Showing papers on "Fiber published in 1971"

Sintered Fiber Metal Composites as a Basis for Attachment of Implants to Bone

Abstract: A fiber titanium composite has been developed and its potential application as a method of skeletal fixation for internal prosthetic devices has been studied.Titanium fibers, 0.19 millimeter in diameter, were cut in short lengths, compressed in dies to predetermined densities, and sintered under vac

Cell fractionation and arrangement on fibers, beads, and surfaces.

Abstract: A new method, fiber fractionation, has been used to isolate and separate cells. The cells are adsorbed to fibers covalently coupled to molecules such as antigens, antibodies, and lectins which can bind specifically to cell-surface components. The cells are then removed mechanically by plucking the taut fibers. Alternatively, competitive inhibitors of binding may be used to remove the cells at a lesser rate. Successful fractionations have been achieved by varying the degree of derivatization of the fibers by the lectin concanavalin A. Lymphoid cells have been separated by the use of different antigens coupled to the fibers. The method may also be used for specific fixation and manipulation of viable cell populations in culture. In addition to fibers, beads and surfaces have been specifically derivatized and used to achieve different geometrical arrangements of the cells.

The Laminate Analogy for 2 and 3 Dimensional Composite Materials

Abstract: A previously developed laminate analogy for predicting the elastic stiffness and thermal expansion properties of a randomly oriented short fiber composite is extended to include a large class of fiber reinforced composites possessing very complex geometry. In particular, the stiffness and thermal expansion coefficients of short fiber com posites having biased filaments, misaligned filaments, and variable fiber aspect ratios are determined from a laminate analogy. In addition, the laminate analogy is extended to 2 and 3 dimensional woven fabric composites. Theoretical results for the short fiber com posites show excellent agreement with experimental results, while theoretical results for the woven fabric composites are shown to be qualitatively correct.

Raman studies of the glass fiber-silane-resin interface

Abstract: Glass-silane-resin composite interfaces were studied with a laser-Raman technique. The data indicate that the silane coupling agent was polymerized and chemically bonded to the surface of E-glass fibers. Application to the glass fiber surface of the silane from aqueous solution resulted in multilayer coverage. From the spectroscopic evidence, polymerization of methyl methacrylate in the presence of a vinyltriethyoxysilane-coated fiber surface resulted in formation of polymethyl methacrylate with 30%–40% of the vinylsiloxane groups.

High temperature insulation module

Abstract: A ceramic fiber mat attached to the interior wall or surface of a high temperature chamber or furnace or adapted to overlie an intermediate insulating member positioned between the mat and a furnace wall, the fibers in the mat lying in planes generally perpendicular to the wall, the mat constituting an improved insulation for the wall where the interior of the chamber or furnace will be operating at temperatures in excess of 1600* F.

Modulus of short carbon and glass fiber reinforced composites

Abstract: A theoretical model for a short fiber reinforced composite is proposed The composite is assumed to consist of an aggregate of sub-units, each sub-unit possessing the elastic properties of a reinforced composite in which the fibers are continuous and fully aligned The elastic constants of a partially oriented composite are then calculated by the Voigt and Reuss averaging procedures, giving upper and lower bounds respectively for the composite modulus Comparison is made with experimental data for such composites The measured modulus of glass and carbon fiber composites is found to be given by the Reuss or lower bound, to a good approximation compared with the difference between the bounds, for fiber orientations ranging from almost isotropic to highly aligned

Some Mechanical Properties of Wool Fibers in the "Hookean" Region from Zero to 100% Relative Humidity

Abstract: At 20°C and for all moisture contents, the mechanical behavior of wool fibers up to 1% extension in the Hookean region is linear viscoelastic. The equilibrium Young's modulus, based on the wet cross-sectional area of the wool fiber, is inde pendent of moisture content and is equal to 1.4X 1010 dynes-cm2. The dynamic or transient behavior of a fiber at any moisture content at 20°C can be replaced by a spring contributing a fixed stiffness of 1.4X 1010 dynes/cm2 to the dynamic Young's modulus together with a viscous dashpot in parallel and having moisture-dependent characteristics. The action of water, which in the original two-phase matrix-microfibril model, was proposed to weaken the matrix, must now be con sidered to increase the segmental mobility of the molecular structure of the matrix. Further, mechanical equilibrium between matrix and microfibril is taken to exist for the wet wool fiber, rather than the dry fiber.

Interferometric Studies of Fibers: Part II: Interferometric Determination of the Refractive Indices and Birefringence of Acrylic Fibers

Abstract: Interferometric determination of the principal refractive indices for light vibrating parallel and perpendicular to the fiber axis and the birefringence for Acrilan® have been carried out. Multiple-beam Fizeau fringes in transmission were used for fibers of irregular cross sections. A new method suitable for evaluating small birefringence in fibers was applied. Variation of refractive index with temperature was also determined. The fringes of equal chromatic order were applied for determining the birefringence of the fibers with diameters of 15-40 microns.

Refractory fibers of zirconia and silica mixtures

Abstract: Refractory fibers of zirconia and silica mixtures are made by shaping and dehydratively gelling, for example by extruding in air, an aqueous mixture of a zirconium compound, such as zirconium diacetate, and colloidal silica, and heating the resulting gelled fiber in a controlled manner to decompose and volatilize undesired constituents and convert the fiber to a refractory fiber having a desired microstructure and useful to form refractory fabrics, reinforced composites, heat or sound insulation, filter or adsorption media, etc.

Optical fiber joining technique

Abstract: This paper describes a method of thermally fusing clad glass fibers, end to end, to obtain a good mechanical joint with low transmission loss. Methods of preparing fiber ends and aligning them for joining are discussed. Two sizes of fibers were joined (10.8-μm core and 20-μm core clad fibers with outside diameters of 75 μm and 150 μm respectively).∗

Reaction‐Rate Model for Fracture in Polymeric Fibers

Abstract: Electron paramagnetic resonance (EPR) techniques were used to determine the number of free radicals produced during deformation leading to fracture of nylon 6 fibers. A reaction‐rate molecular model is proposed to explain some of the deformation and bond‐rupture behavior leading to fracture. High‐strength polymer fibers are assumed to consist of a sandwich structure of crystalline‐block and amorphous‐flaw regions along the fiber axis. In the flaw regions, tie chains connecting the crystalline blocks are assumed to have a statistical distribution in length. These chains are, therefore, subjected to different stresses. The length distribution was determined by EPR. The probability of bond rupture was assumed to be controlled by reaction‐rate theory with a stress‐aided activation energy and behavior of various loadings determined by numerical techniques. The model is successfully correlated with experimental stress, strain, and bond‐rupture results for creep, constant‐rate‐of‐loading, and cyclic‐stress tests.

Short Fiber-Elastomer Composites:

Abstract: A tncomponent system of hexamethylenetetramme, resorcinol and high surface area hydrated silica provides good adhesion in bonding discontinuous fibers to elastomeric matrices. While this system (HR...

Web forming process

Abstract: A process for forming an air-laid, nonwoven web from separate supplies of individualized fibers, such as textile and papermaking fibers. Supplies of fibers are fed to oppositely rotating lickerins that are rotated at speeds which are optimum for the fibers being individualized by the lickerins. The individualized fibers are doffed from the lickerins by centrifugal force and high velocity air streams directed against the fibers clinging to the lickerin clothing. The fibers from each supply are entrained in their respective air streams, which are impelled at high rates of speed toward each other, and the air streams are combined in a mixing zone. The doffed fibers are given an initial trajectory as they leave their respective lickerins, and the inertia of the fibers in the air streams is sufficient to bring the fibers to the mixing zone and effect blending of at least a portion of the fibers from each supply in the mixing zone. The combined air stream has a gas to fiber volume ratio of at least 12,000:1, so that the fibers are relatively widely spaced in their respective streams, as well as in the combined stream. In communication with the mixing zone is a suction actuated condensing means where the fibers are deposited to produce a nonwoven web of fibers, for example, an isotropic nonwoven web. With gas to fiber volume ratios of between about 12,000:1 to about 275,111:1 in the combined stream, highly uniform webs can be produced at a high production rate up to 550 feet per minute or greater.

Effective Electrical, Thermal and Magnetic Properties of Fiber Reinforced Materials:

Abstract: We present here bounds for the effective conductivity (permittivity, permeability) of a fiber reinforced material in terms of volume fractions and a geometric factor. The results are simple algebraic expressions. Two parameters, G1 and G2 are needed to describe the fiber and matrix geometries, respectively. Both parameters lie between 1 and 1; 1 represents a circle and 1 a parallel lamella. We show 4 2 4 2

The fiber arrangement of the human tympanic membrane. A scanning electron microscopic observation.

Abstract: It is generally described that the main fibers of the lamina propria of the tympanic membrane are composed of an outer radial layer and inner circular layer of fibers. Besides these fibers, the crescent-parabolic system in humans or animals 2•3 ,12 and the transverse fibers in humans\" have been reported. Although transmission electron microscopic studies':\" have suggested the existence of transverse and parabolic fibers besides radial and circular fibers, the exact arrangement of transverse and parabolic fibers was not clearly described.

Matrix strengthening mechanisms of an iron fiber-copper matrix composite as a function of fiber size and spacing.

Abstract: Copper matrix-iron fiber composites of fiber diameters from 10 to 5 × 10−3 mils and volume fractions from 0.03 to 0.97 were fabricated in order to study the dependence of mechanical properties on these variables. Composite elastic moduli agreed well with the predictions of the rule of mixtures. However, matrix and composite yielding and plastic flow were quite dependent on fiber diameter and spacing, exhibiting positive deviations from the simple rule of mixtures by factors of more than five in some cases. Yielding behavior may be explained by a combination of dislocation extrusion and pileup models for low volume fractions of fiber. Triaxiality generated by the difference in Poisson coefficients of the phases inhibits matrix yielding in higher volume fraction composites, allowing matrix flow only when the fibers also yield.

Flame-retarded acrylonitrile fibers

Abstract: A FLAME-RETARDANT FIBER OF AN ACRYLONITRILE COPOLYMER THAT CONTAINS AT LEAST 10% BY WEIGHT ATOMS OF CHLORINE OR BROMINE, SAID ATOMS BEING DIRECTLY CONNECTED TO CARBON ATOMS OF THE COPOLYMER; SAID COPOLYMER HAVING DISTRIBUTED THROUGHOUT, FINELY DIVIDED PARTICLES OF AN OXIDE OF ANTIMONY, IN AN AMOUNT OF AT LEAST TWO PERCENT BY WEIGHT BASED ON THE WEIGHT OF THE COPOLYMER, SAID PARTICLES BEING LESS THAN 500 A. IN SIZE; SAID COPOLYMER ALSO HAVING DISTRIBUTED THROUGHOUT, PARTICLES OF A METALLIC OXIDE GREATER THAN 500 A. IN SIZE IN AN AMOUNT SUFFICIENT TO DELUSTER THE FIBER BUT NOT MORE THAN 2.25% OF THE AREA OF AN ELECTRON MICROGRAPH OF A CROSS-SECTION OF THE FIBER.

Shapable fiber-reinforced low molecular weight polyethylene terephthalate

Abstract: Glass fiber-reinforced thermoplastic polymer composite sheets are formed using semicrystalline polymers that have their glass transition temperature above room temperature and may be cold formed, i.e., shaped in a cold mold when preheated outside the mold. Glass-reinforced low molecular weight polyethylene terephthalate, or blends thereof, may be shaped in a cold mold, and exhibit excellent performance.

Rheological and heat transfer aspects of the melt spinning of monofilament fibers of polyethylene and polystyrene

Abstract: Two experimental studies of the melt spinning of fibers have been carried out using low-density polyethylene and polystyrene First, isothermal spinning experiments were carried out and the relationship between the fiber kinematics and drawdown force was studied The data were correlated by using the following two methods: (1) the concept of a non-Newtonian elongational viscosity and (2) a nonlinear integral theory of viscoelastic fluids In the second experiment, the spinline temperature profile of a monofilament fiber being pulled down from a spinneret through stagnant air was measured and the heat transfer coefficient computed A correlation between the local Nusselt number and a fiber Reynolds number was obtained An integral boundary layer analysis of forced convection heat transfer from a descending fiber was carried out

Scanning electron microscopy of the dog periodontium.

Abstract: The periodc-ntium of premolar teeth of dogs has been examined by scanning electron microscopy. lighl microscopy and microradiography. Scanning electron microscopy reveals a highly developed plexus of indifferent fibers associated with the principal fibers, The indifferent fiber plexus may be important in accomodalion of the periodontal ligament to tooth movement through anastomotie relationships between the plexus and principal fibers. Principal fibers perforate alveolar bone as compact bundles of smaller fibers. Perforating fibers of cementum enter calcified matrix as coiled or straight fibers. The number of coiled fibers is greatest in acellular cementum and the straight fibers are largest in diameter at root apices.

Method for impregnation of cellulosic fiber material with digesting liquor while preventing dilution of said liquor

Abstract: The digestion of cellulosic fiber material in a continuous digester is preceded by impregnation of the fiber material with digesting liquor in a separate vessel. In said impregnation vessel where the fiber material moves continuously from the top to the bottom, digesting liquor is supplied and spread at the middle portion of the length of the vessel. A portion of said liquor moves in countercurrent to the fiber material and displaces, at least partly, the liquid introduced into the vessel together with the fiber material and consisting of chips moisture, steam condensate and black liquor, thereby preventing dilution of the liquor with which the fiber material is impregnated in the lower part of the vessel. The displaced liquid is withdrawn through a strainer in the upper part of the vessel and removed from the impregnation vessel.

Method for making a hollow fiber separatory element

Abstract: A moving belt of hollow fibers is prepared by winding a continuous length of hollow fiber (or fibers) transversely around a pair of moving guide members. The moving fiber belt is convolutely wound upon an axis generally transverse to the direction of movement of said belt to form a fiber bundle. A band of solidifiable resin is applied to at least one transverse section of the hollow fiber bundle and subsequently solidified (cured) to form a tube sheet. The separatory element is then prepared by cutting the tube sheet in a plane generally perpendicular to the bundle axis to form a tube sheet face portion having open fiber ends terminating therein.

Fracture mechanics of a composite with ductile fibers

Abstract: F racture mechanics of a metal-matrix composite containing ductile-metallic fibers is described. Experimental verification of the proposed descriptions has been established with an aluminum-base composite containing uni-directional stainless-steel fibers. Theoretical description of the plastic energy dissipation shows that crack propagation across fibers is very difficult because of the high energy density represented by the fiber. The fiber contribution is an increasing function of volume fraction which results in the critical stress-intensity factor increasing with fiber content. On the other hand, crack propagation between fibers is very easy because the inter-fiber spacing limits the plastic energy dissipation in the matrix. The critical stress intensity for crack propagation between fibers is a decreasing function of volume fraction.

Reinforced rubber composition

Abstract: THE INVENTION COMPRISES A REINFORCED RUBBER COMPOSITION INCLUING RUBBER, DISCONTINUOUS FIBER FILAMENTS, A FINRLY-DIVIDED REINFORCING SILICEOUS PIGMENT, AND A RESIN FORMED BY THE REACTION OF A PHENOL WITH A METHYLENE DONOR.

Histochemical fiber types and fiber sizes in human masticatory muscles.

Abstract: – Biopsy specimens from the temporalis or masseter muscles of 12 subjects were studied by histochemical means. The fiber sizes in the masticatory muscles were compared with those of the biceps brachii muscle in 4 females. On the basis of staining reactions for ATPase, two fiber types, Type I (low ATPase activity) and Type II (high ATPase activity), were demonstrated. In the masticatory muscles the Type II fibers generally dominated in number and were smaller in diameter than Type I fibers. Both fiber types had smaller diameters than corresponding fiber types of biceps brachii.

Web forming apparatus

Abstract: An apparatus for forming an air-laid non-woven web wherein a pair of parallel lickerins are positioned adjacent one another with the lickerins being rotated in opposite directions, so that when a first supply of fibrous material is fed to one lickerin and a second supply of fibrous material is fed to the other lickerin, separate supplies of individualized fibers are produced that are entrained in separate air streams impelled toward one another and toward a mixing zone between the lickerins. The individualized fibers are doffed from lickerins by the separate air streams and centrifugal force, and the doffed fibers are given an initial trajectory, whereby the inertia of the fibers is sufficient to allow at least a portion of the fibers from each supply to become homogeneously blended as the air streams are impelled against one another. A suction actuated fiber condensing means is positioned in communication with the mixing zone, and the separate air streams are combined into a common air stream that directs the fibers through the mixing zone and toward the condensing means where the fibers are deposited to produce a web comprised of randomly oriented fibers. When the material fed to the first lickerin includes relatively long fibers, such as textile length fibers, and the material fed to the second lickerin contains relatively short fibers, such as papermaking fibers, a web of randomly arranged fibers can be produced having a dispersion of different length fibers in more or less uniform intermixtures, to create a web having desired properties.

High modulus organic fiber layers alternating with inorganic fiber layers in a resin matrix

Abstract: FIBROUS REINFORCED RESIN COMPOSITES COMPRISING HIGH MODULUS ORGANIC FIBERS AND INORGANIC FIBROUS MATERIALS IN SPECIFIED PROPORTIONS DEMONSTRATE SURPRISING INCREASES IN A STRUCTURAL PROPERTY ABOVE THOSE PREDICTED BY THE RULE OF MIXTURES.

On the strength of notched composites

Abstract: A n analysis is presented of the mechanics of failure of notched unidirectional composites subjected to tensile load in the fiber direction. The applicability of the Griffith-Irwin-Orowan theory to the fracture of composites is discussed. The effects of fiber debonding, matrix and fiber plasticity, and scatter in fiber strength are considered. Statistical lower bounds on the fracture propagation stress are developed.

Method for producing a rearranged fabric having improved cross-strength

Abstract: A method for producing, from a layer of fibrous material such as a fibrous web, nonwoven fabrics that contain apertures or holes or other areas of low fiber density and a pattern of groups of fiber segments defining such apertures, said fabric having improved cross strength. The method includes the steps of treating the fibrous layer by directing fluid rearranging forces against the layer while it is supported, stretching the treated layer in its transverse direction and treating the stretched layer with a plurality of fluid rearranging forces while the stretched layer is supported to produce a fabric having a pattern of fiber bundles defining a pattern of apertures or holes or other areas of low fiber density.

Determination of Lignin in Non-Wood Plant Fiber Sources

Abstract: Lignin contents of representative non-wood plants were determined by a 2-hr treatment at 5°C with 80 % sulfuric acid. Representative genera were selected to give data on stem fibers, leaf or hard fibers, and forages. The results were compared with those of a 16-hr, 72 % sulfuric acid procedure from the literature. Relative standard deviations for the materials by the two methods are comparable; i.e., ±2.41-3.48% and ±2.74-3.60% with 80 and 72% acid, respectively. Analysis of variance showed significant differences between the materials at the 99 % confidence level. However, at the 95 % confidence level, differences due to method were found only for hard-fibered leaf material. The considerable time savings afforded by the 2-hr (5°C), 80% sulfuric acid method is desirable. The 80 % sulfuric acid method has been adopted in our laboratory as the one of choice for determining lignin in fibrous non-wood plants.