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Fibers, Volume 11, Issue 8 (August 2023) – 6 articles

Cover Story (view full-size image): The identification and quantitative determination of wool and fine animal fibers (cashmere, mohair, alpaca, etc.) are of great interest for the labeling of textile garments for the purpose of fraud control, given the large price difference between the fibers; however, they are also important in forensic and archaeological textiles. In this review, starting from the widely used classical methods of optical and electron microscopy, modern methods of image analysis and near-infrared spectroscopy combined with chemometric analysis and proteomic methods have been critically evaluated. The advantages and disadvantages of each method have been analyzed and particular fields of application and future research directions have been identified as well as discussed. View this paper

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16 pages, 7903 KiB

Open AccessArticle

Fabrication of Ultra-High-Performance PVDF-HFP Air Filters by Electrospinning

by Iman Azarian Borojeni, Greg Gajewski, Arash Jenab, Mehdi Sanjari, Charles Boudreault and Reza A. Riahi

Fibers 2023, 11(8), 71; https://doi.org/10.3390/fib11080071 - 21 Aug 2023

Cited by 1 | Viewed by 1144

Abstract

This research aims to fabricate hydrophobic electrospun air filters with ultra-high performance against virions. In order to achieve this goal, constant basis weight electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with low-bead, high-bead, and ultra-high-bead fibre structures were used to fabricate single and multilayer filters by controlling the Dimethylformamide (DMF)-to-acetone ratio of the solvent. The water contact angle of the fabricated layers ranged from 131° for low-bead structures to 135° for ultra-high-bead structures, indicating their overall high hydrophobicity. The size-resolved filtering efficiency and pressure drop tests on the fabricated filters showed that low-bead structure for both single and multilayer filters and high-bead structure for single-layer filters enhance the quality factor remarkably. The results showed that the single-layer ultra-high-bead structure air filters had a filtering efficiency of 99.33%, superior to N95 air filters (96.54%) and comparable to double N95 filters (99.86%). However, the electrospun air filter showed a pressure drop of 169.3 Pa and a quality factor of

27.6 \times 10^{- 3} {P a}^{- 1}

compared to a pressure drop of 388 Pa and quality factor of

16.9 \times 10^{- 3} {P a}^{- 1}

for double N95 air filters. Therefore, it has a high potential to be used as the filtration media in hospitals, long-term care centers, and masks to provide superior protection against virions for healthcare providers and patients. Full article

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17 pages, 5131 KiB

Open AccessArticle

Accelerated Zero-Stress Hydrothermal Aging of Dry E-Glass Fibers and Service Life Prediction Using Arrhenius Model

by John Sunny, Hadi Nazaripoor, Jorge Palacios Moreno and Pierre Mertiny

Fibers 2023, 11(8), 70; https://doi.org/10.3390/fib11080070 - 15 Aug 2023

Viewed by 1181

Abstract

Comprehending the degradation of glass fibers is crucial for service applications involving dry and wet conditions, especially when prolonged contact with water above room temperature is present. Depending on the polymer material, both thermosetting and thermoplastic matrices can permit the ingress of moisture. Therefore, fiber reinforcements embedded in the polymer matrix may experience moisture exposure. Additionally, some structural applications use fiber devoid of any matrix (dry fibers), in which water exposure must be avoided. In all of these cases, moisture may, therefore, have a significant impact on the reinforcing elements and the rate of degradation. The present work focuses on the effects of hydrothermal aging on the mechanical durability of long E-glass fibers by immersion in water at 60 °C, 71 °C, and 82 °C. A service life forecast model was created utilizing the Arrhenius technique, and a master curve of strength variation with exposure time was created for E-glass fibers at 60 °C. Using this modeling approach, it is possible to approximate the amount of time it will take to attain a given degradation level over a specified range of temperatures. Scanning electron microscopy was used to evaluate morphological changes in fiber surfaces due to hydrothermal exposure, while Fourier transform infrared spectroscopy and mass dissolution studies were used to elucidate the mechanism of the strength loss. Full article

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15 pages, 7221 KiB

Open AccessArticle

Antimicrobial Properties of AgNP/TEMPO-Oxidized Cellulose Nanofiber/Chitosan Composite Fibers

by Duangkamol Dechojarassri, Kazuki Komatsu, Atsuhito Sawara, Hiroshi Tamura and Tetsuya Furuike

Fibers 2023, 11(8), 69; https://doi.org/10.3390/fib11080069 - 14 Aug 2023

Cited by 2 | Viewed by 1102

Abstract

This study successfully synthesized functionalized silver nanoparticle/TEMPO-oxidized cellulose nanofiber/chitosan (AgNP/TOCN/CS) composite fibers. First, the TOCN/CS composite fibers were prepared through the wet-spinning technique, yielding Ag/TOCN/CS composite fibers after immersion in a 5 mM AgNO₃ aqueous solution for 3 h, followed by washing with 100 mL of deionized water five times. Second, upon heat treatment without adding other reducing agents, TOCN reduced the Ag+ in the Ag/TOCN/CS composite fibers to AgNP/TOCN/CS composite fibers on the surface of the CS fibers. The fiber color changed from white to yellow-orange when the temperature changed from 100 to 170 °C. In addition, the results suggest that the heat treatment at 130 °C for 20 min was the optimal heat treatment condition. Meanwhile, soaking the fibers in 50 mM ascorbic acid for 1 min is the best condition for ascorbic acid reduction. The antibacterial test results showed that the AgNP/TOCN/CS composite fibers formed via ascorbic acid reduction exhibited better antibacterial activity against both Escherichia coli and Bacillus subtilis than those produced via heat treatment. In summary, AgNPs formed on the fiber surface of AgNP/TOCN/CS composite fibers and showed antibacterial activity, confirming the successful addition of antibacterial properties to TOCN/CS composite fibers. Full article

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17 pages, 3780 KiB

Open AccessArticle

Sensitivity of Offline and Inline Indicators for Fiber Stretching in Continuous Polyacrylonitrile Stabilization

by Mohsen Sadeghi Bogar, Jan Wolf, Daniel Sebastian Jens Wolz, Robert Seidel-Greiff, Evgenia Dmitrieva, Noel Israel, Marco Rosenkranz, Thomas Behnisch, Michael Thomas Müller and Maik Gude

Fibers 2023, 11(8), 68; https://doi.org/10.3390/fib11080068 - 04 Aug 2023

Viewed by 1038

Abstract

In carbon fiber (CF) production, the stabilization process step is the most energy- and time-consuming step in comparison with carbonization and graphitization. To develop optimization routes for energy and productivity, the stabilization needs to be monitored continuously via inline analysis methods. To prognose the evolution of high-performance CF, the density of stabilized fibers has been identified as a robust pre-indicator. As the offline analysis of density is not feasible for inline analysis, a density-soft sensor based on the stabilization indices of Fourier Transform Infrared spectrum (FTIR)-analysis and Electron Paramagnetic Resonance (EPR) Spectroscopy could potentially be used for inline monitoring. In this study, a Polyacrylonitrile-based precursor fiber (PF) stabilized in a continuous thermomechanical stabilization line with varying stretching profiles was incrementally analyzed using density, FTIR-based relative cyclization index (RCI), and EPR-based free radical concentration (FRC). Our findings show RCI and EPR dependencies for density, correlated for RCI with sensitivity by stretching to cubic model parameters, while FRC exhibits linear relationships. Therefore, this study identifies two possible soft sensors for inline density measurement, enabling autonomous energy optimization within industry 4.0-based process systems. Full article

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24 pages, 9868 KiB

Open AccessReview

Analytical Methods for the Identification and Quantitative Determination of Wool and Fine Animal Fibers: A Review

by Marina Zoccola, Parag Bhavsar, Anastasia Anceschi and Alessia Patrucco

Fibers 2023, 11(8), 67; https://doi.org/10.3390/fib11080067 - 02 Aug 2023

Cited by 1 | Viewed by 2408

Abstract

The identification and quantitative determination of wool and fine animal fibers are of great interest in the textile field because of the significant price differences between them and common impurities in raw and processed textiles. Since animal fibers have remarkable similarities in their chemical and physical characteristics, specific identification methods have been studied and proposed following advances in analytical technologies. The identification methods of wool and fine animal fibers are reviewed in this paper, and the results of relevant studies are listed and summarized, starting from classical microscopy methods, which are still used today not only in small to medium enterprises but also in large industries, research studies and quality control laboratories. Particular attention has been paid to image analysis, Nir spectroscopy and proteomics, which constitute the most promising technologies of quality control in the manufacturing and trading of luxury textiles and can find application in forensic science and archeology. Full article

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12 pages, 5696 KiB

Open AccessArticle

Highly Efficient CeO₂–CuCrO₂ Composite Nanofibers Used for Electrochemical Detection of Dopamine in Biomedical Applications

by Heng-Jyun Lei, Homg-Ming Su, Dhanapal Vasu, Yu-Feng You, Te-Wei Chiu and Naratip Vittayakorn

Fibers 2023, 11(8), 66; https://doi.org/10.3390/fib11080066 - 25 Jul 2023

Viewed by 1315

Abstract

Dopamine (DA) plays a crucial role in the functioning of the human central nervous system, participating in both physiological and psychological processes. It is an important research topic in biomedical science. However, we need to constantly monitor the concentration of dopamine in the body, and the sensors required for this usually require good sensitivity in order to achieve fast and accurate measurements. In this research project, a CeO₂ and CuCrO₂ composite nanofiber was prepared for the electrochemical detection of dopamine. Coaxial electrospinning techniques were used to prepare CeO₂–CuCrO₂ composite nanofibers. The characterization techniques of X-ray diffractometer (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) were used to analyze the composite’s crystal structure, vibrational bonds, and elemental composition, while SEM and TEM were used to analyze the composite’s surface structure, morphology, and microstructure. The prepared nanofiber outer layer was found to have an average thickness of 70.96 nm, average fiber diameter of 192.49 nm, and an average grain size of about ~12.5 nm. The BET analysis was applied to obtain the specific surface area (25.03 m²/gm). The proposed nanofiber-decorated disposable screen-printed carbon electrode acted as a better electrochemical sensor for the detection of dopamine. Moreover, the electrocatalyst had a better limit of detection, 36 nM with a linear range of 10 to 100 μM, and its sensitivity was 6.731 μA μM⁻¹ cm⁻². In addition, the proposed electrocatalyst was successfully applied to real-time potential applications, namely, to the analysis of human urine samples in order to obtain better recovery results. Full article

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

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