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Fibers, Volume 7, Issue 3 (March 2019)

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Cover Story (view full-size image) Shape memory nanofiber meshes are fabricated by electrospinning poly(-caprolactone)-based [...] Read more.
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Open AccessArticle Quasi-Static and Low-Velocity Impact Behavior of Intraply Hybrid Flax/Basalt Composites
Fibers 2019, 7(3), 26; https://doi.org/10.3390/fib7030026
Received: 20 February 2019 / Revised: 14 March 2019 / Accepted: 19 March 2019 / Published: 22 March 2019
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Abstract
In an attempt to increase the low-velocity impact response of natural fiber composites, a new hybrid intraply woven fabric based on flax and basalt fibers has been used to manufacture laminates with both thermoplastic and thermoset matrices. The matrix type (epoxy or polypropylene [...] Read more.
In an attempt to increase the low-velocity impact response of natural fiber composites, a new hybrid intraply woven fabric based on flax and basalt fibers has been used to manufacture laminates with both thermoplastic and thermoset matrices. The matrix type (epoxy or polypropylene (PP) with or without a maleated coupling agent) significantly affected the absorbed energy and the damage mechanisms. The absorbed energy at perforation for PP-based composites was 90% and 50% higher than that of epoxy and compatibilized PP composites, respectively. The hybrid fiber architecture counteracted the influence of low transverse strength of flax fibers on impact response, irrespective of the matrix type. In thermoplastic laminates, the matrix plasticization delayed the onset of major damage during impact and allowed a better balance of quasi-static properties, energy absorption, peak force, and perforation energy compared to epoxy-based composites. Full article
(This article belongs to the Special Issue Natural Fiber-Reinforced Hybrid Composites)
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Open AccessArticle Processing Iron Oxide Nanoparticle-Loaded Composite Carbon Fiber and the Photosensitivity Characterization
Fibers 2019, 7(3), 25; https://doi.org/10.3390/fib7030025
Received: 18 February 2019 / Revised: 18 March 2019 / Accepted: 19 March 2019 / Published: 22 March 2019
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Abstract
In this work, iron oxide nanoparticle loaded carbon fibers were prepared by electrohydrodynamic co-casting a polymer and particle mixture followed by carbonization. The precursor used to generate carbon fibers was a linear molecular chain polymer: polyacrylonitrile (PAN). A solution containing iron (II, III) [...] Read more.
In this work, iron oxide nanoparticle loaded carbon fibers were prepared by electrohydrodynamic co-casting a polymer and particle mixture followed by carbonization. The precursor used to generate carbon fibers was a linear molecular chain polymer: polyacrylonitrile (PAN). A solution containing iron (II, III) oxide (Fe3O4) particles and the PAN polymer dissolved in dimethylformamide (DMF) was electrohydrodynamically co-cast into fibers. The fibers were stabilized in air and carbonized in hydrogen at elevated temperatures. The microstructure and composition of the fibers were analyzed using scanning electron microscopy (SEM). A quantitative metallographic analysis method was used to determine the fiber size. It was found that the iron (II, III) oxide particles distributed uniformly within the carbonized fibers. Photosensitivity of the particle containing fibers was characterized through measuring the open circuit potential of the fiber samples under the visible light illumination. Potential applications of the fibers for photovoltaics and photonic sensing were discussed. Full article
(This article belongs to the Special Issue Natural Fibers and Composites: Science and Applications)
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Open AccessReview Mineralogical Asbestos Assessment in the Southern Apennines (Italy): A Review
Fibers 2019, 7(3), 24; https://doi.org/10.3390/fib7030024
Received: 14 February 2019 / Revised: 12 March 2019 / Accepted: 13 March 2019 / Published: 19 March 2019
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Abstract
This paper deals with petrography and mineralogy of serpentinitic rocks occurring in the Southern Apennines (Italy) with the aim to review the already available literature data and furnish new details on asbestos minerals present in the studied area. Two sites of Southern Italy [...] Read more.
This paper deals with petrography and mineralogy of serpentinitic rocks occurring in the Southern Apennines (Italy) with the aim to review the already available literature data and furnish new details on asbestos minerals present in the studied area. Two sites of Southern Italy were taken into account: the Pollino Massif, at the Calabrian-Lucanian border, and the surroundings of the Gimigliano and Mt. Reventino areas where serpentinites of Frido Unit are mainly exposed. Textural and mineralogical features of the studied rocks point to a similar composition for both sites including asbestos minerals such as chrysotile and tremolite-actinolite series mineral phases. Only in the Pollino Massif serpentinites edenite crystals have been detected as well; they are documented here for the first time. This amphibole forms as fibrous and/or prismatic crystals in aggregates associated with serpentine, pyroxene, and calcite. Metamorphism and/or metasomatic alteration of serpentinites are the most probable processes promoting the edenite formation in the Southern Apennine ophiolitic rocks. Full article
(This article belongs to the Special Issue Mineral Fibres)
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Open AccessArticle Probabilistic Seismic Demand Analysis of a Bridge with Unbonded, Post-Tensioned, Concrete-Filled, Fiber-Reinforced Polymer Tube Columns
Fibers 2019, 7(3), 23; https://doi.org/10.3390/fib7030023
Received: 17 September 2018 / Revised: 16 February 2019 / Accepted: 5 March 2019 / Published: 18 March 2019
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Abstract
Ground motions at sites close to a fault are sometimes affected by forward directivity, where the rupture energy arrives at the site in a form of a very short duration pulse. These pulses impose a heavy demand on structures located in the vicinity [...] Read more.
Ground motions at sites close to a fault are sometimes affected by forward directivity, where the rupture energy arrives at the site in a form of a very short duration pulse. These pulses impose a heavy demand on structures located in the vicinity of the fault. In this research, a probabilistic seismic demand analysis (PSDA) for a self-centering bridge is carried out. The bridge columns consisted of unbonded, post-tensioned, concrete-filled, fiber-reinforced polymer tubes. A bridge model was developed and non-linear time history analyses were performed. Three different methodologies that used spectral accelerations to predict structural responses were used, and a time-domain approach was used for PSDA. In addition to the three approaches, a time-domain PSDA methodology was also used. The results of the PSDA from the four approaches are compared, and the advantages of using the time-domain methodology are discussed. The results of the PSDA showed that for a site located very close to the fault (6 km in this study), earthquakes having a magnitude (Mw) as small as 6.5 can be significantly hazardous because the periods of pulses generated by small magnitude earthquakes coincide with the periods of the bridge. Since small magnitude events occur with greater frequency than large magnitude events, they can have important contributions to risk. Full article
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Open AccessFeature PaperArticle Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion
Fibers 2019, 7(3), 22; https://doi.org/10.3390/fib7030022
Received: 11 February 2019 / Revised: 3 March 2019 / Accepted: 5 March 2019 / Published: 12 March 2019
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Abstract
Glass fibres slowly degrade due to dissolution when exposed to water. Such environmental aging results in the deterioration of the mechanical properties. In structural offshore and marine applications, as well as in the wind energy sector, R-glass fibre composites are continuously exposed to [...] Read more.
Glass fibres slowly degrade due to dissolution when exposed to water. Such environmental aging results in the deterioration of the mechanical properties. In structural offshore and marine applications, as well as in the wind energy sector, R-glass fibre composites are continuously exposed to water and humid environments for decades, with a typical design lifetime being around 25 years or more. During this lifetime, these materials are affected by various temperatures, acidity levels, and mechanical loads. A Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was able to explain the long-term dissolution of R-glass fibres, considering the influence of the p H , temperature, and stress corrosion. The effects of these environmental conditions on the dissolution rate constants and activation energies of dissolution were obtained. Experimentally, dissolution was measured using High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). For stress corrosion, a custom rig was designed and used. The temperature showed an Arrhenius-type influence on the kinetics, increasing the rate of dissolution exponentially with increasing temperature. In comparison with neutral conditions, basic and acidic aqueous environments showed an increase in the dissolution rates, affecting the lifetime of glass fibres negatively. External loads also increased glass dissolution rates due to stress corrosion. The model was able to capture all of these effects. Full article
(This article belongs to the Special Issue Advances in Glass Fibers)
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Open AccessReview Actuator Materials: Review on Recent Advances and Future Outlook for Smart Textiles
Fibers 2019, 7(3), 21; https://doi.org/10.3390/fib7030021
Received: 24 January 2019 / Revised: 26 February 2019 / Accepted: 2 March 2019 / Published: 11 March 2019
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Abstract
Smart textiles based on actuator materials are of practical interest, but few types have been commercially exploited. The challenge for researchers has been to bring the concept out of the laboratory by working out how to build these smart materials on an industrial [...] Read more.
Smart textiles based on actuator materials are of practical interest, but few types have been commercially exploited. The challenge for researchers has been to bring the concept out of the laboratory by working out how to build these smart materials on an industrial scale and permanently incorporate them into textiles. Smart textiles are considered as the next frontline for electronics. Recent developments in advance technologies have led to the appearance of wearable electronics by fabricating, miniaturizing and embedding flexible conductive materials into textiles. The combination of textiles and smart materials have contributed to the development of new capabilities in fabrics with the potential to change how athletes, patients, soldiers, first responders, and everyday consumers interact with their clothes and other textile products. Actuating textiles in particular, have the potential to provide a breakthrough to the area of smart textiles in many ways. The incorporation of actuating materials in to textiles is a striking approach as a small change in material anisotropy properties can be converted into significant performance enhancements, due to the densely interconnected structures. Herein, the most recent advances in smart materials based on actuating textiles are reviewed. The use of novel emerging twisted synthetic yarns, conducting polymers, hybrid carbon nanotube and spandex yarn actuators, as well as most of the cutting–edge polymeric actuators which are deployed as smart textiles are discussed. Full article
(This article belongs to the Special Issue Smart Coatings on Fibers and Textiles)
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Open AccessFeature PaperArticle Shape-Memory Nanofiber Meshes with Programmable Cell Orientation
Fibers 2019, 7(3), 20; https://doi.org/10.3390/fib7030020
Received: 14 February 2019 / Revised: 25 February 2019 / Accepted: 25 February 2019 / Published: 1 March 2019
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Abstract
In this work we report the rational design of temperature-responsive nanofiber meshes with shape-memory properties. Meshes were fabricated by electrospinning poly(ε-caprolactone) (PCL)-based polyurethane with varying ratios of soft (PCL diol) and hard [hexamethylene diisocyanate (HDI)/1,4-butanediol (BD)] segments. By altering the PCL diol:HDI:BD molar [...] Read more.
In this work we report the rational design of temperature-responsive nanofiber meshes with shape-memory properties. Meshes were fabricated by electrospinning poly(ε-caprolactone) (PCL)-based polyurethane with varying ratios of soft (PCL diol) and hard [hexamethylene diisocyanate (HDI)/1,4-butanediol (BD)] segments. By altering the PCL diol:HDI:BD molar ratio both shape-memory properties and mechanical properties could be readily turned and modulated. Though mechanical properties improved by increasing the hard to soft segment ratio, optimal shape-memory properties were obtained using a PCL/HDI/BD molar ratio of 1:4:3. Microscopically, the original nanofibrous structure could be deformed into and maintained in a temporary shape and later recover its original structure upon reheating. Even when deformed by 400%, a recovery rate of >89% was observed. Implementation of these shape memory nanofiber meshes as cell culture platforms revealed the unique ability to alter human mesenchymal stem cell alignment and orientation. Due to their biocompatible nature, temperature-responsivity, and ability to control cell alignment, we believe that these meshes may demonstrate great promise as biomedical applications. Full article
(This article belongs to the Special Issue Electrospun Polymer Nanofibers for Food and Health Applications)
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Open AccessArticle Design and Performance Analysis of the WDM Schemes for Radio over Fiber System With Different Fiber Propagation Losses
Fibers 2019, 7(3), 19; https://doi.org/10.3390/fib7030019
Received: 27 December 2018 / Revised: 14 February 2019 / Accepted: 20 February 2019 / Published: 26 February 2019
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Abstract
The integration of optical and wireless networks increases mobility and capacity and decreases costs in access networks. Fibre optic communication can be considered optical communication that combines the methodologies of two communications, and it may be utilised in systems of wired and wireless [...] Read more.
The integration of optical and wireless networks increases mobility and capacity and decreases costs in access networks. Fibre optic communication can be considered optical communication that combines the methodologies of two communications, and it may be utilised in systems of wired and wireless communication. The solution for many problems is radio over fibre (RoF) because it can control many base stations (BS) that are connected to a central station (CS) with an optical fibre. The received RoF signal head for in a low quality; thus, many factors will result in some problems such as a high bit error rate (BER) and low Q-factor values, and the receiver might not be operating in a high data rate network. Wavelength division multiplexing (WDM) network can offer a solution to these problems where the transmission of different signals can be done with a single-mode fibre. BER should be reduced to assured values, and the Q-factor must be increased. The investigation of WDM-RoF with different lengths of fibre at various channel spacing will be simulated using Optisystem software, and the RoF’s receiver performance is measured and analyzed depending on the acquired BER, the value of the Q-factor, and the height of the opening of the eye diagram. The degradation factors effect such as attenuation and dispersion are significantly limited with the addition of an EDFA amplifier to a Single Mode Fibre (SMF). Full article
(This article belongs to the Special Issue Optical Fibers Sensors 2019)
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