Fiber Cross-sectional Shape Research Articles

Effects of Fiber Denier, Fiber Cross-Sectional Shape and Fabric Density on Acoustical Behavior of Vertically Lapped Nonwoven Fabrics

Acoustical insulation and absorption properties of nonwoven fabrics depend on fiber geometry and fiber arrangement within the fabric structure. The different structures of the fibers result in different total surface areas of nonwoven fabrics. Nonwoven fabrics such as vertically lapped fabrics are ideal materials for use as acoustical insulation products, because they have high total surface. Vertically lapped nonwoven technology consists of carding, perpendicular layering of the carded webs, and through-air bonding using synthetic binder fibers. The surface area of the fabric is directly related to the denier and cross-sectional shape of the fibers in the fabric. Smaller deniers yield more fibers per unit weight of the material, higher total fiber surface area, and greater possibilities for a sound wave to interact with the fibers in the fabric structure. The research in the literature uses two methods for measuring acoustical properties of fabric materials: the impedance tube and reverberation room method. Small test samples are in the impedance tube method and sound absorption coefficient is determined at each frequency. Large reverberation rooms and large test samples are used for the reverberation room method. A direct comparative acoustical properties measurement device that was designed and fabricated at Clemson University School of Materials Science & Engineering was used to measure acoustical insulation in this research. This paper provides a description of the measurement devices and acoustical measurement data for vertically lapped nonwoven fabrics made from three different polyester fiber shape and two denier levels.

Effect of fibre diameter and cross-sectional shape on moisture transmission through fabrics

The current work incorporates an experimental study on the effect of fiber cross sectional shape and fibre diameter on moisture transmission properties of the fabric. Water vapour transmission of the fabrics was measured using the PERMETEST. In plane liquid flow through the fabric was measured using a gravimetric in-plane wicking tester and vertical movement of liquid along the fibres against gravity was also observed using a vertical wicking tester. With the change in shape factor and fibre diameter, it is seen that with increase in fibre specific surface area wicking rate through fabric increases, whereas water vapour permeability of the fabric reduces.

A new integral equation approach to elastodynamic homogenization

A new theory of elastodynamic homogenization is proposed, which exploits the integral equation form of Navier's equations and relationships between length scales within composite media. The scheme is introduced by focusing on its leading-order approximation for orthotropic, periodic fibre-reinforced media where fibres have arbitrary cross-sectional shape. The methodology is general but here it is shown for horizontally polarized shear (SH) wave propagation for ease of exposition. The resulting effective properties are shown to possess rich structure in that four terms account separately for the physical detail of the composite (associated with fibre cross-sectional shape, elastic properties, lattice geometry and volume fraction). In particular, the appropriate component of Eshelby's tensor arises naturally in order to deal with the shape of the fibre cross section. Results are plotted for circular fibres and compared with extant methods, including the method of asymptotic homogenization. The leading-order scheme is shown to be in excellent agreement even for relatively high volume fractions.

Comparison of the Performance Properties of Carpets Containing Nylon 6 and Nylon 66 Face Yarns

A parametric analysis of the performance properties of a group of twenty-four well balanced carpet samples, half of which represent nylon 6 and the other half nylon 66 face yarns, shows that nylon 66 carpets offer superior performance in terms of texture retention and color fastness to ozone. There are no significant differences in measured performance properties between nylon 6 and 66 carpets in terms of soil repellency, oil repellency, water repellency, color fastness to light, color fastness to nitrous oxides, and thickness recovery from prolonged application of a static load. A nonparametric evaluation of an expert grader’s assessment through a paired comparison of nylon 6 and 66 carpets subjected to wear on a Vettermann drum tester shows that the grader overwhelmingly prefers nylon 66 over nylon 6 (fifty times out of fifty-four). The comparison, however, is between identically constructed carpets and not between carpets whose construction has been optimized for the specific fiber type. Since the texture of the finished carpet is believed to be influenced by a host of construction parameters such as fiber denier, fiber modulus, fiber cross-sectional shape, yarn denier, yarn twist, heat setting conditions, pile height, pile weight, etc., it would be interesting to see how a fiber-specific carpet construction and design optimization would influence the texture comparison. Both pile type and pile yarn weight exert an influence on texture retention properties as measured on the Vettermann tester. In addition, pile type influences soil repellency. Fluoropolymer treatment has a significant positive influence on color fastness to ozone, soil repellency, oil repellency, and water repellency properties.

Studies of light scattering from ethnic hair fibers

One of the most desirable hair attributes to consumers, irrespective of ethnic background, is hair shine. The light reflected from a fiber has two components, specular and diffuse. The specular fraction of reflected light from the front surface of the fiber is generally recognized as a contributor to high luster. The distinction between specular and diffuse reflection is, however, not always clearly defined. In this study an attempt has been made to differentiate between specular and diffuse reflectance by analyzing mathematically goniophotometric curves of light reflected from unaltered single hair fibers from European, African, and Asian ethnic groups. The effect of macroscopic characteristics of the hair fibers, such as fiber diameter, cross-sectional shape, and curvature on luster is demonstrated. Results indicate that broadening of the specular peak reduces luster values, and is related to these characteristics. Thus, specular peak broadening is one of the important features to take into account when evaluating luster. Therefore, a new method for luster evaluation from goniophotometric curves is proposed. Additionally, we present the general model for light scattering, showing how scattering by surface roughness of different origin and magnitudes, and the scattering and absorption processes by the hair's interior, affect the position of the specular reflectance peak and its broadening.

Influences of Fiber Crimp and Cross-sectional Shape on Particle Collection Performance of Cigarette Filter

Influences of Fiber Crimp and Cross-sectional Shape on Particle Collection Performance of Cigarette Filter

Modified shear lag model for fibers and fillers with irregular cross-sectional shapes

For fibers with irregular cross sections such as ultrahigh modulus polyethylene (UHMPE) fibers and ribbon-like carbon fibers, the original shear lag model would not provide accurate calculations for interfacial shear stress because it assumes a circular fiber cross section. In this study, a modified shear lag model is proposed to calculate the interfacial shear stress that reflects the change of fiber cross-sectional shape. Microbond test on a UHMPE fiber/epoxy system was used for verification of the model. The difference between the interfacial shear strength (IFSS) calculated using the modified model and that using the original model assuming an equivalent fiber diameter was found to be as high as 15% and it linearly increased as the irregularity of the cross-sectional shape increased. When the irregularity constant exceeds 1.12, the error in IFSS involved in using the original shear lag model and an equivalent fiber diameter is greater than 10%.

Modeling elastic and viscous effects on the texture of ribbon-shaped carbonaceous mesophase fibers

Carbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of different fiber textures and cross-sectional shapes. Circular planar polar (PP), circular planar radial (PR), ribbon planar radial (RPR), and ribbon planar line (RPL) textures are ubiquitous ones. This paper presents, solves, and validates a model of mesophase fiber texture formation based on the classical Landau-de Gennes theory of liquid crystals, adapted here to carbonaceous mesophases. The effects of fiber cross-sectional shape and elongational flow on texture formation are characterized. Emphasis is on qualitative model validation using existing experimental data [1]. The role of elasticity and flow-induced orientation on texture selection mechanism on ribbon-shaped mesophase fibers is characterized. The model is able to predict the formation of the commonly observed line texture, and the fine structure of the line is reproduced and explained in terms of classical liquid crystal defect physics. The results provide additional knowledge on how to optimize and control mesophase fiber textures.

Theory and Simulation of Fiber Texture Formation and Rheology of Carbonaceous Mesophase Fibers

ABSTRACTCarbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of different fiber textures and cross-sectional shapes. Circular planar polar (PP), circular planar radial (PR) textures, ribbon planar radial (RPR), and ribbon planar line (RPL) textures are ubiquitous ones. This paper presents, solves, and validates a model of mesophase fiber texture formation based on the classical Landau-de Gennes theory of liquid crystals, adapted here to carbonaceous mesophases. The effects of fiber cross-sectional shape and elongational flow on texture formation are characterized. Emphasis is on qualitative model validation using existing experimental data [1, 2]. The results provide additional knowledge on how to optimize and control mesophase fiber textures.

Influence of Fiber Cross-sectional Shape on Filter Collection Performance.

異形断面繊維からなるフィルタは，一般にたばこフィルタに用いられているが，集塵性能への断面形状の影響は十分に明らかになっていない．そこで，本研究では拡散捕集効率および圧力損失への繊維断面形状の影響を調べるため，繊維が流れに対して垂直に配列された場合について，理論，実験の両面から検討を行った．その結果，繊維断面形状および繊維配向により，単一繊維拡散捕集効率はほとんど変化しないが，繊維の無次元抗力は大きく変化することがわかった．さらに，無次元抗力の変化は，流れ方向の繊維投影幅により繊維間相互作用が変化するために生じることが明らかになった・以上の結果から，異形断面繊維を用いることにより，フィルタの粒子捕集性能を変化させずに，圧力損失を調整できることが示された．

Fiber Reinforcement of Metal Matrices Against Plastic Flow

The uniaxial stress-strain behavior and plastic flow in rate-independent plastic flow for transverse loading of continuous fiber-reinforced metal-matrix composites are examined in this paper. Cell models with different packing arrangements are employed to analyze the effects of fiber cross-sectional shapes (square, circular, and diamond) and periodic distributions (square, hexagonal and diagonal packing arrays) as well as transverse loading directions (45°, 0°, or 90°) on the transverse plastic deformation of metal-matrix composites reinforced with periodically distributed, aligned continuous fibers. Calculations were carried out using increasingly refined meshes to demonstrate numerical convergence. The calculations of the alternations in matrix field quantities in response to controlled changes in the fiber packing array give insights into the effects of fiber clustering on the transverse plastic flow. The results indicated that the overall transverse plastic flow of the composites is sensitive to fiber geometric parameters, such as fiber shape, packing arrangement and volume fraction, and to the transverse loading direction. The stress contours demonstrated that the interference of fibers with flow paths plays an important role in the transverse strengthening mechanism.

Surface Wetting and Energy Properties of Cellulose Acetate, Polyester and Polypropylene Fibers

Using a dynamic wetting force device, involving a sensitive Wilhelmy balance, surface wetting behaviors of polyester, polypropylene, and cellulose acetate fibers, the last two in several different sizes and cross-sectional shapes, were examined. Assessed were the values of the advancing and the receding contact angles and the work of adhesion with water as the fluid. Conducting tests with deionized water and methylene iodide allowed us to assess the value of the total surface energy along with the values of the polar and the dispersion components of it. In a limited number of tests, the surface properties of polyester and polypropylene films were also determined and compared with those of the fibers. The results generally showed that the energy was largely dispersive, hysteresis in contact angles was low, and while the fiber size and cross-sectional shape did not influence the contact angles or the energy, the surface roughness and crystallinity played significant roles.

Physical Properties and Processing of Fine Merino Lamb's Wool

Literature pertinent to fiber properties and handle of fine Merino lamb's and fleece wool is critically discussed. The softness of handle of fine Merino wool varies inversely with loose fiber resistance to compression. This complex raw wool parameter has geo metric and mechanical attributes. Fiber bending and torsional rigidity are important mechanical factors that depend on mean fiber diameter, cross-sectional shape, and Young's modulus. Crimp frequency, amplitude, and form are equally important geo metric factors. Those characteristics that distinguish lamb's and adult wool and appear to account for the relative softness of hand of lamb's compared with fleece wool are presented in Part II.

Effect of Fiber Cross-Section Shape on the Elastic Response of Composite Materials

A laminate analogy is developed for predicting the elastic constants and stresses in a unidirectional composite containing continuous fibers with rectangular pack ing geometry. Although fiber cross-sectional shape can be arbitrary, the present model is developed for circular and elliptical fibers. All nine elastic constants and the stress concen tration factors at the fiber/matrix interface are determined. Effect of fiber shape on in plane and bending properties of laminates is then examined using the results of the micro mechanics as input to classical laminated plate theory calculations.

Friction in Fibrous Materials

In this part of the series, the effects of a number of structural and morphological factors on fiber friction are examined and rationalized on the basis of the structural model discussed in Part I. The factors are fiber cross-sectional shape, molecular ori entation, annealing, and fiber type. Friction tests have been conducted using techniques that allow measurements in both the point contact and line contact modes. Selected tests have also been done with the contact regions immersed in water. The results show that the coefficient of friction μ is higher for annealed than unannealed structures and increases with increasing molecular orientation. Circular fibers exhibit higher values than noncircular fibers. The value of the friction index a varies in the same fashion as the value of the coefficient of friction μ in all cases, except when fiber orientation is the variable. The friction index n increases with orientation and is higher for circular fibers than for noncircular ones. Wetting of the contact region or annealing of the structure has no effect on the value of n. Results are explained in light of the structural model presented in Part I.

The Effect of Fibre Cross-sectional Shape on Fabric Mechanical Properties and Handle

In order to clarify the effects of different fibre cross-sectional shapes on fabric mechanical properties and handle, polyester ‘Shingosen’ fabrics of different fibre cross-sections were investigated using the KES-FB system. The results were discussed by comparing them with typical women's fine dress fabrics and the following conclusions were obtained. Polyester fabric becomes soft and deformable with an increase in the space ratio in the fibre cross-section, however, it does become inelastic and unrecoverable. FUKURAMI (fullness and softness) and SHINAYAKASA (flexibility with a soft feel) of polyester fabrics is greater with higher space ratios, but, KOSHI (stiffness) and HARI (and-drape stiffness), however, is lowered. Fabric bending rigidity is in proportion to fibre bending rigidity if all other conditions such as yarn density, count and finishing conditions remain the same. However, in general, the fabric mechanical properties and handle are controlled by the fibre assembly structure rather than fibre cross-sectional shape.

A shading model for cloth objects

A fundamental light reflection model that takes into account the internal structure of cloth to render the peculiar gloss of cloth objects is presented. In developing this model, the microscopic structure of textiles was considered. The model represents fabric features such as fiber's cross-sectional shape or weave. By measuring the reflected light intensity from actual cloth objects of several typical materials, it was verified that the model can express the properties of several kinds of cloth, and the parameters in the model were defined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

パルプの紙層形成能力 第１報 繊維間結合の定量的評価法

A quantitative evaluation method of the bonding ability of pulp fibers was developed. In order to prepare a paper-cellophane two layered sheet, a wet web and a wet cellophane sheet were pressed together and dried under restrained condition. The bonded area and bond strength between the paper layer and the cellphane sheet were measured. The ability of pulp fibers to form fiber-to-fiber bonded area was evaluated by the percentage of the paper-cellophane bonded area to all cellophane surface. The ability of pulp fibers to develop bond strength was evaluated by the paper-cellophane Z-tensile strength per paper-cellophane unit bonded area.Using this method, the bonding ability of three different bleached hardwood kraft pulps were investigated on the effect of beating conditions. The results showed that the paper-cellophane bonded area was greatly affected by the fiber cross-sectional shape and was increased by progressive beating. The percentage of the paper-cellophane bonded area to all cellophane surface was found to express the conformability of pulp fibers. This value was defined “conformability index”.On the other hand, paper-cellophane unit bond strength was increased by beating and reached to the maximum values at around 400ml CSF. This value was defined “bond strength index”.

Structure and mechanical properties of oxide fibre reinforced metal matrix composites produced by the internal crystallization method

A new method of composite fabrication, called by the authors the internal crystallization method, was invented some years ago. The method is essentially based on growing fibres from a melt within the volume of a matrix. It has been successfully used to obtain a number of composites with a molybdenum matrix and various oxide fibres including those of sapphire, some oxide eutectics, complex oxides or rare earth metals and so on. A fibre can have either a single crystalline structure or a composite structure. The strength description of such fibres needs to take into account a variation of fibre cross-sectional shape with the variation of fibre volume fraction. A strength model of composites of the brittle fibre/metal matrix type suggested earlier is used to obtain statistical strength characteristics of fibres and to relate them to some details of the fabrication process. Creep strength of the composites is also studied and the results show superior performance of composites with eutectic fibres.

Discrimination Among Acrylic Fiber Types by Small-Angle Light Scattering of Single Fibers

Abstract Small-angle light scattering (SALS) patterns and scanning electron photomicrographs of single fibers were recorded for 15 different types of acrylic fibers. SALS was seen to be a sensitive tool for discriminating among the fiber types and for characterizing fiber cross-sectional shapes, surface topography, opacity, and various forms of random bicomponent fibers.