Fibers

18 pages, 6425 KiB

Open AccessArticle

Low-Carbon Concrete Reinforced with Waste Steel Rivet Fibers Utilizing Steel Slag Powder, and Processed Recycled Concrete Aggregate—Engineering Insights

by Dilan Dh. Awla, Bengin M. A. Herki and Aryan Far H. Sherwani

Fibers 2025, 13(8), 109; https://doi.org/10.3390/fib13080109 - 14 Aug 2025

Abstract

The construction industry is a major source of environmental degradation as it is responsible for a significant share of global CO₂ emissions, especially from cement and aggregate consumption. This study fills the need for sustainable construction materials by developing and evaluating a [...] Read more.

The construction industry is a major source of environmental degradation as it is responsible for a significant share of global CO₂ emissions, especially from cement and aggregate consumption. This study fills the need for sustainable construction materials by developing and evaluating a low-carbon fiber-reinforced concrete (FRC) made of steel slag powder (SSP), processed recycled concrete aggregates (PRCAs), and waste steel rivet fibers (WSRFs) derived from industrial waste. The research seeks to reduce dependency on virgin materials while maintaining high values of mechanical performance and durability in structural applications. Sixteen concrete mixes were used in the experimental investigations with control, SSP, SSP+RCA, and RCA, reinforced with various fiber dosages (0%, 0.2%, 0.8%, 1.4%) by concrete volume. Workability, density, compressive strength, tensile strength, and water absorption were measured according to the appropriate standards. Compressive and tensile strength increased in all mixes and the 1.4% WSRF mix had the best performance. However, it was found that a fiber content of 0.8% was optimal, which balanced the improvement in strength, durability, and workability by sustainable reuse of recycled materials and demolition waste. It was found by failure mode analysis that the transition was from brittle to ductile behavior as the fiber content increased. The relationship between compressive, tensile strength, and fiber content was visualized as a 3D response surface in order to support these mechanical trends. It is concluded in this study that 15% SSP, 40% PRCA, and 0.8% WSRF are feasible, specific solutions to improve concrete performance and advance the circular economy. Full article

9 pages, 1953 KiB

Open AccessArticle

Mode-Locked Fiber Lasers with Prism-Based Spectral Filters

by Mintae Kang, Taemin Son and Andy Chong

Fibers 2025, 13(8), 108; https://doi.org/10.3390/fib13080108 - 13 Aug 2025

Abstract

A spectral filter utilizing dispersive prisms and an optical fiber collimator is presented as an attractive alternative to diffraction grating-based spectral filters. A simplified analytical expression for this prism-based spectral filter is derived. A spectral filter constructed using SF11 flint glass prisms demonstrates [...] Read more.

A spectral filter utilizing dispersive prisms and an optical fiber collimator is presented as an attractive alternative to diffraction grating-based spectral filters. A simplified analytical expression for this prism-based spectral filter is derived. A spectral filter constructed using SF11 flint glass prisms demonstrates Gaussian spectral filter profiles with bandwidths of 8 nm and 4 nm, closely matching with theoretical predictions. Using these filters, we demonstrate two types of mode-locking regimes: a dissipative soliton (DS) pulse and a self-similar (SS) pulse. The dissipative soliton pulses deliver 3.3 nJ with dechirped pulse durations of 206 fs, while the self-similar pulses deliver 2.1 nJ with durations of 120 fs. The results demonstrate that the prism-based filters are well-suited for ultrafast mode-locked fiber lasers. Full article

► Show Figures

Figure 1

15 pages, 2101 KiB

Open AccessArticle

Hybrid Laminates Reinforced with Natural and Synthetic Fibers: Experimental Characterization and Preliminary Finite Element Assessment for Prosthetic Applications

by Angel D. Castro-Franco, Miriam Siqueiros-Hernández, Virginia García-Angel, Ismael Mendoza-Muñoz, Benjamín González-Vizcarra, Hernán D. Magaña-Almaguer and Lidia E. Vargas-Osuna

Fibers 2025, 13(8), 107; https://doi.org/10.3390/fib13080107 - 11 Aug 2025

Abstract

Four configuration laminates made of flax, glass, and basalt were fabricated via vacuum-assisted hand lay-up with added weight and tested under ASTM D3039 and D790. The flax–glass–flax lay-up exhibited the highest tensile strength and flexural strength. Orthotropic elastic properties were determined from remanufactured [...] Read more.

Four configuration laminates made of flax, glass, and basalt were fabricated via vacuum-assisted hand lay-up with added weight and tested under ASTM D3039 and D790. The flax–glass–flax lay-up exhibited the highest tensile strength and flexural strength. Orthotropic elastic properties were determined from remanufactured 90°-rotated specimens. A hexahedral-meshed finite element model using these inputs under a 5256 N load predicted the stress and strain within 1% and 5% of the experimental values. These findings demonstrate that flax–glass hybrids offer mechanical reliability, sustainability, and affordability for next-generation prosthetic applications. Full article

► Show Figures

Figure 1

17 pages, 2855 KiB

Open AccessArticle

Ballistic Performance of Lightweight Armor Aramid Fabric with Different Bounding Technologies

by István Péter Kondor, János Líska and Zsolt Ferenc Kovács

Fibers 2025, 13(8), 106; https://doi.org/10.3390/fib13080106 - 5 Aug 2025

Abstract

The aim of this research was to develop a lightweight armor that could be used in bulletproof vests or vehicle protection, offering an alternative to the disadvantageous properties of high-strength steel plates. Specifically, the study focused on investigating the properties of different binders [...] Read more.

The aim of this research was to develop a lightweight armor that could be used in bulletproof vests or vehicle protection, offering an alternative to the disadvantageous properties of high-strength steel plates. Specifically, the study focused on investigating the properties of different binders to identify the most suitable one for further development. The bulletproof characteristics of Kevlar (aramid) fiber fabric (200 g/m², plain weave, CT709) were examined using both the Ansys simulation environment and ballistic laboratory testing. In the experiments, three different layer configurations were tested on 300 × 300 mm specimens, each consisting of 20 layers of Kevlar. The layers were arranged as follows: dry lamination for the first specimen, epoxy binder for the second, and polyurethane binder for the third. Laboratory tests were conducted using 9 mm Parabellum bullets, in accordance with the parameters defined in the MSZ K 1114-1:1999 standard. Both the ballistic and simulation tests indicated that the Kevlar laminated with polyurethane resin demonstrated the most promising performance and is suitable for further development. Full article

► Show Figures

Figure 1

9 pages, 1938 KiB

Open AccessBrief Report

Single-Component Silicon-Containing Polyurethane for High-Performance Waterproof and Breathable Nanofiber Membranes

by Dongxu Lu, Yanbing Li, Yake Chai, Ximei Wen, Liming Chen and Sanming Sun

Fibers 2025, 13(8), 105; https://doi.org/10.3390/fib13080105 - 5 Aug 2025

Abstract

High-performance waterproof and breathable nanofiber membranes (WBNMs) are in great demand for various advanced applications. However, the fabrication of such membranes often relies on fluorinated materials or involves complex preparation processes, limiting their practical use. In this study, we present an innovative approach [...] Read more.

High-performance waterproof and breathable nanofiber membranes (WBNMs) are in great demand for various advanced applications. However, the fabrication of such membranes often relies on fluorinated materials or involves complex preparation processes, limiting their practical use. In this study, we present an innovative approach by utilizing silicon-containing polyurethane (SiPU) as a single-component, fluorine-free raw material to prepare high-performance WBNMs via a simple one-step electrospinning process. The electrospinning technique enables the formation of SiPU nanofibrous membranes with a small maximum pore size (d_max) and high porosity, while the intrinsic hydrophobicity of SiPU imparts excellent water-repellent characteristics to the membranes. As a result, the single-component SiPU WBNM exhibits superior waterproofness and breathability, with a hydrostatic pressure of 52 kPa and a water vapor transmission rate (WVTR) of 5798 g m⁻² d⁻¹. Moreover, the optimized SiPU-14 WBNM demonstrates outstanding mechanical properties, including a tensile strength of 6.15 MPa and an elongation at break of 98.80%. These findings indicate that the single-component SiPU-14 WBNMs not only achieve excellent waterproof and breathable performance but also possess robust mechanical strength, thereby enhancing the comfort and expanding the potential applications of protective textiles, such as outdoor apparel and car seats. Full article

► Show Figures

Graphical abstract

24 pages, 4254 KiB

Open AccessArticle

Strength and Micro-Mechanism of Guar Gum–Palm Fiber Composite for Improvement of Expansive Soil

by Junhua Chen, Yuejian Huang, Aijun Chen, Xinping Ji, Xiao Liao, Shouqian Li and Ying Xiao

Fibers 2025, 13(8), 104; https://doi.org/10.3390/fib13080104 - 31 Jul 2025

Abstract

This study investigates the improvement effect and micro-mechanism of guar gum and palm fibers, two eco-friendly materials, on expansive soil. The study uses disintegration tests, unconfined compressive strength tests, triaxial compression tests, and SEM analysis to evaluate the enhancement of mechanical properties. The [...] Read more.

This study investigates the improvement effect and micro-mechanism of guar gum and palm fibers, two eco-friendly materials, on expansive soil. The study uses disintegration tests, unconfined compressive strength tests, triaxial compression tests, and SEM analysis to evaluate the enhancement of mechanical properties. The results show that the guar gum–palm fiber composite significantly improves the compressive and shear strength of expansive soil. The optimal ratio is 2% guar gum, 0.4% palm fiber, and 6 mm palm fiber length. Increasing fiber length initially boosts and then reduces unconfined compressive strength. Guar gum increases unconfined compressive strength by 187.18%, further improved by 20.9% with palm fibers. When fiber length is fixed, increasing palm fiber content increases and then stabilizes peak stress and shear strength (cohesion and internal friction angle), improving by 27.30%, 52.1%, and 12.4%, respectively, compared to soil improved with only guar gum. Micro-analysis reveals that guar gum enhances bonding between soil particles via a gel matrix, improving water stability and mechanical properties, while palm fibers reinforce the soil and inhibit crack propagation. The synergistic effect significantly enhances composite-improved soil performance, offering economic and environmental benefits, and provides insights for expansive soil engineering management. Full article

► Show Figures

Figure 1

21 pages, 6717 KiB

Open AccessArticle

Structure Design by Knitting: Combined Wicking and Drying Behaviour in Single Jersey Fabrics Made from Polyester Yarns

by Leon Pauly, Lukas Maier, Sibylle Schmied, Ulrich Nieken and Götz T. Gresser

Fibers 2025, 13(8), 103; https://doi.org/10.3390/fib13080103 - 31 Jul 2025

Abstract

The kinetics of liquid transport in textiles are determined by the thermodynamic boundary conditions and the substrate’s structure. The knitting process offers a wide range of possibilities for modifying the fabric structure, making it ideal for high-performance garments and technical applications. Given the [...] Read more.

The kinetics of liquid transport in textiles are determined by the thermodynamic boundary conditions and the substrate’s structure. The knitting process offers a wide range of possibilities for modifying the fabric structure, making it ideal for high-performance garments and technical applications. Given the highly complex nature of textiles’ interaction with liquids, this paper investigates how fabric structure affects combined wicking and drying behaviour. This facilitates comprehension of the underlying transport processes on the yarn and fabric scale, which is important for understanding the behaviour of the material as a whole. The presented experiment combines analysis of wicking through radial liquid spread using imaging techniques and analysis of the drying process through gravimetric measurement of evaporation. Eight samples of single jersey knitted fabrics were produced using polyester yarns of different texturization and fibre diameters on flat and circular knitting machines. The fabrics demonstrate significantly different wicking behaviours depending on their structure. The fabric’s drying time and rate are directly linked to the macroscopic spread of the liquid. Large inter-yarn pores hinder liquid spread. For the lowest liquid saturations, the yarn structure plays a critical role. Using fine, dense yarns can hinder convective drying within the yarn. Textured yarns tend to exhibit higher specific drying rates. The results offer a comprehensive insight into the interplay between the fabric’s structure and its wicking and drying behaviour, which is crucial for the development of functional fabrics in the knitting process. Full article

► Show Figures

Figure 1

12 pages, 2084 KiB

Open AccessArticle

Recycling of PAN Waste into Nonwoven Materials Using Electrospinning Method

by Yaroslav V. Golubev, Igor S. Makarov, Denis N. Karimov, Natalia A. Arkharova, Radmir V. Gainutdinov, Sergey A. Legkov and Sergey V. Kotomin

Fibers 2025, 13(8), 102; https://doi.org/10.3390/fib13080102 - 30 Jul 2025

Abstract

For the first time, electrospinning has been used to recycle polyacrylonitrile terpolymer (PAN) waste following the solid-phase N-methylmorpholine-N-oxide (NMMO) process from PAN solutions in DMSO into nonwoven materials. The morphology of the obtained material has been studied. The material derived from secondary raw [...] Read more.

For the first time, electrospinning has been used to recycle polyacrylonitrile terpolymer (PAN) waste following the solid-phase N-methylmorpholine-N-oxide (NMMO) process from PAN solutions in DMSO into nonwoven materials. The morphology of the obtained material has been studied. The material derived from secondary raw materials was compared to the material from the original PAN using IR spectroscopy, X-ray diffraction, scanning electron microscopy, and atomic force microscopy. It has been demonstrated that the chemical changes of PAN that occur during NMMO processing do not interfere with nonwoven material manufacture. Spun PAN nonwovens with different histories have similar morphology. It has been shown that the elastic modulus of ultrafine fibers depends on the history of PAN. Single monofilaments produced from initial PAN have a threefold greater elastic modulus than fibers spun from NMMO-recycled polymer. The revealed structure and properties of PAN fibers allow them to be considered as filter materials, as well as precursors of carbon nonwoven fabrics. Full article

► Show Figures

Graphical abstract

41 pages, 1835 KiB

Open AccessReview

A Comprehensive Review of Vertical Forest Buildings: Integrating Structural, Energy, Forestry, and Occupant Comfort Aspects in Renovation Modeling

by Vachan Vanian, Theodora Fanaradelli and Theodoros Rousakis

Fibers 2025, 13(8), 101; https://doi.org/10.3390/fib13080101 - 25 Jul 2025

Abstract

This current review examines modeling approaches for renovating reinforced concrete (RC) buildings for vertical forest (VF) application, taking into account structural retrofitting, energy systems, forestry integration, and occupant comfort. The study assesses research conducted with an advanced 3D finite element analysis and the [...] Read more.

This current review examines modeling approaches for renovating reinforced concrete (RC) buildings for vertical forest (VF) application, taking into account structural retrofitting, energy systems, forestry integration, and occupant comfort. The study assesses research conducted with an advanced 3D finite element analysis and the use of retrofitting modeling techniques, including textile-reinforced mortar (TRM), fiber-reinforced polymer (FRP), seismic joints, and green concrete applications. The energy system modeling methods are reviewed, taking into account the complexity of incorporating vegetation and seasonal variations. During forestry integration, three main design parameters are identified, namely, root systems, trunks, and crowns, for their critical role in the structural stability and optimal environmental performance. The comfort models are identified evolving from static to adaptive models incorporating thermal, acoustic, visual and air quality parameters. The current review consists of more than one hundred studies indicating that the integration of natural systems to buildings requires a multidimensional and multidisciplinary approach with sophisticated systems. The findings of this review provide the basis for implementing VF models to RC buildings, while highlighting areas requiring further research and validation. Full article

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

► Show Figures

Figure 1

72 pages, 6900 KiB

Open AccessReview

Multifunctional Fibers for Wound Dressings: A Review

by Ghazaleh Chizari Fard, Mazeyar Parvinzadeh Gashti, Ram K. Gupta, Seyed Ahmad Dehdast, Mohammad Shabani and Alessandro Francisco Martins

Fibers 2025, 13(8), 100; https://doi.org/10.3390/fib13080100 - 24 Jul 2025

Abstract

Wound dressings prevent complications such as infections and potentially severe outcomes, including death, if wounds are left untreated. Wound dressings have evolved from rudimentary coverings made from natural materials to sophisticated, functionalized dressings designed to enhance wound healing and support tissue repair more [...] Read more.

Wound dressings prevent complications such as infections and potentially severe outcomes, including death, if wounds are left untreated. Wound dressings have evolved from rudimentary coverings made from natural materials to sophisticated, functionalized dressings designed to enhance wound healing and support tissue repair more effectively. These materials are often referred to as scaffolds in the literature, with wound dressing scaffolds intended to interact with native skin tissue and support tissue regeneration, whereas conventional wound dressings are designed primarily to protect the wound without directly interacting with the underlying tissue. However, there is a functional overlap between these categories, and the boundary is often blurred due to the increasing multifunctionality of modern wound dressings. This review will focus on developing wound dressings (scaffolds or not) based on fibers, their properties, and applications. Advances in nanomedicine have highlighted significant improvements in wound care by applying electrospun nanofibers that mimic the natural extracellular matrix. Therefore, this review explores recent advances in wound healing physiology, highlights nanofiber-based wound dressing materials developed through electrospinning, and distinguishes conventional dressings from multifunctional wound dressing scaffolds. Full article

(This article belongs to the Special Issue Electrospinning Nanofibers)

► Show Figures

Figure 1

19 pages, 3913 KiB

Open AccessArticle

Temperature-Dependent Elastic and Damping Properties of Basalt- and Glass-Fabric-Reinforced Composites: A Comparative Study

by Hubert Rahier, Jun Gu, Guillermo Meza Hernandez, Gulsen Nazerian and Hugo Sol

Fibers 2025, 13(8), 99; https://doi.org/10.3390/fib13080099 - 24 Jul 2025

Abstract

Fiber-reinforced composite materials exhibit orthotropic behavior, characterized by complex orthotropic engineering constants such as Young’s modulus, Poisson’s ratio, and shear modulus. It is widely recognized that basalt fibers possess superior resistance to elevated temperatures compared to glass fibers. However, the behavior of these [...] Read more.

Fiber-reinforced composite materials exhibit orthotropic behavior, characterized by complex orthotropic engineering constants such as Young’s modulus, Poisson’s ratio, and shear modulus. It is widely recognized that basalt fibers possess superior resistance to elevated temperatures compared to glass fibers. However, the behavior of these fibers within composites at typical operational temperatures for automotive and consumer goods applications has not been thoroughly investigated. A novel measurement setup based on the non-destructive impulse excitation method has been developed for the automated identification of complex orthotropic engineering constants as a function of temperature. This study provides a comparative analysis of the identified engineering constants of bidirectionally fabric-reinforced glass and basalt composites with an epoxy matrix, across a temperature range from −20 °C to 60 °C. The results reveal only minimal differences in stiffness and damping behavior between the examined glass and basalt samples. Full article

► Show Figures

Figure 1

20 pages, 3201 KiB

Open AccessArticle

Effect of Screw Configuration on the Recyclability of Natural Fiber-Based Composites

by Vlasta Chyzna, Steven Rowe, James Finnerty, Trevor Howard, Christopher Doran, Shane Connolly, Noel Gately, Alexandre Portela, Alan Murphy, Declan M. Devine and Declan Mary Colbert

Fibers 2025, 13(7), 98; https://doi.org/10.3390/fib13070098 - 18 Jul 2025

Abstract

The burgeoning crisis of plastic waste accumulation necessitates innovative approaches towards sustainable packaging solutions. Polylactic acid (PLA), a leading biopolymer, emerges as a promising candidate in this realm, especially for environmentally friendly packaging. PLA is renowned for its compostable properties, offering a strategic [...] Read more.

The burgeoning crisis of plastic waste accumulation necessitates innovative approaches towards sustainable packaging solutions. Polylactic acid (PLA), a leading biopolymer, emerges as a promising candidate in this realm, especially for environmentally friendly packaging. PLA is renowned for its compostable properties, offering a strategic avenue to mitigate plastic waste. However, its dependency on specific industrial composting conditions, characterized by elevated temperatures, humidity, and thermophilic microbes, limits its utility for household composting. This study aims to bridge the research gap in PLA’s recyclability and explore its feasibility in mechanical recycling processes. The research focuses on assessing the mechanical characteristics of PLA and PLA-based composites post-recycling. Specifically, we examined the effects of two extrusion methods—conical and parallel—on PLA and its composites containing 20 wt.% basalt fibers (BF). The recycling process encompassed repeated cycles of hot melt extrusion (HME), followed by mechanical grinding to produce granules. These granules were then subjected to injection moulding (IM) after 1, 3 and 5 recycling cycles. The tensile properties of the resulting IM-produced bars provided insights into the material’s durability and stability. The findings reveal that both PLA and PLA/BF composites retain their mechanical integrity through up to 5 cycles of mechanical recycling. This resilience underscores PLA’s potential for integration into existing recycling streams, addressing the dual challenges of environmental sustainability and waste management. The study contributes to the broader understanding of PLA’s lifecycle and opens new possibilities for its application in eco-friendly packaging, beyond the limits of composting. The implications of these findings extend towards enhancing the circularity of biopolymers and reducing the environmental footprint of plastic packaging. Full article

► Show Figures

Figure 1

27 pages, 4282 KiB

Open AccessArticle

Synthesis and Characterization of Keratin-Based Scaffold for Potential Tissue Engineering Applications

by Murugiah Krishani, Jia Ning Chong, Wan Rong Lim, Norwahyu Jusoh, Nonni Soraya Sambudi and Hazwani Suhaimi

Fibers 2025, 13(7), 97; https://doi.org/10.3390/fib13070097 - 17 Jul 2025

Abstract

Keratin, a fibrous structural protein, has been employed as a biomaterial for hemostasis and tissue repair due to its structural stability, mechanical strength, biocompatibility, and biodegradability. While extensive research has focused on developing scaffolds using keratin extracted from various sources, no studies to [...] Read more.

Keratin, a fibrous structural protein, has been employed as a biomaterial for hemostasis and tissue repair due to its structural stability, mechanical strength, biocompatibility, and biodegradability. While extensive research has focused on developing scaffolds using keratin extracted from various sources, no studies to date have explored the use of keratin derived from human nail clippings. In this study, keratin was extracted from human nail clippings using the Shindai method and used to fabricate and compare two types of scaffolds for bone tissue engineering via the freeze-drying method. The first scaffold consisted of keratin combined with gelatin (KG), while the second combined keratin, gelatin, and hydroxyapatite (HAp) (KGH), the latter synthesized from blood cockle clam shells using the wet precipitation method. Physicochemical characterization and surface morphology analysis of keratin and both scaffolds showed promising results. Tensile strength testing revealed a significant difference in Young’s modulus. The KG scaffold exhibited higher porosity, water uptake, and water retention capacity compared to the KGH scaffold. In vitro biocompatibility studies revealed that the KGH scaffold supported higher cell proliferation compared to the KG scaffold. This study demonstrates the potential of using human nail-derived keratin in composite scaffold fabrication and serves as a foundation for future research on this novel biomaterial source. Full article

► Show Figures

Figure 1

19 pages, 2652 KiB

Open AccessArticle

The Effects of Polypropylene Fibres on the Shear Behaviour of a Concrete Crack: An Experimental Study

by Francisco Ortiz-Navas, Juan Navarro-Gregori and Pedro Serna

Fibers 2025, 13(7), 96; https://doi.org/10.3390/fib13070096 - 11 Jul 2025

Abstract

The objective of this study is to investigate the effects of macrosynthetic polypropylene fibres as shear reinforcement in a concrete crack. An experimental study was conducted using twenty push-off specimens with varying volumes of fibres, along with plain concrete specimens as a reference. [...] Read more.

The objective of this study is to investigate the effects of macrosynthetic polypropylene fibres as shear reinforcement in a concrete crack. An experimental study was conducted using twenty push-off specimens with varying volumes of fibres, along with plain concrete specimens as a reference. The testing methodology allowed for the analysis of crack kinematics by measuring the evolution of normal and shear stresses in relation to slip and crack opening. This facilitated the creation of diagrams similar to those presented by Walraven (1980) for crack interface shear transfer, but in this case, applied to concrete reinforced with macrosynthetic polypropylene fibres. The findings demonstrate that macrosynthetic polypropylene fibres significantly enhance shear behaviour, particularly when their volume exceeds 8 kg/m³. This study provides valuable insights into the behaviour of macrosynthetic polypropylene fibres under shear loading conditions and highlights their potential benefits as effective shear reinforcement. Full article

(This article belongs to the Special Issue Fracture Behavior of Fiber-Reinforced Building Materials)

► Show Figures

Figure 1

20 pages, 5375 KiB

Open AccessArticle

Quality of Plywood Bonded with Nanolignin-Enriched Cardanol-Formaldehyde Adhesive

by Maria Rita Ramos Magalhães, Felipe Gomes Batista, Ana Carolina Corrêa Furtini, Mário Vanoli Scatolino, Flávia Maria Silva Brito, Lourival Marin Mendes, Thiago de Paula Protásio and José Benedito Guimarães Junior

Fibers 2025, 13(7), 95; https://doi.org/10.3390/fib13070095 - 10 Jul 2025

Abstract

Cardanol is a derivative of cashew nut shell liquid (CNSL) and has the potential to be used when developing adhesives for wood boards. Adding nanostructures to adhesive can increase its bonding and reduce formaldehyde emission. Therefore, this study aimed to evaluate the different [...] Read more.

Cardanol is a derivative of cashew nut shell liquid (CNSL) and has the potential to be used when developing adhesives for wood boards. Adding nanostructures to adhesive can increase its bonding and reduce formaldehyde emission. Therefore, this study aimed to evaluate the different concentrations of nanolignin (1, 2, and 3%) added to the cardanol-formaldehyde adhesive for gluing plywood, in comparison to the cardanol-formaldehyde adhesive without nanolignin (0%). The plywood’s physical, mechanical, and formaldehyde emission properties were assessed. Plywoods with nanolignin showed shear strength increases of around 160% in the wet condition. With the addition of nanolignin, the modulus of rupture and of elasticity increased by approximately 150% and up to 400% in the parallel direction, respectively. The resistance to combustion also significantly improved. Physical properties did not show statistically significant differences with the percentages of nanolignin. Despite the increase in formaldehyde emission with nanolignin, all treatments met the marketing requirements (≤80 mg of formaldehyde/kg), demonstrating the adhesive potential for indoor use in plywood industries. Natural adhesives using cardanol and nanolignin are an innovative and ecological alternative, combining sustainability and high potential to reduce environmental impacts, which is aligned with at least four sustainable development goals (SDGs). Full article

► Show Figures

Figure 1

14 pages, 7615 KiB

Open AccessArticle

Electrospun Silk Fibroin/Cyclodextrin Nanofibers for Multifunctional Air Filtration

by Papimol Mongyun and Sompit Wanwong

Fibers 2025, 13(7), 94; https://doi.org/10.3390/fib13070094 - 8 Jul 2025

Abstract

Particulate matter (PM) and volatile organic compounds (VOCs) are major air pollutants that can cause significant risks to public health. To mitigate exposure, fibrous filters have been widely utilized for air purification. In this study, we developed electrospun silk fibroin/poly (ethylene oxide)/cyclodextrin (SF/PEO/CD) [...] Read more.

Particulate matter (PM) and volatile organic compounds (VOCs) are major air pollutants that can cause significant risks to public health. To mitigate exposure, fibrous filters have been widely utilized for air purification. In this study, we developed electrospun silk fibroin/poly (ethylene oxide)/cyclodextrin (SF/PEO/CD) nanofibers as multifunctional air filters capable of efficiently reducing PM_2.5 and degrading VOCs. The resulting SF/PEO/10CD demonstrated the best multifunctional filtration performance, achieving PM_2.5 capture efficiencies of 91.3% with a minimal pressure drop of 4 Pa and VOC removal efficiency of 50%. These characteristics highlight the potential of the SF/PEO/10CD nanofiber with effective, multifunctional properties and environmental benefits for sustainable air filtration application. Full article

► Show Figures

Figure 1

14 pages, 3260 KiB

Open AccessArticle

Performance of Hybrid Strengthening System for Reinforced Concrete Member Using CFRP Composites Inside and over Transverse Groove Technique

by Ahmed H. Al-Abdwais and Adil K. Al-Tamimi

Fibers 2025, 13(7), 93; https://doi.org/10.3390/fib13070093 - 8 Jul 2025

Abstract

The use of a carbon-fiber-reinforced polymer (CFRP) for structural strengthening has been widely adopted in recent decades. Early studies focused on externally bonded (EB) techniques, but premature delamination of CFRP from concrete surfaces often limited their efficiency. To address this, alternative methods, such [...] Read more.

The use of a carbon-fiber-reinforced polymer (CFRP) for structural strengthening has been widely adopted in recent decades. Early studies focused on externally bonded (EB) techniques, but premature delamination of CFRP from concrete surfaces often limited their efficiency. To address this, alternative methods, such as Externally Bonded Reinforcement Over Grooves (EBROG) and Externally Bonded Reinforcement Inside Grooves (EBRIG), were developed to enhance the bond strength and delay delamination. While most research has examined longitudinal groove layouts, this study investigates a hybrid system combining a CFRP fabric bonded inside transverse grooves (EBRITG) with externally bonded layers over the grooves (EBROTG). The system leverages the grooves’ surface area to anchor the CFRP and improve the bonding strength. Seven RC beams were tested in two stages: five beams with varied strengthening methods (EBROG, EBRIG, and hybrid) in the first stage and two beams with a hybrid system and concrete cover anchorage in the second stage. Results demonstrated significant flexural capacity improvement—57% and 72.5% increase with two and three CFRP layers, respectively—compared to the EBROG method, confirming the hybrid system’s superior bonding efficiency. Full article

► Show Figures

Figure 1

13 pages, 2665 KiB

Open AccessArticle

Kapok-Derived Super Hollow Porous Carbon Fibers and Their Greenhouse Gases Adsorption

by Hun-Seung Jeong, Cheol-Ki Cho, Dong-Chul Chung, Kay-Hyeok An and Byung-Joo Kim

Fibers 2025, 13(7), 92; https://doi.org/10.3390/fib13070092 - 4 Jul 2025

Abstract

Industrialization and modernization have significantly improved the quality of life but have also led to substantial pollution. Cost-effective technologies are urgently needed to mitigate emissions from major polluting sectors, such as the automotive and transport industries. In this study, we synthesized naturally derived, [...] Read more.

Industrialization and modernization have significantly improved the quality of life but have also led to substantial pollution. Cost-effective technologies are urgently needed to mitigate emissions from major polluting sectors, such as the automotive and transport industries. In this study, we synthesized naturally derived, kapok-based porous carbon fibers (KP-PCFs) with hollow structures. We investigated their adsorption/desorption behavior for the greenhouse gas n-butane following ASTM D5228 standards. Scanning electron microscopy and X-ray diffraction analyses were conducted to examine changes in fiber diameter and crystalline structure under different activation times. The micropore properties of KP-PCFs were characterized using Brunauer–Emmett–Teller, t-plot, and non-localized density functional theory models based on N₂/77K adsorption isotherm data. The specific surface area and total pore volume ranged from 500 to 1100 m²/g and 0.24 to 0.60 cm³/g, respectively, while the micropore and mesopore volumes were 0.20–0.45 cm³/g and 0.04–0.15 cm³/g, respectively. With increasing activation time, the n-butane adsorption capacity improved from 62.2% to 73.5%, whereas retentivity (residual adsorbate) decreased from 6.0% to 1.3%. The adsorption/desorption rate was highly correlated with pore diameter: adsorption capacity was highest for diameters of 1.5–2.5 nm, while retentivity was greatest for diameters of 3.5–5.0 nm. Full article

► Show Figures

Graphical abstract

14 pages, 4803 KiB

Open AccessArticle

Developing JMP and VBA Add-Ins for Finite Mixture Modeling of Cotton Fiber Length Distribution

by Mourad Krifa, Vinusha Garlapati, Vikki B. Martin and Neha Kothari

Fibers 2025, 13(7), 91; https://doi.org/10.3390/fib13070091 - 2 Jul 2025

Abstract

In this study, software add-ins were developed and presented to allow data processing and statistical analysis of the unique shape of cotton fiber length distribution. The approach uses VBA coding in Excel to process the data, as well as the JMP 14-17 application [...] Read more.

In this study, software add-ins were developed and presented to allow data processing and statistical analysis of the unique shape of cotton fiber length distribution. The approach uses VBA coding in Excel to process the data, as well as the JMP 14-17 application and add-in builder tools to fit finite mixture models to empirical fiber length distributions. The resulting model derives a parametric expression for the fiber length probability density function. The analysis add-in was applied and validated on a wide range of empirical length distributions and proved to parameterize the complex distribution patterns with an excellent goodness of fit. Both tools were compiled into installable add-ins that extended the capabilities of MS Excel for the processing of AFIS distribution reports and the statistical toolbox of JMP using the Application Builder JSL coding. Installable add-ins, along with a user manual, are available for download by cotton researchers. Full article

► Show Figures

Figure 1

Journal Description

Fibers

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI