Fiber modification

Electric discharge methods are known [31] to be very effective for nonactive polymer substrates such as polystyrene, polyethylene, polypropylene, etc. They are successfully used for cellulose-fiber modification to decrease the melt viscosity of cellulose-polyethylene composites [32] and to improve the mechanical properties of cellulose-polypropylene composites [28]. 

An older method of cellulose fiber modification is mercerization [22,33-36], which has been widely used on cotton textiles. Mercerization is an alkali treatment of cellulose fibers. It depends on the type and concentration of the alkalic solution, its temperature, time of treatment, tension of the material, and the additives used [33,36]. At present there is a tendency to use mercerization for natural fibers as well. Optimal conditions of mercerization ensure the improvement of the tensile properties [33-35,37] and absorption characteristics [33-35], which are important in the composing process. 

Analog-to-glass fibers silanes are used as coupling agents for natural fiber polymer composites. For example, the treatment of wood fibers with product A-175 improves wood dimensional stability [53]. In contrast, a decrease of mechanical properties was observed for coir-UP composites after a fiber modification with di-chloromethylvinyl silane [54]. The treatment of mercer-... 

Chemical extractants, 10 750 Chemical fiber modification, 16 14 Chemical finishing, of fibers, 11 180-181 Chemical fluid deposition (CFD), of metals, 24 22... 

Fiber glass-reinforced plastic tanks, 24 299 Fiber grating, 11 150-151 Fiber length (FL), 18 148 Fiber manufacture, sodium bisulfite in, 23 673 Fiber-matrix bonding, 26 771-772 Fiber modification, chemical, 16 14 Fibernodes, 11 595 Fiber-optic probes, 16 524 Fiber optics, 11 128-162, 15 469 attenuation in, 11 132-133 dispersion in, 11 134-135 fiber drawing in, 11 141-145 fiber strength in, 11 141-145 history of, 11 128-131 inside processes for, 11 136-140 near-infrared, 23 141 optical amplifiers with, 11 145-146 optical fiber fabrication for,... 

Fiber Modification. Chemical modification ol the fiber is usually a separate operation. The largest such commercial processing is the deacety lation of cellulose acetate hollow fibers, w hich converts them into regenerated cellulose hollow fibers employed in hemodialysis. 

This review will concentrate on non metallic and related areas such as organic fibers and various forms in which organic materials are used such as films, granules and small extruded geometries. Readers will be referred elsewhere for discussions of fundamentals of the technique and instrumentation. Applications of XPS to problems of industrial interest such as fiber modification and analysis carried out in our laboratory will be reviewed. 

Enzymes such as "cellulases" and a-amylases are currently used by several industries to hydrolyze cellulose or starch to products such as dex-trins, syrups, and sugars. Such reactions represent the key first step toward the production of a variety of useful chemicals and sweeteners and are also useful in the pulp and paper industry for fiber modification and de-inking. 

Melt or solution spinning of synthetic fibers is a marvel of modern technology. Fiber lubrication, which is of the utmost importance in this high-speed process, is achieved by the application of spin finish—a combination of oils and surfactants. A typical spin line for the production of polyester staple fiber is shown schematically in Figure 2. The number of filaments, which can vary from tens to thousands, come into contact with various parts of the machinery, some of which are heated for proper fiber modification. To replenish the lost finish and to ensure adequate lubrication,... 

Photo-induced grafting of fibers on pre-wetted fiber substrates occurs by a variety of methods. Introduction of monomer as a vapor in the grafting process on pre-wetted fibers gives rapid photografting with a minimum of homopolymer formation. Biacetyl vapor greatly increases the rate of photografting of monomer vapors on pre-wetted fibers and provides a method of fiber modification without loss of fiber aesthetics. 

Acrylic acid esters Free-radical-initiated chain polymerization Fiber modification, coatings, adhesives, paints... 

The properties of acrylic ester polymers depend largely on the type of alcohol from which the acrylic acid ester is prepared [26]. Solubility in oils and hydrocarbons increases as the length of the side chain increases. The lowest member of the series, poly(methyl acrylate), has poor low-temperature properties and is water sensitive. It is therefore restricted to such applications as textile sizes and leather finishes. Poly(ethyl acrylate) is used in fiber modifications and in coatings and poly(butyl acrylate) and poly(2-ethylhexyl acrylate) are used in the formulation of paints and adhesives. 

Semiquantitative elemental analysis was performed on the fiber samples by SEM-EDAX. The Ti content on the surface ranged around 90-95% and in the interior from 65 to 90%, depending on the conditions of PAN fiber modification. The inner core contained a higher percentage of titanium when the modifications were performed at 20°C, compared to -10°C. Thus temperature possibly affects the rate of titanium monomer diffusion as well as reaction rate of the -C-N group and the titanium monomer. 

Mechanical properties and chemical resistance of short tamarind flber/unsaturated polyester composites Influence of fiber modification and fiber content, 18(7),... 

A number of polymer and fiber modifications have been devised to overcome this problem, although none has been successful enough to allow acrylics to compete in successfully easy-care apparel markets. The fibers may be treated with compounds such as ammonium sulfide [433], hydrazine derivatives [434,435], thiosemicarbazides [436], silicone oils [437], and emulsions of polysiloxane and polyepoxide [438]. Some success has been achieved by incorporating comonomers that increase the wet glass transition temperature of the polymer or make the copolymer more water-resistant [439-444]. Sheath-core fibers have been reported [445] in which the core polymer is stable under hot-wet conditions and the sheath polymer is used to compensate for deficiencies in dyeability. 

Metalized and semiconducting fibers have also been discussed [585-587]. Another key industrial application for acrylic fibers is for asbestos replacement, especially for concrete reinforcement and friction surfaces. An example of a concrete and mortar reinforcement fiber is Dolanit acrylic from Faserwerk Kelheim GmbH [588]. The subject has been reviewed by a number of authors [589-591]. Other acrylic fiber modifications and reviews of acrylic fiber modifications, in general, have been published by several authors [592-596]. A comprehensive summary of specialized acrylic and modacrylic fibers is given in Table 12.35. The major types. 

Persson, P. Strategies for cellulose fiber modification. 2004. Doctoral thesis (Doctor of Chemistry) Fiber- och polymerteknologi, Stockholm. Trita-FPT.7, 1-52 (2004)... 

J. Tong, M. Yunhai, J. Man, Effects of the wollastonite fiber modification on the sliding wear behavior of the UHMWPE composites. Wear 255, 734—741 (2003)... 

Chandra, R. P. Ragauskas, A. J. In Laccase The renegade of fiber modification, Tappi Pulping Conference, 2001. Tappi Press, Atlanta 2001. 

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