scispace - formally typeset
Search or ask a question

Showing papers on "Fiber published in 1975"


Journal ArticleDOI
TL;DR: In this article, a continuous silicon carbide fiber of high-tensile strength (about 350 Kg/mm2) was synthesized by means of the heat-treatment of organosilicon polymer obtained from dodecamethylcyclohexasilane.
Abstract: Continuous silicon carbide fiber of high-tensile strength (about 350 Kg/mm2) was synthesized by means of the heat-treatment of organosilicon polymer obtained from dodecamethylcyclohexasilane. X-ray analysis and high voltage electron microscopic observations revealed that the obtained continuous fiber is an ultrafine grain structure of β-silicon carbide.

437 citations


Journal ArticleDOI
Robert Olshansky1
TL;DR: Mode coupling theory is applied to the study of multimode optical fibers with graded-index cores and the results predict the dependence of the induced losses on the fiber's characteristics.
Abstract: Mode coupling theory is applied to the study of multimode optical fibers with graded-index cores. For coupling caused by random bends in the waveguide axis, the results predict the dependence of the induced losses on the fiber's characteristics. The impulse response is determined for fibers with random bends having several different power spectra. The results are used to predict the transmitted power, the delay time, and the rms pulse width in fibers with graded-index cores.

373 citations


Journal ArticleDOI
TL;DR: Stereological techniques of point and intersection counting were used to measure morphological parameters from light and electron micrographs of frog skeletal muscle to obtain results for sartorius muscle and semitendinosus fibers.
Abstract: Stereological techniques of point and intersection counting were used to measure morphological parameters from light and electron micrographs of frog skeletal muscle. Results for sartorius muscle are as follows: myofibrils comprise 83% of fiber volume; their surface to volume ratio is 3.8 mum-1. Mitochondria comprise 1.6% of fiber volume. Transverse tubules comprise 0.32% of fiber volume, and their surface area per volume of fiber is 0.22 mum-1. Terminal cisternae of the sarcoplasmic reticulum comprise 4.1% of fiber volume; their surface area per volume of fiber is 0.54 mum-1. Longitudinal sarcoplasmic reticullum comprises 5.0% of fiber volume, and its surface area per volume of fiber is 1.48 mum-1. Longitudinal bridges between terminal cisternae on either side of a Z disk were observed infrequently; they make up only 0.035% of fiber volume and their surface area per volume of fiber is 0.009 mum-1. T-SR junction occurs over 67% of the surface of transverse tubules and over 27% of the surface of terminal cisternae. The surface to volume ratio of the caveolae is 48 mum-1; caveolae may increase the sarcolemmal surface area by 47%. Essentially the same results were obtained from semitendinosus fibers.

260 citations


Journal ArticleDOI
TL;DR: In this paper, the processes used to produce high-performance carbon fibers are described from fundamentals, and the resulting fiber microstructures and the consequences of these structures on properties are presented.
Abstract: Graphite has a hexagonal close-packed crystal structure which is strong and stiff in the two directions of the basal plane and, in the third direction—perpendicular to the basal plane—is weak and compliant. High-performance carbon fibers must make use of the strong directions while suffering from the poor properties of the third. This paper describes, from fundamentals, the processes used to produce high-performance carbon fibers. The resulting fiber microstructures and the consequences of these structures on properties are presented.

186 citations


Journal ArticleDOI
TL;DR: The protective quality of a jacket is found to depend on a combination of stiffness and compressibility and on the fiber characteristics, which are related to dimensional variations and lateral forces considered typical for cable packaging.
Abstract: Glass fibers are in general not thick enough to withstand external forces on their own without suffering axial distortion, mode coupling, and loss. Thus, plastic jackets must be carefully designed to provide effective protection. We evaluate jacket designs ranging from the mere use of soft materials to the application of multiple plastic coatings and graphite reinforcement. We compute the distortion loss as a function of dimensional variations and of lateral forces considered typical for cable packaging. The protective quality of a jacket is found to depend on a combination of stiffness and compressibility and on the fiber characteristics.

176 citations


Journal ArticleDOI
TL;DR: A simple method has been devised for the experimental determination of mode conversion coefficients in multimode fibers and involves only the observation of the far-field output as the angle of incidence of a collimated input beam is changed.
Abstract: A simple method has been devised for the experimental determination of mode conversion coefficients in multimode fibers and involves only the observation of the far-field output as the angle of incidence of a collimated input beam is changed. The normalized mode coupling coefficient in a liquid-core fiber is D = 3 x 10-6 rad2 / m and increases by as much as a factor of 10 when transverse pressure is applied. Values some 2 orders of magnitude larger are found in glass-core fibers. There is good agreement between the theory presented and experiment.

168 citations


Journal ArticleDOI
TL;DR: The loss induced in optical fibers by random bends in the fiber axis is studied by winding fibers under constant tension onto a drum surface that is not perfectly smooth to reduce the effect by means of coatings and increased numerical aperture.
Abstract: The loss induced in optical fibers by random bends in the fiber axis is studied by winding fibers under constant tension onto a drum surface that is not perfectly smooth. The tension forces the fibers to conform to slight surface irregularities, which can result in an increase in the optical loss on the order of 100 dB/km. This microbending loss may be a significant design consideration in system applications of low-loss optical fibers. Data are presented on the reduction of the effect by means of coatings and increased numerical aperture.

165 citations


Journal ArticleDOI
TL;DR: It is suggested that potassium and malate act as osmoregulatory solutes and that malate, at least in part, arises from dark CO(2) fixation reactions.
Abstract: Kinetics and osmoregulation of cotton (Gossypium hirsutum L.) fiber growth (primarily extension) have been studied. Growth is dependent on turgor pressure in the fiber. It is inhibited when a decrease in the water potential of the culture medium due to an addition of Carbowax 6000, equals the turgor pressure of the fiber. Potassium and malate accumulate in the fiber and reach peak levels when the growth rate is highest. Maximum concentrations of potassium and malate reached in the fiber can account for over 50% of the osmotic potential of the fiber. As growth slows down, levels of potassium and malate decrease and turgor pressure declines. Cotton ovules are capable of fixing H(14)CO(3) (-) in the dark, predominantly into malate. Fiber growth is inhibited by the absence of potassium and/or atmospheric CO(2). We suggest that potassium and malate act as osmoregulatory solutes and that malate, at least in part, arises from dark CO(2) fixation reactions.

125 citations


Journal ArticleDOI
TL;DR: In this article, a pedestal growth (modified zone melting) technique was used to grow single-crystal fibers of various materials for devices covering a wide range of applications, especially for optical communications.
Abstract: Single−crystal fibers of Nd:YAG have been grown in diameters as small as, but not limited to, 50 μm by a pedestal growth (modified zone melting) technique. Room−temperature cw laser operation has been achieved with 0.5−1−cm−long samples. The method is directly applicable to the growth of single−crystal fibers of various materials for devices covering a wide range of applications, especially for optical communications.

109 citations


Journal ArticleDOI
TL;DR: The starting material of a continuous silicon carbide fiber with very high tensile strength is a polycarbosilane as discussed by the authors, which decomposes from 300°C in vacuum and is gradually converted into a β-silicon carbide fibre by the heat-treatment at the temperature above 800°C.
Abstract: The starting material of a continuous silicon carbide fiber with very high tensile strength is a polycarbosilane. It begins to decompose from 300°C in vacuum and is gradually converted into a β-silicon carbide fiber by the heat-treatment at the temperature above 800°C.

100 citations


Patent
28 Jul 1975
TL;DR: In this paper, an electrical arc discharge is generated at the junction between the fibers and is moved along the junction to ensure complete fusing of the fiber endfaces, which is obtained by applying only enough heat to the fiber junction to cause the fibers to adhere to each other without forming a good optical connection.
Abstract: A method and apparatus are described for permanently splicing glass optical fibers. The fibers are aligned colinearly, and their endfaces are brought into contact. An electrical arc discharge is generated at the junction between the fibers and is moved along the junction to ensure complete fusing of the fiber endfaces. Best results are obtained by first applying only enough heat to the fiber junction to cause the fibers to adhere to each other without forming a good optical connection, and thereafter, increasing the arc current to a value sufficient to cause complete fusion of the fiber endfaces.

Journal ArticleDOI
Zdenek Mencik1
TL;DR: The unit cell of poly(tetramethylene terephthalate) is triclinic with parameters a = 5.96 A, b = 4.83 A, c (fiber axis) = 11.3°; space group P1, calculated crystalline density 1.41 g/cc as mentioned in this paper.
Abstract: The unit cell of poly(tetramethylene terephthalate) is triclinic with parameters a = 5.96 A, b = 4.83 A, c (fiber axis) = 11.62 A, α = 115.2. β = 99.9, and γ = 111.3°; space group P1, calculated crystalline density 1.41 g/cc. The plane of the benzene ring is found to be inclined by about 15° from the fiber axis, contributing to a shortening of the fiber period as compared to the period expected on the basis of analogy with other members of the terephthalate ester series. The remaining shortening of the fiber period occurs in the O°CH2°CH2segment of the chain. No abnormally short distances among neighboring chain atoms were observed. A typical texture pattern was found in specimens of this polymer that were cold rolled and subsequently annealed. In this texture the c axis of the unit cell is highly oriented in the rolling direction; the a and b axes of the unit cell are oriented preferentially so that the terephthalate residue lies as close as possible to the plane of rolling.

Journal ArticleDOI
TL;DR: Preliminary results are described of single warm fiber activity recorded from human cutaneous nerves from fibers excited by noxious heat.
Abstract: In human subjects, afferent impulses elicited by thermal stimulation of the skin have been recorded so far from cutaneous nerve fibers responding to cooling (Hensel and Boman, 1960) and from fibers excited by noxious heat (van Hees and Gybels, 1972; TorebjGrk, 1974; TorebjGrk and Hallin, 1974). In the present note preliminary results are described of single warm fiber activity recorded from human cutaneous nerves.

Patent
11 Jul 1975
TL;DR: A conjugate fiber of a thermoplastic synthetic organic polymer composed of a high-melting polymer component and a low melting polymer component, having a melting point at least 40°C lower than that of the high-merchant component, and having adhered to its surface finely divided particles of an adsorbent, is a good filter having reduced pressure loss and increased adsorbing power.
Abstract: A conjugate fiber of a thermoplastic synthetic organic polymer composed of a high melting polymer component and a low melting polymer component, said low melting polymer component having a melting point at least 40° C. lower than that of the high melting polymer component, and having adhered to its surface finely divided particles of an adsorbent. The fiber is a good filter having reduced pressure loss and increased adsorbing power. Fibrous materials and articles are made from these conjugate fibers.

Journal ArticleDOI
TL;DR: Theoretical and experimental studies on microbuckling compression failure of fiber-reinforced unidirectional composites subjected to compression loads parallel to the fiber direction are presented in this article.
Abstract: Theoretical and experimental studies are presented on microbuckling compression failure of fiber-reinforced unidirectional composites subjected to compression loads parallel to the fiber direction. The approximate microbuckling equation is derived by the energy method. Results predicted from this equation are compared with test data and good agreement is found, indicating that for certain combinations of constituents, microbuckling is a valid failure mode. The influence of the following parameters on microbuckling is investigated theoretically and experimentally: fiber volume fraction, fiber shape, fiber size, properties of fibers and resins, fiber-end configuration, and specimen geometry. Other failure modes for composites subjected to compression loading are also briefly discussed.

Journal ArticleDOI
TL;DR: In this paper, the size and character of the damage zone at the tip of sharp notches in fiber reinforced plastic laminates have been investigated, and a strong dependence of damage zone size and fracture toughness on ply thickness, fiber orientation, and fiber properties is demonstrated and discussed.
Abstract: The size and character of the damage zone at the tip of sharp notches in fiber reinforced plastic laminates have been investigated The variables studied were the stress intensity factor, specimen size, laminate thickness, ply thickness, ply orientation, and fiber properties The damage zone consists of subcracks parallel to the fibers of each ply, in some cases accompanied by delamination between plies The damage zone is found to increase in extent approximately in proportion to K2I up to fracture for notch-sensitive laminates For notch-insensitive laminates, a point is reached where the zone spreads rapidly across the entire specimen prior to fracture A strong dependence of damage zone size and fracture toughness on ply thickness, fiber orientation, and fiber properties is demonstrated and discussed


Patent
29 Dec 1975
TL;DR: In this article, a process for manufacturing finished and semi-finished articles from mixtures of normally incompatible synthetic resin scrap materials is described, which consists of coarsely grinding thermoplastic scrap materials containing two or more mutually incompatible therm-oplastic resins and possibly up to 25 parts % by weight of foreign materials, incorporating into the coarsely ground therm-plastic resin mixture through the application of heat, pressure, or a sequential or simultaneous application of either heat and pressure.
Abstract: A process is disclosed for manufacturing finished and semi-finished articles from mixtures of normally incompatible synthetic resin scrap materials. The process comprises coarsely grinding thermoplastic scrap materials containing two or more mutually incompatible thermoplastic resins and possibly up to 25 parts % by weight of foreign materials, incorporating into the coarsely ground thermoplastic resin mixture through the application of heat, pressure, or a sequential or simultaneous application of heat and pressure, from about 5 to about 25 parts by weight of a fibrous material, the individual fibers in said fibrous material having an average length equal to at least three times the average size of the fragments constituting the coarsely ground thermoplastic resin mixture, and finally, forming the resin/fiber mass into finished or semi-finished article employing known and conventional techniques.


Journal ArticleDOI
TL;DR: It is concluded that hypoinsulinism has differential effects on the 3 fiber types in heterogeneous rat skeletal muscle, and that slow-twitch fibers are least affected by the diabetic condition.
Abstract: The response of rat gastrocnemius muscle fibers to chronic streptozotocin-diabetes was studied. Transverse sections of this muscle from normal and diabetic rats were histochemically assayed for reduced diphosphopyridine nucleotide-diaphorase, myofibrillar adenosine triphosphatase, mitochondrial alpha-glycerophosphate dehydrogenase, beta-hydroxybutyrate dehydrogenase, and alkaline phosphatase activities. Cross-sectional areas of the fiber types were measured, and fiber capillarization and populations estimated. Chemically-induced diabetes appeared to have little effect on the metabolic or morphological properties of slow-twitch fibers. However, a general dedifferentiation occurred in the 2 fast-twitch fiber populations. There was a loss of oxidative potential in the fast-twitch-oxidative-glycolytic fibers, and a significant decrease in size in the fast-twitch-glycolytic fibers. No change in the proportions of slow- and fast-twitch fibers in the muscles of diabetic rats occurred. It is concluded that hypoinsulinism has differential effects on the 3 fiber types in heterogeneous rat skeletal muscle, and that slow-twitch fibers are least affected by the diabetic condition.

Book
01 Jan 1975
TL;DR: In this paper, the authors describe commercially available natural fibers, manmade fibers, and their physical properties, and present laboratory tests for the classification of newly synthesized manmade fiber.
Abstract: Describes commercially available natural fibers, manmade fibers, and their physical properties. Reviews laboratory tests for the classification of newly synthesized manmade fibers. The seventh edition adheres to the schematic approach used in earlier editions but places more emphasis on the use of microscopy in fiber identification. Contains the following chapters: Properties of Textile Fibers (Natural, Manmade, Metal Coated Yarns, and Nonwovens and Other Nontraditional Fiber Assemblies); Photomicrographs; Scheme of Analysis (Microscopical Examination of Fiber Specimens, Identification of Homogeneous Fiber Specimens, Fiber Blends, and Instrumental Methods of Analysis); and Notes on Reagents and Methods of Testing (Stripping of Dyes, Formaldehyde Treatments, Resin Treatments, Refractive Indexes of Fibers, Optical Test for Polyethylene Terephthalate, Fiber Densities, Melting Points of Fibers, Phloroglucinol and Hydrochloric Acid Test, Drying-Twist Test, Meldrum's and Sevron Orange Stains, Solubility and Staining Tests for Acrylics, Regenerated Viscose Fiber Tests, Preparation and Use of Reagents, Fiber Diameters, and Nylon Fiber Staining Methods).

Patent
03 Oct 1975
TL;DR: In this article, a polyethylene hollow fiber made according to the teachings of the prior art is achieved, with gas permeability approaching 10-2 cc (STP) per cm2 per second per cm. transmembrane pressure differential.
Abstract: Normally hydrophobic, polyethylene hollow fibers having contiguous microporosity are prepared by extruding a heated solution of a polyethylene and an ester from a hollow fiber spinnerette, simultaneously cooling and drawing the forming fibers to a ratio of up to 40 to 1, drawing the gelled fibers to an overall ratio of from about 1.5/1 to 800/1 and then removing the ester. The maximum pore radius ranges up to about 50A, and the fibers have gas permeabilities approaching 10- 2 cc (STP) per cm2 per second per cm. Hg. transmembrane pressure differential. A significant increase in permeability over polyethylene hollow fibers made according to the teachings of the prior art is achieved.

Patent
04 Dec 1975
TL;DR: Refractory heat insulating materials consist of 45-75% by weight refractory aluminosilicate fiber, 2-16% binding agent consisting of starch and colloidal silica, and 1-20% particulate aluminum, magnesium and/or silicon as discussed by the authors.
Abstract: Refractory heat insulating materials consist of 45-75% by weight refractory aluminosilicate fiber, 2-16% by weight a binding agent consisting of starch and colloidal silica, and 1-20% by weight particulate aluminum, magnesium and/or silicon.

Journal ArticleDOI
TL;DR: In this article, acrylic acid and acrylonitrile (AN) were used to carry out grafting on polyester (PE) fibers using the techniques of initiation by γ-radiation as well as benzoyl peroxide.
Abstract: Acrylic acid (AA) and acrylonitrile (AN) were used to carry out grafting on polyester (PE) fibers using the techniques of initiation by γ-radiation as well as benzoyl peroxide. The nature of the grafted fiber substance was found to be the same, irrespective of the grafting technique. Extent of grafting depended upon the time, concentration of the initiator, and the monomer as well as on the irradiation dose. The increase in the moisture regain was directly proportional to the amount of graft in the fiber. AA grafted fibers were rendered more hydrophilic than AN grafted fibers for equivalent amount of grafts. Considerable improvement in dyeability of the PE fibers was possible through grafting. About 50% to 100% improvement with disperse dyes was observed in case of PE fibers containing 22.4% and 9.0% graft of AA and AN, respectively. Intense fast dyeing with direct and basic (cationic) dyes was also possible, and the dye content was proportional to the extent of graft introduced in the fiber. The CN groups were reduced to NH2 groups in the AN graft on the fiber. In this way, deep, fast, and bright dyeing was obtained with reactive dyes. Electrokinetic studies were carried out on the grafted fibers. With the increased amount of AA graft, the maxima in the zeta potential curve shifted toward higher acidic pH as greater amounts of alkali was utilized by the COOH groups in the graft. In this respect, CN groups were less sensitive due to their lesser polarity as compared to the carboxylic groups. It was observed from surface charge density (S.C.D.) studies that the effective surface area of the fiber decreased with the increase in the amount of graft, particularly in case of AN graft. Surface conductivity (S.C.) studies revealed that with increase in the number of polar groups (COOH) on the surface of the fiber, the S.C. increased with the increase in the amount of AA graft. In case of AN grafts, the reduction in effective surface area of the fiber played a more important role than the contribution by the CN groups to surface conductivity.

Journal ArticleDOI
TL;DR: It is concluded that graphite Fiber reinforcement is beneficial in improving certain mechanical and thermal properties of surgical bone cement, however, considerable effort remains to produce a clinically usable graphite fiber reinforced bone cement.
Abstract: This paper presents the results of a brief experimental investigation to determine the effects of graphite fiber additives on the flexuaral, compressive, and exothermal characteristics of surgical bone cement. The materials used in the investigation were polymethyl-methacrylate (PMM) and chopped graphite (GY70) fibers. Both fiber reinforced and unrein-forced beam and cylinder specimens were fabricated and tested. The unreinforced specimens were used to develop baseline data.

Patent
30 Jul 1975
TL;DR: In this paper, a room temperature vulcanizable silicone rubber having a high coefficient of thermal expansion is provided at the interface between an optical fiber and a surrounding fiber reinforced resin shell in a cable construction.
Abstract: A room temperature vulcanizable silicone rubber having a high coefficient of thermal expansion is provided at the interface between an optical fiber and a surrounding fiber reinforced resin shell in a cable construction. The surrounding rubber because of high coefficient thermal expansion shrinks more than the optical fiber or the resin shell during the manufacture operation. This relieves radial compressive loads on the optical fiber and prevents the distortion of the optical fiber by the surrounding fiber reinforced shell in manufacture and use. As a consequence, light transmission qualities are not impaired.

Journal ArticleDOI
TL;DR: Muscle fiber fine structure was quantitatively analyzed in 70 longitudinally and 65 transversely sectioned fibers from 10 control subjects without weakness and the feasibility of typing human muscle fibers at the ultrastructural level was evaluated.
Abstract: Muscle fiber fine structure was quantitatively analyzed in 70 longitudinally and 65 transversely sectioned fibers from 10 control subjects without weakness. The average mitochondrial fraction of the fiber volume is close to 4 percent and the mean size of a mitochondrion is about 0.1 μm 2 . The sarcotubular surface area per unit fiber volume is close to 1.5 μm 2 /μm 3 in transverse sections and 0.65 times this value in longitudinal sections. Only one-third of all fibers contain lipid droplets in the sectioned plane, and for all fibers the droplets account for approximately 0.12 percent of the fiber volume. Variations with the age and sex of the subjects and with different muscles were analyzed and the feasibility of typing human muscle fibers at the ultrastructural level was evaluated.

Journal ArticleDOI
TL;DR: In this paper, the effect of fiber anisotropy and lack of perfect bond between fiber and matrix on the shear mode microbuckling of Kevlar 49/epoxy composites was evaluated.

Journal ArticleDOI
TL;DR: In this article, the mixed mode fracture of unidirectional composites is investigated by application of the strain energy density theory, and two analytical models are used: the first assumes that the composite is an ideal homogeneous anisotropic body, and the second assumes that failure takes place in a layer of matrix material whose edges are bonded to two orthotropic plates.
Abstract: The mixed mode fracture of unidirectional composites is investigated by application of the strain energy density theory. Two analytical models are used. The first assumes that the composite is an ideal homogeneous anisotropic body, and the second assumes that failure takes place in a layer of matrix material whose edges are bonded to two orthotropic plates. The expressions for the strain energy density factor, S, are derived for both models, and brittle fracture is assumed to occur when the S-factor in an element of material ahead of the crack reaches a critical value, Sc. Results are presented for E-glass fiber reinforced plastics, stainless steel fiber reinforced aluminum and graphite fiber epoxy materials and compared with available experimental data. The latter model is preferred as it accounts for the effect of nonhomogeneity that is inherent in the filament-reinforced composites.

Journal ArticleDOI
TL;DR: Statistical analysis has shown that the experimental accumulative curves can be best described by a single parameter exponential equation Y = 1 − e−λα where Y is the accumulative fraction of fibers, α is the orientation angle and λ is a single empirical parameter.
Abstract: Oriented short fiberglass mats were prepared by a converging flow technique of fiber/glycerine dispersions. The fiberglass contained 3 percent of identical colored fibers which were counted from enlarged photographs in regard to their deviation from the alignment axis. Representative accumulative data of fiber alignment are shown for optimal and inadequate preparation conditions. In successful experiments over 90 percent of the fibers were found in the angular range of ±15 deg and 57 percent within the range of ±5 deg. Statistical analysis has shown that the experimental accumulative curves can be best described by a single parameter exponential equation Y = 1 − e−λα where Y is the accumulative fraction of fibers, α is the orientation angle and λ is a single empirical parameter.