Fibers

9 pages, 2865 KiB

Open AccessCommunication

The Natural Growth of CaCO₃ Crystals on Hemp Yarns: A Morphology Analysis and the Mechanical Effects on Composites

by Quentin Drouhet, Romain Barbière, Fabienne Touchard, Laurence Chocinski-Arnault and David Mellier

Fibers 2023, 11(10), 88; https://doi.org/10.3390/fib11100088 - 20 Oct 2023

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Abstract

Plant fibres are promising candidates to replace synthetic fibres in polymer matrix composites. However, there is still an important issue to overcome: the poor quality of adhesion at the fibre/matrix interface. Many surface treatments of plant fibres have been developed, most of them [...] Read more.

Plant fibres are promising candidates to replace synthetic fibres in polymer matrix composites. However, there is still an important issue to overcome: the poor quality of adhesion at the fibre/matrix interface. Many surface treatments of plant fibres have been developed, most of them based on non-environmentally friendly processes. In this paper, a 100% natural treatment is proposed. Hemp yarns are immersed in tap water until the natural growth of limestone beads attached to their surface occurs. The morphology analysis reveals that these calcium carbonate crystals have a nanoneedle architecture, with hemp fibres acting as nucleators for these highly ordered coral-like structures. Tensile tests on ±45° woven hemp/epoxy composites show that the presence of CaCO₃ beads improves the adhesion quality of the fibre/matrix interface and, therefore, increases Young’s modulus value. Full article

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

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22 pages, 4062 KiB

Open AccessArticle

Conversion of Animal-Derived Protein By-Products into a New Dual-Layer Nanofiber Biomaterial by Electrospinning Process

by Carmen Gaidău, Maria Râpă, Laura Mihaela Stefan, Ecaterina Matei, Andrei Constantin Berbecaru, Cristian Predescu and Liliana Mititelu-Tartau

Fibers 2023, 11(10), 87; https://doi.org/10.3390/fib11100087 - 14 Oct 2023

Cited by 1 | Viewed by 1594

Abstract

The aim of this study was to design a dual-layer wound dressing as a new fibrous biomaterial based on the valorization of animal-derived proteins. The first layer was fabricated by the deposition of poly(ethylene oxide) (PEO) loaded with keratin hydrolysate (KH) via a [...] Read more.

The aim of this study was to design a dual-layer wound dressing as a new fibrous biomaterial based on the valorization of animal-derived proteins. The first layer was fabricated by the deposition of poly(ethylene oxide) (PEO) loaded with keratin hydrolysate (KH) via a mono-electrospinning process onto a poly(lactic acid) (PLA) film, which was used as a support. The second layer consisted of encapsulating a bovine collagen hydrolysate (CH) into poly(vinyl pyrrolidone) (PVP) through a coaxial electrospinning process, which was added onto the previous layer. This assemblage was characterized by electronic microscopy for morphology and the controlled release of KH. In vitro biocompatibility was evaluated on the L929 (NCTC) murine fibroblasts using quantitative MTT assay and qualitative cell morphological examination after Giemsa staining. Additionally, in vivo biocompatibility methods were used to assess the impact of the biomaterial on white Swiss mice, including the evaluation of hematological, biochemical, and immunological profiles, as well as its impact on oxidative stress. The results revealed a nanofibrous structure for each layer, and the assembled product demonstrated antioxidant activity, controlled release of KH, a high degree of in vitro biocompatibility, negligible hematological and biochemical changes, and minimal impact of certain specific oxidative stress parameters compared to the use of patches with textile support. Full article

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

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22 pages, 14936 KiB

Open AccessArticle

Optimization of the Alkali-Silane Treatment of Agave lechuguilla Fibers (Ixtle) for Potential Reinforcement in Polymeric Composites

by Noemi Jardon-Maximino, Mariamne Dehonor Gómez, Rolando Villa Moreno, M. D. Baeza-Alvarado and Luis Edmundo Lugo Uribe

Fibers 2023, 11(10), 86; https://doi.org/10.3390/fib11100086 - 13 Oct 2023

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Abstract

Reinforced polymeric composites with natural fibers have garnered significant interest in recent years due to the need for biomass utilization and the requirements of various industries, such as automotive and construction. Among these natural fibers, Agave lechuguilla fiber, commonly known as ixtle (FIx) [...] Read more.

Reinforced polymeric composites with natural fibers have garnered significant interest in recent years due to the need for biomass utilization and the requirements of various industries, such as automotive and construction. Among these natural fibers, Agave lechuguilla fiber, commonly known as ixtle (FIx) or Tampico fiber, exhibits important characteristics such as length, high strength, and durability. However, there is limited literature on its conditioning, functionalization, and utilization as a reinforcing material in polymeric composites (CP). This study presents the optimization of the alkali-silane treatment of FIx, identifying the most suitable reaction conditions to enhance their thermal stability, tensile strength, and silane coupling agent (ACSi) grafting on the fiber surface. The chemical treatment with ACSi proved highly effective, resulting in a significant grafting content, which was confirmed through FTIR and SEM–EDS analyses. The high level of functionalization did not compromise the mechanical performance of the fibers, suggesting that functionalized FIx holds great potential as a reinforcing material in CP. These findings open new paths for the sustainable use of Agave lechuguilla fibers, contributing to the development of environmentally friendly and high-performance polymeric composites in various industrial applications. Full article

(This article belongs to the Special Issue Natural Fibers for Advanced Materials: Addressing Challenges)

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16 pages, 2969 KiB

Open AccessFeature PaperArticle

Optimization of Polyvinyl Alcohol-Based Electrospun Fibers with Bioactive or Electroconductive Phases for Tissue-Engineered Scaffolds

by Zeynep Renkler, Iriczalli Cruz Maya and Vincenzo Guarino

Fibers 2023, 11(10), 85; https://doi.org/10.3390/fib11100085 - 12 Oct 2023

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Abstract

The accurate mimicking of the fibrillary structure of the extracellular matrix represents one of the critical aspects of tissue engineering, playing a significant role in cell behavior and functions during the regenerative process. This work proposed the design of PVA-based multi-component membranes as [...] Read more.

The accurate mimicking of the fibrillary structure of the extracellular matrix represents one of the critical aspects of tissue engineering, playing a significant role in cell behavior and functions during the regenerative process. This work proposed the design of PVA-based multi-component membranes as a valuable and highly versatile strategy to support in vitro regeneration of different tissues. PVA can be successfully processed through electrospinning processes, allowing for the integration of other organic/inorganic materials suitable to confer additive bio-functional properties to the fibers to improve their biological response. It was demonstrated that adding polyethylene oxide (PEO) improves fiber processability; moreover, SEM analyses confirmed that blending PVA with PEO or gelatin enables the reduction of fiber size from 1.527 ± 0.66 μm to 0.880 ± 0.30 μm and 0.938 ± 0.245 μm, respectively, also minimizing defect formation. Furthermore, in vitro tests confirmed that gelatin integration allows the formation of bioactive nanofibers with improved biological response in terms of L929 adhesion and proliferation. Lastly, the processability of PVA fibers with conductive phases such as polyvinylpyrrolidone (PVP) or poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has also been verified. From this perspective, they could be promisingly used to design electroactive composite fibers able to support the regeneration process of electrically stimulated tissues such as nerves or muscles. Full article

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

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11 pages, 2707 KiB

Open AccessArticle

Numerical Analysis of Dual-Wavelength Tungsten-Tellurite Fiber Raman Lasers with Controllable Mode Switching

by Elena A. Anashkina and Alexey V. Andrianov

Fibers 2023, 11(10), 84; https://doi.org/10.3390/fib11100084 - 10 Oct 2023

Cited by 1 | Viewed by 1105

Abstract

Fiber laser sources in the spectral range near 1.7–1.8 μm are in highly demand for a lot of applications. We propose and theoretically investigate a dual-wavelength switchable Raman tungsten-tellurite fiber laser in the 1.7–1.8 µm range which can produce two stable modes at [...] Read more.

Fiber laser sources in the spectral range near 1.7–1.8 μm are in highly demand for a lot of applications. We propose and theoretically investigate a dual-wavelength switchable Raman tungsten-tellurite fiber laser in the 1.7–1.8 µm range which can produce two stable modes at frequencies separated by ~7 THz with a pump at 1.55 µm. The Raman waves shifted by 19.8 THz (mode 1) and 27.5 THz (mode 2) from the pump frequency can be generated near two different maxima of the Raman gain spectrum (gain is higher at 19.8 THz and twice lower at 27.5 THz). We numerically simulate two-mode Raman lasing with allowance for energy transfer from the pump wave to modes 1 and 2, and from mode 1 to mode 2 due to inelastic Raman scattering. Diagrams of generation regimes depending on system parameters are constructed. We demonstrate controlled switching between two modes by changing the pump power. For the same intracavity losses for both Raman modes at relatively low pump powers, only mode 1 is generated. At medium pump power, generation occurs simultaneously in both modes. At relatively high pump power, only mode 2 is generated near the weaker maximum. This effect seems surprising, but a rigorous explanation with allowance for the nonlinear interaction between mode 1 and mode 2 is found. When losses for one of the modes change, switching of the generated regimes is also predicted. Full article

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25 pages, 2412 KiB

Open AccessReview

Overcoming Challenges and Limitations Regarding the Atomic Force Microscopy Imaging and Mechanical Characterization of Nanofibers

by Stylianos Vasileios Kontomaris, Andreas Stylianou, Georgios Chliveros and Anna Malamou

Fibers 2023, 11(10), 83; https://doi.org/10.3390/fib11100083 - 09 Oct 2023

Cited by 1 | Viewed by 1856

Abstract

Atomic force microscopy (AFM) is a powerful tool that enables imaging and nanomechanical properties characterization of biological materials. Nanofibers are the structural units of many biological systems and their role in the development of advanced biomaterials is crucial. AFM methods have proven to [...] Read more.

Atomic force microscopy (AFM) is a powerful tool that enables imaging and nanomechanical properties characterization of biological materials. Nanofibers are the structural units of many biological systems and their role in the development of advanced biomaterials is crucial. AFM methods have proven to be effective towards the characterization of fibers with respect to biological and bioengineering applications at the nanoscale. However, both the topographical and mechanical properties’ nanocharacterizations of single fibers using AFM are challenging procedures. In particular, regarding imaging procedures, significant artifacts may arise from tip convolution effects. The geometrical characteristics of the AFM tip and the nanofibers, and the fact that they have similar magnitudes, may lead to significant errors regarding the topographical imaging. In addition, the determination of the mechanical properties of nanofibers is also challenging due to their small dimensions and heterogeneity (i.e., the elastic half-space assumption is not valid in most cases). This review elucidates the origins of errors in characterizing individual nanofibers, while also providing strategies to address limitations in experimental procedures and data processing. Full article

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

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15 pages, 4021 KiB

Open AccessArticle

Preparation and Characterization of Poliglecaprone-Incorporated Polycaprolactone Composite Fibrous Scaffolds

by Felix Tettey, Jaclynn Siler-Dearring, Alexis Moody and Narayan Bhattarai

Fibers 2023, 11(10), 82; https://doi.org/10.3390/fib11100082 - 25 Sep 2023

Cited by 2 | Viewed by 1498

Abstract

Electrospun fibrous scaffolds made from polymers such as polycaprolactone (PCL) have been used in drug delivery and tissue engineering for their viscoelasticity, biocompatibility, biodegradability, and tunability. Hydrophobicity and the prolonged degradation of PCL causes inhibition of the natural tissue-remodeling processes. Poliglecaprone (PGC), which [...] Read more.

Electrospun fibrous scaffolds made from polymers such as polycaprolactone (PCL) have been used in drug delivery and tissue engineering for their viscoelasticity, biocompatibility, biodegradability, and tunability. Hydrophobicity and the prolonged degradation of PCL causes inhibition of the natural tissue-remodeling processes. Poliglecaprone (PGC), which consists of PCL and Poly (glycolic acid) (PGA), has better mechanical properties and a shorter degradation time compared to PCL. A blend between PCL and PGC called PPG can give enhanced shared properties for biomedical applications. In this study, we fabricated a blend of PCL and PGC nanofibrous scaffold (PPG) at different ratios of PGC utilizing electrospinning. We studied the physicochemical and biological properties, such as morphology, crystallinity, surface wettability, degradation, surface functionalization, and cellular compatibility. All PPG scaffolds exhibited good uniformity in fiber morphology and improved mechanical properties. The surface wettability and degradation studies confirmed that increasing PGC in the PPG composites increased hydrophilicity and scaffold degradation respectively. Cell viability and cytotoxicity results showed that the scaffold with PGC was more viable and less toxic than the PCL-only scaffolds. PPG fibers were successfully coated with polydopamine (PDA) and collagen to improve degradation, biocompatibility, and bioactivity. The nanofibrous scaffolds synthesized in this study can be utilized for tissue engineering applications such as for regeneration of human articular cartilage regeneration and soft bones. Full article

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18 pages, 5065 KiB

Open AccessArticle

Petrography, Geochemistry and Mineralogy of Serpentinite Rocks Exploited in the Ophiolite Units at the Calabria-Basilicata Boundary, Southern Apennine (Italy)

by Giovanna Rizzo, Roberto Buccione, Marilena Dichicco, Rosalda Punturo and Giovanni Mongelli

Fibers 2023, 11(10), 81; https://doi.org/10.3390/fib11100081 - 23 Sep 2023

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Abstract

A multi-analytical study on serpentinites in the ophiolite units (Calabria-Basilicata boundary, southern Apennines) was carried out on samples collected from a serpentinite quarry, locally called “Pietrapica”, which sitsin the Pollino UNESCO Global Geopark. Optical microscopy observations revealed the petrographic characteristics, ICP-MS was used [...] Read more.

A multi-analytical study on serpentinites in the ophiolite units (Calabria-Basilicata boundary, southern Apennines) was carried out on samples collected from a serpentinite quarry, locally called “Pietrapica”, which sitsin the Pollino UNESCO Global Geopark. Optical microscopy observations revealed the petrographic characteristics, ICP-MS was used to assess the chemical composition while EMPA mineral chemistry, Raman spectroscopy and X-Ray Powder Diffraction and were used altogether to trace the mineral composition of the rocks. Petrography revealed that serpentinites from Pietrapica quarry are essentially composed of serpentine group minerals, amphibole and carbonate minerals with lower abundances of talc and Cr-spinel. Raman spectroscopy and X-ray powder diffraction analysis clearly allowed to establish that carbonate minerals, serpentine and amphibole-like minerals, are the dominant phases, followed by 2:1 phyllosilicate. Electron probe microanalyses were carried out on different minerals in serpentinites samples including serpentine, amphibole, chlorite, clinopyroxene, magnetite, talc, quartz and titanite which are often associated with carbonate veins. Bulk geochemistry is dominated by major oxides SiO₂, MgO and Fe₂O₃ while the most abundant trace elements are Ni and Cr. Chemical analysis showed that some heavy metals in the studied serpentinites such as Ni and Cr, are beyond the maximum admissible limits for Italian normative for public, private and residential green as well as for commercial and industrial use representing a potential environmental concern. Anyway, some of these heavy metals have been recently listed by Europe as critical raw materials and therefore, the Pietrapica abandoned quarry could represent a new resource considering their economic potentiality. Full article

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15 pages, 7226 KiB

Open AccessArticle

Application of Organosilicon Modifier Based on Tetraethoxysilane for the Production of Heat-Resistant Chrysotile Fibers and Reinforced Cement Composites

by Roman Nikolaevich Yastrebinsky, Vyacheslav Ivanovich Pavlenko, Anna Viktorovna Yastrebinskaya, Andrey Ivanovich Gorodov and Anastasia Vladislavovna Akimenko

Fibers 2023, 11(10), 80; https://doi.org/10.3390/fib11100080 - 22 Sep 2023

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Abstract

This research is aimed at obtaining boron-containing nanotubular chrysotile fibers with increased neutron absorption capacity. The possibility of using an organosilicon modifier based on tetraethoxysilane to increase the hydrothermal stability of chrysotile, as well as the strength of nanoreinforced composites based on a [...] Read more.

This research is aimed at obtaining boron-containing nanotubular chrysotile fibers with increased neutron absorption capacity. The possibility of using an organosilicon modifier based on tetraethoxysilane to increase the hydrothermal stability of chrysotile, as well as the strength of nanoreinforced composites based on a cement binder is considered. The mechanisms for the synthesis of heat-resistant nanotubular fibers of the composition Mg₆(OH)₈SiB₄O₁₀, which have a chrysotile structure, have been established. To increase the hydrothermal stability of chrysotile, crystalline hydrate phases were localized inside nanotubes using amorphous silica formed as a result of hydrolysis of silicon alkoxide under hydrothermal conditions in an alkaline environment. The modification of chrysotile via amorphous silica increases its hydrothermal stability by 97 °C. It is shown that the introduction of an organosilicon modifier based on tetraethoxysilane into the composition of Portland cement composite material leads to an increase in the structural strength and density of the composite due to the activation of silicate formation processes in the cement matrix, especially under hydrothermal conditions. The experiments showed that the strength of silicon alkoxide-modified samples of composite material increased by 34%. Full article

(This article belongs to the Special Issue Development of Eco-Friendly Concrete-, Mortar- and Fiber-Reinforced Composite Systems for Building Applications: Experimental and Theoretical Studies)

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Fibers, Volume 11, Issue 10 (October 2023) – 9 articles

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