Different Kinds Of Fibers Research Articles

Optical Generation of Stable Microwave Signal Using a Dual-Wavelength Brillouin Fiber Laser

We propose and demonstrate a simple scheme to generate highly stable microwave signal by utilizing a dual-wavelength Brillouin fiber laser (DBFL). The DBFL is pumped by a single-frequency distributed-feedback semiconductor laser, and two different kinds of fibers are inserted in the cavity. The frequency of the generated microwave signal is equivalent to the difference between the Brillouin Stokes shifts in the two fibers. Without using any frequency-stabilized mechanism on the light source, the generated microwave signals exhibit high stability both for the injected pump wavelength variation and the environmental temperature fluctuation.

Studies of different kinds of fiber pretreating on the properties of PLA/sweet sorghum fiber composites

AbstractIn this article, truly degradable composites were prepared using sweet sorghum fibers which are residue of ethanol fermentation industry as reinforcement and renewable resource‐based biodegradable polyester, poly(L‐lactide) (PLLA) as matrix, they were fabricated by melt‐blending. The effect of different kinds of pretreatments (dilute sulfuric acid pretreatment, mild alkaline/oxidative pretreatment, steam explosion pretreatment) on mechanical properties of composites were investigated. Besides the composition of untreated and treated fibers as determined by Van soest method, Fourier transformed infrared (FTIR) spectroscopic and scanning electron microscopic (SEM) were also used to study the change of sweet sorghum fibers before and after pretreatments. Mechanical properties testing indicated that tensile strength and impact strength of PLLA/treated fibers were improved except the dilute sulfuric acid pretreated fibers reinforced PLA composite. The mild alkaline/oxidative pretreated fiber reinforced PLA composite showed highest tensile strength of 46.12 MPa and impact strength of 8.02 kJ/m2 which was 15.5 and 33% higher than that of the control. The SEM of impact fracture surface and DMTA test were carried out to investigate the interfacial morphology and interfacial adhesion between the fiber and matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Experimental Study of the Mechanical Properties of Hybrid Fiber Reinforced Concrete

Different kinds of fiber are used to reinforce the concrete to improve the concrete mechanical properties. The high modulus and high flexibility fibers are often used to reinforce in the cement base, which leads to the higher performance compound cement based materials. In the paper, the carbon fiber and glass fiber material are used as flexibility reinforced materials. The polypropylene fiber and the polyethylene fiber are used as strength reinforced materials. The combinations of the flexibility reinforced fiber and strength reinforced fiber are chosen as C-P HF (Carbon and Polypropylene Hybrid Fiber) and G-Pe HF (Glass and Polyethylene Hybrid Fiber). The concrete mixture ratio and the fiber-reinforced amount are determined to the author’s previous study. The relationship between compressive strength, flexural strength and length/diameter aspect ratio of fiber for the carbon and polypropylene hybrid fiber reinforced concrete (C-P HFRC), and for the glass and polyethylene hybrid fiber reinforced concrete (G--Pe HFRC) was tested and discussed. The testing results show that length/diameter aspect ratio of fiber obviously affects the flexural strength of C-P HFRC and G-Pe HFRC, though the compressive strength is slightly affected by the length-diameter aspect ratio.

Dietary Fiber in the Prevention and Treatment of Metabolic Syndrome: A Review

Inclusion of fiber in the diet has been linked to the prevention of a range of illnesses and conditions. This review contains several ideas about the possible benefits of dietary fiber intake in patients with metabolic syndrome. The principal beneficial effects of a fiber-rich diet in these patients are: prevention of obesity, improved glucose levels, and control of the profile of blood lipids. We now also know that dietary fiber may favor the control of arterial blood pressure. Animal experiments have also shown the benefit of different types of fiber on these variables. Of particular relevance are the studies using obese Zucker rats, which present similar anomalies to those seen in patients with metabolic syndrome. There is therefore a growing interest in discovering new sources of natural fiber. Some of these different kinds of fiber may then be used as functional ingredients to obtain foods with properties that are beneficial to health.

High Spatial Resolutional Measurement of Biomagnetic Fields

A high spatial resolution superconducting quantum interference device (SQUID) system was developed. This SQUID system enabled measurement and discrimination of the magnetic field pattern under 800-mum resolution. Magnetic fields produced by the compound nerve action current of the frog sciatic nerve were measured. The compound action potential and compound action magnetic fields when the stimulus current changes from 0.2 to 1 mA were measured. It was possible to observe that several components of the compound action magnetic fields have different conduction velocities in different kinds of fibers of the nerve bundle within 4 ms after stimulation. When the stimulus intensity increased, the waveform of the compound action potential changed and the duration of the late component of the compound action potential became longer. We found that this change was caused by the excitation of the nerve which has slow conduction velocity. We also succeeded in measurement of the auditory evoked magnetic fields of mice with high spatial resolution. The polarity change of peak magnetic fields appear in the 10-mm area. It is difficult to detect these signals using a SQUID magnetometer with a large size pickup coil or measurements of action potential.

Application of Solid-Phase Microextraction to Antidoping Analysis: Determination of Stimulants, Narcotics, and Other Classes of Substances Excreted Free in Urine

This paper describes the application of solid-phase microextraction (SPME) with subsequent injection in a gas chromatograph-mass spectrometer (GC-MS) (electron impact, full scan) for the screening analysis of stimulants and narcotics in urine. Several different kinds of fibers were preliminarily tested and comparatively evaluated considering the influence on the overall analytical performance of the method; other experimental parameters; and, primarily among them, the volume of urine, the pH value, and the time of adsorbtion. The optimal experimental conditions have been recorded using 0.5 mL of urine with the pH value adjusted to 10 with carbonate buffer, and in which is immersed a polydimethylsiloxane/divinylbenzene fiber, with a sampling time of 30 min; the fiber is then directly desorbed in the injection port of the GC-MS equipment. All the analytes show a good linearity (R2 > 0.99 for most substances) and a good reproducibility at the concentration corresponding to the minimum performance requirement limit or at the cut-off value fixed by the World AntiDoping Agency (CV% < 11). The limit of detection of the method is 50 ng/mL for the majority of the substances investigated. Imidazole-based drugs (e.g., naphazoline) and local anesthetics can also be included in this screening method. Whenever necessary, confirmation analyses may also be performed by following the same pre-chromatographic procedure. Integrating the SPME process and the GC-MS analysis with a dedicated autosampler that combines the microextraction and injection capacities maximizes the overall analytical capacity of a single GC-MS system and reduces the human labor necessary for and the environmental impact of screening for stimulants and narcotics excreted free in urine.

Principles and Methods of Modification of Fibres and Fibre Materials. A Review

Thanks to the technical progress in the field of chemical fibres and textiles made from them, in addition to the traditional kinds of first-generation chemical fibres and fibre materials, new types with optimized properties based on the wide use of methods of physical, composite, and chemical modification — second-generation fibres and fibre materials (textiles) — have been created. This significantly affected the evolution of production of different kinds of fibres by partially altering the ratio of the production volumes. Modified fibres and textiles for domestic use with improved properties have become widespread — “people-friendly” materials and articles. Modified types of fibres, filament, and fabrics for industrial use are also manufactured, for example, for reinforcing mechanical rubber goods, fireproofing, antimicrobials, etc. The wide use of methods of modifying fibres and fibre (textile) materials is technically, economically, and environmentally justified. The modified fibres, by acquiring new functional properties, are not only used for manufacturing single-component fibre materials (textile cloth) but also are included in blended materials. The characteristics of the articles made of both hydrated cellulose and synthetic fibres are improved in both cases. Methods of enhancing fireproofing and giving them antimicrobial properties are widely used for viscose fibres. Making them hydrophilic and giving them antistatic and fireproof properties are especially important for synthetic (polyester, acrylic, polypropylene, etc.) fibres.

Investigation of the supercell based orthonormal basis function method for different kinds of fibers

The supercell based orthonormal basis function method is proposed in this paper, in which the eigenequation about the propagation constant and the modal field is derived from the full vectorial coupled wave equations. It is efficient and accurate because all of the overlap integrals and the decomposition coefficients can be evaluated analytically. This method is efficient to investigate almost all the mode characteristics, such as the vector, degeneracy, coupling, absorption or gain properties, for so many kinds of fibers as ring fibers, Bragg fibers, multi-core fibers, elliptical fibers and photonic crystal fibers (PCF).

Fatigue resistance and structural characteristics of fiber posts: three-point bending test and SEM evaluation

Objectives. The aim of the present study was to assess the fatigue resistance of different types of fiber posts, and to observe their ultrastructure through scanning electron microscopy (SEM) before and after undergoing the fatigue test. Methods. Eight types of fiber posts were selected for this study. Easypost (Group 1), Para Post Fiber White (Group 2), FibreKor (Group 3), Ghimas White (Group 4), DT Light-Post radiopaque (Group 5), FRC Postec (Group 6), Luscent Anchors (Group 7), Snowpost (Group 8). Ten out of fifteen posts in each group were used for the fatigue test, and the other five were processed for SEM. A three-point bending machine, loading at an angle of 90° and a frequency of 3 Hz was employed for fatigue testing. The test was carried out until two million cycles were completed or until fracturing of the post. SEM evaluation was performed using a three-step scale method to assess the fiber/resin ratio and fiber dimension. Results. The fatigue test showed statistically significant differences among the different posts. Groups 5 and 6 performed better than all the other groups, withstanding practically all the stipulated number of load cycles. All the other posts fractured before the end of the test. SEM observations of the surface integrity of the fiber posts showed that Groups 4–6 obtained better scores for both longitudinal sections and cross-sections. Significance. There was a large variation in the response of different kinds of fiber posts a fatigue resistance test. The absence of correlation between results of fatigue testing and parameters of structural integrity suggests that the latter mostly reflect random variations in the fiber post manufacturing process.

The novel technology of the functional fabric composed of polypropylene non-woven selvages, polyester filaments and copper wire

Our process and products were innovative and creative. In order to produce multifunctional fibre products, we combined two or more different kinds of fibres, instead of one single fibre, to spin the ply yarn and weave them into fabrics in the hope that the final products would meet our requirements. The process in this research was innovative and high technical. The ply yarn and fabrics we made possessed high performance and diversity, and they were recyclable and practical. The ply yarn consisting of polypropylene non-woven selvages, copper wires and polyester filaments with a rotor twister possessed superior electrical and mechanical properties due to the natural characteristics of the filaments. The ply yarn was produced under different conditions of twister counts and rotor speeds, and then was woven with a rapier loom. By varying manufacturing parameters, the helix angle and tightness of the twist-wrapped yarn were also changed to enhance the mechanical properties and EMI shielding effectiveness. In this paper, the optimum condition for producing the ply yarn wrapped with metallic filaments was under the rotor speed of 8000 rpm and 2.5 turns/cm, and that with polyester filaments was 6000 rpm and 1.0 turn/cm. After the measurement of electromagnetic shielding effectiveness, we found the fabrics that fabricated with the ply yarn could take as the electromagnetic shielding materials. The weight percentage of the metallic fibre was only 3.40–4.45 wt% and the value of the shielding effectiveness was 10–20 dB.

섬유보강 철근콘크리트 보의 강도특성에 관한 실험적 연구

This study aims to provide basic data that can be applied to construct real structures. For this, an experimental structure was manufactured to identify durability according to age of fiber-reinforced concrete which contains fiber reinforcement materials (polypropylene fiber, steel fiber, cellulose fiber) and structural property about flexural behavior and destruction of reinforced concrete beam, and a relation between load and deflection, crack and destruction according to increase of load and ductility capacity was examined. Fiber-reinforced concrete materials and other constructional materials were experimented and the result is presented as follows: The results obtained through material test of concrete and static experiment of members usings 1. The experiment shows that compressive strength of fiber-reinforced concrete was lower than that of non-reinforced concrete. 2. As a result of strength experiment according to different kinds of fiber, compressive strength of an experimented structure that contains cellulose fiber was the highest when age was 28. 3. When deflection of reinforced concrete beam was examined, it was reported that ductility capacity of the experimented structure that contains fiber-reinforced concrete was raise than that of non-reinforced concrete.

Comparative study of the effects of different fibers on the processing and properties of ternary composites based on PP‐EPDM blends

AbstractThe effects of the incorporation of different kinds of fibers on the physical and mechanical properties of thermoplastics elastomers based on blends of isotactic polypropylene (iPP) and ethylene‐propylene diene rubber (EPDM) are described. For this purpose, three different compositions of PP‐EPDM blends reinforced with fibers are studied and reported here. In particular, the flow behavior, mechanical properties (tensile, flexural and impact resistance) and morphology are examined. Rheological measurements confirm the viscosity increase of thermoplastics elastomers with the incorporation of the fibers. This increment is more evident in the presence of aramid fibers. In addition, the results obtained by dynamic‐mechanical analysis and mechanical properties show that the fibers act as an effective reinforcing agent of PP‐EPDM blends. In fact, a significant increase of the modulus and strength is obtained in presence of all fibers, this effect being more noticeable at higher elastomer percentages in the thermoplastic. The morphology of the ternary composites is also analyzed by scanning electron microscopy (SEM). A good interfacial adhesion between fibers and matrix is observed, but also in this case, aramid fibers are the most effective ones.

Raman resonance and orientational order in fibers of single-wall carbon nanotubes

Polarized Raman spectroscopy is used to study Raman resonance and orientational order in fibers of single-wall carbon nanotubes. The polarized Raman intensity follows essentially the same angle dependence for both radial breathing mode and tangential modes and for both semiconducting and metallic nanotubes. A simple resonant model is proposed, which provides good fits of the whole vertical-vertical and vertical-horizontal data in different kinds of fibers. The model is used to describe orientational order of nanotubes in anisotropic fibers.

THE NOVEL TECHNOLOGY OF FUNCTIONAL FABRICS COMPOSED OF POLYPROPYLENE NONWOVEN SELVAGE/POLYESTER/STAINLESS STEEL

Nowadays, the Green Environment Protection is popular, and the synthetic fiber nonwoven is recyclable and reusable to fabricate functional products with high additional values. It is because that the synthetic fibers used in the nonwoven industry are almost thermoplastic polymer. In this study, we adopted stainless steel filament as functional metal fiber, polypropylene nonwoven waste as filled material and reinforced it with polyester filament. Our process and products were innovative and creative. In order to produce multifunctional fiber products, we combined two or more different kinds of fibers, instead of one single fiber, to spin the ply yarn and weave them into fabrics in the hope that the final products would meet our requirements. The process in this research was innovative and high technical. The ply yarn and fabrics we made possessed high performance and diversity, and they were recyclable and practical. The functional ply yarn and its fabric responded to the electrical functional demands. The products can be applied on the anti-electrostatic fabric or processed into artificial composites. In this research, the functional ply yarn was produced with an innovative rotor-wrappingtwister. The yarn consisted of polyester filaments, stainless steel filament and polypropylene nonwoven selvages. The speed of the rotor-wrapping-twister and the wrapping counts were the parameters in the manufacturing process. Then the ply yarn was woven into plain fabrics with a rapier loom. Finally, we investigated the tensile properties and maximum breaking strength utilization factors of the fabrics. The maximum breaking strength and elongation of the PS group (core materials were polyester filaments and polypropylene nonwoven selvages, and wrapping material was a stainless steel filament) were better at higher rotor speed (8000 rpm). The influence of the wrapping counts on the tensile properties was different while we used different wrapping materials. After the measurement of electromagnetic shielding effectiveness, we found the fabrics that fabricated with the ply yarn could take as the electromagnetic shielding materials. The weight percentage of the metallic fiber was only 3.52 ∼ 4.58 wt % and the value of the shielding effectiveness was 10 ∼ 25 dB.

Development of a solid-phase microextraction method for the determination of phthalic acid esters in water

Solid-phase microextraction method (SPME) coupled to GC/ECD has been developed and validated for the determination of phthalic acid esters (dimethyl-, diethyl-, di- n-butyl-, butylbenzyl-, di-2-ethylhexyl- and di- n-octyl phthalate) in water samples. Two types of coatings (PDMS, PA), altogether four different kinds of fibers have been investigated. Both parameters affecting the partition of analytes between a fiber coating and aqueous phase (i.e. extraction time, extraction temperature, agitation) and conditions of the thermal desorption in a GC injector were optimized. The final SPME method employing the polyacrylate fiber, extraction time 20 min, heating and stirring of the sample enabled the determination of all six phthalates in water samples. The method showed linear response over four orders of magnitude and the limits of quantification of the method ranged between 0.001 and 0.050 μg l −1. The repeatability expressed as R.S.D. was in the range 4–10% for the spiking level 7 μg l −1 of each analyte. The applicability of the developed SPME method was demonstrated for real water samples.

Measurement of local beat length and differential group delay in installed single-mode fibers

We present beat length and polarization mode dispersion (PMD) measurements performed on installed fibers. Results regard three different kinds of fibers: standard step index, dispersion shifted and nonzero dispersion (NZD). After a historical comparison with standard differential group delay measurement collected four years ago on the same fibers, we perform a spatial-resolved measurement of the beat length by analyzing the state of polarization of the backscattered field. We compare PMD properties of different fibers and calculate the statistical distribution of the beat length. The differential group delay (DGD) and the beat length statistics depend strongly on fiber type and on fiber position along the link. The influence of the beat length on the DGD is also discussed.

Effects of reinforcing fibers on the crystallization of polypropylene

AbstractThe effects of the incorporation of different types of fibers on the crystallization kinetics and thermodynamics of isotactic polypropylene (iPP) are investigated. The study is mainly performed by thermal analysis, both in isothermal and constant cooling rate conditions, utilizing differential scanning calorimetry (DSC). The crystallization kinetics of the studied composites is successfully described by the Avrami model. Moreover, the effects of different kind of fibers are studied comparing the values of kinetics parameters such as the Avrami exponent n, the kinetic constant of the crystallization rate, Kn and the half‐time of crystallization, T 1/2. The results of the investigation show that the fibers behave as effective nucleant agents for the crystallization of polypropylene. In fact, a dramatic decrease of the half‐time of crystallization, T1/2, as well as a sensible increase of the overall crystallization rate, Kn, are observed in the presence of all the fibers analyzed. These effects are more marked in the presence of aramid fibers. The Avrami model is successfully applied to describe the crystallization kinetics of the composites. The kinetic curves obtained under non‐isothermal conditions confirm the results obtained under isothermal conditions and demonstrate the nucleating action of the fibers on the PP crystallization. Furthermore, the spherulite growth and the transcrystallinity on the surface of the fibers are investigated by optical polarizing microscopy. It is observed that transcrystallinity takes place in all kind of fibers studied, but also in this case, aramid fibers are the most effective in promoting transcrystallinity.

Topographic Study of Glass Fibers by Atomic Force Microscopy

To better understand certain physical behaviors of glass fibers used to reinforce a polymer matrix (in composite materials), it is necessary to know their topography. In this paper, E glass fibers are studied using atomic force microscopy (AFM) and scanning electronic microscopy (SEM). To compare three different kinds of fibers (uncoated or virgin glass fibers and those coated either with an epoxy or aminosilane coupling agent only or with a complete sizing), their topography is analyzed using AFM and SEM, the former permitting the mean rugosity ( Ra) measurement of the fiber surface. Virgin (uncoated) glass fibers show a relatively smooth structure ( Ra = 13 nm) with, here and there, bumps that look like craters. Fibers coated with a coupling agent alone have a non-uniform structure because areas all along the length of each fiber are torn off when it is separated from others in the glass roving. Grooves appear when the coupling agent is removed from the fiber's surface; otherwise, there are longitudinal bumps. Fibers coated with a complete sizing have no tom-off areas. The whole to pography is regular, bumps seldom protrude from the overall surface plane, and the roughness value is always lower than that of virgin fibers.

Numerical simulation of bending effects in erbium-doped fibre amplifiers

A numerical simulation of the effects caused by bends in erbium-doped fibres is presented. The perturbation of the gain and amplified spontaneous emission has been analysed with a model of the evolution of the pump, signal and fluorescence powers, including the bending losses. The values of the curvature radius with no degradation of the characteristics of the amplifier have been studied for two different kinds of fibres.

ＣＦＲＰの酸性水環境でのＩＬＳＳの低下

In order to examine the influence of acidic rain on the CFRP for outdoor use, three kinds of CFRP were immersed in an acidic water of pH 3 at various temperatures for different immersion durations. The weight gain and interlaminar shear strength (ILSS) were measured. The progress of deterioration was about the same or a little faster in an acidic water compared with that in a distilled water. Even if the matrix was the same, the degree of deterioration in ILSS varied among CFRPs containing different kinds of fibers. The apparent activation energy (ΔEa) for 50-75% deterioration of ILSS in an acidic water was 57-60kJ/mol, while that in a distilled water was 41-62kJ/mol.