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Fibers, Volume 11, Issue 9 (September 2023) – 8 articles

Cover Story (view full-size image): Recycling tire fibers (RTF) is a sustainable solution to the environmental challenge posed by discarded tires. The valorization of these materials as a filler/reinforcement in polymer composites stands out as a highly effective means of waste reduction and resource conservation. However, it has attracted limited attention due to several processing difficulties and the presence of significant amounts of residual ground rubber particles. This study proposes a straightforward method for the separation of rubber particles from the fibers, along with techniques to determine their compositions. Then, the incorporation of cleaned fibers into recycled polyethylene leads to a substantial improvement in the mechanical properties. Thus, we propose further investigating RTF as valuable reinforcements in polymer matrices. View this paper
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12 pages, 3588 KiB  
Article
Solution Blow Spinning to Prepare Preferred Oriented Poly(ethylene oxide) Submicrometric Fibers
by Javier González-Benito, Miguel A. Lorente, Dania Olmos and Ana Kramar
Fibers 2023, 11(9), 79; https://doi.org/10.3390/fib11090079 - 21 Sep 2023
Cited by 2 | Viewed by 1121
Abstract
In this work, materials with potential biomedical applications constituted by fibrous poly(ethylene oxide), PEO, are prepared by solution blow spinning (SBS). The SBS setup has a cylindrical collector for which the rotational speed and size are varied to study its effect on the [...] Read more.
In this work, materials with potential biomedical applications constituted by fibrous poly(ethylene oxide), PEO, are prepared by solution blow spinning (SBS). The SBS setup has a cylindrical collector for which the rotational speed and size are varied to study its effect on the final morphology of the materials. The morphology is inspected using field emission scanning electron microscopy and studied using image analysis. As a result, many doubts were generated because of the use of different methods of image analysis, therefore a simpler and more conventional method using Image J open-source software was used to ensure the accuracy of the final interpretation. It is shown that fiber size and orientation depend on the linear speed associated with the surface of the collector more than on its rotational speed; therefore, it can be said that the morphology of materials prepared by SBS will depend on the size, shape, and rotational speed of the collector. When the linear speed of the cylindrical collector increases, fibers get thinner, less entangled, and more oriented. It is clear, therefore, that the linear speed of material collection by solution blow spinning is a very important parameter of processing to control the final morphology of materials manufactured by that method. Since morphology can affect the final properties of the materials the simple variation of the linear speed might have important implications on their final performance for different biomedical applications. Full article
(This article belongs to the Special Issue Nanofibers: Biomedical Applications)
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17 pages, 6427 KiB  
Review
Review of Out-of-Plane Strengthening Techniques of Unreinforced Masonry Walls
by Athanasia K. Thomoglou, P. Jagadesh and Maristella E. Voutetaki
Fibers 2023, 11(9), 78; https://doi.org/10.3390/fib11090078 - 19 Sep 2023
Cited by 2 | Viewed by 1364
Abstract
When a seismic load is applied horizontally or laterally on unreinforced masonry walls (URM), the walls behave in two different ways, viz., in-plane (IP) and out-of-plane (OoP). This review beneficially provides a literature overview of the most cited research papers on Scopus, and [...] Read more.
When a seismic load is applied horizontally or laterally on unreinforced masonry walls (URM), the walls behave in two different ways, viz., in-plane (IP) and out-of-plane (OoP). This review beneficially provides a literature overview of the most cited research papers on Scopus, and the database is evaluated with VOSviewer software for scientometric analysis. This review paper delves into the practical applications of various types of reinforcement for masonry walls, specifically focusing on four commonly used systems: externally bonded strengthening techniques using fiber-reinforced polymers (FRP), steel-reinforced grout (SRG), fabric-reinforced cementitious mortar (FRCM), and textile-reinforced mortars (TRM). The main objective of the paper is to explore the efficacy of these reinforcement techniques in strengthening masonry walls, and to provide a comprehensive overview of their respective advantages and limitations. A further detailed study of the extent of the literature is performed about the effect of the different strengthening systems on the mechanical properties of different categories of masonry walls like a cement block, stone, and clay brick are described and categorized. The efficiency of OoP strengthening can depend on various factors, such as the types of masonry units, the rendering mortar, the type of strengthening system, the bond between the different materials interfaces, the geometry of the wall, and the loading conditions. By utilizing the practical method of Dematel (Decision-making trial and evaluation laboratory) analysis, this review can delve deeply into the impact of various factors and precisely identify the crucial components of the cause-and-effect connection. The results indicate that the bond between material interfaces is the critical factor. This meticulous and structured review offers valuable perspectives for researchers and engineers, showcasing current research trends and presenting potential avenues for future exploration. Full article
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13 pages, 8594 KiB  
Article
Flexural Properties of Thin-Walled Specimens with Square Hollow Sections 3D Printed from ABS Reinforced with Aramid Fibers
by Jerzy Bochnia, Tomasz Kozior and Mateusz Musialek
Fibers 2023, 11(9), 77; https://doi.org/10.3390/fib11090077 - 17 Sep 2023
Viewed by 1214
Abstract
This article studies the flexural behavior of thin-walled specimens with square hollow sections fabricated using fused deposition modeling (FDM). The specimens were 3D printed from an ABS filament reinforced with aramid fibers. Four wall thicknesses were analyzed. The strength data were collected during [...] Read more.
This article studies the flexural behavior of thin-walled specimens with square hollow sections fabricated using fused deposition modeling (FDM). The specimens were 3D printed from an ABS filament reinforced with aramid fibers. Four wall thicknesses were analyzed. The strength data were collected during three-point flexural tests. There are visible, clear differences in the flexural properties between the X- or Y-oriented specimens and those printed in the Z direction, and they vary up to 70%. It was also found that the flexural strength was dependent on the G-codes controlling the print head’s motion, path, and position. For specimens with a thickness up to 1.4 mm, the infill pattern was linear, whereas 1.8 mm and 2 mm specimens needed a stitch, which had some negative effects on the strength properties. Full article
(This article belongs to the Special Issue Fracture Behavior of Fiber-Reinforced Building Materials)
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17 pages, 4220 KiB  
Article
Innovative and Sustainable Composite Material for the Seismic and Energetic Upgrade of Historic Masonry Buildings
by Dora Pugliese, Valerio Alecci, Rosa Romano, Gianfranco Stipo, Mario De Stefano and Antonio Nanni
Fibers 2023, 11(9), 76; https://doi.org/10.3390/fib11090076 - 14 Sep 2023
Viewed by 1445
Abstract
Usually, energy and structural improvements for historic masonry buildings are addressed separately using distinct methods and protocols. This paper covers an integrated assessment of new composite materials to reduce the seismic vulnerability of historic masonry buildings while complying with sustainable conservation requirements, emissions’ [...] Read more.
Usually, energy and structural improvements for historic masonry buildings are addressed separately using distinct methods and protocols. This paper covers an integrated assessment of new composite materials to reduce the seismic vulnerability of historic masonry buildings while complying with sustainable conservation requirements, emissions’ reduction, and energy savings. Firstly, this study focused on selecting suitable thermal mortars that could serve as the base material for the innovative composite. Subsequently, the mechanical characteristics of these mortars were examined by subjecting them to compressive and three-point bending tests. Dynamic thermo-hygrometric simulations were conducted using commercially available software to check the energy performance of the composite material when used on walls of existing masonry buildings. The thermal mortar that exhibited the most favorable mechanical and thermal properties was subsequently reinforced with a basalt fabric. A composite sample was assembled and subjected to direct tensile testing to determine its stress–strain behavior. Full article
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31 pages, 4674 KiB  
Article
The Production of Ultra-Thin Polyethylene-Based Carbon Fibers out of an “Islands-in-the-Sea” (INS) Precursor
by Flávio A. Marter Diniz, Tim Röding, Mohamed Bouhrara and Thomas Gries
Fibers 2023, 11(9), 75; https://doi.org/10.3390/fib11090075 - 08 Sep 2023
Cited by 1 | Viewed by 1335
Abstract
Carbon fibers (CF) and their composites (CC) are one of the world’s most promising and avant-garde high-performance materials, as they combine excellent mechanical characteristics with high weight reduction potential. Polyethylene (PE) is the perfect alternative precursor for CF as it combines widespread availability, [...] Read more.
Carbon fibers (CF) and their composites (CC) are one of the world’s most promising and avant-garde high-performance materials, as they combine excellent mechanical characteristics with high weight reduction potential. Polyethylene (PE) is the perfect alternative precursor for CF as it combines widespread availability, low cost, high carbon content, and, most importantly, precursor fibers that can be produced via melt-spinning. PE-based CF production involves a challenging and time-consuming diffusion-limited chemical stabilization step. The work presented in this article tackles the challenge of reducing the chemical stabilization process time by converting a bicomponent island-in-the-sea fiber, consisting of PA6 as sea matrix and HDPE as island material, into an ultra-thin PE-precursor fiber. The produced precursor fiber is then successfully converted into an ultra-thin PE-based CF through sulfonation and subsequent carbonization in a continuous set-up. The resulting CF has a smooth surface with no observable surface defects and a filament diameter of around 3 µm. The successful conversion to ultra-thin CF is shown in both batch and continuous processes. Additionally, a reduction in sulfonation reaction time from 4 h to 3 h is achieved. Full article
(This article belongs to the Special Issue Fibers 10th Anniversary: Past, Present, and Future)
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15 pages, 11973 KiB  
Article
Recycled Tire Fibers Used as Reinforcement for Recycled Polyethylene Composites
by Hossein Kazemi, Ali Fazli, Jean Philippe Ira and Denis Rodrigue
Fibers 2023, 11(9), 74; https://doi.org/10.3390/fib11090074 - 31 Aug 2023
Viewed by 1577
Abstract
This study proposes a simple approach to separate most rubber particles from recycled tire fibers (RTFs) and to determine their rubber content using thermogravimetric analysis (TGA)/calcination. Furthermore, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), and Fourier transform infrared spectroscopy (FTIR) analyses are [...] Read more.
This study proposes a simple approach to separate most rubber particles from recycled tire fibers (RTFs) and to determine their rubber content using thermogravimetric analysis (TGA)/calcination. Furthermore, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), and Fourier transform infrared spectroscopy (FTIR) analyses are used to investigate the separation process and materials compositions. Afterwards, a series of composites based on recycled post-consumer low-density polyethylene (rLDPE) with clean fiber (CF) and residual ground rubber particles (GR) is prepared at different filler concentrations (0–30%) via extrusion compounding before using compression molding and injection molding for comparison. In all cases, injection molding leads to higher strength and modulus but lower elongation at break. The results show that incorporating 30 wt.% of CF into rLDPE yields a remarkable improvement in tensile strength (15%), tensile modulus (192%) and flexural modulus (142%). On the other hand, the incorporation of up to 30 wt.% of GR results in a reduction in both tensile strength and flexural modulus by 15%, confirming the critical role of the cleaning process for RTF in achieving the best results. Full article
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18 pages, 3545 KiB  
Article
Enhancing the Thermal Comfort of Woven Fabrics and Mechanical Properties of Fiber-Reinforced Composites Using Multiple Weave Structures
by Zafar Arshad and Salman S. Alharthi
Fibers 2023, 11(9), 73; https://doi.org/10.3390/fib11090073 - 29 Aug 2023
Cited by 3 | Viewed by 1433
Abstract
In this study, the different effects of weave structure on the comfort properties of fabrics and the mechanical properties of fiber-reinforced composites were investigated. Fabrics were developed using one type of material (flax spun yarn) in the warp direction and three different materials [...] Read more.
In this study, the different effects of weave structure on the comfort properties of fabrics and the mechanical properties of fiber-reinforced composites were investigated. Fabrics were developed using one type of material (flax spun yarn) in the warp direction and three different materials (flax, sisal and cotton spun yarn) in the weft directions. Four different types of weaves (plain, twill, matt and mock leno) were produced in each type of material. Twelve specimens were produced on a sample weaving machine. These fabrics with multiweave combinations give the wearer a comfort zone for sportswear and outdoor applications. These fabrics maintain the temperature of wearers in extreme weather conditions. But these weaves have different effects when interlaced with different types of weft yarns. Air permeability, overall moisture management, stiffness and thermal resistance were investigated for these fabric specimens. The hybrid fabric produced with pure flax warp and weft cotton/sisal exhibited the highest value of air permeability, overall moisture management capability and thermal resistance followed by flax–sisal and flax–flax. The hybrid fabric produced with the mock leno weave also presented a higher value of air permeability compared to the twill, mat and plain weaves. Bending stiffness was observed to be higher in those fabrics produced with flax/sisal compared to pure flax and flax–cotton. The outerwear fabric produced with a blend of flax yarn in the warp and cotton/sisal spun yarn in the weft exhibited improved properties when compared to the fabric produced with flax/sisal and pure flax yarns. In composites, flax/flax showed enhanced mechanical properties, i.e., tensile and flexural strength. In other combinations, the composites with longer weaves possessed prominent mechanical characteristics. The composites with enhanced mechanical properties can be used for window coverings, furniture upholstery and sports equipment. These composites have the potential to be used in automotive applications. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer and Ceramic Composites: Fracture Mechanics)
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10 pages, 2453 KiB  
Article
Visible to Mid-IR Supercontinuum Generation in Cascaded PCF-Germanate Fiber Using Femtosecond Yb-Fiber Pump
by Maksim Yu. Koptev, Alexander E. Zaprialov, Alexey F. Kosolapov, Alexander N. Denisov, Maria S. Muravyeva, Sergey L. Semjonov, Sergey V. Muravyev and Arkady V. Kim
Fibers 2023, 11(9), 72; https://doi.org/10.3390/fib11090072 - 24 Aug 2023
Viewed by 1228
Abstract
Broadband supercontinuum (SC) fiber sources covering the mid-IR range have many significant applications, largely due to their compactness, reliability, and ease of use. However, most of the existing SC fiber sources cannot boast of either high reliability or a wide bandwidth. Thus, supercontinuum [...] Read more.
Broadband supercontinuum (SC) fiber sources covering the mid-IR range have many significant applications, largely due to their compactness, reliability, and ease of use. However, most of the existing SC fiber sources cannot boast of either high reliability or a wide bandwidth. Thus, supercontinuum sources based on silica fibers are robust, but are not capable of generating SC in the mid-IR range. Sources based on soft glasses (tellurite, chalcogenide, etc.) generate broadband SC in the mid-IR range but are not used commercially, due to the poor mechanical and chemical characteristics of such fibers. In this work, we propose a new approach consisting of cascade generation of a supercontinuum sequentially in a silica photonic crystal fiber (PCF) and a germanate fiber. Using a standard ytterbium chirped-pulse amplification (CPA) laser system for pumping, we have demonstrated a supercontinuum in the range of 450–2950 nm in PCF and germanate fiber firmly connected by a standard fusion splicing technique. Further optimization of the cascade pump will make it possible to create a compact and reliable all-fiber SC source from the visible to mid-IR range. Full article
(This article belongs to the Special Issue Fiber Laser Sources II)
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