Ideal Fibers Research Articles

Spider-silk-inspired strong and tough hydrogel fibers with anti-freezing and water retention properties

Ideal hydrogel fibers with high toughness and environmental tolerance are indispensable for their long-term application in flexible electronics as actuating and sensing elements. However, current hydrogel fibers exhibit poor mechanical properties and environmental instability due to their intrinsically weak molecular (chain) interactions. Inspired by the multilevel adjustment of spider silk network structure by ions, bionic hydrogel fibers with elaborated ionic crosslinking and crystalline domains are constructed. Bionic hydrogel fibers show a toughness of 162.25 ± 21.99 megajoules per cubic meter, comparable to that of spider silks. The demonstrated bionic structural engineering strategy can be generalized to other polymers and inorganic salts for fabricating hydrogel fibers with broadly tunable mechanical properties. In addition, the introduction of inorganic salt/glycerol/water ternary solvent during constructing bionic structures endows hydrogel fibers with anti-freezing, water retention, and self-regeneration properties. This work provides ideas to fabricate hydrogel fibers with high mechanical properties and stability for flexible electronics.

Azimuthal Fourier decomposition for loss analysis of hollow-core tube lattice fibers part I: Ideal fibers

This is the first part of two papers where we propose and apply a methodology for confinement loss analysis in tube lattice fibers (TLFs). The methodology is based on azimuthal Fourier decomposition (AFD) of the fiber’s cladding and core modes along the perimeters of the cladding tubes composing. This technique, combined with coupled mode theory, constitutes an effective approach to gain insight in the inhibited coupling waveguiding mechanism and design, along with fiber non-idealities impact on confinement loss. In this part I, we describe the approach and apply it to loss analysis of ideal TLFs. The approach is then applied to the analysis of the effects of tube thickness variation in part II.

High hydrostatic pressure (HHP) as a green technology opens up a new possibility for the fabrication of electrospun nanofibers: Part I- improvement of soy protein isolate properties by HHP

A common problem of electrospinning of plant proteins is that these kinds of proteins, including soy protein isolate (SPI), should be highly soluble and preferably in a random coil structure rather than the globular conformation. The current solution is to apply thermal treatment; however, it results in extensive organoleptic consequences (e.g. color degradation and off-flavor) and loss of nutrients. Thus, if a non-thermal technology such as high hydrostatic pressure (HHP) increases the disordered structure of the protein, it could facilitate the electrospinning of the protein and eliminate the barriers of thermal treatment, forming our hypothesis in this research. To this end, initially, extensive experiments including protein solubility, sulfhydryl content, turbidity, surface hydrophobicity, circular dichroism, and viscosity tests were carried out on HHP (200, 400 and 600 MPa) and thermally treated SPI samples (3.5% and 7% w/w). The results of sulfhydryl content revealed that disulfide bonds decreased at 400 MPa more intensely than other pressures while surface hydrophobic forces were promoted at this pressure. The circular dichroism test results showed that HHP treatment resulted in higher disordered structures and lower ordered ones, which is particularly helpful for the electrospinning process; besides, lower β-sheet content achieved by HHP treatment is especially useful for attaining defect-free fibers. For the first time, in this research, ideal electrospun fibers with average diameters of 300–400 nm were achieved through HHP processing, without using any thermal energy.

Evaluation of the Structural, Physicochemical and Functional Properties of Dietary Fiber Extracted from Newhall Navel Orange By-Products.

Ultrasound-assisted enzymatic treatment was used to treat Newhall navel orange peel and residue, and then the structural, physicochemical and functional properties of extracted soluble dietary fibers (SDF) and insoluble dietary fibers (IDF) were investigated. The structural properties were determined using scanning electron microscopy, X-ray diffraction, FT-IR and monosaccharide composition. Among these dietary fibers, residue-SDF showed a more complex structure, while peel-IDF exhibited a looser structure. Four samples showed representative infrared spectral features of polysaccharides, typical cellulose crystalline structure and diverse monosaccharide composition. Furthermore, residue-IDF exhibited higher oil-holding capacity (2.08 g/g), water-holding capacity (13.43 g/g) and nitrite ion adsorption capacity (NIAC) than other three samples, and residue-SDF showed the highest swelling capacity (23.33 mL/g), cation exchange capacity (0.89 mmol/g) and cholesterol adsorption capacity (CAC) among these dietary fibers. In summary, this study suggests that the residue-SDF and residue-IDF could be used as the ideal dietary fibers for application in the functional food industry.

The structure of normal modes in parallel ideal optical fibers with strong coupling

In this paper, we studied an effect of strong evanescent coupling on the structure of normal modes in a system of parallel ideal multimode optical fibers. Using the formalism of the degenerate perturbation theory and a scalar waveguide equation for this system, analytical expressions of higher-order supermodes and their propagation constants have been determined. We have shown that the structure of modes in the case of strong evanescent coupling coincides with the structure of normal modes for weakly coupled parallel fibers. We have demonstrated that in the presence of strong coupling, expressions for corrections to the scalar propagation constant are modified, deducing them analytically.

Fabrication of phosphor bronze/Al two-phase material by recycling phosphor bronze chips using hot extrusion process and investigation of their microstructural and mechanical properties

Despite the existence of conventional methods for recycling chips, solid-state techniques have become popular, whereby waste metals are directly recycled into consolidated products with the desired shapes and designs. We investigated the feasibility of recycling phosphor bronze chips through a hot extrusion process using aluminum powder as a metal binder for the fabrication of a metal-fiber-reinforced aluminum matrix composite. To do so, mixtures containing 20vol%–50vol% of chips were prepared, cold-compacted, and extruded. The quality of the consolidated samples was evaluated by determining the density of the fabricated composites and studying their microstructures. In addition, we performed tensile and hardness tests to evaluate the mechanical properties of the fabricated composites. We also analyzed the fracture surfaces of the samples to study the fracture mechanism as a function of the volume fraction of phosphor bronze chips in the fabricated composite. The results indicated that the most effective consolidation occurred in the sample containing 20vol% of chips extruded at 465°C in which the chips serve as ideal fibers for improving the mechanical properties, especially the ultimate tensile strength, in comparison with those of Al matrixes that contain no chips but are produced under the same conditions.

Predicting scattering properties of fiber suspensions using Mie theory and probabilistic cross-sectional diameter of fibers

Scattering of visible light by micrometer-scale natural wood fibers is usually treated by assuming fibers to be perfect long cylindrical scatterers. In industrial processes, however, fibers experience deformations and are far from ideal cylinders. Variation in fiber morphology affects their scattering properties and it poses a challenge for reliable process measurements. In this paper, we have studied experimentally scattering of both deformed natural and ideal artificial non-absorbing fibers in aqueous suspension and their response to mass concentration of fibers. Experimental results are compared with the predictions of the Mie theory which is combined with cross-sectional diameter probability distribution of fibers. It is shown that the diameter distribution of the fibers together with Mie theory provides results that agree with experiments in case of both natural and ideal fibers.

Morphological and crystallographic anisotropy of severely deformed commercially pure aluminium by three-dimensional electron backscatter diffraction

The aim of this paper is to examine the morphological and crystallographic anisotropy that develops during high-pressure torsion (HPT) processing. Commercially pure aluminium was subjected to monotonic HPT deformation at room temperature. The microstructure and texture were studied by large-area electron backscatter diffraction (EBSD) scans. Three-dimensional EBSD scans served to scrutinize the morphological anisotropy and local texture. It was observed that two distinct stages of grain fragmentation and saturation occur during processing. Grains exhibited an ellipsoidal shape rather than an equi-axed one. The major axes of the ellipsoids showed a favorable orientation at the steady-state stage: an almost 20° inclination towards the shear direction. The global texture was characterized by typical shear components of face-centered cubic metals at both stages. However, the local texture revealed a preferential fragmentation pattern in the first stage: orientations in the vicinity of ideal fibers became less heavily fragmented while non-ideal orientations broke up more severely. This phenomenon was linked with the lattice rotation required to bring an initial orientation close to a stable one. Although the texture weakened considerably in the fragmentation stage, the texture index did not further decrease in the saturation stage. Saturation of texture, grain refinement and formation of microstructure are discussed in the light of different microstructural coarsening mechanisms.

Numerical study on the effects of main BCC rolling texture components on the formability of sheet metals

Crystallographic texture considerably affects the formability of crystalline materials. In this paper, the effects of BCC ideal rolling fibers—including α, 𝜖, η, γ, and ξ fibers—on the sheet formability are numerically studied. The simulations are based on the numerical procedure developed by the authors in [1] in which a rate dependent crystal plasticity model along with the power law hardening are employed in a user material subroutine to model the behavior of crystalline materials. In order to determine FLD—in a M-K type approach—second-order derivative of sheet thickness variations with respect to time is used as necking criterion. The calculated FLDs of the fibers are compared with each other and with the FLD of isotropic condition. It was observed that in the case of γ fiber a higher formability with respect to other fibers can be achieved in all regions of the curve. Also, α fiber, although weaker than other fibers at at right-hand side of FLD, shows higher formability at left. Finally, some suggestions are made based on FLD comparisons to improve sheet formability by controlling the texture produced in the manufacturing process.

Multiscale Modeling of Nano Tube Based Composites and Devices

Due to their unique structural, mechanical, thermal, and electrical properties [1], carbon nanotubes (CNTs) have been proposed as ideal fibers for manufacturing the next generation of composite materials [2] with mechanical and thermal management applications. In addition, it has been demonstrated that CNT-based devices exhibit some interesting and unique characteristics, including a high oscillation frequency [3].

Application of Multi-Scale Morphology Gradient in the Foreign Fibers Recognition

The extraction of edge feature is a key technology in the foreign fibers recognition. The traditional algorithm of edge detection operator is more sensitive to noise, which is unable to extract complete edge information. Based on the morphological edge detection, we can get the ideal foreign fibers edge characteristics under the condition of noise for the multi-scale structure elements, combining with inflation and corrosion operator to structure morphology gradient operator, the adjustment of morphology structure elements dimensions. Experiment results show that it has a certain feasibility and effectiveness compared to classic edge detection algorithm in the respect of restraining the noise and improving the testing precision.

Assessment of Poplar Seed Hair Fibers as a Potential Bulk Textile Thermal Insulation Material

Poplar seed hair fibers, harvested from the seed pods of one of the most common trees grown in the United States, have properties that make them ideal fibers for thermal insulation applications. This preliminary study examines some physical, chemical, and thermal characteristics of poplar fiber in relation to wool, down, and polyester. Results show that when compared to wool and down, poplar fiber has a finer diameter, is lighter in weight, and exhibits the highest fill power, a measure of a fiber’s ability to retain bulk. Thermal insulation tests reveal that although slightly less than down, poplar fiber has similar thermal resistance value (Rct) to that of wool and hollow polyester. In addition, the poplar fiber’s exceptionally large hollow core and its ability to resist wetting after treatments of solvents and laundering strongly suggest that poplar fiber has great potential as an environmentally friendly, effective, and lightweight textile bulk insulator.

Sólitons em Fibras Óticas Ideais – Um Desenvolvimento Numérico.

This work developed a numerical procedure for a system of partial differential equations (PDEs) describing the propagation of solitons in ideal optical fibers. The validation of the procedure was implemented from the numerical comparison between the known analytical solutions of the PDEs system and those obtained by using the numerical procedure developed. It was discovered that the procedure, based on the finite difference method and relaxation Gauss-Seidel method, was adequate in describing the propagation of soliton waves in ideals optical fibers.

Simulation of crack propagation in fiber-reinforced bulk metallic glasses

Based on a phase-field model for deformation in bulk metallic glasses (BMGs), shear band formation and crack propagation in the fiber-reinforced BMG are investigated. Ideal unbroken fibers embedded in the BMG matrix are found to significantly influence the shear banding and crack propagation in the matrix. The crack propagation affected by fibers’ length and orientation is quantitatively characterized and is described by micromechanics models for composite materials. Furthermore, fractures in some practical fiber-reinforced BMG composites such as tungsten-reinforced Zr-based BMG are simulated. The relation between the enhanced fracture toughness and the mechanical properties of fiber reinforcements is determined. Different fracture modes of BMG-matrix composites are identified from the systematic simulation studies, which are found to be consistent with experiments. The simulation results suggest that the phase-field modeling approach could be a useful tool to assist the fabrication and design of BMG composites with high fracture toughness and ductility.

Um Desenvolvimento Numérico nas Equações Dinâmicas de Sólitons em Fibras Óticas

We develop and evaluate a numerical procedure for a system of nonlinear differential equations, which describe the propagation of solitons into ideal dielectric optical fibers. This problem has analytical solutions known. The numerical solutions of the system is implemented by the finite element method, using methods of stabilization such as Streamline Upwind Petrov-Galerkin (SUPG) and Consistent Approximate Upwind (CAU). Comparing the numerical and analytical solutions, it was found that the numerical procedure adequately describes the dynamics of this system.

Microstructure and texture evolution during equal channel angular extrusion of interstitial-free steel: Effects of die angle and processing route

Die angle (Φ) and processing route are two important factors that greatly impact microstructure and texture developments during equal channel angular extrusion (ECAE). In this study, the microstructure and texture evolution in interstitial-free steel during ECAE using a Φ=120° die are investigated for up to four passes via three routes (A, BC and C). Finite element simulations and polycrystal modeling using the Taylor and viscoplastic self-consistent models are conducted to help understand deformation behavior and texture formation. Transmission electron microscopy results reveal remarkable microstructural differences between various observation planes for each billet. The effects of Φ and processing route are discussed by comparing the current results with those for the same material processed via the same routes but using a Φ=90° die. The efficiency of grain refinement is found to be only mildly dependent on Φ and processing route. The textures can be completely characterized by predefined ideal fibers, regardless of processing route and pass number. With the exception of even-numbered passes in route C, textures developed after the same route and pass number, but different Φ can be approximately related by a rotation about the axis normal to the flow plane and the rotation angle is half of the Φ difference.

Characterization of deformation textures in pure copper processed by equal channel angular extrusion via route A

Texture evolution in pure copper processed by equal channel angular extrusion (ECAE) for up to eight passes via route A is investigated. The experimental textures develop very closely along ideal orientations and fibers derived from those for simple shear torsion by a rotation about the flow plane normal, and show a continuous strengthening of the B θ / B ¯ θ components with increasing pass number. Such tendencies are satisfactorily predicted by polycrystal plasticity models. The polycrystal simulations also reveal that, despite significant changes of entry textures and strain path in multiple passes, the deformation in each pass is large enough to re-orient grains to the ideal fibers such that shear-type ECAE textures can be re-established. It is suggested that the rotation of the local (or simple shear) reference system from the laboratory (or ECAE) reference system needs to be taken into account in ECAE texture analyses.

Computational modeling of f.c.c. deformation textures over Rodrigues' space

The application of novel tools for texture analysis to a systematic examination of f.c.c. deformation textures over Rodrigues' space is reported. Texture is described using an orientation distribution function (ODF), describing the distribution of crystal orientations over a three-dimensional orientation space. In contrast to existing ODF schemes based on series representations of the ODF, the tools proposed are based on a piecewise polynomial finite element representation, permitting the application of existing finite element technology to quantitative texture analysis. Advantages of such an approach are evident in the following, where a finite element scheme for deformation driven ODF evolution, together with the regularity of Rodrigues' space, lead to substantially simplified characterizations of widely examined f.c.c. textures. As a result, interpretation is straightforward, allowing insight into the structures of and relationships between the range of ideal texture components and orientation fibers encountered.

Stability of bright solitary-wave solutions to perturbed nonlinear Schrödinger equations

The propagation of pulses in ideal nonlinear optical fibers without loss is governed by the nonlinear Schrödinger equation (NLS). When considering realistic fibers one must examine perturbed NLS equations, with the particular perturbation depending on the physical situation that is being modeled. A common example is the complex Ginzburg-Landau equation (CGL), which is a dissipative perturbation. It is known that some of the stable bright solitons of the NLS survive a dissipative perturbation such as the CGL. Given that a wave persists, it is then important to determine its stability with respect to the perturbed NLS. A major difficulty in analyzing the stability of solitary waves upon adding dissipative terms is that eigenvalues may bifurcate out of the essential spectrum. Since the essential spectrum of the NLS is located on the imaginary axis, such eigenvalues may lead to an unstable wave. In fact, eigenvalues can pop out of the essential spectrum even if the unperturbed problem has no eigenvalue embedded in the essential spectrum. Here we present a technique which can be used to track these bifurcating eigenvalues. As a consequence, we are able to locate the spectrum for bright solitary-wave solutions to various perturbed nonlinear Schrödinger equations, and determine precise conditions on parameters for which the waves are stable. In addition, we show that a particular perturbation, the parametrically forced NLS equation, supports stable multi-bump solitary waves. The technique for tracking eigenvalues which bifurcate from the essential spectrum is very general and should therefore be applicable to a larger class of problems than those presented here.

Effect of chemical functionalization on the mechanical properties of carbon nanotubes

Carbon nanotubes (CNTs) have been proposed as ideal fibers for the manufacture of the next generation of composite materials. To ultimately increase the interaction of the CNTs with polymer matrices, researchers have attached chemical functional groups to the nanotube walls. The effects of covalent chemical attachments on the mechanical properties of single-walled CNTs are examined with classical molecular dynamics simulations. The maximum compressive (buckling) force for various functionalized and non-functionalized CNTs is calculated. It is found that covalent chemical attachments decrease the maximum buckling force by about 15% regardless of tubule helical structure or radius.