Fibers

19 pages, 3580 KiB

Open AccessArticle

Predicting the Tensile Properties of Carbon FRCM Using a LASSO Model

by María Rodríguez-Marcos, Paula Villanueva-Llaurado, Jaime Fernández-Gómez, Joaquín Abellán-García and Augusto Sisa-Camargo

Fibers 2024, 12(12), 109; https://doi.org/10.3390/fib12120109 - 9 Dec 2024

Abstract

The use of Fibre Reinforced Cementitious Matrix (FRCM) for structural retrofitting requires prior assessment of the composite’s mechanical properties, particularly its tensile stress–strain response. This paper presents a LASSO regression model applied to 107 uniaxial tensile tests on Carbon FRCM in order to [...] Read more.

The use of Fibre Reinforced Cementitious Matrix (FRCM) for structural retrofitting requires prior assessment of the composite’s mechanical properties, particularly its tensile stress–strain response. This paper presents a LASSO regression model applied to 107 uniaxial tensile tests on Carbon FRCM in order to investigate the impact of both the material and testing parameters on FRCM performance. A highly effective LASSO regression model was trained using k-fold validation, resulting in concise and comprehensible models. Within the testing parameters, both the gripping system and load–speed ratio significantly affected the performance. A substantial impact on ultimate values was found for the load–speed ratio. From the material-related parameters, the most influential was the textile coating in terms of strength and the existence of bilinear or trilinear behaviour. It was also concluded that the combination of textile and matrix properties influenced the stress–strain response at all stages, with high-performance mortars resulting in better textile-to-matrix interaction. Full article

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28 pages, 2189 KiB

Open AccessArticle

Advanced Structural Technologies Implementation in Designing and Constructing RC Elements with C-FRP Bars, Protected Through SHM Assessment

by Georgia M. Angeli, Maria C. Naoum, Nikos A. Papadopoulos, Parthena-Maria K. Kosmidou, George M. Sapidis, Chris G. Karayannis and Constantin E. Chalioris

Fibers 2024, 12(12), 108; https://doi.org/10.3390/fib12120108 - 5 Dec 2024

Abstract

The need to strengthen the existing reinforced concrete (RC) elements is becoming increasingly crucial for modern cities as they strive to develop resilient and sustainable structures and infrastructures. In recent years, various solutions have been proposed to limit the undesirable effects of corrosion [...] Read more.

The need to strengthen the existing reinforced concrete (RC) elements is becoming increasingly crucial for modern cities as they strive to develop resilient and sustainable structures and infrastructures. In recent years, various solutions have been proposed to limit the undesirable effects of corrosion in RC elements. While C-FRP has shown promise in corrosion-prone environments, its use in structural applications is limited by cost, bonding, and anchorage challenges with concrete. To address these, the present research investigates the structural performance of RC beams reinforced with C-FRP bars under static loading using Structural Health Monitoring (SHM) with an Electro-Mechanical Impedance (EMI) system employing Lead Zirconate Titanate (PZT) piezoelectric transducers which are applied to detect damage development and enhance the protection of RC elements and overall, RC structures. This study underscores the potential of C-FRP bars for durable tensile reinforcement in RC structures, particularly in hybrid designs that leverage steel for compression strength. The study focuses on critical factors such as stiffness, maximum load capacity, deflection at each loading stage, and the development of crack widths, all analyzed through voltage responses recorded by the PZT sensors. Particular emphasis is placed on the bond conditions and anchorage lengths of the tensile C-FRP bars, exploring how local confinement conditions along the anchorage length influence the overall behavior of the beams. Full article

13 pages, 5759 KiB

Open AccessArticle

Impact of Micro- and Nanocellulose Coating on Properties of Wool Fabric by Using Solution Blow Spinning

by Yi Zhang, Abu Naser Md Ahsanul Haque and Maryam Naebe

Fibers 2024, 12(12), 107; https://doi.org/10.3390/fib12120107 - 5 Dec 2024

Abstract

This study investigates the impact of micro- and nanocellulose coatings on the properties of wool fabrics using the solution blow spinning technique. The objective is to assess how varying cellulose sizes influence key fabric attributes, including physical properties, UV-shielding ability, air permeability and [...] Read more.

This study investigates the impact of micro- and nanocellulose coatings on the properties of wool fabrics using the solution blow spinning technique. The objective is to assess how varying cellulose sizes influence key fabric attributes, including physical properties, UV-shielding ability, air permeability and water vapour permeability, with a focus on their practical applications. Coating with microcrystalline cellulose (MCC) was found to increase the air permeability of fabric significantly, whereas coating with cellulose nanocrystals (CNCs) enhanced water vapour permeability and reduced pore size. The air permeability could relate to the breathability, and water vapour permeability could relate to the comfortability. Coated fabric with both sizes of cellulose could have different applications, like pollen filtration and printable cloth, and further functionality could be achieved by modifying the cellulose structure. This research establishes a platform for the effective application of cellulose coatings on wool fabric, offering promising advancements for textile performance and sustainability. Full article

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12 pages, 3318 KiB

Open AccessArticle

Carbon Fiber Recycling from Waste CFRPs via Microwave Pyrolysis: Gas Emissions Monitoring and Mechanical Properties of Recovered Carbon Fiber

by Kai-Yen Chin, Angus Shiue, Jhu-Lin You, Yi-Jing Wu, Kai-Yi Cheng, Shu-Mei Chang, Yeou-Fong Li, Chao-Heng Tseng and Graham Leggett

Fibers 2024, 12(12), 106; https://doi.org/10.3390/fib12120106 - 5 Dec 2024

Abstract

Disposing of carbon fiber-reinforced polymers (CFRPs) has become a pressing issue due to their increasing application across various industries. Previous work has focused on removing silane coupling agent residues on recovered carbon fibers via microwave pyrolysis, making them suitable for use in new [...] Read more.

Disposing of carbon fiber-reinforced polymers (CFRPs) has become a pressing issue due to their increasing application across various industries. Previous work has focused on removing silane coupling agent residues on recovered carbon fibers via microwave pyrolysis, making them suitable for use in new materials. However, the mechanical performance and structural characteristics of these fibers have not been fully reported. This study investigates the time–temperature curves of CFRPs treated through microwave pyrolysis and analyzes the mechanical and structural properties of silane-controllable recovered carbon fibers. Additionally, emissions—including carbon monoxide, carbon dioxide, and particulate aerosols—were measured using handheld monitors and thermal desorption–gas chromatography/mass spectrometry to determine the composition of fugitive gases around the microwave pyrolysis system. The pyrolysis process at 950 °C, with an additional 1 h holding time, reduced the crystallite size from 0.297 Å to 0.222 Å, significantly enhancing tensile strength (3804 ± 713 MPa) and tensile modulus (200 ± 13 GPa). This study contributes to more sustainable CFRP waste treatment and highlights the potential for reusing high-quality carbon fibers in new applications, enhancing both environmental and worker safety. Full article

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14 pages, 4358 KiB

Open AccessArticle

Challenges and Opportunities in Recycling Upholstery Textiles: Enhancing High-Density Fiberboards with Recycled Fibers

by Matylda Wojciechowska and Grzegorz Kowaluk

Fibers 2024, 12(12), 105; https://doi.org/10.3390/fib12120105 - 5 Dec 2024

Abstract

Recycling upholstery textiles is challenging due to the complexity of materials, which often include a mix of fabrics, foams, and adhesives that are difficult to separate. The intricate designs and layers in upholstered furniture make it labor-intensive and costly to dismantle for recycling. [...] Read more.

Recycling upholstery textiles is challenging due to the complexity of materials, which often include a mix of fabrics, foams, and adhesives that are difficult to separate. The intricate designs and layers in upholstered furniture make it labor-intensive and costly to dismantle for recycling. Additionally, contaminants like stains, finishes, and flame retardants complicate recycling. Despite these difficulties, recycling upholstery textiles is crucial to reducing landfill waste and conserving resources by reusing valuable materials. It also helps mitigate environmental pollution and carbon emissions associated with producing new textiles from virgin resources. The presented research aimed to establish the feasibility of incorporating textile fibers from waste artificial leather fibers from the upholstery furniture industry into the structure of high-density fiberboards. The bulk density of samples with wood fiber was 28.30 kg m⁻³, while it was 25.77 kg m⁻³ for textile fiber samples. The lowest modulus of elasticity (MOE) was 2430 N mm⁻², and it was 3123 N mm⁻² for the reference sample. The highest bending strength (MOR) was 42 N mm⁻², and the lowest was 27.2 N mm⁻². Screw withdrawal resistance decreased from 162 N mm⁻¹ in the reference sample to 92 N mm⁻¹ with 25% artificial leather fibers. The internal bond (IB) strength ranged from 1.70 N mm⁻² (reference) to 0.70 N mm⁻² (25% of artificial leather fibers content). Water absorption ranged from 81.8% (1% of artificial leather fibers) to 66% (25% of artificial leather fibers content). It has been concluded that it is possible to meet the European standard requirements with 10% addition of the artificial leather fiber content. This approach positively contributes to carbon capture and storage (CCS) policy and mitigates the problem of such waste being sent to landfills. The research shows that while selected mechanical and physical parameters of the panels decrease with a rising content of recycled textile fibers, it is possible to meet proper European standard requirements by adjusting technological parameters such as nominal density. Full article

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23 pages, 4772 KiB

Open AccessReview

Comprehensive Bibliometric Review on the Sustainability and Environmental Impact of Fiber-Reinforced Polymers

by Maria Tănase, Alin Diniță, Daniela Roxana Popovici, Alexandra Ileana Portoacă, Cătălina Călin and Elena-Emilia Sirbu

Fibers 2024, 12(12), 104; https://doi.org/10.3390/fib12120104 - 3 Dec 2024

Abstract

Fiber-reinforced polymers (FRPs) are increasingly recognized in sustainable materials research due to their potential environmental advantages. This study presents a focused bibliometric review of the sustainability research on FRPs. An initial search of the Web of Science (WOS) database identified 803 documents, which [...] Read more.

Fiber-reinforced polymers (FRPs) are increasingly recognized in sustainable materials research due to their potential environmental advantages. This study presents a focused bibliometric review of the sustainability research on FRPs. An initial search of the Web of Science (WOS) database identified 803 documents, which were refined to 749 relevant articles, reviews, and proceedings. A co-authorship analysis highlights the significant contributions of the USA and India, with European countries forming regional collaborations. The research output has steadily increased since 2011, peaking in 2022 and 2023. The multidisciplinary nature of the research spans materials science, engineering, and environmental sciences, with journals such as *Polymers*, *Sustainability*, and the *Journal of Cleaner Production* emphasizing sustainability themes. This analysis covers key aspects such as keyword co-occurrence, overlay visualizations, co-authorship networks, and the distribution of publications by year, research area, and journal. The findings underscore the evolving research landscape of sustainable FRPs and highlight the ongoing need for life cycle assessments and interdisciplinary collaboration. Full article

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17 pages, 6107 KiB

Open AccessArticle

Effects of Ply Misalignment in Material Characterization of Composite Laminates

by Michael Franz, Racim Radjef, Boris Eisenbart and Sandro Wartzack

Fibers 2024, 12(12), 103; https://doi.org/10.3390/fib12120103 - 26 Nov 2024

Abstract

Carbon fiber reinforced plastic (CFRP) parts find a rising number of applications as structural components. Therefore, new manufacturing technologies are developed, enabling high volume production of such parts. With those higher volumes, variation management during product design becomes more critical. While manufacturing variations [...] Read more.

Carbon fiber reinforced plastic (CFRP) parts find a rising number of applications as structural components. Therefore, new manufacturing technologies are developed, enabling high volume production of such parts. With those higher volumes, variation management during product design becomes more critical. While manufacturing variations in CFRP materials occur on different scales, detecting and considering those on the meso (ply) scale becomes more important. Thus, the question arises whether such variations can be detected with standardized testing methods. In this study, artificial fiber misalignment has been introduced into the outer plies of standardized tensile specimens to explore the influence of such variations on the mechanical properties. A simulation model was developed to identify these variations and the test results were used to calibrate and optimize the material parameters of the simulation model. The effects of the artificially induced variation were distinguishable in the test data as well as in the simulation models. Furthermore, the simulation models showed good agreement with the experimental data, which leads to the conclusion that the utilized measuring techniques are well suited to characterize the fiber misalignment. The developed simulation models can be used to investigate the effects of fiber misalignment within the product development process without the need for physical testing. Full article

(This article belongs to the Special Issue Mechanical Behaviour of Reinforced Thermosetting Polymers with Fibers: Analytical/Numerical Models and Experimental Evidence)

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16 pages, 306 KiB

Open AccessReview

The Use of Asbestos and Its Consequences: An Assessment of Environmental Impacts and Public Health Risks

by António Curado, Leonel J. R. Nunes, Arlete Carvalho, João Abrantes, Eduarda Lima and Mário Tomé

Fibers 2024, 12(12), 102; https://doi.org/10.3390/fib12120102 - 25 Nov 2024

Abstract

The use of asbestos, once celebrated for its versatility and fire-resistant properties, has left a lasting legacy of environmental degradation and public health risks. This paper provides a comprehensive assessment of the environmental impacts and health risks associated with asbestos, highlighting its widespread [...] Read more.

The use of asbestos, once celebrated for its versatility and fire-resistant properties, has left a lasting legacy of environmental degradation and public health risks. This paper provides a comprehensive assessment of the environmental impacts and health risks associated with asbestos, highlighting its widespread use, environmental persistence, and adverse effects on human health. Through a literature review, this study examines the historical context of asbestos use, its adverse environmental effects and the mechanisms by which exposure to asbestos poses significant health risks, including the development of asbestos-related diseases such as mesothelioma, lung cancer, asbestosis, etc. It also assesses the current regulatory framework and provides a methodological analysis of the strategy for recycling end-of-life materials containing asbestos fibers, proposing the inclusion of asbestos-containing materials (ACMs) in the rock wool industry to reduce Greenhouse Gasses (GHG) emissions. Drawing on interdisciplinary insights from environmental science, public health, and regulatory analysis, this paper concludes with recommendations for improving asbestos management strategies, promoting safer alternatives and mitigating the long-term environmental and human health impacts of asbestos. Full article

(This article belongs to the Collection Review Papers of Fibers)

17 pages, 7158 KiB

Open AccessArticle

Coaxial Electrospinning of PCL-PVA Membranes Loaded with N-Heterocyclic Gold Complex for Antitumoral Applications

by Raffaele Longo, Luigi Vertuccio, Francesca Aliberti, Annaluisa Mariconda, Marialuigia Raimondo, Pasquale Longo and Liberata Guadagno

Fibers 2024, 12(12), 101; https://doi.org/10.3390/fib12120101 - 21 Nov 2024

Abstract

Coaxial electrospun membranes made of polycaprolactone (PCL) and polyvinylalcohol (PVA) were produced and filled with a promising synthetic gold complex (AuM1) for antitumoral applications. Coaxial nanofibers characterized by a PVA shell and PCL + AuM1 core were made to design a multi-step release [...] Read more.

Coaxial electrospun membranes made of polycaprolactone (PCL) and polyvinylalcohol (PVA) were produced and filled with a promising synthetic gold complex (AuM1) for antitumoral applications. Coaxial nanofibers characterized by a PVA shell and PCL + AuM1 core were made to design a multi-step release in a physiological environment. The coaxial structure can sensitively limit the burst effect, allowing the release of 90% of the active substance AuM1 in about three days. By comparison, the PCL membrane loaded with AuM1 produced via uniaxial electrospinning releases 90% of the drug in about 1 h. The correlation of release kinetic data with the morphological evolution and the spectroscopic investigation highlighted how coaxial electrospinning is a promising process for designing drug delivery systems to control the release of active substances over time. The proper design of core–shell systems could be of great interest for prolonged therapies, such as antitumoral therapy. Full article

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14 pages, 4247 KiB

Open AccessArticle

Thermal, Optical, and Emission Traits of SM³⁺-Ion-Doped Fluoride/Chloride/Oxide Glass for Red/Orange Laser Fiber Applications

by Bozena Burtan-Gwizdala, Jan Cisowski, Radoslaw Lisiecki, Kinga J. Kowalska, Bozena Jarzabek, Natalia Nosidlak, Manuela Reben, Ali M. Alshehri, Khalid I. Hussein and El Sayed Yousef

Fibers 2024, 12(11), 100; https://doi.org/10.3390/fib12110100 - 15 Nov 2024

Abstract

This study examined spectroscopic, thermal, and other qualities, such as the lasing parameters, of Sm³⁺-doped glass with the composition 40P₂O₅–30ZnO–20LiCl–10BaF₂. The ellipsometric data were used in a Sellmeier dispersion relation to estimate the refractive index [...] Read more.

This study examined spectroscopic, thermal, and other qualities, such as the lasing parameters, of Sm³⁺-doped glass with the composition 40P₂O₅–30ZnO–20LiCl–10BaF₂. The ellipsometric data were used in a Sellmeier dispersion relation to estimate the refractive index values of the glasses investigated. The measured absorption spectra of the doped glass reveal the presence of various absorption bands assigned to transitions from the ⁶H_5/2 ground state attributed to Sm³⁺-ion-excited states. We studied the decay of the ⁴G_5/2 level of the Sm³⁺ ions in the doped glass by analyzing its absorption and emission fluorescence spectra. The Judd–Ofelt hypothesis allowed us to determine that the quantum efficiency of the ⁴G_5/2–⁶H_7/2 transition is high: 96% and 97% for glass doped with 4.05

\times

10¹⁹ ions/cm⁻³ and 11

\times

10¹⁹ ions/cm⁻³, respectively. Furthermore, this glass exhibits efficient red/orange enhanced spontaneous emission that matches the excitation band of the photosensitizer material used in medical applications. Full article

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15 pages, 2102 KiB

Open AccessArticle

Waste Bombyx Mori Silk Textiles as Efficient and Reuseable Bio-Adsorbents for Methylene Blue Dye Removal and Oil–Water Separation

by Hansadi Jayamaha, Isabel Schorn and Larissa M. Shepherd

Fibers 2024, 12(11), 99; https://doi.org/10.3390/fib12110099 - 14 Nov 2024

Abstract

Many adsorbent materials are being studied for dye and oil removal from the environment. Bio-based materials such as silk are promising candidates due to their enhanced affinity for dyes and intrinsic hydrophobicity. This work extensively studies various silk textiles as dye and oil [...] Read more.

Many adsorbent materials are being studied for dye and oil removal from the environment. Bio-based materials such as silk are promising candidates due to their enhanced affinity for dyes and intrinsic hydrophobicity. This work extensively studies various silk textiles as dye and oil adsorbents. For comparison, we use electrospun fiber mats and hollow silk microparticle-treated silk fabrics. Our work is motivated by two factors: (i) massive amounts of silk waste is being discarded annually from textile factories, and (ii) the limited studies on the adsorption phenomena of pristine silk textiles. Based on our findings, 12 mg of silk filament yarn has a 90% methylene blue (MB) removal efficiency within 10 min of exposure for concentrations up to 100 ppm and exhibits adsorption capacities of 145 mg/g for 800 ppm concentrations. The adsorption kinetics obey a pseudo-second order, where the rate-controlling step is chemisorption, and isotherms follow the Langmuir model with homogenous monolayer adsorption. Furthermore, noil woven fabrics with contact angles of 140⁰ have oil adsorbent capacities that are double the fabric weight. Our work confirms that silk waste textiles are efficient and reusable bio-adsorbents for MB dye and oil removal, outperforming materials made with additional and energy-intensive techniques such as silk dissolution and electrospinning. Full article

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24 pages, 8849 KiB

Open AccessReview

Non-Circular Cross-Section Fibres for Composite Reinforcement—A Review with a Focus on Flat Glass Fibres

by James Thomason, Andrew Carlin and Liu Yang

Fibers 2024, 12(11), 98; https://doi.org/10.3390/fib12110098 - 11 Nov 2024

Abstract

Glass fibre reinforcements form the backbone of the composites industry. Today, glass fibre products account for more than 95% of the fibre reinforcements used in the composites industry. Since the first commercialisation of glass fibres for composite reinforcement in the 1930s, the cross-sectional [...] Read more.

Glass fibre reinforcements form the backbone of the composites industry. Today, glass fibre products account for more than 95% of the fibre reinforcements used in the composites industry. Since the first commercialisation of glass fibres for composite reinforcement in the 1930s, the cross-sectional shape of glass fibres has remained exclusively circular. However, many of the other types of fibre reinforcement have a non-circular cross section (NCCS). This paper reviews the available knowledge on the production of NCCS glass fibres and some of the possibilities that such fibres offer to enhance the performance of glass reinforced polymer composites. The three parts of the review focus on early research work on different shapes of glass fibre, the developments leading to industrial-level production of NCCS glass fibres, and the more recent data available on the influence of the available commercially produced NCCS flat glass fibres on composite performance. It Is concluded that the continued development of NCCS glass fibres may offer interesting potential to generate composites with increased performance and may also enable further tailoring of composite performance to enable new applications to be developed. Full article

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20 pages, 21295 KiB

Open AccessArticle

Influence of the PAN:PEO Ratio on the Morphology of Needleless Electrospun Nanofiber Mats Before and After Carbonization

by Nonsikelelo Sheron Mpofu, Yusuf Topuz, Elzbieta Stepula, Uwe Güth, Timo Grothe, Jan Lukas Storck, Martin Wortmann, Boris Mahltig and Andrea Ehrmann

Fibers 2024, 12(11), 97; https://doi.org/10.3390/fib12110097 - 8 Nov 2024

Abstract

Nanofiber mats with a high surface-to-volume ratio can be prepared by electrospinning. The Porosity is sometimes reported to be tunable by blending different materials, e.g., water-soluble poly(ethylene oxide) (PEO) with not water-soluble poly(acrylonitrile) (PAN). Here, nanofiber mats were electrospun from different PAN:PEO ratios, [...] Read more.

Nanofiber mats with a high surface-to-volume ratio can be prepared by electrospinning. The Porosity is sometimes reported to be tunable by blending different materials, e.g., water-soluble poly(ethylene oxide) (PEO) with not water-soluble poly(acrylonitrile) (PAN). Here, nanofiber mats were electrospun from different PAN:PEO ratios, using a wire-based electrospinning machine “Nanospider Lab”. Investigations of the as-spun nanofiber mats as well as of membranes after washing off the water-soluble PEO by scanning electron microscopy (SEM) revealed severe differences in the nanofiber mat morphologies, such as varying fiber diameters and especially non-fibrous areas in the carbonized nanofiber mats, depending on the amount of PEO in the nanofiber mat as well as the molecular weight of the PEO. Similarly, the ratio and molecular weight of PEO influenced the results of stabilization and carbonization. This paper discusses the possibility of tailoring nanofiber porosity for the potential use of PAN nanofiber mats in tissue engineering, filtration, and other applications. Full article

(This article belongs to the Special Issue Electrospinning Nanofibers)

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20 pages, 7109 KiB

Open AccessArticle

Coating of Hemp Fibres with Hydrophobic Compounds Extracted from Pine Bark

by Robert Abbel, Regis Risani, Maxime Nourtier, Lloyd Donaldson, Christel Brunschwig, Claire Mayer-Laigle, James H. Bridson, Armin Thumm, Alan Dickson, Rachel Murray, Jessica Harris, Johnny Beaugrand and Stefan Hill

Fibers 2024, 12(11), 96; https://doi.org/10.3390/fib12110096 - 7 Nov 2024

Abstract

Applying coatings of paraffins and other synthetic waxes is a common approach to impart hydrophobic properties to fibres and thus control their surface characteristics. Replacing these fossil-based products with alternatives derived from renewable resources can contribute to humankind’s transition to a sustainable bioeconomy. [...] Read more.

Applying coatings of paraffins and other synthetic waxes is a common approach to impart hydrophobic properties to fibres and thus control their surface characteristics. Replacing these fossil-based products with alternatives derived from renewable resources can contribute to humankind’s transition to a sustainable bioeconomy. This study presents the coating of hemp fibres with waxes extracted from pine bark as an exemplar application. Two bio-based emulsifiers were used to prepare wax emulsions suitable for a dry blending process. The coatings on the fibres were characterised, quantified, and visualised using a combination of spectroscopic and microscopic techniques. Confocal fluorescence microscopy was an excellent tool to investigate the spatial distribution of the pine bark waxes on the fibre surfaces. While successful deposition was demonstrated for all tested formulations, coating homogeneity varied for different emulsifiers. Compounding the hemp fibres with a bio-based polyester resulted in the substantial improvement of the mechanical behaviour. However, the presence of a wax coating on the fibres did not lead to a significant change in mechanical properties compared to the controls with uncoated fibres. Optimising the composite chemistry or adjusting the processing conditions might improve the compatibility of the hemp fibres with the matrix material, resulting in enhanced mechanical performance. Full article

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22 pages, 7258 KiB

Open AccessArticle

Self-Healing and Mechanical Behaviour of Fibre-Reinforced Ultra-High-Performance Concrete Incorporating Superabsorbent Polymer Under Repeated and Sustained Loadings

by Mohammad Alameri, M.S. Mohamed Ali, Mohamed Elchalakani, Abdul Sheikh and Rong Fan

Fibers 2024, 12(11), 95; https://doi.org/10.3390/fib12110095 - 5 Nov 2024

Abstract

This study investigated the mechanical responses and self-healing capability of incorporating superabsorbent polymer (SAP) particles in Fibre-Reinforced Ultra-High-Performance Concrete (UHPC) mixes under repetitive flexural and sustained tensile loadings. UHPC with SAP addition of 0.3% and 0.4% of the binder ratio were studied along [...] Read more.

This study investigated the mechanical responses and self-healing capability of incorporating superabsorbent polymer (SAP) particles in Fibre-Reinforced Ultra-High-Performance Concrete (UHPC) mixes under repetitive flexural and sustained tensile loadings. UHPC with SAP addition of 0.3% and 0.4% of the binder ratio were studied along with a control UHPC mix. The methodology included investigating the mechanical properties of these mixes under ambient, water, and 100% of relative humidity (RH) curing conditions. In addition, the mechanical performance of ambient-, water-, and 100% RH-cured prismatic specimens (100 mm × 100 mm × 500 mm) under repeated load was studied under the same curing conditions. Prismatic specimens (75 mm × 75 mm × 500 mm) were kept under cure conditions of wet and dry cycles with applied tensile load for 28 days for the sustained tensile load. The results showed that incorporating SAP into UHPC enhances the elastic modulus, flexural strength, and tensile strength. Also, mixes with SAP have exhibited compressive strength above 120 MPa after 90 days. Furthermore, the load recovery of the prisms under repetitive flexural load and prisms under sustained tensile loading demonstrated the self-healing efficiency of SAP incorporated into the UHPC mixes higher than the control mix specimens. Full article

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15 pages, 3412 KiB

Open AccessArticle

Experimental and Statistical Investigations for Tensile Properties of Hemp Fibers

by Peyman Sadeghi, Quang Cao, Ragab Abouzeid, Mohammad Shayan, Meensung Koo and Qinglin Wu

Fibers 2024, 12(11), 94; https://doi.org/10.3390/fib12110094 - 1 Nov 2024

Abstract

This study investigated the tensile behaviors of hemp fiber bundles and examined how properties including tensile strength and Young’s modulus vary with the bundle diameter. Hemp fibers were extracted, degummed, and separated into bundles of different diameters ranging from less than 50 μm [...] Read more.

This study investigated the tensile behaviors of hemp fiber bundles and examined how properties including tensile strength and Young’s modulus vary with the bundle diameter. Hemp fibers were extracted, degummed, and separated into bundles of different diameters ranging from less than 50 μm to over 150 μm. Tensile tests were conducted on these fiber bundles using a rheometer-based tensile testing machine. The results showed that hemp fibers exhibited a tensile strength of 97.33 MPa and a Young’s modulus of 3.77 GPa at a 50% survival probability. However, the scale parameters for breaking stress and Young’s modulus were determined to be 620.57 MPa and 29.88 GPa, respectively. As the fiber bundle diameter increased, the tensile strength decreased significantly. This was attributed to the higher probability of defects and irregularities acting as weakness points in larger fiber bundles. In contrast, Young’s modulus (stiffness) increased with increasing bundle diameter, likely due to improved fiber–fiber interactions. To further understand the variability and reliability of the tensile properties, statistical models were developed. The Weibull distribution analysis was applied, revealing critical insights into the variability of diameter, stress at break, Young’s modulus, and strain at break. The Weibull parameters provided a comprehensive understanding of the fibers’ mechanical reliability. Additionally, the Griffith model was employed to predict the strength and Young’s modulus based on fiber diameters, supporting the observation that thinner fibers generally exhibited higher tensile strength due to fewer defects. Overall, this work highlights the importance of understanding structure–property relationships in natural fibers like hemp for optimizing their performance in composites. Full article

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15 pages, 3387 KiB

Open AccessReview

A Brief Review of Hemp Fiber Length Measurement Techniques

by Joia Green, Xiaorui Liu and Rong Yin

Fibers 2024, 12(11), 93; https://doi.org/10.3390/fib12110093 - 31 Oct 2024

Abstract

Accurate fiber length measurement is essential for the processing and quality management of textile products. This article reviews the current methods used to measure fiber length, including manual, photoelectric, capacitive, and optical techniques. Existing sample preparation processes for natural fiber characterization have been [...] Read more.

Accurate fiber length measurement is essential for the processing and quality management of textile products. This article reviews the current methods used to measure fiber length, including manual, photoelectric, capacitive, and optical techniques. Existing sample preparation processes for natural fiber characterization have been primarily developed for cotton and wool fibers. However, hemp fibers present unique challenges due to their greater length variability, high strength, and low elongation, making some traditional sample preparation methods less effective. Image processing offers a promising approach for scalable and precise measurement of hemp fiber length. Nevertheless, current image processing techniques are limited by the inability to effectively handle overlapping fibers, which increases both the time and cost of testing. Continued research into developing more advanced segmentation algorithms could lead to more widely adopted commercial methods for fiber measurement. Full article

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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

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

(This article belongs to the Collection Feature Papers in Fibers)

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16 pages, 5248 KiB

Open AccessArticle

The Influence of Dew Retting on the Mechanical Properties of Single Flax Fibers Measured Using Micromechanical and Nanomechanical Approaches

by Ali Reda, Thomas Dargent, Louis Thomas, Sebastien Grec, Lionel Buchaillot and Steve Arscott

Fibers 2024, 12(10), 91; https://doi.org/10.3390/fib12100091 - 18 Oct 2024

Abstract

The mechanical properties of single flax fibers are characterized here as a function of dew retting. The fibers are measured using micromechanical and nanomechanical techniques over a large retting period (91 days). Damage-free single flax fibers in various stages of dew retting were [...] Read more.

The mechanical properties of single flax fibers are characterized here as a function of dew retting. The fibers are measured using micromechanical and nanomechanical techniques over a large retting period (91 days). Damage-free single flax fibers in various stages of dew retting were manually extracted from retted flax plant stems. The flexural modulus and strength of the flax fibers were determined using micromechanical methods. The effective modulus of the outer surface of the single fibers was measured using AFM-based nanoindentation. The micromechanical methods revealed that the flexural modulus and strength of the manually extracted single fibers does not vary significantly as the retting progresses. The micromechanical methods revealed two distinct values of flexural strength in the fibers attributed to different failure modes. The values of these strengths do not vary significantly with retting or over-retting. The nanomechanical methods revealed that the effective modulus of the outer surface of the single fibers does evolve with retting. The physical/chemical origin of these observations remains to be established and could be the objective of future work. Full article

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