Fibers

1521 KiB

Open AccessReview

High Strength and High Modulus Electrospun Nanofibers

by Jian Yao, Cees W. M. Bastiaansen and Ton Peijs

Fibers 2014, 2(2), 158-186; https://doi.org/10.3390/fib2020158 - 30 Apr 2014

Cited by 226 | Viewed by 37412

Electrospinning is a rapidly growing polymer processing technology as it provides a viable and simple method to create ultra-fine continuous fibers. This paper presents an in-depth review of the mechanical properties of electrospun fibers and particularly focuses on methodologies to generate high strength [...] Read more.

Electrospinning is a rapidly growing polymer processing technology as it provides a viable and simple method to create ultra-fine continuous fibers. This paper presents an in-depth review of the mechanical properties of electrospun fibers and particularly focuses on methodologies to generate high strength and high modulus nanofibers. As such, it aims to provide some guidance to future research activities in the area of high performance electrospun fibers. Full article

(This article belongs to the Special Issue Nanofibres: Friend or Foe?)

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242 KiB

Open AccessArticle

Side-Detecting Optical Fiber Doped with Tb³⁺ for Ultraviolet Sensor Application

by Jacek Zmojda, Marcin Kochanowicz, Piotr Miluski and Dominik Dorosz

Fibers 2014, 2(2), 150-157; https://doi.org/10.3390/fib2020150 - 16 Apr 2014

Cited by 20 | Viewed by 7610

Abstract

In the article a novel construction of a side-detecting luminescent optical fiber for an UV sensor application has been presented. In the fiber, structure phosphate glass doped with 0.5 mol% Tb³⁺ ions was used as a UV sensitive core/ribbon. The luminescence spectrum [...] Read more.

In the article a novel construction of a side-detecting luminescent optical fiber for an UV sensor application has been presented. In the fiber, structure phosphate glass doped with 0.5 mol% Tb³⁺ ions was used as a UV sensitive core/ribbon. The luminescence spectrum of glass and the optical fiber was measured under UV excitation using a deuterium lamp. It was found that large energy gap between upper (metastable) and lower (ground) levels of terbium ions incorporated in phosphate matrix leads to the effective emission at wavelengths of 489, 543, 586 and 621 nm, which correspond to ⁵D₄ → ⁷F_J, (J = 3, 4, 5, 6) transitions respectively. Phosphate glass doped with optimal (the strongest VIS emission) concentration of Tb³⁺ (0.5 mol%) was used as the active core/ribbon in the construction of UV side-detecting optical fiber. Full article

(This article belongs to the Special Issue Advances on Optical Fibers)

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523 KiB

Open AccessArticle

Ultra-High Sensitive Strain Sensor Based on Post-Processed Optical Fiber Bragg Grating

by Marta S. Ferreira, Jörg Bierlich, Martin Becker, Kay Schuster, José L. Santos and Orlando Frazão

Fibers 2014, 2(2), 142-149; https://doi.org/10.3390/fib2020142 - 14 Apr 2014

Cited by 15 | Viewed by 6491

Abstract

An ultra-high sensitive strain sensor is proposed. The sensing head, based on the post-processing of a fiber Bragg grating, is used to perform passive and active strain measurements. Both wavelength and full width half maximum dependences with the applied strain are studied for [...] Read more.

An ultra-high sensitive strain sensor is proposed. The sensing head, based on the post-processing of a fiber Bragg grating, is used to perform passive and active strain measurements. Both wavelength and full width half maximum dependences with the applied strain are studied for the passive sensor, where maximum sensitivities of 104.1 pm/µε and 61.6 pm/µε are respectively obtained. When combining the high performance of this sensor with a ring laser cavity configuration, the Bragg grating will act as a filter and high resolution measurements can be performed. With the proposed sensor, a resolution of 700 nε is achieved. Full article

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964 KiB

Open AccessArticle

Diesel Exhaust After-Treatment by Silicon Carbide Fiber Filter

by Kazuhiro Yamamoto and Kenta Matsui

Fibers 2014, 2(2), 128-141; https://doi.org/10.3390/fib2020128 - 10 Apr 2014

Cited by 6 | Viewed by 6914

Abstract

To reduce particulate matter (PM) in diesel exhaust gas, a diesel particulate filter (DPF) has been developed. The thermal durability of existing platinum catalyst-supported DPFs is inadequate. We are focusing on a non-catalytic after-treatment of silicon carbide (SiC) fibers with highly thermal durability. [...] Read more.

To reduce particulate matter (PM) in diesel exhaust gas, a diesel particulate filter (DPF) has been developed. The thermal durability of existing platinum catalyst-supported DPFs is inadequate. We are focusing on a non-catalytic after-treatment of silicon carbide (SiC) fibers with highly thermal durability. In this study, we simulated the processes of soot deposition and oxidation. Results show that even in exhaust gas without soot, a complex flow pattern is observed. The porosity of the filter is not constant along the flow direction, and the pressure gradient varies. The friction factor is slightly larger than the predicted value by the empirical equation in uniform porous media flow. Since the soot deposition occurs inside the filter, the depth filtration by SiC fibers was confirmed. In addition, the effects of filter temperature and oxygen concentration are clearly revealed. That is, comparing the oxidation at 700 °C, the deposited soot amount at 1200 and 1400 °C is decreased by 60% and 92%, respectively. Raising the oxygen concentration from 10% to 20% increases the oxidation efficiency from 42% to 64%. Although more work is needed over a wide range of operating conditions, a combination of these two parameters is important to achieve the non-catalytic exhaust after-treatment. Full article

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2394 KiB

Open AccessReview

Release of Carbon Nanotubes from Polymer Nanocomposites

by Lukas Schlagenhauf, Frank Nüesch and Jing Wang

Fibers 2014, 2(2), 108-127; https://doi.org/10.3390/fib2020108 - 28 Mar 2014

Cited by 72 | Viewed by 8294

Abstract

Carbon nanotube (CNT)/polymer nanocomposites have superior properties compared to the neat polymer matrix. They now are widely used in industry, but questions have been raised about the risks of such materials since CNTs can be toxic when inhaled. For a risk assessment of [...] Read more.

Carbon nanotube (CNT)/polymer nanocomposites have superior properties compared to the neat polymer matrix. They now are widely used in industry, but questions have been raised about the risks of such materials since CNTs can be toxic when inhaled. For a risk assessment of CNT nanocomposites, it is crucial to know whether CNTs from nanocomposites can be released into the environment or if they remain embedded in the matrix. This review article summarizes the studies that investigated the release of CNTs from nanocomposites during the service life. Three scenarios are reviewed, the release of particles due to mechanical impact, the release due to weathering processes, and the release due to fire. A release during composite production and disposal is not incorporated. Full article

(This article belongs to the Special Issue Nanofibres: Friend or Foe?)

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Fibers, Volume 2, Issue 2 (June 2014) – 5 articles , Pages 108-186

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