Showing papers on "Fiber published in 1995"

Renewable Agricultural Fibers as Reinforcing Fillers in Plastics: Mechanical Properties of Kenaf Fiber-Polypropylene Composites

Abstract: Kenaf (Hibiscus Cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In our experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the non-polar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50 % by volume (39 % by volume) of kenaf-PP composites compares favorably with a 40 % by weight of glass fiber-PP injection molded composites, These results suggest that kenaf fibers are a viable alternative to inorganic/mineral based reinforcing fibers as long as the right processing conditions are used and for applications where the higher water absorption is not critical.

Short coir fiber‐reinforced natural rubber composites: Effects of fiber length, orientation, and alkali treatment

Abstract: Natural rubber is reinforced with untreated coir fiber chopped to different lengths, viz., 6, 10, and 14 mm. Mixes were also prepared using 10 mm-long coir fibers treated with 5% sodium hydroxide solution for different time intervals, viz., 4, 24, 48, and 72 h. These composites were vulcanized at 150°C. The vulcanization parameters, processability characteristics, and stress–strain properties of these composites were analyzed. The rubbercoir interface bonding was improved by the addition of a resorcinol–hexamethylenetetramine dry-bonding system. The reinforcing property of the alkali-treated fiber was compared with that of the untreated one. The extent of fiber orientation in the composite was determined from green strength measurements. From anisotropic swelling studies, the extent of fiber alignment and the strength of fiber–rubber interface adhesion were analyzed. Scanning electron microscopic studies were carried out to investigate the fiber surface morphology, fiber pullout, and fiber–rubber interface. © 1995 John Wiley & Sons, Inc.

Development and Optimization of a TiO2-Coated Fiber-Optic Cable Reactor: Photocatalytic Degradation of 4-Chlorophenol.

Abstract: We have developed, characterized, and utilized a photochemical reactor system that employs an optical fiber cable as a means of light transmission to solid supported TiO_2. Light energy is transmitted to TiO_2 particles, which are chemically anchored onto quartz fiber cores, via radial refraction of light out of the fiber. Operational factors that influence the efficiency of the bundled-array optical fiber reactor are as follows: the uniformity and extent of light propagation down the fiber, the degree of light absorption by the TiO_2 coating of the refracted light, and the ability of the chemical substrates to diffuse into the TiO_2 coating. A TiO_2 coating layer that minimizes the interfacial surface area of the quartz core and TiO_2 particles and operation with incident irradiation angles near 90" enhance light propagation down the fibers. A maximum quantum efficiency of Φ = 0.011 for the oxidation of 4-chlorophenol was achieved. This can be compared to a maximum quantum efficiency of Φ = 0.0065 for 4-chlorophenol oxidation in a TiO_2 slurry reactor operated under similar conditions.

Human adenovirus serotypes 3 and 5 bind to two different cellular receptors via the fiber head domain.

Abstract: The adenovirus fiber protein is responsible for attachment of the virion to cell surface receptors. The identity of the cellular receptor which mediates binding is unknown, although there is evidence suggesting that two distinct adenovirus receptors interact with the group C (adenovirus type 5 [Ad5]) and the group B (Ad3) adenoviruses. In order to define the determinants of adenovirus receptor specificity, we have carried out a series of competition binding experiments using recombinant native fiber polypeptides from Ad5 and Ad3 and chimeric fiber proteins in which the head domains of Ad5 and Ad3 were exchanged. Specific binding of fiber to HeLa cell receptors was assessed with radiolabeled protein synthesized in vitro, and by competition analysis with baculovirus-expressed fiber protein. Fiber produced in vitro was found as both monomer and trimer, but only the assembled trimers had receptor binding activity. Competition data support the conclusion that Ad5 and Ad3 interact with different cellular receptors. The Ad5 receptor distribution on several cell lines was assessed with a fiber binding flow cytometric assay. HeLa cells were found to express high levels of receptor, while CHO and human diploid fibroblasts did not. A chimeric fiber containing the Ad5 fiber head domain blocked the binding of Ad5 fiber but not Ad3 fiber. Similarly, a chimeric fiber containing the Ad3 fiber head blocked the binding of labeled Ad3 fiber but not Ad5 fiber. In addition, the isolated Ad3 fiber head domain competed effectively with labeled Ad3 fiber for binding to HeLa cell receptors. These results demonstrate that the determinants of receptor binding are located in the head domain of the fiber and that the isolated head domain is capable of trimerization and binding to cellular receptors. Our results also show that it is possible to change the receptor specificity of the fiber protein by manipulation of sequences contained in the head domain. Modification or replacement of the fiber head domain with novel ligands may permit adenovirus vectors with new receptor specificities which could be useful for targeted gene delivery in vivo to be engineered.

Integrable fiberoptic coupler and resulting devices and systems

Abstract: A fiberoptic coupler capable of many functions is presented. The basic fiberoptic coupler has a first sleeve (33), a second sleeve (36), a first collimating GRIN (34) or conventional lens, and a second collimating lens (35) or conventional lens. The first sleeve (33) holds end sections of two or more input optical fibers (30, 31) along the longitudinal axis of the sleeve. The second sleeve (36) holds an end section of at least one output optical fiber (32). The end face of the second sleeve faces the first sleeve end face. The first collimating GRIN (34) or conventional lens in front of the first sleeve end face collimates light signals from the input optical fibers and the second collimating GRIN (35) or conventional lens in form of the second sleeve end face focusses light signals from at least one of the input optical fibers (30, 31) into the single output fiber (32), or at least one of the output optical fibers (32, 39). With only one output fiber the coupler operates as a combiner. If more than one output fiber is held by the second sleeve, the input and output fibers can be arranged so that a light signal from one input fiber is sent to one output fiber. For added functionality, optical elements, such as isolators and wavelength-dependent filters can be inserted between the first and second collimating lenses.

Diesel particulate filter apparatus

Abstract: According to the present invention, a filter body for collecting particulates is constituted of a fiber laminate material produced by laminating a fiber material comprising a core material in the form of a fiber, and a covering layer of a material different from that of the core material formed around the outer periphery of the core material by coating. The core material of the fiber material is selected from among inorganic fibers such as glass or ceramic fibers containing alumina, and heat-resistant alloy fibers each made of a heat-resistant alloy selected from among Ti-Al alloys, Fe alloys containing at least one of Mo, Cr and Ni, and Fe-Cr-Al-Y alloys. The covering layer is made of a material selected from among silicon carbide ceramics respectively derived from polytitanocarbosilane, polysilazane and polycarbosilane, thermoplastic materials, silicon carbide ceramics such as Si-C, Si-Ti-C-O and Si-C-O or silicon nitride ceramics such as Si-N-C-O, alumina ceramics, and zirconia ceramics.

Complex grating structures with uniform phase masks based on the moving fiber-scanning beam technique.

Abstract: We present experimental results of complex grating structures fabricated with uniform phase masks by the moving fiber-scanning beam approach. Pure apodized gratings with side-mode-suppression levels in excess of 40 dB, self-apodized linearly chirped gratings, and phase shifted gratings with narrow-band transmission peaks have all been realized.

Liquid distribution layer for absorbent articles

Abstract: The present invention provides a liquid distribution layer for absorbent articles which exhibits directional liquid distribution properties and has desirable physical integrity. The liquid distribution layer is a nonwoven web of substantially continuous microfibers that has its fibers substantially aligned along one planar dimension of the web, wherein the fibers are hydrophilically modified or hydrophilic. Additionally, the liquid distribution layer may have an increasing fiber alignment gradient as well as a decreasing fiber thickness gradient in the direction of the web thickness. Further provided are suitable processes for producing the liquid distribution layer.

Hydrolysis of polycaprolactone fibers by lipase: Effects of draw ratio on enzymatic degradation

Abstract: Using polycaprolactone (PCL) fibers drawn with various draw ratios, the effects of draw ratio on enzymatic degradation were studied in order to understand the influence of fine structure on biodegradation. Degradability of PCL fibers as monitored by total organic carbon (TOC) formation or weight loss decreased with increase in draw ratio due to higher crystalline content. There were some distinct features of degradation behavior among the fibers, because the fibers underwent significant change in molecular organization of the polymer, such as crystallinity and orientation, during drawing processes. From scanning electron microscopy (SEM) photographs showing that the enzyme preferentially attacked amorphous or less ordered regions rather than crystalline or more ordered regions of the fiber, spherulites were observed in the undrawn fiber, and on the other hand, fibrillar stripes along the fiber axis were observed in the drawn fibers, which suggest that the spherulites in the undrawn fiber were extended to be broken, and fibril structures were formed during the drawing processes. These SEM photographs suggest that there are differences of crystal structures in addition to crystallinity among the fibers with different draw ratio, which significantly affects the enzymatic degradation behavior of the fibers. The diameter of the fibers became gradually slim, macroscopically uniform, as enzymatic degradation proceeded although it was dependent on draw ratio. It is evident that the degradation proceeded in the crystalline regions as well as the amorphous regions. © 1995 John Wiley & Sons, Inc.

Creep Behavior of Fiber-Reinforced Polymeric Composites: A Review of the Technical Literature:

Abstract: This report provides a review of the technical literature related to the creep behavior of fiber reinforced polymer (FRP) composites. The review presented here was directed toward those papers that...

Hollow fiber cartridge

Abstract: A cartridge containing a plurality of hollow fiber membranes is disclosed. The cartridge comprises a plurality of fibers (20) arranged in a bundle and at least one end of the bundle embedded in a tubesheet (30). The tubesheets (30) are fitted with end caps (28) to provide a chamber for the permeate. A feed tube (36) extends longitudinally through the bundle and a permeate discharge tube (40) is housed, preferably concentrically, within a feed tube (36). The cartridge does not required a high pressure seal, such as an O-ring seal, against the inner wall of the pressure vessel (10). The cartridge is configured as a single unit adapted for simple drop-in installation into a pressure vessel (10). Multiple cartridges may readily be inserted into a pressure vessel (10), and arranged so as to operate in series or in parallel. The hollow fiber membrane cartridge is adapted for industrial performance with high volumetric efficiency and high solute rejection.

The effect of hydrodynamic interactions on the orientation distribution in a fiber suspension subject to simple shear flow

Abstract: A single, non‐Brownian fiber suspended in a viscous, Newtonian fluid undergoing simple shear flow rotates in one of a set of closed orbits known as Jeffery orbits. In a fiber suspension, the hydrodynamic interactions among the fibers determine the distribution of fibers among these orbits. The hydrodynamic interactions in dilute and semidilute suspensions have been studied using slender‐body theory. Hydrodynamic, orientational diffusivities were obtained from an ensemble average of the fiber–fiber interactions. The steady‐state fiber orientation distribution is controlled by the anisotropy and orientation dependence of the diffusivities. The steady‐state and transient fiber orientation distributions are derived using a perturbation analysis for weak hydrodynamic orientational diffusion that is an extension of the work of Leal and Hinch [J. Fluid Mech. 46, 685 (1972)] for weak, isotropic, rotary Brownian motion. In the dilute regime, the steady‐state experimental distributions of Anczurowski and Mason [J. Colloid Interface Science 23, 522 (1967)] do not agree with the theoretical predictions. An explanation for these discrepancies accompanied with new experimental results is presented in this work. The theoretical predictions for the steady‐state orientation distribution, and the temporal orbit constant correlation function in the semidilute regime are in good agreement with the experimental results of Stover et al. [J. Fluid Mech. 238, 277 (1992)]. The correlation time for the fiber orientation is approximately inversely proportional to fiber concentration in both the dilute and semidilute regimes.

Erbium-doped silica fibers for intrinsic fiber-optic temperature sensors

Abstract: The variation in the green intensity ratio (2H11/2 and 4S3/2 energy levels to the ground state) of Er ions in silica fibers has been studied as a function of temperature. The different processes that are used to determine the population of these levels are investigated, in particular 800-nm excited-state absorption in Er-doped fibers and 980-nm energy transfer, in Yb–Er-codoped fibers. The invariance of the intensity ratio at a fixed temperature with respect to power, wavelength, and doped fiber length has been investigated and shown to permit the realization of a high-dynamic-range (greater than 600 °C), autocalibrated fiber-optic temperature sensor.

Short pineapple-leaf-fiber-reinforced low-density polyethylene composites

Abstract: Short pineapple-leaf-fiber- (PALF)-reinforced low-density polyethylene (LDPE) composites were prepared by melt-mixing and solution-mixing methods. In the melt-mixing technique, a mixing time of 6 min, rotor speed of 60 rpm, and mixing temperature of 130°C were found to be the optimum conditions. Tensile properties of melt-mixed and solution-mixed composites were compared. Solution-mixed composites showed better properties than melt-mixed composites. The influence of fiber length, fiber loading, and orientation on the mechanical properties has also been evaluated. Fiber breakage and damage during processing were analyzed from fiber distribution curve and optical and scanning electron micrographs. Considering the overall mechanical properties and processability characteristics, fiber length of 6 mm was found to be the optimum length of pineapple leaf fiber for the reinforcement in LDPE. The mechanical properties were found to be enhanced and elongation at break reduced with increasing fiber loading. Longitudinally oriented composites showed better properties than randomly and transversely oriented composites. Recyclability of the composite was found to be very good. A comparison of the properties of the PALF-reinforced LDPE composites with those of other cellulose-fiber-reinforced LDPE systems indicated superior performance of the PALF-LDPE composites. © 1995 John Wiley & Sons, Inc.

High-power cw neodymium-doped fiber laser operating at 9.2 W with high beam quality.

Abstract: We report on a 9.2-W cw, two-times diffraction-limited, neodymium-doped fiber laser operating in the 1.06-microm region. For a silica-based double-clad fiber, slope efficiencies of more than 25% are observed for pumping by a diode-laser system operating near 810 nm.

Modification of the surface properties of carbon fibers via the catalytic growth of carbon nanofibers

Abstract: The surface of commercial pitch and PAN-based carbon fibers has been modified by coating the structures with catalytically formed carbon nanofibers. Reaction conditions have been established that enable one to achieve optimum coverage by the secondary nanostructures without inducing any degradation in the mechanical properties of the parent fibers. Using this approach it is possible to produce a dramatic increase in the surface area of the fibrous structure from a nominal value of about 1.0 m2/g (untreated condition) up to between 250 and 300 m2/g (complete nanofiber coverage). This process results in a significant enhancement in the adhesion properties at the interface between the fiber and matrix components in a composite material. Mechanical tests performed on single uncoated and coated T300 carbon fibers demonstrated that it was possible to obtain an improvement of over 4.75 times in the interfacial shear strength of the fibers following deposition of a critical amount of nanofibers.

Optical fiber sensors

Abstract: The results of high temperature fatigue tests are introduced Fiber optic strain sensors, specifically designed for high temperature environments, were used to monitor strain on stainless steel specimens at elevated temperatures up to 2460/spl deg/F (1349/spl deg/C) The fatigue loading test results presented here were conducted by the Fiber and Electro-Optics Research Center (FEORC) in coordination with Wright Laboratories, Materials Directorate The strain, resulting from fatigue loading at high temperature, was monitored through the application and operation of short gauge length, low finesse, extrinsic Fabry-Perot interferometric (EFPI) optical fiber strain gauges constructed with metal coated silica-based fibers

Tension increase correlated to refractive-index change in fibers containing UV-written Bragg gratings.

Abstract: A strong axial tension increase induced by UV laser radiation is observed in the cores of single-mode optical fibers containing Bragg gratings, independently of the initial core stress. The induced index modulation of the gratings is linearly correlated to stress changes with a slope of (0.8 +/- 0.2) x 10(-4) mm(2)/kg. The phenomenon can be explained by a structural change of the glass in the fiber core into a more compact configuration.

Effect of Fiber Rupture on Tensile Properties of Short Fiber Composites

Abstract: A probabilistic-based micromechanical model has been developed for the postcracking behavior of a brittle matrix reinforced with short, randomly distributed fibers. The model predicts the composite-bridging stress crack-opening displacement (COD) relationship, accounts for fiber pullout, fiber tensile rupture, and a local frictional effect called snubbing. However, it does not account for fiber bending rupture, and the possible effect of matrix spalling at the exit points of inclined fibers from the matrix. The model assumes a fiber/matrix interface that is controlled by a constant frictional bond stress. The model is used to predict the composite tensile strength and fracture energy. Comparisons of model-predicted bridging stress-COD relationship with experimental data, where fiber rupture has occurred, show reasonable agreement supporting the validity of the proposed model. The model is then used to perform a parametric study to evaluate the effect of the micromechanical parameters on the composite tensile strength and fracture energy. The study suggests that this model can be used to design the composite for optimum performance.

Process for making fullerene fibers

Abstract: This invention provides a method and apparatus for producing fullerene fibers by establishing an electric field between a needle electrode and an opposing electrode in the presence of carbon and a heat source. Carbon is directed by the electric field to the needle electrode and heated by the heat source to form a carbon-carbon bonded fullerene network. The needle electrode may be moved to lengthen the fullerene network into a fullerene fiber. Fullerene fibers of 0.5 cm or longer may be produced by this method.

Comparison of one-photon and two-photon effects in the photosensitivity of germanium-doped silica optical fibers exposed to intense ArF excimer laser pulses

Abstract: The growth rate of fiber Bragg gratings written using 193 nm light from an ArF excimer laser is linearly proportional to the laser pulse energy density for fibers with high germanium doping but proportional to the square of the pulse energy density for standard telecommunications fibers with low germanium concentration. The two‐photon process in standard fibers yields refractive index increases that saturate around 10−3, an order of magnitude improvement over previous results in this type of fiber without sensitization treatment. The two types of photoinduced refractive index gratings have comparable thermal stability and preserve about 50% of their initial magnitude after 30 min at 600 °C.