Fibers

17 pages, 4500 KiB

Open AccessArticle

Cementitious Composites with Cellulose Nanomaterials and Basalt Fiber Pellets: Experimental and Statistical Modeling

by O. M. Hosny, A. M. Yasien, M. T. Bassuoni, K. Gourlay and A. Ghazy

Fibers 2024, 12(1), 12; https://doi.org/10.3390/fib12010012 - 17 Jan 2024

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The production of high-performance fiber-reinforced cementitious composites (HPFRCCs) as a durable construction material using different types of fibers and nanomaterials critically relies on the synergic effects of the two materials as well as the cementitious composite mixes. In this study, novel HPFRCCs were [...] Read more.

The production of high-performance fiber-reinforced cementitious composites (HPFRCCs) as a durable construction material using different types of fibers and nanomaterials critically relies on the synergic effects of the two materials as well as the cementitious composite mixes. In this study, novel HPFRCCs were developed, which comprised high content (50%) slag by mass of the base binder as well as nano-silica (NS) or nano-crystalline cellulose (NCC). In addition, nano-fibrillated cellulose (NFC), and basalt fiber pellets (BFP), representing nano-/micro- and macro-fibers, respectively, were incorporated into the composites. The response surface method was used in this study’s statistical modeling part to evaluate the impact of key factors (NS, NCC, NFC, BFP) on the performance of 15 mixtures. The composites were assessed in terms of setting times, early- and late-age compressive strength, flexural performance, and resistance to freezing-thawing cycles, and the bulk trends were corroborated by fluid absorption, thermogravimetry, and microscopy tests. Incorporating NS/NCC in the slag-based binders catalyzed the reactivity of cement and slag with time, thus maintaining the setting times within an acceptable range (maximum 9 h), achieving high early- (above 33 MPa at 3 days) and later-age (above 70 MPa at 28 days) strength, and resistance to fluid absorption (less than 2.5%) and frost action (DF above 90%) of the composites. In addition, all nano-modified composites with multi-scale fibers showed notable improvement in terms of post-cracking flexural performance (Residual Strength Index above 40%), which qualify them for multiple infrastructure applications (i.e., shear key bridge joints) requiring a balance between high-strength properties, ductility, and durability. Full article

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15 pages, 18908 KiB

Open AccessArticle

Silica Scaling Inhibition in Water Treatment Process Using Fibrous Al₂O₃-Nylon 6 Adsorbents

by Ngan Thi Thu Phan, Minehiko Sato and Takaomi Kobayashi

Fibers 2024, 12(1), 11; https://doi.org/10.3390/fib12010011 - 15 Jan 2024

Cited by 1 | Viewed by 1736

Abstract

This study describes a novel approach using fibrous Al₂O₃-Nylon 6 composites to induce inhibition behavior in silica scaling systems. The composite fibers were fabricated with a wet-spinning process using the coagulation of a methanolic Nylon-CaCl₂ solution with Al [...] Read more.

This study describes a novel approach using fibrous Al₂O₃-Nylon 6 composites to induce inhibition behavior in silica scaling systems. The composite fibers were fabricated with a wet-spinning process using the coagulation of a methanolic Nylon-CaCl₂ solution with Al₂O₃ powder after immersing the thread-like solution in water. The mesoporous nylon fibers composed of Al₂O₃ powders ranging from 10 to 30 wt% loading demonstrated superior adsorption capabilities to silica in water, behaving with the Freundlich model and exhibiting effective multilayer adsorption onto the Al₂O₃ sites embedded in the fiber. Furthermore, the composite fibers inhibited silica scaling, even at high concentrations, due to a substantially efficient reduction in soluble silica when the composite fiber was present in the system. The utilization of 15 g of composite fibers resulted in a rapid drop to approximately 30 mg/L within the initial 10 h, which is a considerable improvement compared to the 300 mg/L observed in the fiber-free control sample. Notably, the presence of an elevated fiber content exceeding 7.5 g demonstrated the complete inhibition of silica precipitation. An analysis of the pore volume using nitrogen adsorption experiments before and after silica adsorption showed that silica adsorption resulted in a significant decrease in mesoporous properties at the alumina sites. This indicated an efficient adsorption of silica onto the alumina site, effectively removing silica from the system. Full article

(This article belongs to the Special Issue Fibers 10th Anniversary: Past, Present, and Future)

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15 pages, 5904 KiB

Open AccessArticle

Effect of the Sizing Removal Methods of Fiber Surface on the Mechanical Performance of Basalt Fiber-Reinforced Concrete

by Yeou-Fong Li, Jia-Yin Hung, Jin-Yuan Syu, Shih-Han Chen, Chih-Hong Huang, Shu-Mei Chang and Wen-Shyong Kuo

Fibers 2024, 12(1), 10; https://doi.org/10.3390/fib12010010 - 15 Jan 2024

Cited by 2 | Viewed by 1725

Abstract

In this study, comprehensive analyses were used to evaluate the physical and chemical properties of basalt fibers, employing a variety of instruments. Additionally, heat treatment and solvent treatment methods were used to eliminate the sizing present on fiber surfaces. The heat treatment process [...] Read more.

In this study, comprehensive analyses were used to evaluate the physical and chemical properties of basalt fibers, employing a variety of instruments. Additionally, heat treatment and solvent treatment methods were used to eliminate the sizing present on fiber surfaces. The heat treatment process involved determining the optimal temperature and duration required to remove the sizing from the basalt fibers. The appearance, chemical composition, and crystal structure of the original fibers were examined, including those subjected to heat treatment and those treated with solvents. These treated fibers were then incorporated into concrete to create basalt fiber-reinforced concrete (BFRC) specimens for mechanical tests, which assessed their compressive, flexural, and splitting tensile strengths. The results revealed that heat treatment at 300 °C for 180 min effectively removed the sizing on the basalt fibers, and the heat-treated basalt fibers exhibited uniform dispersion inside the BFRC specimens. In addition, solvent treatment primarily removed the soluble components of the sizing. The mechanical properties of specimens with sizing-removed basalt fibers were better than the specimens with original basalt fibers and the benchmark specimens. Crucially, the mechanical test results demonstrated that BFRC incorporating heat-treated basalt fibers exhibited a superior mechanical performance compared to BFRC incorporating original fibers or fibers subjected to the solvent treatment. Full article

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19 pages, 8938 KiB

Open AccessFeature PaperArticle

Methodological Aspects and Mesh Convergence in Numerical Analysis of Athermal Fiber Network Material Deformation

by Nishan Parvez, Syed Nabeel Amjad, Mithun K. Dey and Catalin R. Picu

Fibers 2024, 12(1), 9; https://doi.org/10.3390/fib12010009 - 12 Jan 2024

Cited by 1 | Viewed by 2036

Abstract

A balance between model complexity, accuracy, and computational cost is a central concern in numerical simulations. In particular, for stochastic fiber networks, the non-affine deformation of fibers, related non-linear geometric features due to large global deformation, and size effects can significantly affect the [...] Read more.

A balance between model complexity, accuracy, and computational cost is a central concern in numerical simulations. In particular, for stochastic fiber networks, the non-affine deformation of fibers, related non-linear geometric features due to large global deformation, and size effects can significantly affect the accuracy of the computer experiment outputs and increase the computational cost. In this work, we systematically investigate methodological aspects of fiber network simulations with a focus on the output accuracy and computational cost in models with cellular (Voronoi) and fibrous (Mikado) network architecture. We study both p and h-refinement of the discretizations in finite element solution procedure, with uniform and length-based adaptive h-refinement strategies. The analysis is conducted for linear elastic and viscoelastic constitutive behavior of the fibers, as well as for networks with initially straight and crimped fibers. With relative error as the determining criterion, we provide recommendations for mesh refinement, comment on the necessity of multiple realizations, and give an overview of associated computational cost that will serve as guidance toward minimizing the computational cost while maintaining a desired level of solution accuracy. Full article

(This article belongs to the Special Issue Fibers 10th Anniversary: Past, Present, and Future)

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12 pages, 2752 KiB

Open AccessEditor’s ChoiceArticle

Production of Nanofibers by Blow Spinning from Polylactide Containing Propolis and Beeswax

by Agata Penconek, Maciej Kilarski, Anna Soczewka, Michał Wojasiński and Arkadiusz Moskal

Fibers 2024, 12(1), 8; https://doi.org/10.3390/fib12010008 - 12 Jan 2024

Cited by 2 | Viewed by 1985

Abstract

The growing pollution of the environment with slowly decomposing waste, as well as the increasing drug resistance of pathogens, including the antibiotic resistance of bacteria, has led to a search for new solutions based on biodegradable and natural materials, which are known for [...] Read more.

The growing pollution of the environment with slowly decomposing waste, as well as the increasing drug resistance of pathogens, including the antibiotic resistance of bacteria, has led to a search for new solutions based on biodegradable and natural materials, which are known for their potential bacteriostatic properties. This study aimed to produce nanofibers by blowing from a polylactide (PLA) polymer solution containing natural compounds (e.g., beeswax, propolis). As a result of the conducted research, nanofibers were produced from PLA solutions containing various additives. The fibers’ mean diameter ranges from 0.36 to 2.38 µm, depending on the process parameters. To the authors’ knowledge, fibers were produced for the first time by blow spinning from a polymer solution containing propolis and beeswax. Full article

(This article belongs to the Special Issue Nanofibers: Biomedical Applications)

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15 pages, 4586 KiB

Open AccessArticle

Flexural Behavior of Pultruded GFRP–Concrete Composite Beams Strengthened with GFRP Stiffeners

by Muataz I. Ali, Abbas A. Allawi and Ayman El-Zohairy

Fibers 2024, 12(1), 7; https://doi.org/10.3390/fib12010007 - 9 Jan 2024

Cited by 2 | Viewed by 1734

Abstract

The utilization and incorporation of glass fiber-reinforced plastics (GFRP) in structural applications and architectural constructions are progressively gaining prominence. Therefore, this paper experimentally and numerically investigates the use of GFRP I-beams in conjunction with concrete slabs to form composite beams. The experimental design [...] Read more.

The utilization and incorporation of glass fiber-reinforced plastics (GFRP) in structural applications and architectural constructions are progressively gaining prominence. Therefore, this paper experimentally and numerically investigates the use of GFRP I-beams in conjunction with concrete slabs to form composite beams. The experimental design incorporated 2600 mm long GFRP I-beams which were connected compositely to concrete slabs with a 500 mm width and 80 mm thickness. The concrete slabs are categorized into two groups: concrete slabs cast using normal-strength concrete (NSC), and concrete slabs prepared using high-strength concrete (HSC). Various parameters like the type of concrete (normal and high-strength concrete), type of stiffeners bonded to the composite section (bolt–epoxy or bolt only), and inclusion of corrugated metal sheets were investigated. To obtain the full shear connection between the GFRP I-sections and concrete slabs, two rows of shear connectors in the form of bolts were utilized. These shear connectors were erected to the top flange of the GFRP I-sections to compositely connect between the GFRP I-beams and the concrete slabs as well as the corrugated metal sheets. The strengthening of the shear webs of GFRP I-beams with GFRP T-section stiffeners resulted in an enhancement in the flexural and shear strength. The failure loads in the case of the bolt–epoxy connection for the stiffeners were 8.2% and 10.0% higher than those in the case of bolt only when the concrete compressive strengths were 20.1 MPa and 52.3 MPa, respectively. Moreover, the effect of the concrete compressive strength was vital where the failure loads increased by 79.9% and 77.1% when HSC was used instead of NSC for the cases of bolt–epoxy and bolt only, respectively. The epoxy adhesive used in conjunction with mechanical connectors, specifically bolts, resulted in sufficient composite action and delayed shear failure within the web of the GFRP beam. For the specimens with bolt–epoxy connection, strain levels in the concrete slabs were consistently higher than in the other specimens with bolts alone at the same loading level. The concrete slabs integrated with HSC registered strain levels that were 20.0% and 21.8% greater for bolt–epoxy and bolt-only connections, respectively, when compared to those using normal-strength concrete (NSC). This discrepancy can likely be credited to the enhanced composite interaction between the concrete slabs and the GFRP I-beams. In addition, ABAQUS software (version 6.2) was used to develop FE models to analyze the tested composite beams and provide a parametric study using the verified models. Full article

(This article belongs to the Special Issue The Use of Fibers in the Field of Structural and Earthquake Engineering: Experimental Measurements and Numerical Simulations)

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17 pages, 5565 KiB

Open AccessArticle

Investigation of the Effect of Chemical Treatment on the Properties of Colombian Banana and Coir Fibers and Their Adhesion Behavior on Polylactic Acid and Unsaturated Polyester Matrices

by Ismael Barrera-Fajardo, Oswaldo Rivero-Romero and Jimy Unfried-Silgado

Fibers 2024, 12(1), 6; https://doi.org/10.3390/fib12010006 - 3 Jan 2024

Cited by 2 | Viewed by 2191

Abstract

In this work, the adhesion behavior of chemically treated banana and coir Colombian fibers embedded in polylactic acid (PLA) and unsaturated polyester resin (UPR) matrices was investigated. Both types of fibers were treated with a 5 wt.% sodium hydroxide solution for one hour. [...] Read more.

In this work, the adhesion behavior of chemically treated banana and coir Colombian fibers embedded in polylactic acid (PLA) and unsaturated polyester resin (UPR) matrices was investigated. Both types of fibers were treated with a 5 wt.% sodium hydroxide solution for one hour. The properties of treated and untreated fibers were determined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and tensile tests. To evaluate the adhesion behavior of the fibers in PLA and UPR matrices, pull-out tests were performed, and the percentage of broken fibers was determined. The results showed that alkaline treatment improved the fibers’ physicochemical, mechanical, and thermal properties. In addition, the alkaline treatment was able to improve the adhesion behavior of coir and banana fibers to PLA and UPR matrices. The banana fibers showed a percentage of broken fibers of 100%, while the coir fibers showed a slight increase in IFSS value. This behavior is attributed to the improvement in surface roughness due to the removal of non-cellulosic composites and impurities. Full article

(This article belongs to the Special Issue Natural Fiber Competitiveness and Sustainability)

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13 pages, 2919 KiB

Open AccessArticle

Raman Spectra of Delignified Plant Fibers: Exploring the Impact of Xylan’s Presence on the Spectral Features of Cellulose

by Umesh P. Agarwal and Sally A. Ralph

Fibers 2024, 12(1), 5; https://doi.org/10.3390/fib12010005 - 27 Dec 2023

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Abstract

Wood and plants are made of fibers that contain, in addition to cellulose, lignin and hemicelluloses. Xylan and galactoglucomannan are the dominant secondary cell wall hemicelluloses. In modern times, fibers are important materials for the biorefinery industry and for developing biocomposites. For these [...] Read more.

Wood and plants are made of fibers that contain, in addition to cellulose, lignin and hemicelluloses. Xylan and galactoglucomannan are the dominant secondary cell wall hemicelluloses. In modern times, fibers are important materials for the biorefinery industry and for developing biocomposites. For these and other applications, the structural analysis of fibers is important, and Raman spectroscopy is among the many analytical techniques used. However, given the structural similarity between hemicelluloses and cellulose, many of their Raman contributions overlap, and the extent to which the overlapping features of hemicellulose modify the spectrum of cellulose is not yet fully understood. The present investigation focuses on this aspect by examining xylan, one of the hemicelluloses. As a model system, samples with various mass ratios of cotton microcrystalline cellulose (MCC) and xylan (birch wood) were prepared and analyzed using FT-Raman spectroscopy. In most cases, the Raman intensities were sample-composition-dependent, and, when the selected band intensities were plotted against the xylan content, good linear correlations (with an R² between 0.69 and 1.0) were obtained. The results indicated that with increased xylan content, the peak intensities increased at 1460, 898, and 494 cm⁻¹ and declined at 1480, 1121, 1096, and 520 cm⁻¹. Additionally, intensity changes (%) in the MCC bands with respect to MCC’s fractions in various mixture samples showed that, in most cases, the mixture intensities increased and were highly correlated with the xylan amounts in the mixtures (with an R² between 0.75 and 0.97). These findings were applied to interpret Raman spectra of selected xylan-containing delignified plant fibers. It is hoped that the insights gained in this study will allow for better interpretation of the spectra of natural and treated plant materials. Full article

(This article belongs to the Special Issue Alternative Bio-Based Fibers for Paper, Packaging, Textile and Other Materials)

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13 pages, 3631 KiB

Open AccessArticle

Theoretical and Experimental Investigations of Oxygen Activation Effect of Carbon Nanofibers Interacting with Polypyrrole

by Yibing Xie, Yiting Wang, Lijun Wang and Jiawei Liang

Fibers 2024, 12(1), 4; https://doi.org/10.3390/fib12010004 - 27 Dec 2023

Cited by 5 | Viewed by 1692

Abstract

Theoretical modeling calculations and experimental measurements were adopted to investigate the oxygen activation effect of carbon nanofibers (CNFs) interacting with polypyrrole (PPY). The CNF undergoes a hydrothermal oxidation process to form epoxy and hydroxyl groups containing carbon nanofibers (CNF-O). The oxygen activation effect [...] Read more.

Theoretical modeling calculations and experimental measurements were adopted to investigate the oxygen activation effect of carbon nanofibers (CNFs) interacting with polypyrrole (PPY). The CNF undergoes a hydrothermal oxidation process to form epoxy and hydroxyl groups containing carbon nanofibers (CNF-O). The oxygen activation effect of CNF on the electronic and electrochemical properties was investigated through the interfacial interaction between CNF-O and PPY. Theoretical modeling calculation discloses that CNF-O/PPY exhibits lower electronic bandgaps (0.64 eV), a higher density of states (10.039 states/eV), and a lower HOMO–LUMO molecular orbital energy gap (0.077 eV) than CNF/PPY (1.56 eV, 7.946 states/eV and 0.112 eV), presenting its superior electronic conductivity and electroactivity. The Mulliken population and charge density difference analysis disclose the stronger interface interaction of CNF-O/PPY caused by epoxy and hydroxyl groups. Cyclic voltammogram measurements reveal that CNF-O/PPY exhibits a higher response current and a higher specific capacitance (221.1–112.2 mF g⁻¹) than CNF/PPY (57.6–24.2 mF g⁻¹) at scan rates of 5–200 mV s⁻¹. Electrochemical impendence spectrum measurements disclose that CNF-O/PPY exhibits a lower charge transfer resistance (0.097 Ω), a lower ohmic resistance (0.336 Ω), a lower Warburg impedance (317 Ω), and a higher double-layer capacitance (0.113 mF) than CNF/PPY (1.419 Ω, 9.668 Ω, 7865 Ω, and 0.015 mF). Both theoretical and experimental investigations prove that CNF-O/PPY presents an intensified intermolecular interaction rather than CNF/PPY. The promotive oxygen activation effect of CNF could contribute to improving the electronic and electrochemical properties of CNF-O/PPY. Full article

(This article belongs to the Special Issue Nanofibers: Biomedical Applications)

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23 pages, 13389 KiB

Open AccessArticle

Innovative Flexural Repair Technique of Pre-Damaged T-Beams Using Eco-Friendly Steel-Fibre-Reinforced Geopolymer Concrete

by Ashraf Khalifa, Abo El-Wafa El-Thakeb, Ahmed El-Sebai and Ahmed Elmannaey

Fibers 2024, 12(1), 3; https://doi.org/10.3390/fib12010003 - 26 Dec 2023

Cited by 1 | Viewed by 2130

Abstract

This paper presents an innovative flexural repair technique for pre-damaged reinforced concrete T-beams using eco-friendly steel-fibre-reinforced geopolymer concrete (SFRGPC). The study considers various parameters such as repair layer depth, location and configuration, and the use of additional reinforcement in one beam. The beams [...] Read more.

This paper presents an innovative flexural repair technique for pre-damaged reinforced concrete T-beams using eco-friendly steel-fibre-reinforced geopolymer concrete (SFRGPC). The study considers various parameters such as repair layer depth, location and configuration, and the use of additional reinforcement in one beam. The beams were preloaded to 50% of their ultimate flexural capacity. Extensive measurements were taken, including crack initiation and propagation, crack width, initial stiffness, load deflection, peak loads, ductility index, and strain values. The structural performance of the repaired T-beams under flexural loading was predicted using an analytical model. The repaired beams showed an increase in carrying capacity, stiffness, and ductility, but the failure mode was identical to the control samples. The study shows that SFRGPC shows great promise as a technique for not only repairing pre-damaged reinforced concrete beams but also for their strengthening. The best results were obtained with three-sided jackets with fibrous geopolymer concrete only, resulting in a load-carrying capacity increase of 25.8% compared to reference T-beams. The bonding between SFRGPC and existing concrete was effective, with no slippage or disintegration at the interface. The repaired beams’ structural behaviour and performance under flexural loads were successfully predicted using the analytical model, with a precision of about 98%. Full article

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21 pages, 1232 KiB

Open AccessArticle

Pulp Particle Classification Based on Optical Fiber Analysis and Machine Learning Techniques

by Stefan B. Lindström, Rabab Amjad, Elin Gåhlin, Linn Andersson, Marcus Kaarto, Kateryna Liubytska, Johan Persson, Jan-Erik Berg, Birgitta A. Engberg and Fritjof Nilsson

Fibers 2024, 12(1), 2; https://doi.org/10.3390/fib12010002 - 25 Dec 2023

Cited by 2 | Viewed by 2858

Abstract

In the pulp and paper industry, pulp testing is typically a labor-intensive process performed on hand-made laboratory sheets. Online quality control by automated image analysis and machine learning (ML) could provide a consistent, fast and cost-efficient alternative. In this study, four different supervised [...] Read more.

In the pulp and paper industry, pulp testing is typically a labor-intensive process performed on hand-made laboratory sheets. Online quality control by automated image analysis and machine learning (ML) could provide a consistent, fast and cost-efficient alternative. In this study, four different supervised ML techniques—Lasso regression, support vector machine (SVM), feed-forward neural networks (FFNN), and recurrent neural networks (RNN)—were applied to fiber data obtained from fiber suspension micrographs analyzed by two separate image analysis software. With the built-in software of a commercial fiber analyzer optimized for speed, the maximum accuracy of 81% was achieved using the FFNN algorithm with Yeo–Johnson preprocessing. With an in-house algorithm adapted for ML by an extended set of particle attributes, a maximum accuracy of 96% was achieved with Lasso regression. A parameter capturing the average intensity of the particle in the micrograph, only available from the latter software, has a particularly strong predictive capability. The high accuracy and sensitivity of the ML results indicate that such a strategy could be very useful for quality control of fiber dispersions. Full article

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20 pages, 20500 KiB

Open AccessArticle

Mechanical Performance of Cementitious Materials Reinforced with Polyethylene Fibers and Carbon Nanotubes

by Rashad R. AlAraj, Adil K. Tamimi, Noha M. Hassan and Kazi Parvez Fattah

Fibers 2024, 12(1), 1; https://doi.org/10.3390/fib12010001 - 20 Dec 2023

Cited by 1 | Viewed by 1773

Abstract

The cracking of cementitious materials due to their quasi-brittle behavior is a major concern leading to a loss in strength and durability. To limit crack growth, researchers have incorporated microfibers in concrete mixes. The objective of this study is to determine if nano-reinforcements [...] Read more.

The cracking of cementitious materials due to their quasi-brittle behavior is a major concern leading to a loss in strength and durability. To limit crack growth, researchers have incorporated microfibers in concrete mixes. The objective of this study is to determine if nano-reinforcements can arrest cracks and enhance the material performance in comparison to microfibers. A total of 28 specimens were prepared to investigate and compare the effects of incorporating carbon nanotubes (CNTs) as a nano-reinforcement and polyethylene (PE) fibers at a macro-level and their combination. Compressive and flexural strengths were experimentally tested to assess the mechanical performance. The microstructure of the mortar samples was also examined using a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The ductility increased by almost 50% upon the addition of CNTs, while no significant enhancement was witnessed for the compressive strength. The flexural strength increased by 169% and the flexural strain by 389% through the addition of the combination of CNTs and PE fibers. Full article

(This article belongs to the Special Issue The Use of Fibers in the Field of Structural and Earthquake Engineering: Experimental Measurements and Numerical Simulations)

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Fibers, Volume 12, Issue 1 (January 2024) – 12 articles

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