Inorganic Fibers Research Articles

The effect of the production method on the mechanical strength of an alumina porous hollow fiber

The mechanical strength of inorganic porous hollow fibers is an important property and is strongly affected by the production method. Three production methods for fibers are compared: non-solvent induced phase separation (NIPS), bio-ionic gelation with an internal multivalent ion source (BIG-I), and with an external ion source (BIG-E). The BIG-E fibers show insufficient mechanical integrity for strength analysis. Fibers prepared via BIG-I have a larger bending strength compared to fibers prepared using NIPS or BIG-E, combined with a larger scatter in their strength data. The large scatter likely originates from surface deformations present in the fiber wall, which can be reduced by further optimization of the production method. Statistical models are fitted to the measured strength data. The NIPS and BIG-I production methods yield fibers of which the strength distribution follows the Weibull model, presuming failure occurs at the weakest link.

Study the Effect of Glass and Carbon Fibers on the Firebrick Properties

This work was carried out to investigate effect of glass fiber (GF) and carbon fiber (CF) on kaolin-clay firebrick properties. GF and CF are considered inorganic fibers with application of high temperatures. Kaolin clay is mixed with short GF and CF separately by different percentages (0, 0.5, 1, 1.5 and 2) wt%. Kaolin-GF and kaolin-CF mixtures were compacted by using the semi-dry pressing method. The compacted specimens were fired at different temperatures (1100, 1200 and 1300)°C. Properties which include bulk density, apparent porosity, water absorption, thermal conductivity and fracture strength were obtained from the firebrick specimens. The results show that the addition of GF has beneficial in lowering of firing temperature, and consequently accelerating the densification via enhanced grain boundary diffusivity. Increasing GF content in the firebrick mixture enhances the fracture strength due to increase amount of glassy and mullite phases. Incorporation of CF has inversely affected than GF on the firebrick properties. As the percentage of CF increased the density of firebrick decreased, and the porosity and water absorption increased.

Mineral-Based Coating of Plasma-Treated Carbon Fibre Rovings for Carbon Concrete Composites with Enhanced Mechanical Performance.

Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving.

Remarkable mechanical enhancement achieved by interfacial strengthening of organic/inorganic/fiber composites

In this study, a series of organic/inorganic composites were fabricated by melt-mixing ultra-high molecular weight polyethylene (UHMWPE) powder with a mixture of magnesia, potassium di-hydrogen phosphate and water. The microstructure and chemical composition of the composites were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Three point bending tests showed that the flexural strength and toughness of the composites were improved with the increase of polymer content. The flexural strength of the composite with 25.0wt% UHMWPE was 7.7MPa, and can be dramatically enhanced to 21.1MPa by incorporating only 0.1vol% of oriented thermotropic liquid crystalline copolyester (TLCP) fibers. The improvement is due to the enhanced interfacial bonding between the polymer and fibers, which was much stronger than that between the inorganic phase and fibers, making the fibers adequately contribute to the mechanical strength of the three-component composite. Our results demonstrated that the interfacial strengthening between fiber and inorganic matrix achieved by interpenetrated organic phase helps to establish a strong composite system.

Ultralong well-aligned TiO2:Ln3+ (Ln\u2009=\u2009Eu, Sm, or Er) fibres prepared by modified electrospinning and their temperature-dependent luminescence

Electrospinning has emerged as an attractive technique for the fabrication of ultrafine fibres in micro-/nano-scale fineness: however, it remains a significant technological challenge to assemble aligned fibre arrays via an conventional electrospinning method due to the inherent whipping instability of the polymeric jet. We herein have first developed a simple modified electrospinning method with which to prepare ultralong (>300 mm) well-aligned inorganic fibre arrays, i.e., using an ultrahigh molecular weight polymer to suppress or eliminate the whipping motion of the electrospun jet, has emerged as a facile approach for the continuous fabrication of well-aligned, ultralong fibres through simply using a rotating cylinder as the collector (it was not found necessary to use a very high rotating speed, extra magnetic, electrical field) in the electrospinning process. As result, the ultralong well-aligned TiO2:Ln3+ (Ln = Eu, Sm, or Er) fibre arrays can be obtained from ultrahigh molecular weight poly(ethylene oxide), tetra-n-butyl titanate (Ti(OC4H9)4) and lanthanide nitrate in the modified electrospinning approach. The grow mechanism and luminescent properties of these ultralong well-aligned TiO2:Ln3+ fibre arrays were also investigated.

A review of fibrous reinforcements of concrete

Fibrous reinforcements, specifically those derived from agricultural sources, instead of steel make concrete more sustainable and provide unique properties to structures. Organic, inorganic and metallic fibers have been extensively studied as reinforcement and as aggregates for concrete. Steel, glass and carbon in fibrous forms have been used as reinforcement along with concrete or as a separate structure to improve performance or buttress dilapidated structures. Although these traditional materials provide good improvement in properties, they are derived from non-renewable and unsustainable sources. Recent focus has been to use renewable and sustainable materials in concrete instead of the traditional materials such as glass, carbon and steel. A plethora of fibers and fibrous materials, especially those derived from agricultural residues, have the potential to be used in concrete and make concrete structure more sustainable and environmentally friendly. In addition to the different types of fibers, various forms of the same fibers have also been used as reinforcement. Fibers, fabrics, tubes, rods and other structures have been used as reinforcement. In this review, we summarize the various types of fibers used in concrete and discuss the potential of using biofibers derived from agricultural residues as reinforcement and aggregates in concrete. We have broadly grouped the fibers into eight categories and further divided into sub-groups depending on the form of the reinforcement. Major focus has been to cover literature on natural fibers and agricultural residue-based reinforcements. Advantages of using fibrous materials including increase in performance properties have been reviewed. Limitations of the reinforcements and approaches to overcome the limitations have also been discussed.

Improved performances of lithium-ion batteries with a separator based on inorganic fibers

In lithium ion batteries, separators reinforced by inorganic fibers offer more advantages over those based on inorganic powders.

Electrospun TiO2–SiO2 fibres with hierarchical pores from phase separation

Design and fabrication of hierarchically porous inorganic fibres holds exciting implications for applications in catalysis, separation, and energy devices. In this article, we present a general phase separation strategy for the fabrication of TiO2–SiO2 fibres with hierarchical pores via a typical electrospinning procedure. The porous hierarchy of the as-fabricated products and the possible formation mechanism have been investigated in detail. The results confirmed that the hydrophilic–hydrophobic repulsion between the PVP@TBT@TEOS 3D network complex and the solvent, the hydrolysis and polycondensation of inorganic alkoxides, and the slow solvent evaporation during the process of electrospinning may be responsible for the phase separation, leading to the formation of macropores in the fibres. The obtained hierarchically macro-/mesoporous TiO2–SiO2 fibres exhibited amazing structure stability even at a high calcination temperature of 850 °C. The current work may guide the further design of functional inorganic fibres with controllable hierarchical porous structures.

A Review on Mechanical Behaviour of Bast-Glass Fibre Based Hybrid Polymer Composites

Natural fibres are gaining interest as reinforcement for polymer composite due to their environ mental and cost-effective benefits. Bast fibres is a prominent reinforcement for use in polymeric materials because of its low weight and cost, eco -friendly and abundant innature. Several authors manifest the advantageous usage of cellulosic bast fibres based polymeric materials in automobile industries and structural applications, but certain problems have been observed with the use of such fibres such as high water-uptake tendency and low mechanical strength than the inorganic fibres. The adverse properties of such bast fibres based composites can be overcome by hybridization with synthetic fibres. In the present article, we have reviewed the effect of hybridization of glass fibres on mechanical properties of bast fibre (jute, hemp, kenaf, flax) based hybrid polymer composites.

Polypropylene/high-density polyethylene/carbon fiber composites: Manufacturing techniques, mechanical properties, and electromagnetic interference shielding effectiveness

This study uses polypropylene (PP)/high-density polyethylene (HDPE) polyblends (80/20 wt.%) as matrices, which are then melt-blended with inorganic carbon fibers (CF) as reinforcement to form electrically conductive PP/HDPE composites. Tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) are performed to evaluate different physical properties of samples. A surface resistance and electromagnetic interference shielding effectiveness (EMI SE) measurements are used to evaluate the electrical properties of the PP/HDPE/CF composites. Test results show that an increasing content of carbon fibers results in an 18 %, 23 %, and 60 % higher tensile strength, flexural strength, and impact strength, respectively. SEM results show that carbon fibers break as a result of applied force, thereby bearing the force and increasing the mechanical properties of composites. DSC and XRD results show that the addition of carbon fibers causes heterogeneous nucleation in PP/HDPE polyblends, thereby increasing crystallization temperature. However, the crystalline structure of PP/HDPE composites is not affected. Surface resistivity results show that 5 wt.% of carbon fibers can form a conductive network in PP/HDPE polyblends and reduce the surface resistivity from 12×1012 ohm/sq to 4×103 ohm/sq. EMI SE results show that, with a 20 wt.% CF and a frequency of 2-3 GHz, the average EMI SE of PP/HDPE/CF composites is between -48 and -52 dB, qualifying their use for EMI SE, which is required for standard electronic devices.

Establishment of cure kinetic model and study on reaction mechanism of resin-based thermal insulation coatings

This paper deals with the preparation of epoxy resin-based thermal insulation coatings using epoxy resin as matrix, in which a suitable amount of inorganic filler and fibre is added. The curing reaction rate versus time curves were obtained through analysing the isothermal curing process of the coating using the differential scanning calorimetry (DSC) method. The phenomenological method was used to study its curing kinetics, and the data fitting method was adopted to get some kinetic parameters of the n-order curing model, autocatalytic model and Kamal model. The dynamic DSC method and Fourier transform infrared spectroscopy were used to discuss its curing mechanism. Results show that the isothermal process of this coating conforms to the Kamal model, with a total reaction order m + n of 1.3-2.14. Both of the two curing reaction rate constants increase with the rise in temperature.

Bionanocomposite foams based on the assembly of starch and alginate with sepiolite fibrous clay

Bionanocomposite foams based on alginate, potato starch and the microfibrous clay mineral sepiolite as reinforcing filler were prepared by lyophilization. Spectroscopic techniques were applied in order to assess the interaction mechanism established between the inorganic fibers and the polysaccharide chains, which is established between the hydroxyl groups in the polysaccharide chains and the silanol groups at the external surface of the sepiolite fibers. The textural properties studied by means of mercury intrusion porosimetry, FE-SEM and X-ray microtomography, revealed a decrease in porosity as the sepiolite content increased. Mechanical properties were also determined for the studied foams, showing an increase in compression moduli from 7.3MPa in the foam without sepiolite to 29MPa in foams containing 10% starch, 40% sepiolite and 50% alginate. Horizontal burning tests were carried out for a preliminary evaluation of the role of the inorganic fibers on the fire resistance properties of the bionanocomposite foams, revealing that bionanocomposite foams with sepiolite content >25% behave as auto-extinguishable materials. Post-synthesis cross-linking with CaCl2 was carried out in some of these samples, leading to an increase in the compression modulus up to 40MPa for the optimal composition.

The mechanical strength of a ceramic porous hollow fiber

The mechanical strength of inorganic porous hollow fibers is a critical constraint that limits their wide scale application. Various methods, including 3-point bending, 4-point bending, and diametrical compression are used for the quantification of the mechanical strength. Here, we show that these methods cannot be used in an interchangeable manner. For large sets of alumina hollow fibers, the parameters describing the cumulative probability of failure functions depend on the type of measurement, i.e., 3 or 4-point, the span size, and the measurement geometry. This implies that reporting data on mechanical properties of inorganic hollow fibers requires that extensive information about the experimental details is provided, and that a direct quantitative comparison between datasets is unjustifiable. The mechanical strength of the alumina hollow fibers tends to follow a normal distribution, or log-normal distribution, instead of the often used Weibull distribution. Monte Carlo simulations demonstrate that, especially at small sample set sizes, it is difficult to accurately determine the shape of the probability distribution. However, detailed knowledge of the type and the shape of this distribution function is essential when mechanical strength values are to be used in further design.

Analysis of respired amphibole fibers (asbestos and non-asbestos classified): discrimination between natural and anthropogenic sources using sentinel animals

To evaluate the degree of exposure and to distinguish the contributions of respirable amphibole fibers (both asbestos and non-asbestos) from natural and anthropogenic sources, we investigated their burden in the lungs of sentinel animals. Lung samples of sentinel animals are more easily and continuously available in comparison to humans and are not affected by human variables such as occupational exposure and smoking habit. Fiber identification and quantification have been performed using a scanning electron microscope (SEM) with an energy-dispersive spectrometer (EDS). Results for detected amphibole fibers (both asbestos and non-asbestos) were obtained from six studied areas in Northwest Italy (Piedmont) and correlated to lithological and urbanization data. Detected amphibole fiber species have been classified as asbestos minerals occur naturally (NOA) or to anthropogenically sourced asbestos (ASA). This pilot study is a potentially useful tool for the evaluation of the distribution and sources of respirable inorganic fibers. The model should be applicable in any areas where lithological and anthropogenic characteristics are known.

Water-equivalent fiber radiation dosimeter with two scintillating materials.

An inorganic scintillating material plastic optical fiber (POF) dosimeter for measuring ionizing radiation during radiotherapy applications is reported. It is necessary that an ideal dosimeter exhibits many desirable qualities, including water equivalence, energy independence, reproducibility, dose linearity. There has been much recent research concerning inorganic dosimeters. However, little reference has been made to date of the depth-dose characteristics of dosimeter materials. In the case of inorganic scintillating materials, they are predominantly non water-equivalent, with their effective atomic weight (Zeff) being typically much greater than that of water. This has been a barrier in preventing inorganic scintillating material dosimeter from being used in actual clinical applications. In this paper, we propose a parallel-paired fiber light guide structure to solve this problem. Two different inorganic scintillating materials are embedded separately in the parallel-paired fiber. It is shown that the information of water depth and absorbed dose at the point of measurement can be extracted by utilizing their different depth-dose properties.

Dry Sliding Wear Assessment of Organic–Inorganic Fibre Reinforced Friction Composites Using Design of Experiment Approach

Dry Sliding Wear Assessment of Organic–Inorganic Fibre Reinforced Friction Composites Using Design of Experiment Approach

Hydroxyundecanethiol-Modified Steel Fibers for the Selective Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons from River and Wastewater

ABSTRACTA novel organic–inorganic composite-coated fiber was developed for selective solid-phase microextraction (SPME) by direct electrodeposition of zinc oxide microparticles on a pretreated stainless steel wire followed by self-assembly of hydroxyundecanethiol with zinc–sulfur bonds. The performance of the hydroxyundecyl-modified zinc oxide-coated steel fiber was then assessed for SPME of polar aromatic compounds coupled to high-performance liquid chromatography with ultraviolet detection. Excellent extraction and selectivity were obtained for polycyclic aromatic hydrocarbons. The extraction and desorption times, temperature, stirring rate, and ionic strength were optimized. The limits of detection were from 0.034 to 0.132 µg L−1. The relative standard deviations were from 3.4 to 4.9% for a single fiber and from 5.1 to 6.4% for multiple fibers. The recovery of polycyclic aromatic hydrocarbons in environmental water fortified at 5.0 and 50 µg L−1 was from 83.1 to 103% with relative standard deviations below 8.4%. This fiber was shown to withstand at least 200 extraction and desorption cycles. The method was used for the preconcentration and determination of polycyclic aromatic hydrocarbons in environmental water.

Research activity with different types of scintillation materials

Nowadays there is a growing interest and demand in the development of new types of scintillation materials for experimental high energy physics. Future detector developments will focus on cheap, fast, and radiation hard materials, especially for application in collider experiments. The most recent results obtained by the Giessen group in close cooperation with colleagues from different institutes will be presented. The new start of the mass production of high quality lead tungstate crystals (PbWO4, PWO) for electromagnetic calorimetry was started by the company CRYTUR (Turnov, Czech Republic). We will present a detailed progress report on the research program of lead tungstate performed in the last two years. The latest results in the development of LuAG:Ce, YAG:Ce and LYSO:Ce inorganic fibers, grown by the micro pulling down method and cut with the heated wire technique as well as new glass ceramics material BaO*2SiO2 (DSB) doped by Ce and Gd will be presented. In addition, different samples of the organic plastic scintillator EJ-260 produced by the company Eljen Technology (Sweetwater, USA) have been characterized. The study has focused on the change of performance after irradiation with 150 MeV protons up to an integral fluence of 5-1013 protons/cm2 as well as with a strong 60Co gamma-source accumulating an integral dose of 100 Gy.

Physicochemical and photocatalytic properties of carbonaceous char and titania composite hollow fibers for wastewater treatment

This work shows the concept of a simple, single-step, partial pyrolysis approach to prepare inorganic composite hollow fibers at low temperature conditions. Two series of robust, photocatalytic and high-performance membranes were synthesized by changing the pyrolysis temperature (Series 1: 500–600 °C for 8 h) and time (Series 2: 550 °C for 3–12 h), leading to the formation of a composite matrix consisted of carbonaceous char and titania nanoparticles. Chemical composition, phase of crystallinity, mechanical strength, textural characteristics, morphology and photocatalytic activity of the hollow fibers were comprehensively characterized. Mechanical strength of the hollow fibers was found to directly attribute to the amount of char and porosity. Hollow fibers, prepared using 8 h at 550 and 575 °C or 6 h at 550 °C condition, displayed a good balance between the highest mechanical strength of 52 MPa and photo-degradation of 90.4% of acid orange 7 under ultra-violet light. This was attributed to the optimization of degree of char derived from the binder and the exposure of anatase titania nanoparticles on the hollow fiber surface made available for photo-oxidation. This work offers the opportunity for future development of a fully integrated photocatalysis and membrane operation for wastewater treatment applications.

Atmospheric pressure plasma assisted calcination of composite submicron fibers

The plasma assisted calcination of composite organic/inorganic submicron fibers for the preparation of inorganic fibers in submicron scale was studied. Aluminium butoxide/polyvinylpyrrolidone fibers prepared by electrospinning were treated using low-temperature plasma generated by special type of dielectric barrier discharge, so called diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in ambient air, synthetic air, oxygen and nitrogen. Effect of plasma treatment on base polymer removal was investigated by using Attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy. Influence of working gas on the base polymer reduction was studied by energy-dispersive X-ray spectroscopy (EDX) and CHNS elemental analysis. Changes in fibers morphology were observed by scanning electron microscopy (SEM). High efficiency of organic template removal without any degradation of fibers was observed after plasma treatment in ambient air. Due to the low-temperature approach and short exposure time, the plasma assisted calcination is a promising alternative to the conventional thermal calcination.