energy absorption properties, they cannot be compared to synthetic fibres. To solve this problem, hybridization techniques can be considered, since the combination of synthetic and natural fibres allows for good performances. The aim of this study was to characterize the delamination and in-plane crashworthiness behaviour of carbon, flax and hybrid composites from experimental and numerical points of view. Double Cantilever Beam and Four-Point End Notched Flexure tests were carried out to determine the interlaminar fracture modes. In-plane crashworthiness tests were then performed to investigate the delamination phenomenon and the energy absorption capacity considering two different geometries: flat and corrugated. Numerical models were created and validated on both geometries, comparing the obtained load–displacement curves with the experimental ones. Crush force efficiency and specific energy absorption were quantified to provide a proper comparison of the investigated materials. The good results achieved represent a promising starting point for the design of future and more complex structures. Full article

(This article belongs to the Section Fiber Composites)

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15 pages, 6173 KiB

Open AccessArticle

Performance of GFRP-Confined Rubberized Engineered Cementitious Composite Columns

by Mahmoud T. Nawar, Mohamed Selim, Mahmoud Zaghlal, Ayman El-Zohairy and Mohamed Emara

J. Compos. Sci. 2024, 8(8), 330; https://doi.org/10.3390/jcs8080330 - 20 Aug 2024

Cited by 3 | Viewed by 914

Abstract

In coastal regions, the deterioration of structures and bridges due to environmental conditions and corrosion is a significant concern. To combat these issues, the use of corrosion-resistant materials like fiber-reinforced polymers (FRPs) materials, engineered cementitious composites (ECCs), and rubberized ECCs (RECC) shows promise [...] Read more.

In coastal regions, the deterioration of structures and bridges due to environmental conditions and corrosion is a significant concern. To combat these issues, the use of corrosion-resistant materials like fiber-reinforced polymers (FRPs) materials, engineered cementitious composites (ECCs), and rubberized ECCs (RECC) shows promise as normal concrete (NC) alternatives by providing increased ductility and energy absorption properties. The effectiveness of confining concrete columns using GFRP tubes with ECC/RECC was assessed in this research by evaluating their performance through compression and push-out tests. The study explored key parameters such as GFRP tube thickness and the presence of shear connectors along the tube height, as well as examining various types of concrete. Additionally, a comprehensive parametric investigation utilizing finite element analysis (FEA) was conducted to analyze how different factors influence the behavior of confined concrete columns. These factors included the effect of GFRP tube thickness and diameter on the overall behavior of different types of confined concretes. The results demonstrate that GFRP tubes significantly enhance column capacity, while the presence of ECC/RECC exhibits even greater improvements in capacity, stiffness, and toughness compared to NC. This approach shows promise in reinforcing coastal infrastructure and addressing corrosion-related concerns effectively. Full article

(This article belongs to the Special Issue Polymer Composites and Fibers, Volume II)

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15 pages, 6149 KiB

Open AccessArticle

Effect of Bismuth Ferrite Nanoparticles on Physicochemical Properties of Polyvinylidene Fluoride-Based Nanocomposites

by Denis Petrukhin, Vitalii Salnikov, Aleksey Nikitin, Ibtissame Sidane, Sawssen Slimani, Stefano Alberti, Davide Peddis, Alexander Omelyanchik and Valeria Rodionova

J. Compos. Sci. 2024, 8(8), 329; https://doi.org/10.3390/jcs8080329 - 20 Aug 2024

Cited by 3 | Viewed by 2175

Abstract

Bismuth ferrite (BiFeO₃, BFO) is one of the few single-phase crystalline compounds exhibiting strong multiferroic properties at room temperature, which makes it promising for use in various fields of science and technology. The remarkable characteristics of BFO at the nanoscale position [...] Read more.

Bismuth ferrite (BiFeO₃, BFO) is one of the few single-phase crystalline compounds exhibiting strong multiferroic properties at room temperature, which makes it promising for use in various fields of science and technology. The remarkable characteristics of BFO at the nanoscale position it as a compelling candidate for enhancing the functionalities of polymeric nanocomposite materials. In this study, we explore the fabrication of polyvinylidene fluoride (PVDF) nanocomposites with a variable content of BFO nanopowders (0, 5, 10, 15, 20, and 25 wt%) by solution casting in the form of thin films with the thickness of ~60 µm. Our findings reveal that the presence of BFO nanoparticles slightly facilitates the formation of β- and γ-phases of PVDF, known for their enhanced piezoelectric properties, thereby potentially expanding the utility of PVDF-based materials in sensors, actuators, and energy harvesting devices. On the other hand, the increase in filler concentration leads to enlarged spherulite diameter and porosity of PVDF, as well as an increase in filler content above 20 wt% resulting in a decrease in the degree of crystallinity. The structural changes in the surface were found to increase the hydrophobicity of the nanocomposite surface. Magnetometry indicates that the magnetic properties of nanocomposite are influenced by the BFO nanoparticle content with the saturation magnetization at ~295 K ranging from ~0.08 emu/g to ~0.8 emu/g for samples with the lowest and higher BFO content, respectively. Full article

(This article belongs to the Section Nanocomposites)

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Graphical abstract

18 pages, 16113 KiB

Open AccessTechnical Note

A Comparative Study of Airbag Covers for Automotive Safety Using Coconut Shell Fiber/PP Composite Materials

by Jinsong Li, You Zhou, Jiatao Chen, Hongtao Hu and Mingze Sun

J. Compos. Sci. 2024, 8(8), 328; https://doi.org/10.3390/jcs8080328 - 19 Aug 2024

Cited by 1 | Viewed by 1657

Abstract

In this study, we compared the physical properties of coconut fiber/polypropylene (PP) composite materials with coconut fiber as a reinforcing agent, produced through a hybrid injection molding process and a layered hot-pressing process. Through comparative experiments, the mechanical properties of both the hybrid [...] Read more.

In this study, we compared the physical properties of coconut fiber/polypropylene (PP) composite materials with coconut fiber as a reinforcing agent, produced through a hybrid injection molding process and a layered hot-pressing process. Through comparative experiments, the mechanical properties of both the hybrid injection-molded and layered hot-pressed materials were validated. The results indicated that, when using a coconut fiber content of 5%, the layered hot-pressed composite material exhibited optimal comprehensive performance. Specifically, its tensile strength reached 25.12 MPa, showing a 37.6% increase over that of pure PP materials of the same brand and batch. Its tensile modulus was 1.17 GPa, representing an 11.4% decrease. Additionally, its bending strength was 35.94 MPa, marking a 49.8% increase, and its bending modulus was 2.69 GPa, which is nearly double that of pure PP materials. Furthermore, through Creo modeling and an ANSYS simulation analysis, it was verified that this material could be applied to airbag covers in the field of automotive safety. This study confirmed that layered hot-pressed coconut fiber/PP composite materials exhibit superior mechanical properties to traditional materials and injection-molded composite materials, making them more suitable for airbag covers. Full article

(This article belongs to the Topic Advanced Composites Manufacturing and Plastics Processing)

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12 pages, 3548 KiB

Open AccessArticle

Co-Deposition of Bimetallic Au-Pt with L-Cysteine on Electrodes and Removal of Copper by Iron Powder for Trace Aqueous Arsenic Detection

by Wei-Zhi Zhang, Kan Wang, Ning Bao and Shou-Nian Ding

J. Compos. Sci. 2024, 8(8), 327; https://doi.org/10.3390/jcs8080327 - 18 Aug 2024

Viewed by 1474

Abstract

Much progress has been made in the determination of As (III), while numerous electrochemical sensors based on metal nanomaterials with significant sensitivity and precision have been developed. However, further research is still required to achieve rapid detection and avoid interference from other metal [...] Read more.

Much progress has been made in the determination of As (III), while numerous electrochemical sensors based on metal nanomaterials with significant sensitivity and precision have been developed. However, further research is still required to achieve rapid detection and avoid interference from other metal ions (especially copper ions). In this study, bimetallic AuPt nanoparticles are electrochemically modified with screen printing electrodes. What’s more, L-cysteine also self-assembles with AuNPs through Au-S bond to enhance the electrochemical performance. To overcome the interference of Cu (II) in the sensing process, the reduced iron powder was chosen to remove Cu (II) and other oxidizing organics in aqueous solutions. The lowest detectable amount is 0.139 ppb, a linear range of 1~50 ppb with superlative stability by differential pulse anodic stripping voltammetry. Fortunately, the reduced iron powder could eliminate the Cu (II) with no effect on the As (III) signal. Full article

(This article belongs to the Special Issue Metal Composites, Volume II)

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23 pages, 7759 KiB

Open AccessArticle

Machine Learning Algorithms for Prediction and Characterization of Cohesive Zone Parameters for Mixed-Mode Fracture

by Arash Ramian and Rani Elhajjar

J. Compos. Sci. 2024, 8(8), 326; https://doi.org/10.3390/jcs8080326 - 17 Aug 2024

Viewed by 1502

Abstract

Fatigue and fracture prediction in composite materials using cohesive zone models depends on accurately characterizing the core and facesheet interface in advanced composite sandwich structures. This study investigates the use of machine learning algorithms to identify cohesive zone parameters used in the fracture [...] Read more.

Fatigue and fracture prediction in composite materials using cohesive zone models depends on accurately characterizing the core and facesheet interface in advanced composite sandwich structures. This study investigates the use of machine learning algorithms to identify cohesive zone parameters used in the fracture analysis of advanced composite sandwich structures. Experimental results often yield non-unique solutions, complicating the determination of cohesive parameters. Numerical determination can be time-consuming due to fine mesh requirements near the crack tip. This research evaluates the performance of Support Vector Regression (SVR), Random Forest (RF), and Artificial Neural Network (ANN) machine learning methods. The study uses features extracted from load–displacement responses during the fracture of the Asymmetric Double-Cantilever Beam (ADCB) specimen. The inputs include the displacement at the maximum load (δ*), the maximum load (

P_{m a x}

), the total area under the load–displacement curve (

A_{t}

), and the initial slope of the linear region of the load–displacement curve (m). There are two objectives in this research: the first is to investigate which method performs best in identifying the interfacial cohesive parameters between the honeycomb core and carbon-epoxy facesheets, while the second objective is to reduce the dimensionality of the dataset by reducing the number of input features. Reducing the number of inputs can simplify the models and potentially improve the performance and interpretability. The results show that the ANN method produced the best results, with a mean absolute percentage error (MAPE) of 0.9578% and an R-squared (R²) value of 0.7932. These values indicate a high level of accuracy in predicting the four cohesive zone parameters: maximum normal contact stress (

σ_{I}

), critical fracture energy for normal separation (

G_{I}

), maximum equivalent tangential contact stress (

σ_{I I}

), and critical fracture energy for tangential slip (

G_{I I}

). Full article

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

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17 pages, 3079 KiB

Open AccessArticle

Determining the Advanced Frequency of Composited Functionally Graded Material Plates Using Third-Order Shear Deformation Theory and Nonlinear Varied Shear Coefficients

by Chih-Chiang Hong

J. Compos. Sci. 2024, 8(8), 325; https://doi.org/10.3390/jcs8080325 - 16 Aug 2024

Viewed by 1005

Abstract

The shear effect is usually considered in the numerical calculation of thick composited FGM plates. The characteristics that have the greatest effect on thickness are displacement type, shear correction coefficient, material property and temperature. For the advanced frequency study of thick composited functionally [...] Read more.

The shear effect is usually considered in the numerical calculation of thick composited FGM plates. The characteristics that have the greatest effect on thickness are displacement type, shear correction coefficient, material property and temperature. For the advanced frequency study of thick composited functionally graded material (FGM) plates, it is interesting to consider the extra effects of the nonlinear coefficient c₁ term of the third-order shear deformation theory (TSDT) of displacement on the calculation of varied shear correction coefficients. The values of nonlinear shear correction coefficients are usually functions of c₁, the power-law exponent parameter and environment temperature. Numerical frequency computations are calculated using a simple homogeneous equation, and are investigated using TSDT and the nonlinear shear correction coefficient for thick composited FGM plates. Results for natural frequencies are found via the functions of length-to-thickness ratio, the power-law exponent parameter, c₁ and environment temperature. This novel study in advanced frequency aims to determine the effects of the TSDT and nonlinear shear correction on thick FGM plates under free vibration. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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30 pages, 13909 KiB

Open AccessReview

A Review of the Current State of Research and Future Prospectives on Stimulus-Responsive Shape Memory Polymer Composite and Its Blends

by Rajita Sanaka, Santosh Kumar Sahu, P. S. Rama Sreekanth, K. Senthilkumar, Nitesh Dhar Badgayan, Bathula Venkata Siva and Quanjin Ma

J. Compos. Sci. 2024, 8(8), 324; https://doi.org/10.3390/jcs8080324 - 16 Aug 2024

Cited by 12 | Viewed by 2491

Abstract

Shape-memory polymers (SMPs) possess unique properties that respond to external stimuli. The current review discusses types of SMPs, fabrication methods, and the characterization of their mechanical, thermal, and shape recovery properties. Research suggests that SMP composites, when infused with fillers, demonstrate enhanced mechanical [...] Read more.

Shape-memory polymers (SMPs) possess unique properties that respond to external stimuli. The current review discusses types of SMPs, fabrication methods, and the characterization of their mechanical, thermal, and shape recovery properties. Research suggests that SMP composites, when infused with fillers, demonstrate enhanced mechanical and thermal characteristics. On the other hand, blends, particularly incorporating polylactic acid (PLA), exhibit the most efficient shape recovery. Furthermore, the crosslinking density in polymer blends impacts the shape recovery force, showcasing a correlation between energy storage capacity and shape recovery force in SMP networks. Overall, SMP blends show promising mechanical, thermal, and shape recovery features, rendering them advantageous for applications of artificial muscles, soft actuators, and biomedical devices. This review also discusses the future prospectives of SMP for robust applications. Full article

(This article belongs to the Special Issue Composites: A Sustainable Material Solution)

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15 pages, 4627 KiB

Open AccessArticle

Linear Actuators Based on Polyvinyl Alcohol/Lithium Chloride Hydrogels Activated by Low AC Voltage

by Tarek Dayyoub, Mikhail Zadorozhnyy, Kseniia V. Filippova, Lidiia D. Iudina, Dmitry V. Telyshev, Pavel V. Zhemchugov, Dmitriy G. Ladokhin and Aleksey Maksimkin

J. Compos. Sci. 2024, 8(8), 323; https://doi.org/10.3390/jcs8080323 - 15 Aug 2024

Viewed by 1117

Abstract

The development of fast-responding electrically conductive polymers as actuators activated by low electrical current is now regarded as an urgent matter. Due to their limited electrical conductivity, actuators based on polymeric hydrogels must be activated using a high voltage (up to 200 V) [...] Read more.

The development of fast-responding electrically conductive polymers as actuators activated by low electrical current is now regarded as an urgent matter. Due to their limited electrical conductivity, actuators based on polymeric hydrogels must be activated using a high voltage (up to 200 V) and frequency (up to 500 Hz) when employing AC power. In this work, to improve the electrical conductivity of the hydrogel and decrease the required activation voltage of the hydrogel actuators, lithium chloride (LiCL) was added as a conductive filler to the polymer matrix of polyvinyl alcohol (PVA). In order to ascertain the deformation of actuators, activation and relaxation times, actuator efficiencies, and generated force under the conditions of activation, linear actuators that can be activated by extension/contraction (swelling/shrinking) cycles were prepared and investigated depending on the LiCl content, applied voltage, and frequency. Under a load of approximately 20 kPa and using a 90 V AC power at a 50 Hz frequency with a 30 wt.% LiCl content, it was found that the actuators’ total contraction, reinforced by a woven mesh braided material, was about 20% with a ~2.2 s activation time, while the actuators’ total extension, reinforced by a spiral weave material, was about 52% with a ~2.5 s activation time, after applying a 110 V AC at a 50 Hz frequency with a 10 wt.% LiCl content. Furthermore, as the lowest voltage, a 20 V AC power can operate these actuators by increasing the LiCl weight content to the same PVA mass content. Moreover, the PVA/LiCl hydrogels’ activation force can be greater than 0.5 MPa. The actuators that have been developed have broad applications in soft robotics, artificial muscles, medicine, and aerospace fields. Full article

(This article belongs to the Section Composites Applications)

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19 pages, 4526 KiB

Open AccessArticle

Increasing the Photovoltaic Efficiency of Semiconductor (Cu_1−xAg_x)₂ZnSnS₄ Thin Films through Ag Content Modification

by A. M. Bakry, Lamiaa S. El-Sherif, S. Hassaballa and Essam R. Shaaban

J. Compos. Sci. 2024, 8(8), 322; https://doi.org/10.3390/jcs8080322 - 15 Aug 2024

Cited by 1 | Viewed by 1109

Abstract

The research referred to in this study examines the morphological, structural, and optical characteristics of kesterite (Cu_1−xAg_x)₂ZnSnS₄ (CAZTS) thin films, which are produced using a process known as thermal evaporation (TE). The study’s main goal was [...] Read more.

The research referred to in this study examines the morphological, structural, and optical characteristics of kesterite (Cu_1−xAg_x)₂ZnSnS₄ (CAZTS) thin films, which are produced using a process known as thermal evaporation (TE). The study’s main goal was to determine how different Ag contents affect the characteristics of CAZTS systems. X-ray diffraction (XRD) and Raman spectroscopy were used to confirm the crystal structure of the CAZTS thin films. Using a mathematical model of spectroscopic ellipsometry, the refractive index (n) represented the real part of the complex thin films, the extinction coefficient (k) portrayed the imaginary part, and the energy bandgap of the fabricated thin films was calculated. The energy bandgap is a crucial parameter for solar cell applications, as it determines the wavelength of light that the material can absorb. The energy bandgap was found to decrease from 1.74 eV to 1.55 eV with the increasing Ag content. The ITO/n-CdS/p-CAZTS/Mo heterojunction was well constructed, and the primary photovoltaic characteristics of the n-CdS/p-CAZTS junctions were examined for use in solar cells. Different Ag contents of the CAZTS layers were used to determine the dark and illumination (current–voltage) characteristics of the heterojunctions. The study’s findings collectively point to CAZTS thin layers as potential absorber materials for solar cell applications. Full article

(This article belongs to the Section Metal Composites)

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23 pages, 6844 KiB

Open AccessArticle

Sensor Systems for Measuring Force and Temperature with Fiber-Optic Bragg Gratings Embedded in Composite Materials

by Aliya Kalizhanova, Ainur Kozbakova, Murat Kunelbayev, Zhalau Aitkulov, Anar Utegenova and Ulzhan Imanbekova

J. Compos. Sci. 2024, 8(8), 321; https://doi.org/10.3390/jcs8080321 - 14 Aug 2024

Viewed by 1621

Abstract

Currently, there is a lot of interest in smart sensors and integrated composite materials in various industries such as construction, aviation, automobile, medical, information technology, communication, and manufacturing. Here, a new conceptual design for a force and temperature sensor system is developed using [...] Read more.

Currently, there is a lot of interest in smart sensors and integrated composite materials in various industries such as construction, aviation, automobile, medical, information technology, communication, and manufacturing. Here, a new conceptual design for a force and temperature sensor system is developed using fiber-optic Bragg grating sensors embedded within composite materials, and a mathematical model is proposed that allows one to estimate strain and temperature based on signals obtained from the optical Bragg gratings. This is important for understanding the behaviors of sensors under different conditions and for creating effective monitoring systems. Describing the strain gradient distribution, especially considering different materials with different Young’s modulus values, provides insight into how different materials respond to applied forces and temperature changes. The shape of the strain gradient distribution was obtained, which is a quadratic function with a maximum value of 1500 µ, with a maximum value at the center of the lattice and a symmetrically decreasing strain value with distance from the central part of the fiber Bragg grating. With the axial strain at the installation site of the Bragg grating sensor under applied force values ranging from 10 to 11 N, the change in strain was linear. As a result of theoretical research, it was found that the developed system with fiber-optic sensors based on Bragg gratings embedded in composite materials is resistant to external influences and temperature changes. Full article

(This article belongs to the Section Fiber Composites)

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20 pages, 4718 KiB

Open AccessArticle

Buckling Analysis of Variable-Angle Tow Composite Plates through Variable Kinematics Hierarchical Models

by Gaetano Giunta, Domenico Andrea Iannotta, Levent Kirkayak and Marco Montemurro

J. Compos. Sci. 2024, 8(8), 320; https://doi.org/10.3390/jcs8080320 - 13 Aug 2024

Viewed by 1245

Abstract

Variable-Angle Tow (VAT) laminates can improve straight fiber composites’ mechanical properties thanks to the application of curvilinear fibers. This characteristic allows one to achieve ambitious objectives for design and performance purposes. Nevertheless, the wider design space and the higher number of parameters result [...] Read more.

Variable-Angle Tow (VAT) laminates can improve straight fiber composites’ mechanical properties thanks to the application of curvilinear fibers. This characteristic allows one to achieve ambitious objectives for design and performance purposes. Nevertheless, the wider design space and the higher number of parameters result in a more complex structural problem. Among the various approaches that have been used for VAT study, Carrera’s Unified Formulation (CUF) allows one to obtain multiple theories within the same framework, guaranteeing a good compromise between the results’ accuracy and the computational cost. In this article, the linear buckling behavior of VAT laminates is analyzed through the extension of CUF 2D plate models within Reissner’s Mixed Variational Theorem (RMVT). The results show that RMVT can better approximate the prebuckling nonuniform stress field of the plate when compared to standard approaches, thus improving the prediction of the linear buckling loads of VAT composites. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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12 pages, 2826 KiB

Open AccessArticle

Water Diffusion in Additively Manufactured Polymers: Effect of Voids

by Boyu Li, Konstantinos P. Baxevanakis and Vadim V. Silberschmidt

J. Compos. Sci. 2024, 8(8), 319; https://doi.org/10.3390/jcs8080319 - 12 Aug 2024

Cited by 1 | Viewed by 945

Abstract

This study investigates the effect of void features in additively manufactured polymers on water diffusion, focusing on polyethylene terephthalate glycol (PETG) composites. The additive manufacturing (AM) of polymers, specifically, material extrusion AM (MEAM), results in manufacturing-induced voids, therefore affecting the water resistance of [...] Read more.

This study investigates the effect of void features in additively manufactured polymers on water diffusion, focusing on polyethylene terephthalate glycol (PETG) composites. The additive manufacturing (AM) of polymers, specifically, material extrusion AM (MEAM), results in manufacturing-induced voids, therefore affecting the water resistance of the printed parts. The research analyses the effects of size, shape, orientation and the hydrophilicity of voids on moisture diffusion in PETG composites employing numerical (finite-element) simulations. Two void types were examined: voids of Type I that retard the moisture propagation and voids of Type II that enhance it. Simulations demonstrate that a higher volume fraction of voids and their orientation with regard to the diffusion direction significantly hinder the moisture transport for Type I voids. Conversely, due to their high diffusivity, Type II voids serve as channels for rapid moisture transmission. Consequently, for such materials, the global diffusion rates mainly depend on the volume fraction of voids rather than their shape. These findings indicate the critical role of voids in the design of AM parts for environments exposed to moisture, such as marine and offshore applications. Understanding the void effects is critical for optimising the durability and performance of MEAM components underwater exposure. Full article

(This article belongs to the Special Issue Progress in Polymer Composites, Volume III)

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32 pages, 6776 KiB

Open AccessReview

A Review on the Modelling of Aligned Discontinuous Fibre Composites

by Chantal Lewis, Burak Ogun Yavuz, Marco L. Longana, Jonathan P.-H. Belnoue, Karthik Ram Ramakrishnan, Carwyn Ward and Ian Hamerton

J. Compos. Sci. 2024, 8(8), 318; https://doi.org/10.3390/jcs8080318 - 12 Aug 2024

Cited by 3 | Viewed by 2747

Abstract

Aligned discontinuous fibre-reinforced composites are becoming more popular because they have the potential to offer stiffness and strength comparable to their continuous counterparts along with better manufacturability. However, the modelling of highly aligned discontinuous fibre composites is still in its infancy. This paper [...] Read more.

Aligned discontinuous fibre-reinforced composites are becoming more popular because they have the potential to offer stiffness and strength comparable to their continuous counterparts along with better manufacturability. However, the modelling of highly aligned discontinuous fibre composites is still in its infancy. This paper aims to provide a comprehensive review of the available literature to understand how modelling techniques have developed and consider whether all aspects which could affect the performance of aligned discontinuous fibre composites have been addressed. Here, for the first time, a broad view of the advantages, perspectives, and limitations of current approaches to modelling the performance and behaviour of aligned discontinuous fibre composites during alignment, forming, and mechanical loading is provided in one place as a route to design optimisation. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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18 pages, 3926 KiB

Open AccessReview

The Development of Polylactide Nanocomposites: A Review

by Purba Purnama, Zaki Saptari Saldi and Muhammad Samsuri

J. Compos. Sci. 2024, 8(8), 317; https://doi.org/10.3390/jcs8080317 - 10 Aug 2024

Viewed by 1239

Abstract

Polylactide materials present a promising alternative to petroleum-based polymers due to their sustainability and biodegradability, although they have certain limitations in physical and mechanical properties for specific applications. The incorporation of nanoparticles, such as layered silicate (clay), carbon nanotubes, metal or metal oxide, [...] Read more.

Polylactide materials present a promising alternative to petroleum-based polymers due to their sustainability and biodegradability, although they have certain limitations in physical and mechanical properties for specific applications. The incorporation of nanoparticles, such as layered silicate (clay), carbon nanotubes, metal or metal oxide, cellulose nanowhiskers, can address these limitations by enhancing the thermal, mechanicals, barriers, and some other properties of polylactide. However, the distinct characteristics of these nanoparticles can affect the compatibility and processing of polylactide blends. In the polylactide nanocomposites, well-dispersed nanoparticles within the polylactide matrix result in excellent mechanical and thermal properties of the materials. Surface modification is required to improve compatibility and the crystallization process in the blended materials. This article reviews the development of polylactide nanocomposites and their applications. It discusses the general aspect of polylactides and nanomaterials as nanofillers, followed by the discussion of the processing and characterization of polylactide nanocomposites, including their applications. The final section summarizes and discusses the future challenges of polylactide nanocomposites concerning the future material’s requirements and economic considerations. As eco-friendly materials, polylactide nanocomposites offer significant potential to replace petroleum-based polymers. Full article

(This article belongs to the Special Issue Sustainable Biocomposites, Volume II)

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19 pages, 3111 KiB

Open AccessArticle

Development of a Tool Concept for Prestressed Fibre Metal Laminates and Their Effect on Interface Failure

by Hayrettin Irmak, Steffen Tinkloh, Thorsten Marten and Thomas Tröster

J. Compos. Sci. 2024, 8(8), 316; https://doi.org/10.3390/jcs8080316 - 10 Aug 2024

Viewed by 729

Abstract

The use of hybrid materials as a combination of fibre-reinforced plastic (FRP) and metal is of great interest in order to meet the increasing demands for sustainability, efficiency, and emission reduction based on the principle of lightweight design. These two components can therefore [...] Read more.

The use of hybrid materials as a combination of fibre-reinforced plastic (FRP) and metal is of great interest in order to meet the increasing demands for sustainability, efficiency, and emission reduction based on the principle of lightweight design. These two components can therefore be joined using the intrinsic joining technique, which is formed by curing the matrix of the FRP component. In this study, for the hybrid joint, unidirectionally pre-impregnated semi-finished products (prepregs) with duromer matrix resin and micro-alloyed HC340LA steel were used. In order to conduct a detailed investigation, the damage mechanisms of intrinsically produced fibre metal laminates (FMLs), a new clamping device, and a novel pressing tool were designed and put into operation. The prepregs were prestressed by applying a preloading force using a specially designed prestressing frame. Hybrid specimens were then produced and subjected to nanoindentation and a shear tensile test. In particular, the effect of the residual stress state by varying the defined prestressing force on the damage mechanisms was studied. The results showed that no fracture patterns occurred in the interface of the specimens without preloading as a result of curing at 120 °C, whereas specimens with preloading failed at the boundary layer in the tensile range. Nevertheless, all specimens cured at 160 °C failed at the boundary layer in the tensile range. Furthermore, it was proven that the force and displacement of the preloaded specimens were promisingly higher than those of the unpreloaded specimens. Full article

(This article belongs to the Section Composites Applications)

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17 pages, 4465 KiB

Open AccessArticle

The Development of Sustainable Polyoxymethylene (POM)-Based Composites by the Introduction of Natural Fillers and Melt Blending with Poly(lactic acid)-PLA

by Anna Soćko and Jacek Andrzejewski

J. Compos. Sci. 2024, 8(8), 315; https://doi.org/10.3390/jcs8080315 - 10 Aug 2024

Viewed by 1340

Abstract

The conducted study was focused on the development of a new type of technical blend reinforced with natural fillers. The study was divided into two parts, where, in the first stage of the research, unmodified POM was reinforced with different types of natural [...] Read more.

The conducted study was focused on the development of a new type of technical blend reinforced with natural fillers. The study was divided into two parts, where, in the first stage of the research, unmodified POM was reinforced with different types of natural fillers: cellulose, wood flour, and husk particles. In order to select the type of filler intended for further modification, the mechanical characteristics were assessed. The 20% wood flour (WF) filler system was selected as the reinforcement. The second stage of research involved the use of a combination of polyoxymethylene POM and poly(lactic acid) PLA. The POM/PLA blend (ratio 50/50%) was modified with an elastomeric compound (EBA) and chain extender as the compatibilized reactive (CE). The microscopic analysis revealed that for the POM/PLA system, the filler–matrix interface is characterized by better wettability, which might suggest higher adhesion. The mechanical performance revealed that for POM/PLA-based composites, the properties were very close to the results for POM-WF composites; however, there is still a significant difference in thermal resistance in favor of POM-based materials. The increase in thermomechanical properties for POM/PLA composites occurs after heat treatment. The increasing crystallinity of the PLA phase allows for a significant increase in the heat deflection temperature (HDT), even above 125 °C. Full article

(This article belongs to the Special Issue Progress in Polymer Composites, Volume III)

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12 pages, 2051 KiB

Open AccessArticle

PEBAX^® 5533D Formulation for Enhancement of Mechanical and Thermal Properties of Material Used in Medical Device Manufacturing

by Mildred Guillén-Espinoza, Fabián Vásquez Sancho, Ricardo Starbird-Perez and Roy Zamora-Sequeira

J. Compos. Sci. 2024, 8(8), 314; https://doi.org/10.3390/jcs8080314 - 9 Aug 2024

Viewed by 1806

Abstract

The medical device industry is constantly innovating in the search for materials that demonstrate superior performance, better intrinsic characteristics, profitability, and a positive impact on potential patients. The thermoplastic polymer resin Pebax^® 5533D is one of the most widely used commercial materials [...] Read more.

The medical device industry is constantly innovating in the search for materials that demonstrate superior performance, better intrinsic characteristics, profitability, and a positive impact on potential patients. The thermoplastic polymer resin Pebax^® 5533D is one of the most widely used commercial materials for manufacturing medical device parts due to its easy processability. However, its mechanical and thermal properties require improvements to mitigate identified manufacturing defects, such as a decrease in material flexibility, high susceptibility to moisture, and thermal degradation during processing. Therefore, this study integrated different materials, such as plasticizers and filler additives, to produce a polymer compound prototype formula as a solution technique to enhance the current material’s performance. Modifying mechanical and rheological properties allows to evaluate the impacts on the polymeric material’s flexibility and thermal behavior. This was achieved by processing mixed additives using injector-molding equipment to obtain equal-molded samples of every formula. In addition, material characterization was performed to determine the variations in the samples’ crystallization, flexural strength, and moisture content. Calcium stearate was determined to be the most significant component serving as a mechanical resistance modifier and thermal stabilizer alongside calcium chloride as a moisture content reducer combined with Pebax^® 5533D. Full article

(This article belongs to the Section Polymer Composites)

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20 pages, 5934 KiB

Open AccessArticle

Axial Compressive Behavior of CFRP and MWCNT Incorporated GFRP Confined Concrete Cylinders after Exposure to Various Aggressive Environments

by Sruthi Sreekumar Kavitha, Mini K. Madhavan, Karingamanna Jayanarayanan and Prabir Kumar Sarker

J. Compos. Sci. 2024, 8(8), 313; https://doi.org/10.3390/jcs8080313 - 9 Aug 2024

Viewed by 1073

Abstract

Fiber-reinforced polymer confinement is considered to be effective in the retrofitting of concrete structures. The current study explores the effectiveness of one- and two-layer carbon fiber reinforced polymer (CFRP) and multiwalled carbon nanotube (MWCNT) incorporated three-layer glass fiber reinforced polymer (GFRP) confinement on [...] Read more.

Fiber-reinforced polymer confinement is considered to be effective in the retrofitting of concrete structures. The current study explores the effectiveness of one- and two-layer carbon fiber reinforced polymer (CFRP) and multiwalled carbon nanotube (MWCNT) incorporated three-layer glass fiber reinforced polymer (GFRP) confinement on concrete cylinders under aggressive exposures, such as acid, alkaline, marine, water, and elevated temperatures. At 1 wt.% MWCNT by weight of the epoxy matrix, mechanical characteristics of the laminate show a significant improvement. In the case of acid exposure, the axial load-carrying capacity of concrete specimens with single-layer CFRP confinement was equal to that of MWCNT incorporated three-layer GFRP confinement (GF₃C₁-AC). The axial strain of GF₃C₁-AC was 23% and 12% higher than one and two-layer CFRP confinement. After exposure at 400 °C, in comparison with one- and two-layer CFRP confinement, the axial strain of MWCNT incorporated three-layer GFRP confined specimens increased by 50% and 20%, respectively, which proved the efficacy of MWCNT as a heat-resistant nanofiller. The ultrasonic pulse velocity (UPV) test indicates that the confinement system protects the concrete core from sudden failure by impeding crack propagation. The test results proved that the MWCNT incorporated FRP system can be considered as a prospective substitute for CFRP systems for retrofitting applications in severe environmental conditions. Full article

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18 pages, 8835 KiB

Open AccessArticle

Influence of Long-Term Moisture Exposure and Temperature on the Mechanical Properties of Hybrid FRP Composite Specimens

by Getahun Tefera, Glen Bright and Sarp Adali

J. Compos. Sci. 2024, 8(8), 312; https://doi.org/10.3390/jcs8080312 - 9 Aug 2024

Cited by 2 | Viewed by 1289

Abstract

The present experimental study assesses the mechanical properties of glass/carbon/glass hybrid composite laminates after being exposed to moisture in a deep freezer and elevated temperatures for extended periods. The top and bottom layers of the hybrid laminates are reinforced with glass fibre, and [...] Read more.

The present experimental study assesses the mechanical properties of glass/carbon/glass hybrid composite laminates after being exposed to moisture in a deep freezer and elevated temperatures for extended periods. The top and bottom layers of the hybrid laminates are reinforced with glass fibre, and the middle layer is reinforced with carbon fibre using the epoxy matrix as a binder polymer material. The hybrid laminates were manufactured using the resin transfer moulding method, and their compressive and tensile properties were determined using a tensile testing machine. The storage modulus, loss modulus, and damping factors of all groups of laminates were identified using a dynamic mechanical analysis as a function of temperature and vibration frequency. The experimental results on compressive and tensile properties revealed slight variations when the hybrid laminates were kept at low temperatures in a deep freezer for extended periods. This might occur due to the increasing molecular crosslinking of the polymer network. As the testing temperature increased, compressive, tensile, storage modules, loss modulus, and damping factors decreased. This might occur due to the increasing mobility of the binder material. Particularly, the highest stiffness parameters were obtained at −80 °C/GCG (glass/carbon/glass) laminates due to the presence of a beta transition in the glassy region. The relationships between the glass transitions and the targeted frequencies were characterized. The values of the glass transition shift towards higher temperatures as the frequency increases. This might occur due to a reduction in the gaps between the crosslinking of the epoxy network when the frequency increases. The accuracy of the storage modulus results was compared with the empirical models. The model based on the Arrhenius law provided the closest correlation. Meanwhile, another model was observed that was not accurate enough to predict when gamma and beta relaxations occur in a glassy state. Full article

(This article belongs to the Section Fiber Composites)

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16 pages, 3013 KiB

Open AccessArticle

A Study on the Early Degradation of the Non-Additive Polypropylene–Polyethylene Composite Sampled between the Polymerization Reactor and the Deactivation-Degassing Tank

by Joaquín Alejandro Hernández Fernández, Rodrigo Ortega-Toro and Eduardo Antonio Espinosa Fuentes

J. Compos. Sci. 2024, 8(8), 311; https://doi.org/10.3390/jcs8080311 - 9 Aug 2024

Viewed by 1377

Abstract

The industrial production of polypropylene–polyethylene composites (C-PP-PE) involves the generation of waste that is not usable, resulting in a significant environmental impact globally. In this research, we identified different concentrations of aluminum (8–410 ppm), chlorine (13–205 ppm), and iron (4–100 ppm) residues originating [...] Read more.

The industrial production of polypropylene–polyethylene composites (C-PP-PE) involves the generation of waste that is not usable, resulting in a significant environmental impact globally. In this research, we identified different concentrations of aluminum (8–410 ppm), chlorine (13–205 ppm), and iron (4–100 ppm) residues originating from traces of the Ziegler–Natta catalyst and the triethylaluminum (TEAL) co-catalyst. These residues accelerate the generation of plastic waste and affect the thermo-kinetic performance of C-PP-PE, as well as the formation of volatile organic compounds that reduce the commercial viability of C-PP-PE. Several families of organic compounds were quantified by gas chromatography with mass spectrometry, and it is evident that these concentrations varied directly with the ppm of Al, Cl, and Fe present in C-PP-PE. This research used kinetic models of Coats–Redfern, Horowitz–Metzger, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose. The activation energy values (Ea) were inversely correlated with Al, Cl, and Fe concentrations. In samples PP0 and W3, with low Al, Cl, and Fe concentrations, the values (Ea) were 286 and 224 kJ mol⁻¹, respectively, using the Horowitz method. Samples W1 and W5, with a high ppm of these elements, showed Ea values of 80.83 and 102.99 kJ mol⁻¹, respectively. This knowledge of the thermodynamic behavior and the elucidation of possible chemical reactions in the industrial production of C-PP-PE allowed us to search for a suitable remediation technique to give a new commercial life to C-PP-PE waste, thus supporting the management of plastic waste and improving the process—recycling to promote sustainability and industrial efficiency. One option was using the antioxidant additive Irgafos P-168 (IG-P168), which stabilized some of these C-PP-PE residues very well until thermal properties similar to those of pure C-PP-PE were obtained. Full article

(This article belongs to the Special Issue Progress in Polymer Composites, Volume III)

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20 pages, 23973 KiB

Open AccessArticle

Molecular Dynamics Assessment of Mechanical Properties of Fullerphene and Fullerphene/Graphene Composite

by Mingjun Han, Taotao Yu, Yinghe Zhang, Xue Chen, Xiao-Jia Chen, Qing Peng and Ho-Kin Tang

J. Compos. Sci. 2024, 8(8), 310; https://doi.org/10.3390/jcs8080310 - 8 Aug 2024

Cited by 1 | Viewed by 1317

Abstract

Quasi-hexagonal-phase fullerene (qHPC₆₀) is an asymmetrically ordered arrangement of fullerene in the two-dimensional plane, which has been synthesized recently. In this study, we performed a comprehensive investigation of the anisotropic mechanical properties of a qHPC₆₀/graphene composite by means of [...] Read more.

Quasi-hexagonal-phase fullerene (qHPC₆₀) is an asymmetrically ordered arrangement of fullerene in the two-dimensional plane, which has been synthesized recently. In this study, we performed a comprehensive investigation of the anisotropic mechanical properties of a qHPC₆₀/graphene composite by means of molecular dynamics simulations. We assessed the mechanical properties of the 2D torsion-angle fullerene model with three force-fields: AIREBO, REAXFF, and TERSOFF. The results of the uniaxial tensile tests show that while the variations in fracture stress and fracture strain, with respect to pre-crack size, had similar trends for the three force-fields, AIREBO was more sensitive than REAXFF. The presence of cracks degraded the mechanical properties. Simulations of tensile tests on the qHPC₆₀/graphene composite revealed that the graphene substrate significantly increased mechanical strength. Our results suggest qHPC₆₀ holds various promising implications for composites. Full article

(This article belongs to the Special Issue Graphene Composites)

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17 pages, 6933 KiB

Open AccessArticle

Evidence for a Giant Magneto-Electric Coupling in Bulk Composites with Coaxial Fibers of Nickel–Zinc Ferrite and PZT

by Bingfeng Ge, Jitao Zhang, Sujoy Saha, Sabita Acharya, Chaitrali Kshirsagar, Sidharth Menon, Menka Jain, Michael R. Page and Gopalan Srinivasan

J. Compos. Sci. 2024, 8(8), 309; https://doi.org/10.3390/jcs8080309 - 8 Aug 2024

Cited by 1 | Viewed by 1518

Abstract

This report is on magneto-electric (ME) interactions in bulk composites with coaxial fibers of nickel–zinc ferrite and PZT. The core–shell fibers of PZT and Ni_1−xZn_xFe₂O₄ (NZFO) with x = 0–0.5 were made by electrospinning. Both kinds [...] Read more.

This report is on magneto-electric (ME) interactions in bulk composites with coaxial fibers of nickel–zinc ferrite and PZT. The core–shell fibers of PZT and Ni_1−xZn_xFe₂O₄ (NZFO) with x = 0–0.5 were made by electrospinning. Both kinds of fibers, either with ferrite or PZT core and with diameters in the range of 1–3 μm were made. Electron and scanning probe microscopy images indicated well-formed fibers with uniform core and shell structures and defect-free interface. X-ray diffraction data for the fibers annealed at 700–900 °C did not show any impurity phases. Magnetization, magnetostriction, ferromagnetic resonance, and polarization P versus electric field E measurements confirmed the ferroic nature of the fibers. For ME measurements, the fibers were pressed into disks and rectangular platelets and then annealed at 900–1000 °C for densification. The strengths of strain-mediated ME coupling were measured by the H-induced changes in remnant polarization P_r and by low-frequency ME voltage coefficient (MEVC). The fractional change in P_r under H increased in magnitude, from +3% for disks of NFO–PZT to −82% for NZFO (x = 0.3)-PZT, and a further increase in x resulted in a decrease to a value of −3% for x = 0.5. The low-frequency MEVC measured in disks of the core–shell fibers ranged from 6 mV/cm Oe to 37 mV/cm Oe. The fractional changes in P_r and the MEVC values were an order of magnitude higher than for bulk samples containing mixed fibers with a random distribution of NZFO and PZT. The bulk composites with coaxial fibers have the potential for use as magnetic field sensors and in energy-harvesting applications. Full article

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

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15 pages, 1937 KiB

Open AccessReview

Conductive Polymer-Based Thermoelectric Composites: Preparation, Properties, and Applications

by Erwei Song, Peiyao Liu, Yifan Lv, Erqiang Wang and Cun-Yue Guo

J. Compos. Sci. 2024, 8(8), 308; https://doi.org/10.3390/jcs8080308 - 8 Aug 2024

Cited by 2 | Viewed by 1850

Abstract

Thermoelectric (TE) materials are capable of realizing the direct conversion between heat and electricity, holding a giant prospect in the sustainable development of modern society. Conductive polymers (CPs) are suitable for the preparation of TE materials given their low-cost, lightweight, flexible, and easy [...] Read more.

Thermoelectric (TE) materials are capable of realizing the direct conversion between heat and electricity, holding a giant prospect in the sustainable development of modern society. Conductive polymers (CPs) are suitable for the preparation of TE materials given their low-cost, lightweight, flexible, and easy processing properties. With the accelerating pace of flexible composite development, there is intensive interest in their emerging applications in various aspects such as wearable electronics and thermoelectric sensors. In order to further improve the thermoelectric properties, a series of new methods have been proposed to prepare conductive polymer-based thermoelectric composites and improve their thermoelectric properties. In this review, we discuss the compositing methods, properties, and applications of conductive polymer-based TE composites. The challenges and future development directions in the design and application of conductive polymer matrix composites are also pointed out. Full article

(This article belongs to the Special Issue Composite Materials Containing Conjugated and Conductive Polymers)

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3 pages, 194 KiB

Open AccessEditorial

Editorial for the Special Issue on Carbon Fiber Composites, Volume II

by Jiadeng Zhu

J. Compos. Sci. 2024, 8(8), 307; https://doi.org/10.3390/jcs8080307 - 6 Aug 2024

Viewed by 917

Abstract

Fibers with lengths much larger than their widths have been developed over centuries because of their unique properties [...] Full article

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

16 pages, 5687 KiB

Open AccessArticle

Investigation of the Physico-Chemical and Mechanical Properties of Expanded Ceramsite Granules Made on the Basis of Coal Mining Waste

by Yerkebulan Kocherov, Alexandr Kolesnikov, Gulnaz Makulbekova, Aigul Mamitova, Lazzat Ramatullaeva, Bahtiyor Medeshev and Olga Kolesnikova

J. Compos. Sci. 2024, 8(8), 306; https://doi.org/10.3390/jcs8080306 - 6 Aug 2024

Cited by 3 | Viewed by 1076

Abstract

In this article, one of the main scientific directions was the search for ways of recycling coal mining waste to produce expanded clay granules. There are a number of scientific studies devoted to the use of various industrial wastes in the production of [...] Read more.

In this article, one of the main scientific directions was the search for ways of recycling coal mining waste to produce expanded clay granules. There are a number of scientific studies devoted to the use of various industrial wastes in the production of thermal insulation and fireproof expanded clay granules. The authors consider the production of granular porous aggregates based on pulverized fractions of igneous rocks—basalt, granite, and synertite, as well as man-made materials of various origins, to be promising. According to the results of the conducted studies, it was found that the optimal interval of the amount of waste in expanded clay was 4.0–6.0%, and the optimal firing temperature was 1150 °C with the production of samples with a bulk density of 0.337–0.348 t/m³ and with a compressive strength of 1.37–1.51 MPa under these conditions. Full article

(This article belongs to the Special Issue Advancements in Processing and Properties of Ceramic Matrix Composites)

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17 pages, 5046 KiB

Open AccessArticle

Process–Property Correlation in Sustainable Printing Extrusion of Bio-Based Filaments

by Antonella Patti

J. Compos. Sci. 2024, 8(8), 305; https://doi.org/10.3390/jcs8080305 - 5 Aug 2024

Cited by 2 | Viewed by 1160

Abstract

This study investigated the effect of two critical variables for environmental process sustainability, i.e., extruder temperature and printing rate, on thermomechanical performance and accuracy in overall sample sizes, when printing bio-based materials. In this context, 3D specimens produced from basic polylactide (n-PLA) and [...] Read more.

This study investigated the effect of two critical variables for environmental process sustainability, i.e., extruder temperature and printing rate, on thermomechanical performance and accuracy in overall sample sizes, when printing bio-based materials. In this context, 3D specimens produced from basic polylactide (n-PLA) and wood-filled PLA polymer (f-PLA) were realized using extrusion-based additive manufacturing technology (MEX) by varying the nozzle temperatures (200 °C, 210 °C, and 220 °C) and speed (from 70 mm/s to 130 mm/s). Dynamic mechanical analysis (DMA) was carried out on the produced specimens, providing information on changes in storage modulus at testing temperature of 30 °C (E′₃₀) and glass transition temperature (Tg) for each printing condition. Measurements of sample sizes allowed for printing precision considerations as a function of processing temperature and speed. The results revealed similar trends in E′₃₀ changes in printed specimens at a fixed extruder temperature as a function of printing speed for n-PLA and f-PLA. Infrared spectroscopy was performed on printed samples and unextruded material to attest potential material degradation under various operating conditions. Finally, images of sample surface allowed to verify the homogeneity of the diameter of the extruded material and the layer–layer contact at the interface. Full article

(This article belongs to the Special Issue Sustainable Biocomposites, Volume II)

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18 pages, 3939 KiB

Open AccessArticle

Influence of Additives on Flame-Retardant, Thermal, and Mechanical Properties of a Sulfur–Triglyceride Polymer Composite

by Perla Y. Sauceda-Oloño, Bárbara G. S. Guinati, Ashlyn D. Smith and Rhett C. Smith

J. Compos. Sci. 2024, 8(8), 304; https://doi.org/10.3390/jcs8080304 - 5 Aug 2024

Cited by 2 | Viewed by 1499

Abstract

Plastics and composites for consumer goods often require flame retardants (FRs) to mitigate flammability risks. Finding FRs that are effective in new sustainable materials is important for bringing them to the market. This study evaluated various FRs in SunBG₉₀ (a composite made [...] Read more.

Plastics and composites for consumer goods often require flame retardants (FRs) to mitigate flammability risks. Finding FRs that are effective in new sustainable materials is important for bringing them to the market. This study evaluated various FRs in SunBG₉₀ (a composite made from triglycerides and sulfur)—a high sulfur-content material (HSM) promising for use in Li–S batteries, where flame resistance is critical. SunBG₉₀ was blended with FRs from several classes (inorganic, phosphorus-based, brominated, and nitrogen-containing) to assess compliance with UL94 Burning Test standards. Inorganic FRs showed poor flame retardancy and lower mechanical strength, while organic additives significantly improved fire resistance. The addition of 20 wt. % tetrabromobisphenol A enabled SunBG₉₀ to achieve the highest flame retardancy rating (94V-0), while also enhancing wear resistance (52 I_W, ASTM C1353) and bonding strength (26 psi, ASTM C482). Selected organic FRs also enhance compressive strength compared to the FR-free SunBG₉₀. This research highlights the potential of HSMs with traditional FRs to meet stringent fire safety standards while preserving or enhancing the mechanical integrity of HSM composites. Full article

(This article belongs to the Special Issue Progress in Polymer Composites, Volume III)

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18 pages, 22467 KiB

Open AccessArticle

Microstructural Evolution and Mechanical Behaviors of C_f/C_m-SiC-(Zr_xHf_1−x)C Composites with Different Carbon Matrices

by Zaidong Liu, Yalei Wang, Xiang Xiong, Hongbo Zhang, Zhiyong Ye, Quanyuan Long, Jinming Wang, Tongqi Li and Congcong Liu

J. Compos. Sci. 2024, 8(8), 303; https://doi.org/10.3390/jcs8080303 - 5 Aug 2024

Viewed by 1012

Abstract

In this study, two types of porous C_f/C_m composites were obtained by introducing pyrolytic carbon (PyC) and pyrolytic carbon/furan resin carbon (PyC/FRC). Subsequently, C_f/C_m-SiC-(Zr_xHf_1−x)C composites with different carbon matrices were prepared by [...] Read more.

In this study, two types of porous C_f/C_m composites were obtained by introducing pyrolytic carbon (PyC) and pyrolytic carbon/furan resin carbon (PyC/FRC). Subsequently, C_f/C_m-SiC-(Zr_xHf_1−x)C composites with different carbon matrices were prepared by introducing SiC and (Zr_xHf_1−x)C matrices into the porous C_f/C_m composites via the reactive melt infiltration method, specifically termed as C_f/PyC-SiC-(Zr_xHf_1−x)C and C_f/PyC/FRC-SiC-(Zr_xHf_1−x)C composites. The microstructures of the porous C_f/C_m and C_f/C_m-SiC-(Zr_xHf_1−x)C composites with different carbon matrices were examined, and a comprehensive analysis was conducted on microstructural evolution and mechanical behaviors of the C_f/C_m-SiC-(Zr_xHf_1−x)C composites. The results indicate that both C_f/C_m-SiC-(Zr_xHf_1−x)C composites underwent similar microstructural evolution processes, differing only in terms of evolution kinetics and final microstructure. Differences in the pore structures of porous C_f/C_m composites, as well as in the reactivities of carbon matrices, were identified as primary influencing factors. Additionally, both C_f/C_m-SiC-(Zr_xHf_1−x)C composites exhibited “pseudo-ductile” fracture characteristics, with flexural strengths of 214.1 ± 8.8 MPa and 149.6 ± 12.2 MPa, respectively. In the C_f/PyC-SiC-(Zr_xHf_1−x)C composite, crack initiation during loading primarily originated from the ceramic matrix, while in the C_f/PyC/FRC-SiC-(Zr_xHf_1−x)C composite, failure initially arose from the residual FRC matrix. Excessive fiber corrosion and the presence of residual low-modulus FRC matrix resulted in lower mechanical performance. Full article

(This article belongs to the Special Issue Advanced in Ceramic Matrix Composites)

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