Fibers

2024

Jump to: 2023, 2022

22 pages, 12067 KiB

Open AccessArticle

Cent-Hydro: A Novel Temperature and Pressure-Controlled Hybrid System for Large-Scale Nanofiber Production

by Samia Farhaj, Noman Ahmad, Alan M. Smith, Barbara R. Conway and Muhammad Usman Ghori

Fibers 2024, 12(10), 92; https://doi.org/10.3390/fib12100092 - 21 Oct 2024

Cited by 1 | Viewed by 1619

Abstract

The present study aimed to develop a novel temperature and pressure-controlled hybrid system (Cent-Hydro) for large-scale nanofiber production. Nanofibers from a hydrophilic carrier matrix were prepared using the Cent-Hydro system. This study explores the effect of increasing working temperature on the surface tension [...] Read more.

The present study aimed to develop a novel temperature and pressure-controlled hybrid system (Cent-Hydro) for large-scale nanofiber production. Nanofibers from a hydrophilic carrier matrix were prepared using the Cent-Hydro system. This study explores the effect of increasing working temperature on the surface tension and viscosity of polymer solutions. The Cent-Hydro system was calibrated through the process of jet formation, and spinning parameters were identified for the jet path. The formation of fingers in front of the thin liquid occurred due to Rayleigh–Taylor instability, and a lower concentration of polymer solution favoured the development of thinner and longer fingers. The critical angular velocity and initial velocity for jet formation were obtained when the balance between surface tension, centrifugal force, and viscous force was achieved. The effect of increasing rotational speed and working temperature on finger velocity and length was experimentally evaluated, concluding that an increase in working temperature increases finger velocity and length. Additionally, the effect of increasing rotational speed, polymer concentration, and working temperature on the diameter of the nanofiber was evaluated. Overall, the Cent-Hydro system presents a compelling proposition for large-scale nanofiber production, offering distinct advantages over conventional methods and paving the way for advancements in various applications. Full article

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20 pages, 8190 KiB

Open AccessArticle

Evaluation of Peripheral Milling and Abrasive Water Jet Cutting in CFRP Manufacturing: Analysis of Defects and Surface Quality

by Alejandro Sambruno, Álvaro Gómez-Parra, Pablo Márquez, Iñaki Tellaeche-Herrera and Moisés Batista

Fibers 2024, 12(10), 78; https://doi.org/10.3390/fib12100078 - 25 Sep 2024

Cited by 1 | Viewed by 1346

Abstract

The use of carbon fiber reinforced polymers (CFRP) is crucial in industries, such as aerospace, automotive, and marine, due to their excellent strength-to-weight ratio and corrosion resistance. However, machining CFRP is challenging due to its abrasive nature, which can cause premature tool wear. [...] Read more.

The use of carbon fiber reinforced polymers (CFRP) is crucial in industries, such as aerospace, automotive, and marine, due to their excellent strength-to-weight ratio and corrosion resistance. However, machining CFRP is challenging due to its abrasive nature, which can cause premature tool wear. Some of the commonly used processes for machining these materials are dry milling and abrasive water jet machining (AWJM), which offer the best alternatives from an environmental point of view. This article presents an analysis of the defects and surface quality obtained in CFRP after machining by AWJM and milling. For this purpose, combinations of relevant parameters have been chosen for each process: cutting speed and tool wear in milling and traverse feed rate and hydraulic pressure in AWJM. The results obtained have been evaluated from two points of view: macroscopically, through the evaluation of delamination, and microscopically, through the study of the roughness in terms of Ra. Furthermore, a discussion on functional, environmental, economic, and social terms has been made between both processes. In summary, each machining process generates a specific type of delamination: Type II in milling and Type I in AWJM. In addition, the best Ra results are obtained for pressures of 1200 bar in AWJM. Full article

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20 pages, 20552 KiB

Open AccessArticle

The Effect of Carbon Nanotubes and Carbon Microfibers on the Piezoresistive and Mechanical Properties of Mortar

by Irene Kanellopoulou, Ioannis A. Kartsonakis, Athanasia I. Chrysanthopoulou and Costas A. Charitidis

Fibers 2024, 12(8), 62; https://doi.org/10.3390/fib12080062 - 31 Jul 2024

Viewed by 1872

Abstract

Sustainability, safety and service life expansion in the construction sector have gained a lot of scientific and technological interest during the last few decades. In this direction, the synthesis and characterization of smart cementitious composites with tailored properties combining mechanical integrity and self-sensing [...] Read more.

Sustainability, safety and service life expansion in the construction sector have gained a lot of scientific and technological interest during the last few decades. In this direction, the synthesis and characterization of smart cementitious composites with tailored properties combining mechanical integrity and self-sensing capabilities have been in the spotlight for quite some time now. The key property for the determination of self-sensing behavior is the electrical resistivity and, more specifically, the determination of reversible changes in the electrical resistivity with applied stress, which is known as piezoresistivity. In this study, the mechanical and piezoresistive properties of mortars reinforced with carbon nanotubes (CNTs) and carbon micro-fibers (CMFs) are determined. Silica fume and a polymer with polyalkylene glycol graft chains were used as dispersant agents for the incorporation of the CNTs and CMFs into the cement paste. The mechanical properties of the mortar composites were investigated with respect to their flexural and compressive strength. A four-probe method was used for the estimation of their piezoresistive response. The test outcomes revealed that the combination of the dispersant agents along with a low content of CNTs and CMFs by weight of cement (bwoc) results in the production of a stronger mortar with enhanced mechanical performance and durability. More specifically, there was an increase in flexural and compressive strength of up to 38% and 88%, respectively. Moreover, mortar composites loaded with 0.4% CMF bwoc and 0.05% CNTs bwoc revealed a smooth and reversible change in electrical resistivity vs. compression loading—with unloading comprising a strong indication of self-sensing behavior. This work aims to accelerate progress in the field of material development with structural sensing and electrical actuation via providing a deeper insight into the correlation among cementitious composite preparation, admixture dispersion quality, cementitious composite microstructure and mechanical and self-sensing properties. Full article

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14 pages, 3011 KiB

Open AccessFeature PaperArticle

Influence of Precursor Mixtures on the Laser Chemical Vapor Deposition of TiC Fibers

by Kendall J. Mitchell and Gregory B. Thompson

Fibers 2024, 12(5), 43; https://doi.org/10.3390/fib12050043 - 13 May 2024

Viewed by 1493

Abstract

In this study, the hyperbaric (2 bar) laser chemical vapor deposition of TiC fibers grown under various percent pressures of hydrogen and ratios of ethylene and titanium tetrachloride (2:1 or 1:1) are reported. In the hydrogen-rich (85%) condition, sequential fiber depositions became stunted [...] Read more.

In this study, the hyperbaric (2 bar) laser chemical vapor deposition of TiC fibers grown under various percent pressures of hydrogen and ratios of ethylene and titanium tetrachloride (2:1 or 1:1) are reported. In the hydrogen-rich (85%) condition, sequential fiber depositions became stunted as a result of a loss of hydrogen, which served as a reducing agent for the metal halide as hydrogen evolved with the hydrocarbon gas in the reaction zone because of the Le Chatelier principle. For the hydrogen-lean (25%) condition, the intrinsic fiber growth rate was invariant, but gas phase nucleation resulted in the hydrocarbon forming carbon soot in the chamber which subsequently deposited and coated on the fibers. In the hydrogen-balanced composition (50%), the 2:1 precursor ratio resulted in inconsistent intrinsic growth rates which ranged from approximately 30 μm/s to 44 μm/s. However, for the hydrogen-balanced (50%) 1:1 condition, the intrinsic growth rate variation was reduced to approximately 12 μm/s. The differences in fiber uniformity, composition, and structure under these process conditions are discussed in terms of hydrogen’s ability to serve as a reducing agent, a fluid to transport heat from the deposition zone, and alter the structure of the fiber through thermophoresis. Full article

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15 pages, 6530 KiB

Open AccessArticle

Strength and Erosion Resistance of Spinifex Fibre Reinforced Mudbrick

by Dongxiu Guo, Ali Rajabipour, Milad Bazli, Cat Kutay, Varuna Sumanasena and Truong Nhat Phuong Pham

Fibers 2024, 12(5), 39; https://doi.org/10.3390/fib12050039 - 26 Apr 2024

Viewed by 2120

Abstract

This study assesses the usability of natural materials available in Australia’s remote communities for making fibre-reinforced mudbricks. The present construction cost for housing in remote areas is too high to maintain the level of housing required for the remote Australian population. As this [...] Read more.

This study assesses the usability of natural materials available in Australia’s remote communities for making fibre-reinforced mudbricks. The present construction cost for housing in remote areas is too high to maintain the level of housing required for the remote Australian population. As this includes mostly First Nations communities, more culturally appropriate housing materials and construction methods are being considered. This study looks at mudbricks made from laterite soil reinforced by spinifex fibre, both available in abundance in remote communities. Hence, this material is more acceptable to communities as it is more sustainable, and the construction methods are more suited for First Nations engagement. Various mixes were tested for compressive strength and erosion resistance. Results suggest that spinifex can significantly improve compressive strength and reduce erosion effects; however, spinifex showed adverse effects at the early stage of the spray test. The results satisfy the minimum strength and erosion resistance requirements for construction and suggest that spinifex-reinforced mudbricks could potentially be considered as an alternative material in remote housing. Full article

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17 pages, 7063 KiB

Open AccessArticle

Strengthening of Laminated Veneer Lumber Slabs with Fiber-Reinforced Polymer Sheets—Preliminary Study

by Michał Marcin Bakalarz and Paweł Grzegorz Kossakowski

Fibers 2024, 12(3), 22; https://doi.org/10.3390/fib12030022 - 28 Feb 2024

Cited by 5 | Viewed by 2402

Abstract

Analyzing the feasibility of reinforcing new and existing wooden structures is a valid problem, being the subject of numerous scientific papers. The paper presents the preliminary results of a study on reinforcing Laminated Veneer Lumber (LVL) panels with composite materials bonded to exterior [...] Read more.

Analyzing the feasibility of reinforcing new and existing wooden structures is a valid problem, being the subject of numerous scientific papers. The paper presents the preliminary results of a study on reinforcing Laminated Veneer Lumber (LVL) panels with composite materials bonded to exterior surfaces using epoxy resin. Glass-Fiber-Reinforced Polymer (GFRP) sheets, Carbon-Fiber-Reinforced Polymer (CFRP) sheets, and Ultra-High-Modulus (UHM) CFRP sheets were used as reinforcement. The variables in the analysis were the type of reinforcement and the number of reinforcement layers. The tests were carried out on small samples (45 × 45 × 900 mm) subjected to the so-called four-point bending test. Reinforcement positively affected the mechanical properties of composite section. The highest increases in load bearing were 37 and 48% for two layers of GFRP and CFRP, respectively. The bending stiffness increased up to 53 and 62% for two layers of CFRP and UHM CFRP, respectively. There was a change in failure mode from cracking in the tension zone for unreinforced beams to veneer shear in the support zone (for CFRP and GFRP sheets) and sheet rupture (UHM CFRP). Good agreement was obtained for estimating bending stiffness with the presented numerical and mathematical model; the relative error was up to 6% for CFRP and GFRP and up to 20% for UHM CFRP. This preliminary study proved the effectiveness of combining LVL with FRP sheets and indicated their weak spots, which should be further analyzed to improve their competitiveness against the traditional structures. The key limitation was the shear strength of LVL. Full article

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24 pages, 34614 KiB

Open AccessArticle

Electrospinning Poly(acrylonitrile) Containing Magnetite Nanoparticles: Influence of Magnetite Contents

by Ana Karen Graciano Alvarez, Marius Dotter, Khorolsuren Tuvshinbayar, Laila Bondzio, Inga Ennen, Andreas Hütten, Tomasz Blachowicz and Andrea Ehrmann

Fibers 2024, 12(3), 19; https://doi.org/10.3390/fib12030019 - 21 Feb 2024

Cited by 2 | Viewed by 2307

Abstract

Magnetic nanofibers were prepared by electrospinning polymer/metal solutions of poly(acrylonitrile) (PAN) with magnetite (Fe₃O₄) nanoparticles. At a mass ratio of PAN:magnetite of 2:1, the total solid content in the dimethyl sulfoxide (DMSO) solution was varied between 15 wt.% and [...] Read more.

Magnetic nanofibers were prepared by electrospinning polymer/metal solutions of poly(acrylonitrile) (PAN) with magnetite (Fe₃O₄) nanoparticles. At a mass ratio of PAN:magnetite of 2:1, the total solid content in the dimethyl sulfoxide (DMSO) solution was varied between 15 wt.% and 25 wt.%, which represents the limits of the spinnable range. The results show that the most homogeneous nanofiber mats were 21 wt.% solid contents. At 15 wt.% solid contents, a nano-membrane with some fibrous regions was produced. Nanofibers at 25 wt.% had a much larger and more inhomogeneous diameter. Nevertheless, the magnetic properties of all samples were very similar, indicating that the distribution of magnetite nanoparticles in the fibers is comparable in all samples. The results also suggested that the samples spun from solutions with near-ideal solid contents (19–21 wt.%) contain agglomerations of the nanoparticles inside the nanofibers. Full article

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2023

Jump to: 2024, 2022

18 pages, 6092 KiB

Open AccessEditor’s ChoiceArticle

Effect of Elevated Temperature on the Behavior of Amorphous Metallic Fibre-Reinforced Cement and Geopolymer Composites

by Faiz Uddin Ahmed Shaikh, Narwinder Singh Kahlon and Attiq Ur Rahman Dogar

Fibers 2023, 11(4), 31; https://doi.org/10.3390/fib11040031 - 28 Mar 2023

Cited by 6 | Viewed by 2359

Abstract

To improve the tensile, flexural, and ductility properties of geopolymer composites, amorphous metallic fibres (AMF) are used to reinforce these composites, and the behavior of these composites at elevated temperatures has been assessed in this study. Four types of composites, i.e., cement, reinforced [...] Read more.

To improve the tensile, flexural, and ductility properties of geopolymer composites, amorphous metallic fibres (AMF) are used to reinforce these composites, and the behavior of these composites at elevated temperatures has been assessed in this study. Four types of composites, i.e., cement, reinforced cement, geopolymer, and reinforced geopolymer composites have been prepared. The composites have been reinforced using AMF with a fibre volume fraction of 0.75%. The composites have been assessed for change in mass loss, cracking, compressive strength, and flexural strength at four elevated temperatures of 200 °C, 400 °C, 600 °C, and 800 °C, and conclusions have been drawn concerning these composites. The results have shown that an increase in temperature has an adverse effect on these composites, and geopolymer composites exhibit higher performance than their counterpart cement composites at elevated temperatures. The mass loss and surface cracking were significantly lower in geopolymer composites, and the fibre reinforcement had a negligible effect on mass loss. Also, the residual compressive and flexural strength of reinforced geopolymer composites was significantly higher than that of the reinforced cement composites. In addition, scanning electron microscopic images also showed that even at higher temperatures, the geopolymer matrix is present on the AMF fibre, which results in higher residual strength than the cement composites in which a negligible amount of matrix is present on the fibres. Full article

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21 pages, 8315 KiB

Open AccessEditor’s ChoiceReview

Textile Fabrics as Electromagnetic Shielding Materials—A Review of Preparation and Performance

by Tomasz Blachowicz, Dariusz Wójcik, Maciej Surma, Mirosław Magnuski, Guido Ehrmann and Andrea Ehrmann

Fibers 2023, 11(3), 29; https://doi.org/10.3390/fib11030029 - 15 Mar 2023

Cited by 22 | Viewed by 8618

Abstract

Shielding of instruments and humans from electromagnetic interference (EMI) has become increasingly important during the last decades due to more and more machines and devices radiating electromagnetic waves. While several applications can use rigid shields, more flexibility is enabled by developing bendable, drapable, [...] Read more.

Shielding of instruments and humans from electromagnetic interference (EMI) has become increasingly important during the last decades due to more and more machines and devices radiating electromagnetic waves. While several applications can use rigid shields, more flexibility is enabled by developing bendable, drapable, ideally even stretchable EMI shielding. Textile fabrics can have these properties, combined with potentially good mechanical properties, depending on the textile structure and the chosen material. On the other hand, the necessary physical properties, especially conductivity and magnetic properties, cannot be taken for granted in normal textile fabrics. These properties have to be added by conductive yarn or layer coatings, integration of conductive or magnetic fibers, producing intrinsically conductive or magnetic fibers, etc. The article gives a critical comparison of the properties of materials typically used for this purpose, such as intrinsically conductive polymers, metal-coated fabrics and metal wires, MXene coatings, MXene fibers, carbon coatings, and fibers. The review concentrates on thematically suitable papers found in the Web of Science and Google Scholar from the last five years and shows that especially MXenes are highly investigated recently due to their high conductivity and EMI shielding effectiveness, while other conductive and magnetic coatings and fibers are nevertheless still interesting for the preparation of EMI shielding textile fabrics. Full article

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15 pages, 2976 KiB

Open AccessArticle

Comparative Study of Atmosphere Effect on Wood Torrefaction

by Rafael Lopes Quirino, Larissa Richa, Anelie Petrissans, Priscila Rios Teixeira, George Durrell, Allen Hulette, Baptiste Colin and Mathieu Petrissans

Fibers 2023, 11(3), 27; https://doi.org/10.3390/fib11030027 - 7 Mar 2023

Cited by 4 | Viewed by 2754

Abstract

Climate change, biomass utilization, and bioenergy recovery are among the biggest current global concerns. Wood is considered an environmentally benign material. Nevertheless, it must be processed for desired applications. Upon thermal treatment ranging from 180 °C to 280 °C, under low oxygen concentrations, [...] Read more.

Climate change, biomass utilization, and bioenergy recovery are among the biggest current global concerns. Wood is considered an environmentally benign material. Nevertheless, it must be processed for desired applications. Upon thermal treatment ranging from 180 °C to 280 °C, under low oxygen concentrations, wood becomes a material with improved dimensional stability, resistance to fungal attacks, grindability, hydrophobicity, and storage stability. Several strategies for wood treatment have been investigated over the course of the past decades, including the use of steam, nitrogen, smoke, vacuum, water, and hot oil. The goal of this work is to investigate the influence of pressure and atmosphere on the torrefaction of poplar. Through a systematic analysis of poplar wood samples treated under reduced pressures and different atmospheres, while keeping the same heating profile, it was possible to establish that changes observed for mass loss, color change, wood composition (via TGA/DTG analysis), functional groups (via FTIR), elemental analysis, and X-ray diffractograms relate directly to known reaction pathways occurring during torrefaction. Changes observed under reduced pressures have been associated with the relative concentration of oxygen in the reaction atmosphere and to the reduced diffusion times experienced by reactive by-products during the treatment. Conversely, extended diffusion times resulted in more significant changes for reactions carried out under N₂, water vapor, and air. Full article

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2022

Jump to: 2024, 2023

22 pages, 9488 KiB

Open AccessArticle

Performance of Steel Bar Lap Splices at the Base of Seismic Resistant Reinforced Concrete Columns Retrofitted with FRPs—3D Finite Element Analysis

by Evgenia Anagnostou and Theodoros Rousakis

Fibers 2022, 10(12), 107; https://doi.org/10.3390/fib10120107 - 14 Dec 2022

Cited by 13 | Viewed by 3674

Abstract

This paper examines analytically the design criteria for the composite retrofit of reinforced concrete (RC) columns with a short lap splice length of steel rebars inside the critical region. The advanced potential of pseudo-dynamic three-dimensional (3D) finite element (FE) modelling is utilized to [...] Read more.

This paper examines analytically the design criteria for the composite retrofit of reinforced concrete (RC) columns with a short lap splice length of steel rebars inside the critical region. The advanced potential of pseudo-dynamic three-dimensional (3D) finite element (FE) modelling is utilized to investigate critical design parameters for the required carbon fiber-reinforced polymer (FRP) jacketing of RC columns with a rectangular cross-section based on the experimental lateral force-to-drift envelope behavior of characteristic cases from the international literature. The satisfactory analytical reproduction of the experimental results allows for the systematic numerical investigation of the developed stress along the lap splice length. The maximum lateral force and the horizontal displacement ductility of the column, as well as the maximum developed tensile axial force on the longitudinal bars, their variation along the lap, the bar yielding, and the plastic hinge length variation, are considered to determine the seismic behavior of the columns. For the first time, cases of smooth bar slip together with delayed bar yielding or without bar yielding are identified that may be recorded through a “ductile” P-d seismic response. Such pseudo-ductile response cases are revisited through suitably revised redesign criteria for adequate FRP jacketing. Full article

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8 pages, 10681 KiB

Open AccessArticle

Angular Momentum of Leaky Modes in Hollow-Core Fibers

by Grigory Alagashev, Sergey Stafeev, Victor Kotlyar and Andrey Pryamikov

Fibers 2022, 10(10), 92; https://doi.org/10.3390/fib10100092 - 21 Oct 2022

Cited by 2 | Viewed by 2014

Abstract

It is known that angular momentum (AM) is an important characteristic of light, which can be separated into the spin (SAM) and orbital parts (OAM). The dynamical properties of the spin and orbital angular momentums are determined by the polarization and spatial degrees [...] Read more.

It is known that angular momentum (AM) is an important characteristic of light, which can be separated into the spin (SAM) and orbital parts (OAM). The dynamical properties of the spin and orbital angular momentums are determined by the polarization and spatial degrees of freedom of light. In addition to optical vortex beams possessing spatial polarization and phase singularities, optical fibers can be used to generate and propagate optical modes with the orbital and spin parts of the angular momentum. In this paper, using the example of hollow-core fibers, we demonstrate the fact that their leaky air core modes also have an orbital part of AM in the case of circular polarization arising from the spin–orbit interaction of the air core modes. The reason for the appearance of AM is the leakage of the air core mode energy. Full article

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14 pages, 4780 KiB

Open AccessArticle

A Unique Crustacean-Based Chitin Platform to Reduce Self-Aggregation of Polysaccharide Nanofibers

by Carolina Londoño-Zuluaga, Hasan Jameel, Ronalds Gonzalez, Kimberly Nellenbach, Ashley Brown, Guihua Yang and Lucian Lucia

Fibers 2022, 10(10), 87; https://doi.org/10.3390/fib10100087 - 14 Oct 2022

Cited by 2 | Viewed by 3180

Abstract

Every year, over 8 million tons of crustacean shells are discarded. However, there exists an opportunity for valorizing the chitin and calcium carbonate part of the composition of the shells. Our study revealed crustacean chitin reduces self-aggregation effects. It was shown that crustacean-based [...] Read more.

Every year, over 8 million tons of crustacean shells are discarded. However, there exists an opportunity for valorizing the chitin and calcium carbonate part of the composition of the shells. Our study revealed crustacean chitin reduces self-aggregation effects. It was shown that crustacean-based nanofibers alone or added to cellulose offer unprecedented reductions in viscosity even after drying to produce foams impossible for cellulose. Polysaccharide nanofibers suffer from increased viscosity from strong hydrogen bonding addressed by the incorporation of crustacean-based nanofibers. The ability of the nanocomposite to overcome self-aggregation and collapse was attributed to organized chitin nanofiber morphology in the crustacean matrix. As a result of enhanced surface area from reduced fiber aggregation, the chitin/crustacean-cellulose blend was tested for a biomedical application requiring a high surface area: coagulation. Preliminary experiments showed the crustacean matrices, especially those containing calcium carbonate, induced blood clotting when 35 s. A materials platform is proposed for bio-based nanofiber production overcoming intractable and difficult-to-address self-aggregation effects associated with polysaccharides. Full article

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13 pages, 3561 KiB

Open AccessArticle

Numerical Study of Mid-IR Ultrashort Pulse Reconstruction Based on Processing of Spectra Converted in Chalcogenide Fibers with High Kerr Nonlinearity

by Arseny A. Sorokin, Alexey V. Andrianov and Elena A. Anashkina

Fibers 2022, 10(10), 81; https://doi.org/10.3390/fib10100081 - 21 Sep 2022

Cited by 1 | Viewed by 1905

Abstract

Ultrashort optical pulses play an important role in fundamental research and applications. It is important to have reliable information about pulse parameters such as duration, intensity profile, and phase. Numerous methods for characterizing pulses in the near-IR range have been well developed by [...] Read more.

Ultrashort optical pulses play an important role in fundamental research and applications. It is important to have reliable information about pulse parameters such as duration, intensity profile, and phase. Numerous methods for characterizing pulses in the near-IR range have been well developed by now. However, there is a challenge with pulse measurement in the mid-IR, which is largely related to the underdeveloped component base in this spectral range. We investigate by means of numerical simulations a simple method of pulse reconstruction applicable in the mid-IR. The method is based on measuring and processing only the initial pulse spectrum and two converted spectra in elements with Kerr nonlinearity for different B-integrals characterizing nonlinear phase accumulation. The hardware implementation of the proposed method is very simple. This method requires only a one-dimensional data set, has no moving parts in the optical scheme, and allows for working with high-energy as well as low-energy pulses. We propose a novel simple, efficient, noise-tolerant algorithm for data processing that assumes spectral phase approximation by a polynomial function. We demonstrate numerically the reconstruction of mid-IR ultrashort pulses, namely 3 μm wavelength pulses, using commercial chalcogenide As₂S₃-based glass fibers as nonlinear elements. Full article

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11 pages, 2356 KiB

Open AccessFeature PaperArticle

Assessment of Composite with Fibers as a Support for Antibacterial Nanomaterials: A Case Study of Bacterial Cellulose, Polylactide and Usual Textile

by Ilya Lyagin, Olga Maslova, Nikolay Stepanov, Denis Presnov and Elena Efremenko

Fibers 2022, 10(9), 70; https://doi.org/10.3390/fib10090070 - 24 Aug 2022

Cited by 10 | Viewed by 2661

Abstract

To obtain composite fiber materials with antibacterial properties, the samples of bacterial cellulose (BC), polylactide (PLA) and usual fibers (FM) were modified by poly-ε-caprolactone or polyhydroxybutyrate and then functionalized by the enzyme-polyelectrolyte complex of quorum-quenching enzymes, such as hexahistidine-tagged organophosphorus hydrolase with poly(glutamic [...] Read more.

To obtain composite fiber materials with antibacterial properties, the samples of bacterial cellulose (BC), polylactide (PLA) and usual fibers (FM) were modified by poly-ε-caprolactone or polyhydroxybutyrate and then functionalized by the enzyme-polyelectrolyte complex of quorum-quenching enzymes, such as hexahistidine-tagged organophosphorus hydrolase with poly(glutamic acid) or by suspension of tantalum nanoparticles (Ta NPs) in ethanol. The structures of the composite fibers were analyzed using scanning electron microscopy. It was shown that the introduction of additional natural polymers into the matrix of BC, PLA and FM resulted in decreasing of the structural porosity. Comparative studies of the antibacterial activity of the composite materials were carried out using Escherichia coli and Bacillus subtilis cells. The decrease of adenosine triphosphate concentration in cell samples loaded onto fiber materials was applied as a measurable characteristic of antibacterial effect typical for the new fiber materials. The profound improvement of antibacterial activity was determined in composite materials with polyhydroxybutyrate and Ta NPs. Full article

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19 pages, 8758 KiB

Open AccessArticle

The Significance of Multi-Size Carbon Fibers on the Mechanical and Fracture Characteristics of Fiber Reinforced Cement Composites

by Mohammed Abdellatef, Daniel Heras Murcia, Joshua Hogancamp, Edward Matteo, John Stormont and Mahmoud M. Reda Taha

Fibers 2022, 10(8), 65; https://doi.org/10.3390/fib10080065 - 28 Jul 2022

Cited by 6 | Viewed by 2933

Abstract

One of the main challenges of using a high fiber volume content in a cement composite is the narrow margin of fiber volume content beyond which fibers can cause an adverse effect on the mechanical properties. In this paper, the significance of fiber [...] Read more.

One of the main challenges of using a high fiber volume content in a cement composite is the narrow margin of fiber volume content beyond which fibers can cause an adverse effect on the mechanical properties. In this paper, the significance of fiber size distribution and fiber volume content of different proportions of chopped and milled carbon microfibers are investigated. The mixes’ flowability showed improvement with altering the fiber size distribution despite having a high fiber content. Uniaxial compression cylinders and unnotched and notched beams were cast and then tested at 7 and 28 days of age. It was found that the compressive strength is significantly affected by fiber size distribution more than fiber volume content. On the other hand, the modulus of rupture and fracture toughness are proportional to the fiber volume content with little effect of fiber size distribution. Finally, neither high fiber volume content nor altered fiber size distribution significantly affected the elastic modulus of the fiber cement composites. Full article

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15 pages, 6194 KiB

Open AccessArticle

Interlaminar Shear Properties of Bamboo Composite for Structural Applications

by Ali Rajabipour, Alireza Javadian, Milad Bazli and Mark Masia

Fibers 2022, 10(7), 59; https://doi.org/10.3390/fib10070059 - 12 Jul 2022

Cited by 5 | Viewed by 2778

Abstract

Interlaminar shear strength in bamboo composite (BC) is mainly provided by epoxy resin as the matrix in BC. This may greatly change due to humidity. This study aims at evaluating the shear strength of BC by testing and developing probabilistic relationships. The interlaminar [...] Read more.

Interlaminar shear strength in bamboo composite (BC) is mainly provided by epoxy resin as the matrix in BC. This may greatly change due to humidity. This study aims at evaluating the shear strength of BC by testing and developing probabilistic relationships. The interlaminar shear strength of bamboo composite (BC) in different moisture conditions was tested according to ASTM D2344. The results show that the maximum shear stress does not generally occur at the centroid of samples, which could be associated with imperfections in BC layers. An extreme value theory-based model is suggested to evaluate the probability of shear failure in BC samples. The shear capacity decreased from 20.4 MPa to 14 MPa as the humidity increased from 60% to 90%. A summary of findings is as follows: It was found that under transient moisture conditions, local failure is likely to happen before the first significant crack occurs. Local failure is suggested to be considered in the design for serviceability. Stress drop caused by the local failure could exceed 10% of total shear strength and, therefore, should be regarded as a serviceability design. The probabilistic model developed in this study could be used for developing structural design safety factors. Full article

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16 pages, 4390 KiB

Open AccessArticle

Experimental Investigation of Effect of Fiber Length on Mechanical, Wear, and Morphological Behavior of Silane-Treated Pineapple Leaf Fiber Reinforced Polymer Composites

by Praveena Bindiganavile Anand, Avinash Lakshmikanthan, Manjunath Patel Gowdru Chandrashekarappa, Chithirai Pon Selvan, Danil Yurievich Pimenov and Khaled Giasin

Fibers 2022, 10(7), 56; https://doi.org/10.3390/fib10070056 - 29 Jun 2022

Cited by 59 | Viewed by 6919

Abstract

The development of the best properties in polyester composite from pineapple leaf fiber (PALF) as a reinforcing material is a subject of interest. The properties of PALF are reliant upon fiber length, wherein technical difficulties in production of long fibers and processing for [...] Read more.

The development of the best properties in polyester composite from pineapple leaf fiber (PALF) as a reinforcing material is a subject of interest. The properties of PALF are reliant upon fiber length, wherein technical difficulties in production of long fibers and processing for better characteristics in polyester composites possess inherent challenges. The PALFs are subjected to silane treatment for altering fiber properties. This research attempts to analyze the impact of silane-treated PALF with varying fiber lengths (5, 10, 15, 20, and 25 mm) on the performance of natural fiber composites (NFC) properties. Open mold and hand lay-up techniques were employed to develop the polyester composites. The prepared PALF-based polyester composites were examined for different properties (impact, flexural, tensile strength, and wear rate). Coefficient of friction and wear studies are performed on the prepared composites subjected to different loads (10, 20, and 30 N) via a pin on disc test rig. Polymer composite fracture surfaces were analyzed to observe the interfacial bonding between fibers and matrix via scanning electron microscopy (SEM). SEM results showed that the application of silane treatment resulted in better surface topography (fiber length of 5–10 mm showed smooth surface resulted in crack proliferation possessing low fracture toughness of 15–32 MPa; whereas a 15–20 mm fiber length resulted in better fiber–matrix bonding, improving the fracture toughness from 42–55 MPa) as a result of change in chemical structure in PALF. The 20 mm length of PALF resulted in better properties (flexural, tensile, impact, and wear resistance) which are attributed to fiber–matrix interfacial bonding. These properties ensure the developed polymer composites can be applied to walls, building insulation, and artificial ceilings. Full article

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22 pages, 13230 KiB

Open AccessEditor’s ChoiceArticle

Multifunctional Material Extrusion 3D-Printed Antibacterial Polylactic Acid (PLA) with Binary Inclusions: The Effect of Cuprous Oxide and Cellulose Nanofibers

by Markos Petousis, Nectarios Vidakis, Nikolaos Mountakis, Vassilis Papadakis, Sotiria Kanellopoulou, Aikaterini Gaganatsiou, Nikolaos Stefanoudakis and John Kechagias

Fibers 2022, 10(6), 52; https://doi.org/10.3390/fib10060052 - 10 Jun 2022

Cited by 49 | Viewed by 4385

Abstract

In this work, we present an effective process easily adapted in industrial environments for the development of multifunctional nanocomposites for material extrusion (MEX) 3D printing (3DP). The literature is still very limited in this field, although the interest in such materials is constantly [...] Read more.

In this work, we present an effective process easily adapted in industrial environments for the development of multifunctional nanocomposites for material extrusion (MEX) 3D printing (3DP). The literature is still very limited in this field, although the interest in such materials is constantly increasing. Nanocomposites with binary inclusions were prepared and investigated in this study. Polylactic acid (PLA) was used as the matrix material, and cuprous oxide (Cu₂O) and cellulose nanofibers (CNF) were used as nanoadditives introduced in the matrix material to enhance the mechanical properties and induce antibacterial performance. Specimens were built according to international standards with a thermomechanical process. Tensile, flexural, impact, and microhardness tests were conducted. The effect on the thermal properties of the matrix material was investigated through thermogravimetric analysis, and Raman spectroscopic analysis was conducted. The morphological characteristics were evaluated with atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDS) analyses. The antibacterial performance of the prepared nanomaterials was studied against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria, with a screening agar well diffusion method. All nanocomposites prepared exhibited biocidal properties against the bacteria tested. The tested PLA/1.0 CNF/0.5 Cu₂O material had 51.1% higher tensile strength and 35.9% higher flexural strength than the pure PLA material. Full article

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12 pages, 1418 KiB

Open AccessArticle

Understanding the PLA–Wood Adhesion Interface for the Development of PLA-Bonded Softwood Laminates

by Warren J. Grigsby, Marc Gaugler and Desiree Torayno

Fibers 2022, 10(6), 51; https://doi.org/10.3390/fib10060051 - 9 Jun 2022

Cited by 2 | Viewed by 2419

Abstract

With polylactic acid (PLA) usage projected to increase in wood-based composite materials, a study comparing composite processing parameters with resulting PLA−wood adhesion and panel performance is warranted. In this study, PLA-softwood veneer laminates have been prepared and spatial chemical imaging via FTIR analysis [...] Read more.

With polylactic acid (PLA) usage projected to increase in wood-based composite materials, a study comparing composite processing parameters with resulting PLA−wood adhesion and panel performance is warranted. In this study, PLA-softwood veneer laminates have been prepared and spatial chemical imaging via FTIR analysis was applied to identify PLA bondlines characterizing bondline thickness and the extent of PLA migration into the wood matrix. These PLA–wood adhesion interface characteristics have been compared with the performance of panels varying in pressing temperature, pressing time and PLA grades. For amorphous PLA, bondline thicknesses (60–120 μm) were similar, pressing at 140 °C or 160 °C, whereas with semi-crystalline PLA, the bondline thickness (340 μm) significantly reduced (155–240 μm) only when internal panel temperatures exceeded 140 °C during pressing. Internal temperatures also impacted PLA penetration, with greater PLA migration from bondlines evident with higher pressing temperatures and times with distinctions between PLA grades and bondline position. Performance testing revealed thinner PLA bondlines were associated with greater dry strength for both PLA grades. Cold-water soaking revealed laminated panels exhibit a range of wet-strength performance related to panel-pressing regimes with the semi-crystalline PLA pressed at 180 °C having similar tensile strength in dry and wet states. Moreover, an excellent correlation between wet-strength performance and bondline thickness and penetration values was evident for this PLA grade. Overall, study findings demonstrate PLA wood composite performance can be tuned through a combination of the PLA grade and the pressing regime employed. Full article

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16 pages, 3466 KiB

Open AccessEditor’s ChoiceReview

Electromagnetic Interference Shielding with Electrospun Nanofiber Mats—A Review of Production, Physical Properties and Performance

by Tomasz Blachowicz, Andreas Hütten and Andrea Ehrmann

Fibers 2022, 10(6), 47; https://doi.org/10.3390/fib10060047 - 24 May 2022

Cited by 21 | Viewed by 4958

Abstract

With a steadily increasing number of machines and devices producing electromagnetic radiation, especially, sensitive instruments as well as humans need to be shielded from electromagnetic interference (EMI). Since ideal shielding materials should be lightweight, flexible, drapable, thin and inexpensive, textile fabrics belong to [...] Read more.

With a steadily increasing number of machines and devices producing electromagnetic radiation, especially, sensitive instruments as well as humans need to be shielded from electromagnetic interference (EMI). Since ideal shielding materials should be lightweight, flexible, drapable, thin and inexpensive, textile fabrics belong to the often-investigated candidates to meet these expectations. Especially, electrospun nanofiber mats are of significant interest since they can not only be produced relatively easily and cost efficiently, but they also enable the embedding of functional nanoparticles in addition to thermal or chemical post-treatments to reach the desired physical properties. This paper gives an overview of recent advances in nanofiber mats for EMI shielding, discussing their production, physical properties and typical characterization techniques. Full article

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15 pages, 4480 KiB

Open AccessArticle

Effects of Incorporating Titanium Dioxide with Titanium Carbide on Hybrid Materials Reinforced with Polyaniline: Synthesis, Characterization, Electrochemical and Supercapacitive Properties

by Hafida Belhadj, Imane Moulefera, Lilia Sabantina and Abdelghani Benyoucef

Fibers 2022, 10(5), 46; https://doi.org/10.3390/fib10050046 - 23 May 2022

Cited by 16 | Viewed by 3462

Abstract

We report on the synthesis of titanium dioxide by titanium carbide for the preparation of hybrid material reinforced with polyaniline (PANI@TiO₂–TiC) using the in situ polymerization technique. The effectiveness of the samples on the thermal, optical and electrochemical properties was investigated. [...] Read more.

We report on the synthesis of titanium dioxide by titanium carbide for the preparation of hybrid material reinforced with polyaniline (PANI@TiO₂–TiC) using the in situ polymerization technique. The effectiveness of the samples on the thermal, optical and electrochemical properties was investigated. The XRD, XPS, FTIR, SEM and TEM results confirm the successful synthesis of the PANI, PANI@TiC and PANI@TiO₂–TiC samples. Through this, a good connection, an excellent relationship between the structures and the properties of the synthesized hybrid materials were obtained. Moreover, the electrical conductivity and optical bandgap were also tested. Remarkably good electrochemical characteristics were identified by cyclic voltammetry. Moreover, the galvanostatic charge–discharge (GCD) of the supercapacitor was remarkably high. Cyclic stability showed good retention after 1500 cycles at 1.5 A·g⁻¹. Full article

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15 pages, 4650 KiB

Open AccessArticle

Flax Noils as a Source of Cellulose for the Production of Lyocell Fibers

by Igor S. Makarov, Lyudmila K. Golova, Alexander G. Smyslov, Markel I. Vinogradov, Ekaterina E. Palchikova and Sergei A. Legkov

Fibers 2022, 10(5), 45; https://doi.org/10.3390/fib10050045 - 23 May 2022

Cited by 14 | Viewed by 4921

Abstract

The production of long flax fiber for the subsequent production of textile yarn is accompanied by the formation of a significant amount of waste—noils, which is a mechanical mixture of long and short flax fibers and shives. Comparative studies of the structure and [...] Read more.

The production of long flax fiber for the subsequent production of textile yarn is accompanied by the formation of a significant amount of waste—noils, which is a mechanical mixture of long and short flax fibers and shives. Comparative studies of the structure and chemical composition of the fibrous fraction of noils and shives were carried out using IR spectroscopy. The solubility of shives and flax noils in N-methylmorpholine-N-oxide (NMMO) was studied, a comparative analysis of the rheological behavior of solutions of flax and wood cellulose was carried out and the optimal temperature–concentration conditions for obtaining flax fibers from noils were determined. It was shown for the first time that using the method of solid-phase activation of the cellulose-solvent system makes it possible to obtain fibers in a short period of time (no more than 10 min). The structure of both the raw material and the resulting fibers was studied by X-ray diffraction analysis. The thermal properties of a new type of cellulose fibers was evaluated. The complex of the conducted studies allows us to consider flax fibers from noils along with flax fibers from long-staple flax, as a real alternative to fibers from wood pulp. Full article

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10 pages, 4076 KiB

Open AccessArticle

Wear Properties and Post-Moisture Absorption Mechanical Behavior of Kenaf/Banana-Fiber-Reinforced Epoxy Composites

by Sivasubramanian Palanisamy, Mayandi Kalimuthu, Alavudeen Azeez, Murugesan Palaniappan, Shanmugam Dharmalingam, Rajini Nagarajan and Carlo Santulli

Fibers 2022, 10(4), 32; https://doi.org/10.3390/fib10040032 - 2 Apr 2022

Cited by 13 | Viewed by 4028

Abstract

The contribution of natural lignocellulosic fibers to the reduction in wear damage in polymer resins is of interest, especially when two of these fibers can combine their respective effects. Wear properties of hybrid kenaf/banana epoxy composites have been investigated using three different total [...] Read more.

The contribution of natural lignocellulosic fibers to the reduction in wear damage in polymer resins is of interest, especially when two of these fibers can combine their respective effects. Wear properties of hybrid kenaf/banana epoxy composites have been investigated using three different total amount of fibers, 20, 30 and 40 wt.%, at loading forces up to 30 N and to sliding distances of up to 75 m. This demonstrated that the introduction of the highest level of fibers proved the most suitable for consistency of results and containment of wear with increasing load, as was also found from the morphological evaluation of wear degradation using scanning electron microscopy (SEM). Subsequently, tensile, flexural and impact properties of as-received and post-water-saturation hybrid composites were examined. The tests revealed a limited reduction in tensile and flexural strength, not exceeding 10% of the initial values, which were very high compared to similar materials, almost reaching 140 MPa for tensile strength and exceeding 170 MPa for flexural strength. In contrast, a higher standard deviation of values was found for impact strength, although the decrease in average values was only slightly above 10%. The results suggest the availability of these hybrids for wear-resisting applications in high-moisture environments, and the even more limited water absorption conferred by banana fibers added to kenaf ones. Full article

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