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Fibers, Volume 7, Issue 10 (October 2019) – 14 articles

Cover Story (view full-size image): An optical fiber microsphere coupled to a taper is demonstrated as a sensor device for a wide range of curvature radii. This new sensing design may be used in large structures, especially in civil engineering applications such as bridges or large construction projects. View this paper.
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12 pages, 1770 KiB  
Article
Flexural Behavior of Hybrid-Reinforced Concrete Exterior Beam-Column Joints under Static and Cyclic Loads
by Ammar Yaser Ali and Ali Abdulameer Al-Rammahi
Fibers 2019, 7(10), 94; https://doi.org/10.3390/fib7100094 - 22 Oct 2019
Cited by 7 | Viewed by 6217
Abstract
This study presents an experimental investigation of the flexure behavior of exterior beam-column joints made from hybrid concrete (normal concrete (NC) and reactive powder concrete (RPC)) or hybrid reinforcement (steel and carbon fiber reinforced polymer (CFRP) bars internally or externally by near surface [...] Read more.
This study presents an experimental investigation of the flexure behavior of exterior beam-column joints made from hybrid concrete (normal concrete (NC) and reactive powder concrete (RPC)) or hybrid reinforcement (steel and carbon fiber reinforced polymer (CFRP) bars internally or externally by near surface mounted (NSM) technique). Nine hybrid-reinforced concrete beam-column joint specimens under the effect of static or cyclic loading were studied and tested within three test groups. Several variables that affect the behavior of the beam-column joint region are investigated such as: type of loading (static or cyclic), type of hybridization (concrete hybridization or reinforcement hybridization), and area of concrete hybridization. The results showed that using RPC as a replacement concrete at different areas of beam-column joint under static loading improved the ultimate load capacity and first cracking load to about 8–32% and 20–60%, respectively, compared with the reference NC joint with increase in the ductility of about 6–14%. Moreover, using the same technique under cyclic loading condition showed an increase in the ultimate load of about 39%, with improvement in the cumulative ductility of about 12% compared with the reference NC joint. On the other hand, using CFRP bars as (internal or external) hybridization system (33% of main reinforcement) under static loading caused increments of ultimate and first cracking loads of about 11%, 8% and 0%, 30%, respectively compared with the reference steel reinforced joint; while the ductility ratio increased about 36%, 5%, respectively. Moreover, the internal hybrid reinforcement system exhibited a decrease in the ultimate load of about 15% and reduction in the cumulative ductility of about 40% under cyclic loading. Full article
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10 pages, 4323 KiB  
Article
Effects of Reinforcing Fiber Strength on Mechanical Properties of High-Strength Concrete
by Hyun-Do Yun, Seong-Hoon Lim and Won-Chang Choi
Fibers 2019, 7(10), 93; https://doi.org/10.3390/fib7100093 - 21 Oct 2019
Cited by 9 | Viewed by 5464
Abstract
This paper investigates the effects of the tensile strength of steel fiber on the mechanical properties of steel fiber-reinforced high-strength concrete. Two levels of steel fiber tensile strength (1100 MPa and 1600 MPa) and two steel fiber contents (0.38% and 0.75%) were used [...] Read more.
This paper investigates the effects of the tensile strength of steel fiber on the mechanical properties of steel fiber-reinforced high-strength concrete. Two levels of steel fiber tensile strength (1100 MPa and 1600 MPa) and two steel fiber contents (0.38% and 0.75%) were used to test the compression, flexure, and direct shear performance of steel fiber-reinforced high-strength concrete specimens. The aspect ratio for the steel fiber was fixed at 80 and the design compressive strength of neat concrete was set at 70 MPa to match that of high-strength concrete. The performance of the steel fiber-reinforced concrete that contained high-strength steel fiber was superior to that which contained normal-strength steel fiber. In terms of flexural performance in particular, the tensile strength of steel fiber can better indicate performance than the steel fiber mixing ratio. In addition, a compression prediction model is proposed to evaluate compression toughness, and the model results are compared. The predictive model can anticipate the behavior after the maximum load. Full article
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18 pages, 4495 KiB  
Article
Resistance of Injection Molded Wood-Polypropylene Composites against Basidiomycetes According to EN 15534-1: New Insights on the Test Procedure, Structural Alterations, and Impact of Wood Source
by Kim Christian Krause, Christian Brischke, Tim Koddenberg, Andreas Buschalsky, Holger Militz and Andreas Krause
Fibers 2019, 7(10), 92; https://doi.org/10.3390/fib7100092 - 21 Oct 2019
Cited by 2 | Viewed by 4345
Abstract
In this study, we investigated injection molded wood-polypropylene composites based on various wood sources and their decay resistance against white rot (Trametes versicolor) and brown rot (Coniophora puteana) in a laboratory test according to EN 15534-1:2014. The manufactured composites [...] Read more.
In this study, we investigated injection molded wood-polypropylene composites based on various wood sources and their decay resistance against white rot (Trametes versicolor) and brown rot (Coniophora puteana) in a laboratory test according to EN 15534-1:2014. The manufactured composites consisted of poplar (Populus spp.), willow (Salix spp.), European beech (Fagus sylvatica L.), Norway spruce (Picea abies (L.) H. Karst.), and a commercial wood source (Arbocel® C100), respectively. All formulations were compounded on a co-rotating twin screw extruder and subsequently injection molded to wood–PP specimens with a wood content of 60% or 70% by weight. It was found that the test procedure had a significant effect on the mechanical properties. Loss in mechanical properties was primarily caused by moisture and less by fungal decay. Moisture caused a loss in the modulus of rupture and modulus of elasticity of 34 to 45% and 29 to 73%, respectively. Mean mass and wood mass losses were up to a maximum of 3.7% and 5.3%, respectively. The high resistance against fungal decay was generally attributed to the encapsulation of wood by the polymer matrix caused by sample preparation, and enhanced by reduced moisture uptake during the preconditioning procedure. Notable differences with respect to the wood particle source and decay fungi were also observed. Structural characterization confirmed the decay pattern of the fungi such as void cavities close the surface and the deposition of calcium oxalates. Full article
(This article belongs to the Special Issue Wood Plastic Composites)
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16 pages, 9257 KiB  
Article
Osage Orange, Honey Locust and Black Locust Seed Meal Adhesives Employed to Fabricate Composite Wood Panels
by Brent Tisserat and Rogers Harry-O’kuru
Fibers 2019, 7(10), 91; https://doi.org/10.3390/fib7100091 - 14 Oct 2019
Cited by 2 | Viewed by 6161
Abstract
Seed meal of three trees common to the Midwest region of the USA (Honey locust, Gleditsia triacanthos L., family Fabaceae), Osage orange (Maclura pomifera (Raf.) Schneid., family Moraceae) and Black locust (Robinia pseudoacacia L., family Fabaceae) were tested for their adhesive [...] Read more.
Seed meal of three trees common to the Midwest region of the USA (Honey locust, Gleditsia triacanthos L., family Fabaceae), Osage orange (Maclura pomifera (Raf.) Schneid., family Moraceae) and Black locust (Robinia pseudoacacia L., family Fabaceae) were tested for their adhesive abilities. Seed meals were employed at dosage levels of 10, 15, 25, 50, 75, and 100% reinforced with Paulownia elongata L. wood (PW) or Osage orange wood (OOW) chips to fabricate composite wood panels (CWPs). A comparison of the flexural properties of various tree seed meal CWPs reinforced with PW showed that their flexural properties met or exceeded European Union standards. However, their dimensional stability properties were inferior to nominal standards. Therefore, tree seed meal CWPs could probably have applications in interior environments where such CWPs accept negligible dimensional stability standards. Full article
(This article belongs to the Special Issue Natural Fibers and Composites: Science and Applications)
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25 pages, 5598 KiB  
Article
Effect of Cyclic Damage on the Performance of RC Square Columns Strengthened Using Hybrid FRP Composites under Axial Compression
by M. Chellapandian, Saumitra Jain, S. Suriya Prakash and Akanshu Sharma
Fibers 2019, 7(10), 90; https://doi.org/10.3390/fib7100090 - 14 Oct 2019
Cited by 21 | Viewed by 5211
Abstract
The effectiveness of hybrid fibre-reinforced polymer (FRP) strengthening is evaluated for rapid repair of the pre-damaged plain concrete (PC) and reinforced concrete (RC) columns. The objective of this study is to understand the efficiency of hybrid technique for completely restoring the initial stiffness, [...] Read more.
The effectiveness of hybrid fibre-reinforced polymer (FRP) strengthening is evaluated for rapid repair of the pre-damaged plain concrete (PC) and reinforced concrete (RC) columns. The objective of this study is to understand the efficiency of hybrid technique for completely restoring the initial stiffness, load carrying capacity and ductility of pre-damaged columns under cyclic compression loads. Two series of PC and RC square columns were cast. The columns were pre-damaged by loading up to 80% of peak load capacity for three cycles under pure compression. After cyclic damage, the columns were strengthened with two techniques, namely (a) near-surface mounted (NSM) carbon FRP (CFRP) laminates and (b) hybrid FRP technique, which uses a combination of NSM and externally bonded (EB) CFRP fabric. Analytical modelling was carried out for predicting the behaviour of columns with initial cyclic pre-damage. Additionally, a phased three-dimensional nonlinear finite element (FE) analysis was performed to validate the behaviour of pre-damaged columns with different strengthening techniques. Test results show that cyclic pre-loading and resulting damage causes a reduction in axial stiffness of all damaged specimens. Hybrid strengthening completely restored the stiffness and strength under compression. Prediction of analytical and FE analysis correlated well with the tests. Full article
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12 pages, 1370 KiB  
Article
Estimation of the Effects of the Cross-Head Speed and Temperature on the Mechanical Strength of Kenaf Bast Fibers Using Weibull and Monte-Carlo Statistics
by Richard Ntenga, Saïdjo SAÏDJO, Tibi Beda and Alexis Béakou
Fibers 2019, 7(10), 89; https://doi.org/10.3390/fib7100089 - 11 Oct 2019
Cited by 7 | Viewed by 4924
Abstract
Methods used by different researchers to evaluate plant fibers’ (PFs) mechanical performance, show great variance in results. In this work, 320 single kenaf fibers of gage lengths 10 and 20 mm were tensile-tested using four speed levels (0.05; 0.5; 1 and 5 mm·min [...] Read more.
Methods used by different researchers to evaluate plant fibers’ (PFs) mechanical performance, show great variance in results. In this work, 320 single kenaf fibers of gage lengths 10 and 20 mm were tensile-tested using four speed levels (0.05; 0.5; 1 and 5 mm·min−1). Sixty-three other specimens were also tested under three temperature levels (50, 100, and 150 °C). Mechanical characteristics, namely Young’s modulus, tensile strength, and failure strain were determined. Estimation of the dispersion on the data was performed using Weibull and Monte-Carlo statistics. Results showed a low scatter for cross-head speeds of 0.05, 0.5, and 1 mm·min−1, compared to 5 mm·min−1 for the two gage lengths used. Monte-Carlo average failure strength values were found to be close to the experimental values. A drastic drop in the tensile strength was observed for the temperature of 150 °C for varying hold times. The reported findings are likely to be used in the elaboration of a tensile test standard on PFs. Full article
(This article belongs to the Special Issue Plant Fibers)
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24 pages, 1996 KiB  
Article
ANN-Based Shear Capacity of Steel Fiber-Reinforced Concrete Beams without Stirrups
by Miguel Abambres and Eva O.L. Lantsoght
Fibers 2019, 7(10), 88; https://doi.org/10.3390/fib7100088 - 11 Oct 2019
Cited by 24 | Viewed by 6416
Abstract
Comparing experimental results of the shear capacity of steel fiber-reinforced concrete (SFRC) beams without stirrups to the capacity predicted using current design equations and other available formulations shows that predicting the shear capacity of SFRC beams without mild steel shear reinforcement is still [...] Read more.
Comparing experimental results of the shear capacity of steel fiber-reinforced concrete (SFRC) beams without stirrups to the capacity predicted using current design equations and other available formulations shows that predicting the shear capacity of SFRC beams without mild steel shear reinforcement is still difficult. The reason for this difficulty is the complex mechanics of the problem, where the steel fibers affect the different shear-carrying mechanisms. Since this problem is still not fully understood, we propose the use of artificial intelligence (AI) to derive an expression based on the available experimental data. We used a database of 430 datapoints obtained from the literature. The outcome is an artificial neural network-based expression to predict the shear capacity of SFRC beams without shear reinforcement. For this purpose, many thousands of artificial neural network (ANN) models were generated, based on 475 distinct combinations of 15 typical ANN features. The proposed “optimal” model results in maximum and mean relative errors of 0.0% for the 430 datapoints. The proposed model results in a better prediction (mean Vtest/VANN = 1.00 with a coefficient of variation 1 × 10−15) as compared to the existing code expressions and other available empirical expressions, with the model by Kwak et al. giving a mean value of Vtest/Vpred = 1.01 and a coefficient of variation of 27%. Until mechanics-based models are available for predicting the shear capacity of SFRC beams without shear reinforcement, the proposed model thus offers an attractive solution for estimating the shear capacity of SFRC beams without shear reinforcement. With this approach, designers who may be reluctant to use SFRC because of the large uncertainties and poor predictions of experiments, may feel more confident using the material for structural design. Full article
(This article belongs to the Special Issue Steel Fibre Reinforced Concrete Behaviour)
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7 pages, 3161 KiB  
Article
Fiber Microsphere Coupled in a Taper for a Large Curvature Range
by Paulo Robalinho and Orlando Frazão
Fibers 2019, 7(10), 87; https://doi.org/10.3390/fib7100087 - 09 Oct 2019
Cited by 1 | Viewed by 4157
Abstract
This work consists of using an optical fiber microsphere as a sensor for a wide range of curvature radii. The microsphere was manufactured in a standard fiber with an electric arc. In order to maximize system efficiency, the microsphere was spliced in the [...] Read more.
This work consists of using an optical fiber microsphere as a sensor for a wide range of curvature radii. The microsphere was manufactured in a standard fiber with an electric arc. In order to maximize system efficiency, the microsphere was spliced in the center of a taper. This work revealed that the variations of the wavelength where the maxima and minima of the spectrum are located varies linearly with the curvature of the system with a maximum sensitive of 580 ± 20 (pm km). This is because the direction of the input beam in the microsphere depends on the system curvature, giving rise to interferometric variations within the microsphere. Full article
(This article belongs to the Special Issue Optical Fibers Sensors 2019)
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15 pages, 10234 KiB  
Article
Sol–Gel Treatments to Flame Retard PA11/Flax Composites
by Fabienne Samyn, Maxence Vandewalle, Séverine Bellayer and Sophie Duquesne
Fibers 2019, 7(10), 86; https://doi.org/10.3390/fib7100086 - 07 Oct 2019
Cited by 4 | Viewed by 4418
Abstract
This work investigates the efficiency of sol–gel treatments to flame retard flax fabric/PA11 composites. Different sol–gel treatments applied to the flax fabrics were prepared using TEOS in combination with phosphorus and/or nitrogen containing co-precursors (DEPTES, APTES) or additives (OP1230, OP1311). When the nitrogen [...] Read more.
This work investigates the efficiency of sol–gel treatments to flame retard flax fabric/PA11 composites. Different sol–gel treatments applied to the flax fabrics were prepared using TEOS in combination with phosphorus and/or nitrogen containing co-precursors (DEPTES, APTES) or additives (OP1230, OP1311). When the nitrogen and the phosphorus co-precursors were used, two coating methods were studied: a ‘one-pot’ route and a successive layer deposition method. For the “one-pot” method, the three precursors (TEOS, DEPTES, and APTES) were mixed together in the same solutions whereas for the different layers deposition method, the three different treatments were deposited on the fibers successively, first the TEOS, then a mix of TEOS/DEPTES, and finally a mix of TEOS/APTES. After deposition, the sol–gel coatings were characterized using scanning electron microscope, electron probe microanalyzer, and 29Si and 31P solid-state NMR. When only TEOS or a mix of TEOS and DEPTES is used, homogeneous coatings are obtained presenting well-condensed Si units (mainly Q units). When APTES is added, the coatings are less homogenous and agglomerates are present. A lower condensation rate of the Si network is also noticed by solid-state NMR. When additives are used in combination with TEOS, the TEOS forms a homogenous and continuous film at the surface of the fibers, but the flame retardants are not well distributed and form aggregates. The flame retardant (FR) efficiency of the different treatments on flax fabrics was evaluated using horizontal flame spread test. The following ranking of the different systems is obtained: TEOS + Additives > TEOS > TEOS + DEPTES ~ TEOS + DEPTES + APTES > multilayers. All the sol–gel coatings improve the flame retardant properties of the flax fabric, except the multilayer treatment. Based on these results, the three most efficient sol–gels were selected to prepare sol–gel-modified flax/PA11 composites. The composite modified with only TEOS showed the best FR properties. Surprisingly, the composite modified with the phosphorus-based flame retardant (AlPi) did not exhibit improved FR properties. This effect was attributed to the fact that the amount of the FR additive deposited on the fabrics was too low. Full article
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22 pages, 4948 KiB  
Article
Tailoring Acoustic Performances of Resin Reinforced Biomass Fiber-Based Panel with Single and Multiple Tailed Cavity Inclusions for Interior Work
by Erni Setyowati, Gagoek Hardiman and Purwanto Purwanto
Fibers 2019, 7(10), 85; https://doi.org/10.3390/fib7100085 - 05 Oct 2019
Cited by 6 | Viewed by 4837
Abstract
The aim of this research is to observe the acoustic performance of absorber-based biomass fiber-reinforced polyester resins that were experimentally associated with the design of tailed cavity resonator inclusion, i.e., the cavities are partly in the form of a narrow slit. The model [...] Read more.
The aim of this research is to observe the acoustic performance of absorber-based biomass fiber-reinforced polyester resins that were experimentally associated with the design of tailed cavity resonator inclusion, i.e., the cavities are partly in the form of a narrow slit. The model of electro-acoustic resonators and several treatments were developed and became the bases for understanding the changes of acoustic reactance in the new structure. Variations in the inclusion cavity and the addition of a narrow slit were tested experimentally using an impedance tube technique based on ASTM E1050-98 and ASTM E2611-09. The improvements of acoustic performance were conducted by single and multiple cavity tailed inclusions with the addition of a Dacron fibrous layer and back cavity. The experimental results showed that a sample of 15 mm single tailed cavity kenaf fiber had higher sound absorption and wider broadband frequencies than did the hemp fiber, with a peak on 0.31–0.32 between 1.00–2.00 kHz. Meanwhile on multiple tailed cavities, the 30 mm hemp fiber had higher and wider broadband frequencies than did the kenaf, with peaks on 0.45–0.63 at frequencies between 1.75–2.10 kHz. It can be concluded that the tailed cavity inclusions could improve performance. Compared to the coco-husk with resonators in previous studies, the tailed cavity was a little bit lower, but the tailed cavities hemps and kenafs samples showed good sound absorption performance with lower band frequencies capabilities. Full article
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12 pages, 3326 KiB  
Article
Improvement in Carbonization Efficiency of Cellulosic Fibres Using Silylated Acetylene and Alkoxysilanes
by Maria Mironova, Igor Makarov, Lyudmila Golova, Markel Vinogradov, Georgy Shandryuk and Ivan Levin
Fibers 2019, 7(10), 84; https://doi.org/10.3390/fib7100084 - 28 Sep 2019
Cited by 12 | Viewed by 6172
Abstract
Comparative studies of the structure and thermal behavior of cellulose and composite precursors with additives of silyl-substituted acetylene and alkoxysilanes were carried out. It is shown that the introduction of silicon-containing additives into the cellulose matrix influenced the thermal behavior of the composite [...] Read more.
Comparative studies of the structure and thermal behavior of cellulose and composite precursors with additives of silyl-substituted acetylene and alkoxysilanes were carried out. It is shown that the introduction of silicon-containing additives into the cellulose matrix influenced the thermal behavior of the composite fibers and the carbon yield after carbonization. Comparison of the activation energies of the thermal decomposition reaction renders it possible to determine the type of additive and its concentration, which reduces the energy necessary for pyrolysis. It is shown that the C/O ratio in the additive and the presence of the Si–C bond affected the activation energy and the temperature of the beginning and the end of the pyrolysis reaction. Full article
(This article belongs to the Special Issue Sustainable Precursors, Additives and Approaches for Carbon Fibers)
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18 pages, 5813 KiB  
Article
Influence of Spinning Temperature and Filler Content on the Properties of Melt-Spun Soy Flour/Polypropylene Fibers
by Ozgun Guzdemir and Amod A. Ogale
Fibers 2019, 7(10), 83; https://doi.org/10.3390/fib7100083 - 25 Sep 2019
Cited by 6 | Viewed by 5731
Abstract
Polypropylene (PP) fibers are heavily used in disposable nonwovens fabrics because of their desirable properties and low-cost, but they are not biodegradable. With the goal of reducing non-biodegradable plastic waste in the environment, the primary aim of this study was to produce fibers [...] Read more.
Polypropylene (PP) fibers are heavily used in disposable nonwovens fabrics because of their desirable properties and low-cost, but they are not biodegradable. With the goal of reducing non-biodegradable plastic waste in the environment, the primary aim of this study was to produce fibers with reduced content of PP for disposable fabrics by incorporating soy flour, a bio-based renewable material. An optimum processing temperature of 190 °C was established, and thin fibers with a diameter under 60 µm were successfully melt-spun. Inclusion of compatibilized soy (SFM) at 30 wt% resulted in fibers with a tensile modulus of 674 ± 245 MPa and a yield strength of 18 ± 4 MPa. At 15 wt% SFM, fiber tensile modulus and yield strength were 914 ± 164 and 29 ± 3, respectively. Although lower than those of neat PP fibers (1224 ± 136 MPa and 37 ± 3 MPa), these SFM/PP fiber properties are suitable for nonwoven applications. Additionally, partial presence of soy particulates on fiber surface imparted enhanced water absorption and colorability properties to the fibers while imparting the fibers the feel of natural fibers.Although more difficult to produce, soy-PP fibers possessed similar properties as compared to those of than soy-PE fibers reported in earlier studies. Full article
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8 pages, 1575 KiB  
Article
Microstructure and Phase Composition of Yttria-Stabilized Zirconia Nanofibers Prepared by High-Temperature Calcination of Electrospun Zirconium Acetylacetonate/Yttrium Nitrate/Polyacrylonitrile Fibers
by Vyacheslav V. Rodaev, Svetlana S. Razlivalova, Alexander I. Tyurin, Andrey O. Zhigachev and Yuri I. Golovin
Fibers 2019, 7(10), 82; https://doi.org/10.3390/fib7100082 - 25 Sep 2019
Cited by 9 | Viewed by 5170
Abstract
For the first time, dense nanofibers of yttria-stabilized tetragonal zirconia with diameter of ca. 140 nm were prepared by calcination of electrospun zirconium acetylacetonate/yttrium nitrate/polyacrylonitrile fibers at 1100–1300 °C. Ceramic filaments were characterized by scanning electron microscopy, X-ray diffractometry, and nitrogen adsorption. With [...] Read more.
For the first time, dense nanofibers of yttria-stabilized tetragonal zirconia with diameter of ca. 140 nm were prepared by calcination of electrospun zirconium acetylacetonate/yttrium nitrate/polyacrylonitrile fibers at 1100–1300 °C. Ceramic filaments were characterized by scanning electron microscopy, X-ray diffractometry, and nitrogen adsorption. With a rise in the calcination temperature from 1100 to 1300 °C, the fine-grain structure of the nanofibers transformed to coarse-grain ones with the grain size equal to the fiber diameter. It was revealed that fully tetragonal nanofibrous zirconia may be obtained at Y2O3 concentrations in the range of 2–3 mol% at all used calcination temperatures. The addition of 2–3 mol% yttria to zirconia inhibited ZrO2 grain growth, preventing nanofibers’ destruction at high calcination temperatures. Synthesized well-sintered, non-porous, yttria-stabilized tetragonal zirconia nanofibers can be considered as a promising material for composites’ reinforcement, including composites with ceramic matrix. Full article
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14 pages, 4890 KiB  
Article
Improve in CO2 and CH4 Adsorption Capacity on Carbon Microfibers Synthesized by Electrospinning of PAN
by Reyna Ojeda-López, J. Marcos Esparza-Schulz, Isaac J. Pérez-Hermosillo, Armin Hernández-Gordillo and Armando Domínguez-Ortiz
Fibers 2019, 7(10), 81; https://doi.org/10.3390/fib7100081 - 21 Sep 2019
Cited by 16 | Viewed by 4885
Abstract
Carbon microfibers (CMF) has been used as an adsorbent material for CO2 and CH4 capture. The gas adsorption capacity depends on the chemical and morphological structure of CMF. The CMF physicochemical properties change according to the applied stabilization and carbonization temperatures. [...] Read more.
Carbon microfibers (CMF) has been used as an adsorbent material for CO2 and CH4 capture. The gas adsorption capacity depends on the chemical and morphological structure of CMF. The CMF physicochemical properties change according to the applied stabilization and carbonization temperatures. With the aim of studying the effect of stabilization temperature on the structural properties of the carbon microfibers and their CO2 and CH4 adsorption capacity, four different stabilization temperatures (250, 270, 280, and 300 °C) were explored, maintaining a constant carbonization temperature (900 °C). In materials stabilized at 250 and 270 °C, the cyclization was incomplete, in that, the nitrile groups (triple-bond structure, e.g., C≡N) were not converted to a double-bond structure (e.g., C=N), to form a six-membered cyclic pyridine ring, as a consequence the material stabilized at 300 °C resulting in fragile microfibers; therefore, the most appropriate stabilization temperature was 280 °C. Finally, to corroborate that the specific surface area (microporosity) is not the determining factor that influences the adsorption capacity of the materials, carbonization of polyacrylonitrile microfibers (PANMFs) at five different temperatures (600, 700, 800, 900, and 1000 °C) is carried, maintaining a constant temperature of 280 °C for the stabilization process. As a result, the CMF chemical composition directly affects the CO2 and CH4 adsorption capacity, even more directly than the specific surface area. Thus, the chemical variety can be useful to develop carbon microfibers with a high adsorption capacity and selectivity in materials with a low specific surface area. The amount adsorbed at 25 °C and 1.0 bar oscillate between 2.0 and 2.9 mmol/g adsorbent for CO2 and between 0.8 and 2.0 mmol/g adsorbent for CH4, depending on the calcination treatment applicated; these values are comparable with other material adsorbents of greenhouse gases. Full article
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