Fibers


Figure 3.6 shows four examples of cake filtration in which the filter medium is a cloth of natural or artificial fibers or even metal. Figure 3.6a shows the filter cloth arranged between plates in an enclosure. Figure 3.66 shows the cloth arranged as a thimble. This arrangement is common for the separation of solid particles from vapor and is known as a bag filter. Figure 3.6c shows a rotating belt for the separation of a slurry of solid particles in a liquid, and Fig. 3.6d shows a rotating drum in which the drum rotates through the slurry. When filtering solids from liquids, if the purity of the filter cake is not important, filter aids, which are particles of porous solid, can be  [c.73]

Figure I represents a two-dimensional damage distribution of an impact in a 0/90° CFRP laminate of 3 mm thickness. Unlike in ultrasonic testing, which is usually the standard method for this problem, there is no shadowing effect on the successive layers by delamination echos. With the method of X-ray refraction the exact concentration of debonded fibers can be calculated for each position averaged over the wall thickness. Additionally the refraction allows the selection of the fiber orientation. The presented X-ray refraction topograph detects selectively debonded fibers of the 90° direction. Figure I represents a two-dimensional damage distribution of an impact in a 0/90° CFRP laminate of 3 mm thickness. Unlike in ultrasonic testing, which is usually the standard method for this problem, there is no shadowing effect on the successive layers by delamination echos. With the method of X-ray refraction the exact concentration of debonded fibers can be calculated for each position averaged over the wall thickness. Additionally the refraction allows the selection of the fiber orientation. The presented X-ray refraction topograph detects selectively debonded fibers of the 90° direction.
Fig. 1 High re.solution X-ray refraction topography of low energy impact (5J) at CFRP epoxy laminate. Image area 2 mm X 4 mm. Horizontal resolution 0.2 mm. The image represents selectively an area of debonded fibers of vertical fiber orientation. Fig. 1 High re.solution X-ray refraction topography of low energy impact (5J) at CFRP epoxy laminate. Image area 2 mm X 4 mm. Horizontal resolution 0.2 mm. The image represents selectively an area of debonded fibers of vertical fiber orientation.
One more application area is composite materials where one wants to investigate the 3D structure and/or reaction to external influences. Fig.3a shows a shadow image of a block of composite material. It consists of an epoxy matrix with glass fibers. The reconstructed cross-sections, shown in Fig.3b, clearly show the fiber displacement inside the matrix. The sample can be loaded in situ to investigate the reaction of matrix and fibers to external strain. Also absorption and transmission by liquids can be visualized directly in three-dimensions. This method has been applied to the study of oil absorption in plastic granules and water collection inside artificial plant grounds.  [c.581]

There are various situations where good contact is desired between a liquid, usually an aqueous one, and an oily, greasy, or waxy surface. Examples would include sprays of various kinds, such as insecticidal sprays, which should wet the waxy surface of leaves or the epidermis of insects animal dips, where wetting of greasy hair is desired inks, which should wet the paper properly scouring of textile fibers, including the removal of unwanted natural oils and the subsequent wetting of the fibers by desirable lubricants the laying of dust, where a fluid must penetrate between dust particles as on roads or in coal mines [22]. The eye is lubricated by a tear film, important both for the normal eye and for contact lens tolerance [23] since both surfaces should be wet.  [c.467]

For some types of wetting more than just the contact angle is involved in the basic mechanism of the action. This is true in the laying of dust and the wetting of a fabric since in these situations the liquid is required to penetrate between dust particles or between the fibers of the fabric. TTie phenomenon is related to that of capillary rise, where the driving force is the pressure difference across the curved surface of the meniscus. The relevant equation is then Eq. X-36,  [c.469]

Fabrics may be made water-repellent by reversing the conditions previously discussed in the promotion of the wetting of fabrics. In other words, it is again a matter of capillary action, but now a large negative value of AP is desired. As illustrated in Fig. XIII-3a, if AP is negative (and hence if the contact angle is greater than 90°), the liquid will tend not to penetrate between the fibers, whereas if AP is positive, liquid will pass through easily. It should be noted  [c.470]

The cleaning process proceeds by one of three primary mechanisms solubilization, emulsification, and roll-up [229]. In solubilization the oily phase partitions into surfactant micelles that desorb from the solid surface and diffuse into the bulk. As mentioned above, there is a body of theoretical work on solubilization [146, 147] and numerous experimental studies by a variety of spectroscopic techniques [143-145,230]. Emulsification involves the formation and removal of an emulsion at the oil-water interface the removal step may involve hydrodynamic as well as surface chemical forces. Emulsion formation is covered in Chapter XIV. In roll-up the surfactant reduces the contact angle of the liquid soil or the surface free energy of a solid particle aiding its detachment and subsequent removal by hydrodynamic forces. Adam and Stevenson s beautiful photographs illustrate roll-up of lanoline on wood fibers [231]. In order to achieve roll-up, one requires the surface free energies for soil detachment illustrated in Fig. XIII-14 to obey  [c.485]

A fabric is made of wool fibers of individual diameter 25 fiva and density 1.5 g/cm. The advancing angle for water on a single fiber is 120°. Calculate (a) the contact angle on fabric so woven that its bulk density is 0.8 g/cm and (b) the depth of a water layer that could rest on the fabric without running through. Make (and state) necessary simplifying assumptions.  [c.489]

One approach has been to build on the DR equation by adding a Gaussian [228] or gamma function-type [224] distribution of B values. Another approach makes use of a modified Fowler-Guggenheim equation (see Eq. XVII-53) [229]. A rather different method for obtaining a micropore size distribution was proposed by Mikhail, Brunauer, and Bodor [230], often known as the MP method. The method is an extension of the t-curve procedure for obtaining surface areas (Section XVII-9) a plot of cubic centimeters STP adsorbed per gram v versus the value of t for the corresponding P/F (as given, for example, by Table XVII-4) should, according to Eq. XVII-84, give a straight line of slope proportional to the specific surface area E. As illustrated in Fig. XVII-30, such plots may bend over. This is now interpreted not as a deviation from the characteristic isotherm principle but rather as an indication that progressive reduction in surface area is occurring as micropores fill. The proposal of Mikhail et al. was that the slope at each point gave a correct surface area for the P/P and v value. The drop in surface area between successive points then gives the volume of micropores that filled at the average P/P of the two points, and the average t value, the size of the pores that filled. In this way a pore size distribution can be obtained. Figure XVII-31a shows adsorption isotherms obtained for an adsorbent consisting of a-FeOOH dispersed on carbon fibers, and Fig. XVII-31b, the corresponding distribution of micropore diameters [231].  [c.670]

Fig. XVII-31. (a) Nitrogen adsorption isotherms expressed as /-plots for various samples of a-FeOOH dispersed on carbon fibers, (h) Micropore size distributions as obtained by the MP method. [Reprinted with permission from K. Kaneko, Langmuir, 3, 357 (1987) (Ref. 231.) Copyright 1987, American Chemical Society.] Fig. XVII-31. (a) Nitrogen adsorption isotherms expressed as /-plots for various samples of a-FeOOH dispersed on carbon fibers, (h) Micropore size distributions as obtained by the MP method. [Reprinted with permission from K. Kaneko, Langmuir, 3, 357 (1987) (Ref. 231.) Copyright 1987, American Chemical Society.]
The essence of chemistry is to produce compounds, or mixtures of compounds, with a wide range of physical, chemical, or biological properties. Our society could not exist any longer in its present form without the achievements of chemists plastics and fibers, colors and dyestuffs, drugs, agrochemicals, washing powder, glues, etc.. The properties have to be measured in order to put them on a quantitative basis as a prerequisite for further optimization. Chapter 5 deals with the wide variety of data to be handled, and their processing to prepare them for inductive learning. The massive amounts of data accumulated over the years, and being accumulated with increasing speed, can only be managed by storing them in databases. Chapter 6 therefore deals with databases containing chemical information.  [c.9]

S.4J Helical Micellar Fibers  [c.352]

The diazonium salt of 2-aminothiazole couples with 2-dimethylamino-4-phenylthiazole, giving the corresponding azo dye (194) (Scheme 123) used for dyeing synthetic fibers (404).  [c.77]

The use of 2-aminothiazole derivatives as dyeing compounds is direct related to the development of synthetic fibers. Some typical examples are given in Table VI-14. The importance of these dyes lies in their performance on acetate fibers. They have excellent fastness to gas fumes, produce a bright blue shade, and have a high tinctorial strength. Their only disadvantage is their relatively low light fastness, which does limit their application.  [c.154]

Dyes with good wet. light, and sublimation fastness for polyesters, nylon, and acetate fibers  [c.163]

Dyes polyester fibers fast blue, brown, and red shades  [c.163]

Dyes synthetic fibers  [c.164]

Dyes for dyeing and printing polyester and cellulose acetate fibers fast blue and red shades  [c.165]

Gives blue and violet shades on polyester fibers  [c.166]

The major uses of ethylene and propene are as starting materials for the preparation of polyethyl ene and polypropylene plastics fibers and films These and other applications will be described in Chapter 6  [c.189]

Several groups found good agreement with the apparent contact angle of water drops on screens and textiles [45-47] this is important in processes for waterproofing fabrics. A natural example occurs in the stmcture of feathers where an interlocking set of barbules, the fine support fibers on feather barbs, produce a highly porous (fj = 0.5) resilient structure. The apparent contact typical of water on a duck s back" is about 150° (receding), whereas the true contact angle of the feather material is about 100°.  [c.356]

Agrawal G P 1989 Ultrashort pulse propagation in nonlinear dispersive fibers The Supercontinuum  [c.1993]

Mollenauer L F, Gordon J P and Islam M N 1986 Soliton propagation in long fibers with periodically compensated loss IEEE J. Quantum. Electron. 22 157-73  [c.1994]

Gloge D 1971 Dispersion in weakly guiding fibers Appi. Opt. 10 2442  [c.2876]

Trentler T J ef a/1997 Solution-liquid-solid growth of indium phosphide fibers from organometallic precursors elucidation of molecular and non-molecular components of the pathway J. Am. Chem. Soc. 119 2172  [c.2917]

As the conformation of NAs is dependent on the properties of their environment the next step to understanding the physical basis of the conformational dynamics of the NAs could be the direct consideration of the in-tc raction of macromolecule with its nearest surrounding ion-hydrate. In the [jresent study we restrict our consideration to the hydration shell of the NA, assuming that the countreion content is constant. A convenient sample to investigate the interaction of NA with water is wet NA fibers and films. The hydration shell stabilizes the ordered forms of NA by means of forming regular structures due to H-bonds between adsorbed water molecules, water backbone , and is one of the main factors influencing the NA conformational. state. Such water bridges considerably contribute to the stabilization of the helical structure up to 70 % of the melting enthalpy of B-DNA in wet lilms and gels [5]. The regular hydration shells of the distinct nucleic acid conformations are known to be considerably different and distinct groups of I,he adsorbed water molecules play different roles in the stabilization of the distinct NA conformations [2], [11], [3]. The dry NA is known to be unordered  [c.117]

Lindsay, S. M., Lee, S. A., Powell, J. M., Weidlich, T., DeMarko, C., Lewen, G. D., Tao, N. J. Rupprecht, A. The origin of the A to B transition in DNA fibers and films. Biopolymers 27 (1988) 1015-1043  [c.126]

Figure 9-12 shows a sketch of a biological neuron the dendrites are branching fibers which connect the neuron to different neighboring neurons. They receive the incoming information to convey it to the neuron. This bundle of information is converted into one single information signal in the cell body, the soma of the neuron, and transmitted to the axon if it is larger than a certain threshold value i.e., the nemon fires). The axon then carries the information to the dendrites of other neurons or to muscle fibers. The information is transmitted from the axon to the dendrites of other neurons through a synapse. The building of synapse strengths is the essence of learning.  [c.452]

Bismanol" is a permanent magnet of high coercive force, made of MnBi, by the U.S. Naval Surface Weapons Center. Bismuth expands 3.32% on solidification. This property makes bismuth alloys particularly suited to the making of sharp castings of objects subject to damage by high temperatures. With other metals such as tin, cadmium, etc., bismuth forms low-melting alloys which are extensively used for safety devices in fire detection and extinguishing systems. Bismuth is used in producing malleable irons and is finding use as a catalyst for making acrylic fibers. When bismuth is heated in air it burns with a blue flame, forming yellow fumes of the oxide. The metal is also used as a thermocouple material, and has found application as a carrier  [c.146]

An organic chemist can learn most from Nature. Detailed knowledge of biological molecules and processes is an essential prerequisite for this teaming process. An organic chemist nowadays, however, profits most from moving beyond Nature towards artiflcial analogues. This has been valuable for the development of synthetic reagents (e.g., metal complex catalysts instead of metalloproteins) and of industrial and academic target molecules (e. g., nylon instead of protein fibers, crown-type ligands instead of natural ion carriers). At the present time, the details of the architectures of cell membranes, proteins, and nucleic acids are elucidated by electron microscopy, crystal structure analysis, molecular biology, and modem spectroscopic methods. Attempts are then made to understand the construction principles and to apply them in syntheses of molecular systems or of supramolecules which arc held together by weak intermolecular forces. Alternatively, organic chemistry may be combined with biochemical expertise and computer-aided molecular modelling. In general it turns out, that with simple, repetitive reaction sequences and well-planned or luckily discovered self-assembly processes, molecular buildings and chemical machineries of astounding complexity may be synthesized on often surprisingly large scales.  [c.341]

Porphyrin monomers have a strong tendency to form stacked dimeric aggregates in solutions. If the porphyrins possess side chains with hydrophilic, hydrogen-bonding head groups, they assemble to form long fibers in aqueous suspension (J.-H. Fuhrhop, 1992). The spectroscopic properties of these fibers arc very similar to those of the 1,8-anthrylcnc linked stacked oligomers. The properties of noncovalent oligomers forming by spontaneous self-assembly are often found to be similar to those of certain covalent synthetic oligomers thus providing helpful information on structures and reactivities.  [c.350]

The self-organization of amphiphiles with chiral head groups often results in complex helical superstructures. The easily accessible N-octyl-o-gluconamide, for example, dissolves in hot water and forms double and quadruple helical micellar fibers with ratios of length to diameter of more than Iff 1. The diameter of the single twisted helical cylinders, 3.6 nm, corresponds to the length of two amphiphile molecules. The hydrophobic effect and helical chains of amide hydrogen bonds cause the formation of these cylindrical micelles, and the chiral carbohydrate head groups enforce helical twists and determine the right-handed helicity of the chiral superstructures (J.-H. Fuhrhop, 1987, 1988, 1990 A, B).  [c.352]

Highly colored, they have been used to dye cellulose acetate (552) and acrylic fibers (553). Cationic dyes prepared from 2-azothiazoles by simple alkylation on the ring nitrogen (552) have been used increasingly with the introduction of polyacrylonitrile fibers with basic sites that can be colored with such dyes (554).  [c.105]

Orange dye that gives on qiiaternizalion a new fast-ted dye oti acrylic fibers  [c.167]

Pressure-sensitive copying paper containing 431 was recently patented (1650). 2-Thiazolyldiazonium chloride enters in the composition of synthetic fibers with ion-exchange properties (1551).  [c.171]

Thiazoloazatrimethine dyes, as generally basic dyes, possess a good affinity for acrylic fibers. It seems that the light fastness of trimethine thiazolo dyes can be increased by the progressive replacement of methine groups by nitrogen atoms, and an excellent fastness to light is reported to be displayed by three nitrogen atoms in the chromophoric chain (66).  [c.80]

The synthetic fiber industry as we know it began m 1928 when E I Du Pont de Nemours Company lured Professor Wallace H Carothers from Harvard University to direct their research department In a few years Carothers and his associates had pro duced nylon the first synthetic fiber and neoprene a rubber substitute Synthetic fibers and elastomers are both products of important contemporary industries with an economic influence far beyond anything imaginable m the middle 1920s  [c.4]


See pages that mention the term Fibers : [c.595]    [c.1727]    [c.1796]    [c.2876]    [c.352]    [c.167]    [c.439]    [c.5]    [c.14]   
See chapters in:

Encyclopedia of chemical technology volume 10  -> Fibers

Encyclopedia of chemical technology volume 19  -> Fibers


Introduction to protein structure (1999) -- [ c.0 ]

The coming of materials science (2003) -- [ c.0 ]

Mechanics of composite materials (1999) -- [ c.0 ]

Machanics of composite materials (1998) -- [ c.0 ]

Chemistry of Petrochemical Processes (2000) -- [ c.0 ]