Showing papers on "Fiber published in 1978"

Light propagation in graded-index optical fibers

Abstract: An accurate numerical method is described for solving the Helmholtz equation for a general class of optical fibers. The method yields detailed information about the spatial and angular properties of the propagating beam as well as the modal propagation constants for the fiber. The method is applied to a practical graded-index fiber under the assumptions of both coherent and incoherent illumination. A spectral analysis of the calculated field shows that leaky modes are lost and steady-state propagating conditions are established over a propagation distance of a fraction of a meter.

Size and Density of Fibrin Fibers from Turbidity

Abstract: In agreement with earlier observations that the angular dependence of light scattering by fibrin gels obeys the theory for light scattering by very long and thin rigid rodlike particles (intensity proportional to the square of half the scattering angle), we find that the turbidity, tau, of the less opaque gels varies as the inverse third power of the wavelength, lambda. Mass-length ratios of the fibers calculated from these two measurements closely agree. For fibrin gels containing fibers with a very high mass-length ratio (of which we had not been able to obtain interpretable scattering data), the turbidity is found not quite to vary as 1/lambda3. For these opaque gels, the fiber diameter is no longer negligible with respect to the wavelength. It is shown how the radius of gyration of the fiber cross section (and therefore the radius of cylindrical fibers) can be obtained from the ratio of slope and intercept of a plot of 1/tau lambda3 vs. 1/lambra2. The square of the radius of the fibers is found to be proportional to the mass-length ratio. The density of the fibers is calculated to be 0.28. This corresponds to a ratio of fiber volume to volume of protein contained in the fiber of 5.0.

The Crystal Structures of A‐, B‐ and C‐Polymorphs of Amylose and Starch

Abstract: The crystal structures of the A-, B- and C-polymorphs of amylose have been determined through a combination of fiber x-ray diffraction analysis and computer-based structure refinement. The three structures correspond to the naturally occurring A-, B- and C-starches. A- and B-structures differ in the crystalline packing of the helices and the water content. The C-structure is a mixture of A- and B-unit cells and, therefore, intermediate between the A- and B-forms in packing density.

Temperature dependence of critical fiber length for glass fiber-reinforced thermosetting resins

Abstract: In discontinuous fiber-reinforced composites, the critical fiber length plays an essential role in determining the mechanical properties. A method was devised to accurately determine the critical fiber length and the temperature dependence of the critical fiber length was studied for glass fiberepoxy and glass fiber-unsaturated polyester resin composites. If a continuous glass fiber is embedded in the matrix and the system is subjected to a tensile strain greater than the fiber ultimate tensile strain, the fiber breaks into many pieces. If the average length of these broken pieces (l) is measured, the critical fiber length (lc) is expressed as lc = 4/3l. The critical fiber length greatly increases with increasing temperature and the apparent shear strength at the interface, calculated from the critical fiber length, decreases linearly with increasing temperature.

Fiber optic light delivery apparatus and medical instrument utilizing same

Abstract: Disclosed is a fiber optic fiber transmission line which transmits light a distance from its source and is terminated, at its light delivery end, by a second fiber optic fiber of a larger diameter than the first fiber. An interlocking connector keeps the first and second fiber in positive contact in an efficient light energy transmission relationship. A plurality of second fibers form a set of tips for use in causing light convergence or divergence at the transmission line output.

Spontaneous and stimulated Raman scattering in long low loss fibers

Abstract: This paper considers the problem of forward Raman scattering process in a single transverse mode fiber. Both pump wave depletion and spontaneous scattering are considered in the analysis. Analytic solutions of the governing differential equations are obtained. We examine the conditions under which a nondepleted pump approximation is valid. Expressions are derived for the maximum fiber loss and the minimum fiber length which allow significant pump to Stokes wave conversion. It is shown that for a given fiber length there is an optimal pumping power, or at a given pump power there is an optimal fiber length that yields maximum first-order Stokes power output. Good agreement with published experimental results in the threshold power prediction is obtained.

Process and product thereof for stretching a non-woven web of an orientable polymeric fiber

Abstract: A non-woven web of synthetic fibers is selectively stretched in incremental portions in a first and second station wherein the first and second station are provided with sets of rolls having grooves parallel and perpendicular, respectively, to the axis of each set of rolls to form a bi-axially stretched web. One groove pattern of the rolls is generally a sinosoidal wave with distances between grooves being less than 1.0 millimeters times the web basis weight in grams per square meter.

Adsorptive nonwoven fabric comprising fused fibers, non-fused fibers and absorptive material and method of making same

Abstract: A novel adsorptive nonwoven fabric having good strength as well as good permeability and softness and a method of making the same is disclosed. This product consists essentially of supporting fibers containing a heat-fusible fiber and an adsorptive material, said supporting fibers being disintegrated in air before they are admixed with an adsorptive material, and a web is formed from the final mixture followed by being subjected to a heat treatment at a temperature above the melting point of said heat-fusible fiber to firmly fix said adsorptive material in the web by heat-fusion of the heat-fusible fiber.

Fourier transform infrared spectroscopic study of the structure of silane coupling agent on E-glass fiber

Abstract: Infrared spectra of silane coupling agents deposited on E-glass fiber were obtained by Fourier transform infrared spectroscopy (FT-IR). A spectral subtraction technique resolved all vibrational modes of the coupling agent deposited from various concentrations of treating solutions. The amount of vinyl functional coupling agent was determined by measuring the integrated peak intensities of the organic functional group. It revealed that the thickness of the coupling agent layer on the glass fiber depended on the concentrations of the treating solution. The rates of condensation reaction of polysiloxanol with and without glass fiber were followed. The coupling agent on the glass fiber reacted much faster than without glass at room temperature. It was concluded that the coupling agent molecules near the glass fiber surface have some order and can easily participate in the condensation reaction. The carbonyl group of a methacryl functional silane hydrogen bonds with hydroxyl groups. The methacryl functional silane on the glass fiber showed less hydrogen bonded groups than the precipitated polysiloxanol suggesting a mechanism of predominant head-to-head adsorption.

Stochastic strength and fatigue of fiber bundles

Abstract: Stochastic models for the failure of single fibers and fiber bundles are considered with a historical perspective. All surviving fibers in the bundle at any time t are assumed to share the load equally. Of particular interest is the tensile strength and time to failure in fatigue of such fibers and bundles. The stochastic model for the failure of single fibers is shown to have realistic features and a very favorable evaluation of the model is carried out using recently reported experimental data. Using asymptotic results for bundles which were recently obtained by the author, bundle failure is compared with single fiber failure. Many behavioral features carry over from fiber to bundle. But bundle lifetime is typically far less under fatigue loadings, though a moderate reduction in bundle load restores the lost lifetime. Most important, the variability in bundle lifetime and strength is inversely proportional to the square root of the number of fibers in the bundle. The results have implications in the design of cable structures.

Strength of discontinuous reinforced composites: I. Fiber reinforced composites

Abstract: The strength of randomly oriented short fiber composites has been modeled by a quasi-isotropic laminate. Lamination theory and a failure criterion will be used to approximate the stress-strain response of a composite as it is loaded to failure. Experimental data are presented and compared with the maximum-strain failure criterion.

Electropolymerization on graphite fibers

Abstract: The electrodic polymerization on graphite fibers of a variety of monomers having different types of functional groups has been investigated. In addition to vinyl polymerization, some novel polymerizations of cyclic functional groups have been conducted under appropriate polymerization conditions. In many instances, the grafting of the surface polymer to the fiber has been confirmed. The stereochemical configuration of poly(methyl methacrylate) resulting from electropolymerization was measured, but conclusive evidence could not be obtained for the occurrence of stereo-regulation in electrochemical polymerization on graphite fiber surface; Composite specimens were prepared by the incorporation of the coated fibers in an epoxy matrix. It was demonstrated that the effect of electropolymerization on the interfacial properties of the resulting composite was manifested in variations of the measured interlaminar shear and impact strengths of the composite specimens. The increase or decrease in interlaminar shear was accompanied by the usually observed reverse change in impact strength. In exception to this general trend, it was also indicated that the shear and impact strengths could simultaneously be increased. Implicit in these findings is the contribution of the electrochemically formed interlayer to one or more of the toughening mechanisms that are available to fiber reinforced composites. The potential value of interphase modification by electrochemical polymerization is thus clearly indicated.

Multi-zoned hollow fiber permeator

Abstract: Transversely-fed permeators containing a plurality of selectively permeable hollow fibers suitable for the selective permeation of at least one fluid in a fluid mixture containing at least one other fluid, said fibers being generally parallelly oriented within an elongated shell, are provided with at least one essentially fluid impermeable partition which is substantially transverse to the orientation of the hollow fibers and intermediate a fluid ingress means and a fluid egress means, each of said fluid ingress means and fluid egress means communicating through the elongated shell to the exterior of the hollow fibers, said at least one partition defining zones in said permeator, wherein the zone into which the fluid ingress means communicates is significantly smaller in available membrane surface area to effect the fluid separation than the available membrane surface area in at least one subsequent zone, and means for fluid communication between said zones such that the fluid flow in each zone is substantially transverse to the orientation of the hollow fibers.

Acoustic Emission Monitoring of Fiber Composite Materials and Structures

Abstract: A review of the current acoustic emission literature relating to fiber reinforced composite materials is presented. Summary tables which assist m the prompt delineation of the achievements in this research area are developed. Because of the qualitative character of much of the current literature, suggestions to develop quantitative AE standards are strongly recommended

Method of making same

Abstract: Method of making a casing reinforced by a stretchable glass fiber preform is disclosed. The casing may be reinforced by metal or a glass fiber mat which is shaped to provide positive engagement with the stretchable fiber preform before its impregnation by a matrix-forming resin.

The Combined Packing of Rods and Spheres in Reinforcing Plastics

Abstract: This paper produces some of the basic principles of the combined packing of rods and spheres and illustrates how the ratio of sphere to fiber diameter affects void volume, which is resin demand. It also points out how minimum packing parameters change with respect to fiber length to diameter ratio and how choosing size combinations can optimize benefits from packing. It is believed that these concepts can be applied to other aspects of the reinforced plastics business.

Dimensionally stable cellulosic backing web

Abstract: An improved dimensionally stable backing web is disclosed, especially for resilient flooring product and linoleum, comprising cellulosic fiber, a binder, antioxidant, fungicide and glass fiber, as well as optionally dyes or pigments, surfactants and vulcanizing agents. Also optionally present are calcium silicate mineral fiber or synthetic fiber, such as polyolefin, polyester, nylon, acrylic or modacrylic fiber, a cellulose acetate or mixtures thereof. The binder can be a natural rubber or synthetic rubber latex or mixtures thereof. The synthetic rubber latex is preferably selected from the following: styrene-butadiene; carboxylated styrene-butadiene, polyacrylic ester, polyvinyl acetate; polyisobutylene, a copolymer formed from vinyl acetate monomers and acrylic acid; polychloroprene, acrylonitrile-butadiene or carboxylated acrylonitrile-butadiene; polyurethane; a copolymer of ethylene and vinyl acetate; or other elastomeric copolymers. The glass fiber is dispersed into a slurry which is introduced in manufacturing the backing web by wet web impregnation, dry web impregnation, latex beater deposition, or continuous latex wet-end deposition, preferably by wet web impregnation. The web can be used alone or in combination with one or more surface coatings to form a layered material.

Poly(ethylene terephthalate) flat yarns and tows

Abstract: New poly(ethylene terephthalate) flat yarns and tows having physical properties and dyeability more akin to cellulose acetate than to conventional poly(ethylene terephthalate) flat yarns are prepared directly by spinning at speeds of about 4000 meters/minute. Among the useful physical properties are a modulus of 30 to 65, which is relatively unaffected by boiling, low boil-off shrinkage, no need for heat setting, low shrinkage tension, large crystal size, and low amorphous orientation which is measured by a value termed "amorphous modulus." The flat yarns may be used, e.g. in textile fabrics, without drawing, and may be modified, e.g. by air-jet texturing. The tows may be converted into staple fiber.

Coatings for fiber waveguides

Abstract: Microbending loss is reduced and abrasion protection is afforded for optical fibers by relatively thick polymer coatings characterized in part by a preferred elastic tensile modulus and cold flow property. The coating process uses rapid cooling of a liquid application to promote rapid gelation or solidification and thus achieve uniform coating diameter without beading. Fibers so coated are formed into ribbon structures having definite center-to-center fiber spacing. Preparation of coated fibers or ribbon structures for splicing is achieved by solvent stripping of the coating.

Hollow fiber permeator apparatus

Abstract: The performance of axially-fed permeators containing a plurality of selectively permeable hollow fibers suitable for the selective permeation of at least one fluid in a fluid mixture containing at least one other component, wherein the hollow fibers are positioned in the permeator to form an elongated bundle of hollow fibers, is enhanced by the use of means to longitudinally compact the bundle.

Removal of oligosaccharides from soybean water extracts by ultrafiltration

Abstract: The feasibility of using ultrafiltration (UF) for removal of oligosaccharides from aqueous extracts of soybeans was investigated. Soybeans were soaked, blanched, ground, prefiltered, and the resulting full-fat extract processed in a hollow fiber UF unit. Initial permeate flux of 43-60 L/m2/hr at 3.5% total solids decreased semi-logarithmically to 13 L/m2/hr at 14% total solids. Low pH resulted in higher flux. Rates of removal of oligosaccharides closely followed theoretical behavior for a nonrejected solute during ultrafiltration and continuous diafiltration, and up to 96% could be removed by a two-stage UF process. Final product assayed 60% protein, 35% fat and 0.6% oligosaccharides (dry basis).

Monitoring arrangement utilizing fiber optics

Abstract: An arrangement for monitoring a particular condition, specifically temperature in a preferred embodiment, is disclosed herein and includes a sensor in the form of at least one optical fiber. This optical fiber cooperates with a light source and detector for sensing changes in the temperature being monitored and is accomplished by selecting the fiber such that the amount of light which passes through it varies with changes in temperature.

Higher order structure in metaphase chromosomes. II. The relationship between the 250 A fiber, superbeads and beads-on-a-string.

Abstract: The morphology of metaphase chromosome-derived chromatin fibers released from cells by non-ionic detergent cell lysis in the presence of divalent cations has been studied by electron microscopy. In these preparations the euchromatic arms appear as a series of loops, 200-300 A in diameter, which are composed of closely-apposed nucleosome arrays. The higher order fiber in chromosomes derived from detergent-lysed cells appears to be less stable than chromatin fibers obtained by mechanical cell lysis. The fiber breaks down into a series of non-uniform nucleosome aggregates (superbeads) and finally to chromatin in a beads-on-a-string morphology upon incubation at 31 degrees for 20 min. These observations allow us to suggest a relationship between uniform thick fibers, superbead-containing fibers, and beads-on-a-string chromatin within metaphase chromosomes.

Fiber/slag composition

Abstract: A composition comprising an admixture of pulped fibers and a slag characterized by an open pore structure.

Thermal cycling-induced deformation of fibrous composites with particular reference to the tungsten-copper system

Abstract: Dimensional stability of fibrous composites under conditions of elevated temperature cycling has been examined with reference to the familiar model system, tungsten wirereinforced copper. Preferential growth of the matrix in the direction parallel to the reinforcing fibers, the amount of which increased with the number of cycles, was observed in specimens subjected to hundreds of repctitive thermal cycles in the temperature range between 0.35 and 0.8 of the matrix homologous temperature. The amount of growth per unit length after a given number of cycles was found to increase with increasing the holding time at the upper cycling temperature; it was also dependent on such composite variables as the fiber length, fiber diameter, and fiber volume fraction. This observation strongly suggests that interface sliding plays an important role in elevated temperature deformation of this class of material. On the basis of a model which assumes a viscous nature of the phase boundaries, the phenomenon observed is theoretically explained in terms of interfacial sliding-induced relaxation of the internal stress built up in the composite due to differential thermal expansion of the composite constituents.

Hydraulically needling fabric of continuous filament textile and staple fibers

Abstract: A lightweight composite fabric characterized by high retention of fiber content during initial laundering and exceptionally high strength as measured close to the edge of the fabric with cover and fabric aesthetics equivalent to conventional fabrics having 50% higher basis weight are produced by hydraulically needling short staple fibers and a substrate of continuous filaments formed into an ordered cross-directional array. The individual continuous filaments of the array are well spread and separated so that they have a spaced-apart relationship allowing interentangling of the short staple fibers with the continuous filaments to form more than about two reversals in the staple fibers per cm of staple fiber length between the faces of the fabric. The staple fibers have a linear density of less than about 0.3 tex per filament, are from about 0.5 cm to about 1 cm in length and comprise about 20% to about 50% of the weight of the composite fabric.