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Fibers, Volume 9, Issue 3 (March 2021) – 7 articles

Cover Story (view full-size image): Carbon nanotube incorporation in cement-based materials can enhance their mechanical performance by acting as bridges across cracks and voids. The usual functionalization methods improve the dispersion of nanotubes but tend to cause delays in cement hydration kinetics, slowing down the formation of the microstructure of the composite. To prevent such undesired delay, a combined treatment with H2SO4, HNO3 , and Ca(OH) 2 was developed for carbon nanotube functionalization. View this paper
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Addendum
Addendum: Sultana, J., et al. Terahertz Hollow Core Antiresonant Fiber with Metamaterial Cladding. Fibers 2020, 8, 14
Fibers 2021, 9(3), 20; https://doi.org/10.3390/fib9030020 - 09 Mar 2021
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Abstract
This paper [...] Full article
Article
Synthesis of Curcumin Loaded Smart pH-Responsive Stealth Liposome as a Novel Nanocarrier for Cancer Treatment
Fibers 2021, 9(3), 19; https://doi.org/10.3390/fib9030019 - 08 Mar 2021
Cited by 2 | Viewed by 799
Abstract
The innovation of drug delivery vehicles with controlled properties for cancer therapy is the aim of most pharmaceutical research. This study aims to fabricate a new type of smart biocompatible stealth-nanoliposome to deliver curcumin for cancer treatment. Herein, four different types of liposomes [...] Read more.
The innovation of drug delivery vehicles with controlled properties for cancer therapy is the aim of most pharmaceutical research. This study aims to fabricate a new type of smart biocompatible stealth-nanoliposome to deliver curcumin for cancer treatment. Herein, four different types of liposomes (with/without pH-responsive polymeric coating) were synthesized via the Mozafari method and then characterized with several tests, including dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), Zeta potential, and field emission scanning electron microscopes (FE-S EM). The loading and release profile of curcumin were evaluated in two pH of 7.4 and 6.6. Finally, the MTT assay was used to assess the cytotoxicity of the samples. FE-SEM results revealed a mean size of about 40 and 50 nm for smart stealth-liposome and liposome, respectively. The results of drug entrapment revealed that non-coated liposome had about 74% entrapment efficiency, while it was about 84% for PEGylated liposomes. Furthermore, the drug released pattern of the nanocarriers showed more controllable release in stealth-liposome in comparison to non-coated one. The results of the cytotoxicity test demonstrated the toxicity of drug-loaded carriers on cancer cells. Based on the results of this study, the as-prepared smart stealth pH-responsive nanoliposome could be considered as a potential candidate for cancer therapy. Full article
(This article belongs to the Special Issue Natural Fibers and Composites: Science and Applications)
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Article
Synthesis and Transformation of Hollow Rutile Titania Wires by Single Spinneret Electrospinning with Sol-Gel Chemistry
Fibers 2021, 9(3), 18; https://doi.org/10.3390/fib9030018 - 06 Mar 2021
Viewed by 633
Abstract
The work described below was carried out to understand how to control the morphology of nanostructured titania calcined from electrospun nanofibers. This is the first report of hollow rutile nanofibers synthesized from electrospun nanofibers with short calcination time. Titanium isopropoxide was incorporated into [...] Read more.
The work described below was carried out to understand how to control the morphology of nanostructured titania calcined from electrospun nanofibers. This is the first report of hollow rutile nanofibers synthesized from electrospun nanofibers with short calcination time. Titanium isopropoxide was incorporated into the nanofibers as the titania precursor. The electrospinning technique was used to fabricate ceramic/polymer hybrid nanofibers. The electrospun nanofibers were then calcined to produce rutile titania nanofibers with different morphologies (hollow or solid nanofibers), which were characterized by SEM and TEM. The initial concentration of ceramic precursor and the calcination time were shown to control the morphology of the nanofiber. The hollow morphology was only obtained with a concentration of the precursor within a certain level and with short calcination times. The heat treatment profile contributed to particle growth. At longer times, the particle growth led to the closure of the hollow core and all the nanofibers resembled strings of solid particles. A formation mechanism for the hollow nanofibers is also proposed. Full article
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Article
Online Pre-Treatment of Thermomechanical Pulp with Emulsified Maleated Polypropylene for Processing of Extruded Thermoplastic Composites
Fibers 2021, 9(3), 17; https://doi.org/10.3390/fib9030017 - 03 Mar 2021
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Abstract
The effectiveness of maleated polypropylene (MAPP) in emulsified form for the pre-treatment of thermo-mechanical pulp (TMP) before extrusion with polypropylene fibres was evaluated. MAPP in pellet form, which was applied during the compounding step, served as a benchmark. In addition, commercial softwood flour [...] Read more.
The effectiveness of maleated polypropylene (MAPP) in emulsified form for the pre-treatment of thermo-mechanical pulp (TMP) before extrusion with polypropylene fibres was evaluated. MAPP in pellet form, which was applied during the compounding step, served as a benchmark. In addition, commercial softwood flour was included as a reference. The influence of the temperature during the defibration process and the presence or absence of the coupling agent on composite performance were evaluated. Composites were processed with a high wood content of 70 wt.%, which is common for extruded profiles. It was found that TMP based on Robinia (Robinia pseudoacacia L.) conferred higher strength properties to the composites compared to TMP based on Scots pine (Pinus sylvestris L.), which was attributed to the higher length/diameter ratio of fibres in Robinia. However, under the conditions of this study, strength properties were superior and water uptake and swelling were reduced when wood flour was used instead of TMP. On the other hand, in many formulations, larger improvements in flexural and tensile strength due to MAPP were found for the TMP-based composites compared to the wood flour-based composites. This could be due to the larger surface/volume ratio for TMP compared to wood flour and more efficient stress transfer from fibres to the matrix. Results from X-ray photoelectron spectroscopy (XPS) showed that TMP surfaces were more hydrophobic than wood flour due to coverage with lignin, which reduced the effectiveness of MAPP. Esterification between the emulsified MAPP and fibre surfaces was determined using Fourier-Transform Infrared (FTIR) spectroscopy, but some non-activated maleic anhydride remained. Under the conditions of this study, MAPP added during compounding provided better performance compared to MAPP which included a non-ionic emulsifier and which was added during the refining process. Lower temperature (150 °C) during defibration was shown to be beneficial for the strength properties of composites compared to high temperature (180 °C) when MAPP was included in the formulations. Full article
(This article belongs to the Special Issue Wood Plastic Composites)
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Article
Mechanical Performance of Fiber Reinforced Cement Composites Including Fully-Recycled Plastic Fibers
Fibers 2021, 9(3), 16; https://doi.org/10.3390/fib9030016 - 01 Mar 2021
Cited by 4 | Viewed by 1017
Abstract
The use of virgin and recycled plastic macro fibers as reinforcing elements in construction materials has recently gained increasing attention from researchers. Specifically, recycled fibers have become more attractive owing to their large-scale availability, negligible cost, and low environmental footprint. In this work, [...] Read more.
The use of virgin and recycled plastic macro fibers as reinforcing elements in construction materials has recently gained increasing attention from researchers. Specifically, recycled fibers have become more attractive owing to their large-scale availability, negligible cost, and low environmental footprint. In this work, we investigate the benefits related to the use of fully-recycled synthetic fibers as dispersed reinforcement in Fiber Reinforced Cement Composites (FRCCs). In light of the reference performance of FRCCs including virgin polypropylene (PP) fibers only, the mechanical response of composites reinforced with polyolefin filaments treated with a sol-gel silica coating and polyethylene terephthalate (PET)/polyethylene (PE) cylindrical draw-wire fibers is here assessed through three-point bending tests. Remarkably, recycled polyolefins lead to a notable enhancement in terms of peak strength and post-crack energy dissipation capability. This improvement is ascribed to both the flattened shape of fibers and the surface coating, which turns out to be very effective at strengthening the fiber-to-matrix bond. On the other hand, PET/PE fibrous reinforcement generally leads to a lower toughness, if compared to the virgin fibers. However, no reduction in terms of peak stress is evidenced. Balancing the significance of mechanical performance and environmental sustainability in the framework of a circular economy approach, both fully-recycled fibers at hand can be regarded as promising candidates for innovative structural applications. Full article
(This article belongs to the Special Issue Fiber Reinforced Composites (FRCs) for Construction Applications)
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Article
Fabrication and Characterization of Er/Yb Co-Doped Fluorophosphosilicate Glass Core Optical Fibers
Fibers 2021, 9(3), 15; https://doi.org/10.3390/fib9030015 - 01 Mar 2021
Cited by 1 | Viewed by 778
Abstract
The technical process of the synthesis of a fluorophosphosilicate (FPS) glass core was thoroughly investigated for the first time utilizing a modified chemical vapor deposition (MCVD) all-gas-phase fabrication method. It was discovered that the limiting doping level of the silica glass simultaneously co-doped [...] Read more.
The technical process of the synthesis of a fluorophosphosilicate (FPS) glass core was thoroughly investigated for the first time utilizing a modified chemical vapor deposition (MCVD) all-gas-phase fabrication method. It was discovered that the limiting doping level of the silica glass simultaneously co-doped with phosphorus (P) and fluorine (F) was found to be confined by the formation of POF3 gas. The dopants content was achieved as high as 4.7 at% of P and 1.1 at% of F in a glass core, respectively. A developed “in-house” manufacturing method makes it possible to fabricate a large mode area (LMA) purely single-mode Er–Yb co-doped optical fibers with a core diameter of 20 μm and with a lasing efficiency comparable to commercially available LMA Er–Yb optical fibers. Full article
(This article belongs to the Special Issue Optical Fibers as a Key Element of Distributed Sensor Systems)
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Article
Combined Functionalization of Carbon Nanotubes (CNT) Fibers with H2SO4/HNO3 and Ca(OH)2 for Addition in Cementitious Matrix
Fibers 2021, 9(3), 14; https://doi.org/10.3390/fib9030014 - 01 Mar 2021
Cited by 3 | Viewed by 828
Abstract
Acid treatment is commonly used to improve the dispersion of carbon nanotubes (CNT) in a cementitious matrix, but it causes undesired delay on cement hydration kinetics. This work reports a combined CNT functionalization method with H2SO4/HNO3 and Ca(OH) [...] Read more.
Acid treatment is commonly used to improve the dispersion of carbon nanotubes (CNT) in a cementitious matrix, but it causes undesired delay on cement hydration kinetics. This work reports a combined CNT functionalization method with H2SO4/HNO3 and Ca(OH)2 for addition in a cementitious matrix. Results showed that the Ca(OH)2 exposure neutralized the active sites generated by acid exposure, compensating the delay in hydration. As a result, CNT exposed to H2SO4/HNO3 for 9 h and further Ca(OH)2 treatment led to equivalent hydration kinetics than un-treated CNT did with improved stability. Full article
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