Fiber modification, surface

Battistel E, Morra M, Marinetti M (2001) Enzymatic surface modification of acrylonitrile fibers. Appl Surface Sci 177 32 1... 

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. 

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. 

Patino, A., Canal, C., Rodriguez, C., Caballero, G., Navarro, A., Canal, J.M., 2011. Surface and bulk cotton fiber modifications plasma and cationization. Influence on dyeing with reactive dye. Cellulose 18,1073-1083. 

Carbon fibers are used as reinforcement material in composites, the mechanical properties of which are dependent upon the matrix/fiber adhesion. Surface modification such as dry or wet oxidation of die carbon fibers may be used to improve those characteristics [3]. 

The effect of flax fiber modification and the effect on the presence of TCL were also studied by Arbelaiz et al. [17]. In his studies, fibers were subjected to maleic anhydride, vinyltrimetoxy silane, and aUcali with addition of MAPP-grafted polypropylene. All applied modifications produced improvement in the thermal stability of lignocellulosic material. Analysis of the crystalline structure showed the increase of crystallinity as a result of fiUer addition. Nucleation density around unmodified fibers was higher than around fibers modified with maleic anhydride. Surfaces of unmodified fibers had the surface active for initialization of transcrystaUization, which, in the case of modified fibers, did not occur. Son et al. [32] explained this phenomenon as... 

The interface is a region at least several molecular layers thick with properties intermediate between those of the fiber and matrix phases and arises due to the peculiar restrictions on molecular motions in this zone. Matrix molecules may be anchored to the fiber surface by chemical reaction or adsorption and determine the extent of interfacial adhesion. Fiber modification reduces hydrophilicity of the fiber and improves the physical/chemical interactions between the fiber and matrix. Treatment makes the surface of the fiber very rough and provides better mechanical interlocking with the polymer matrix. 

For the improvement of the performance of the biocomposite different alternatives exist including fiber modification, matrix modification, and coupling agent addition. Fiber modification may concern alterations on the physical and chemical properties by causing changes in the surface, chemical composition, and moisture uptake behavior of the plant fiber [26]. Research studies on physical and chemical treatments of agroresidual fibers are listed in Table 11.1. 

Prior to fiber s surface fabrication, raw fibers were cut into 3mm size and were subsequently chemically modified at optimized parameters as per methods reported earlier [20, 21]. The various surface modification processes are presented below. 

In the development of a composite system, wettability, adhesion and more uniform distribution of cellulosic material within the matrix play a major role. Compatibility of nanofibrills in polymer matrix can be improved by decreasing the hydrophilicity of fibers through surface modification or by using suitable coupling agents. The availability... 

Traditional surface treatments (Hatch, 1993) are often hmited because laundering, or even normal use of the treated garment, may cause removal of the active agents. The use of chemically bound reagents on the fiber may also have a negative influence if restrictions at the binding site alter the mechanical behavior of the fiber. Modification at air-fabric and fluid-fabric interfaces is of particular relevance to textile chemistry because many performance characteristics are critically dependent on the behavior of this region. 

A modification of the foregoing procedure is to suspend the plate so that it is partly immersed and to determine from the dry and immersed weights the meniscus weight. The procedure is especially useful in the study of surface adsorption or of monolayers, where a change in surface tension is to be measured. This application is discussed in some detail by Gaines [57]. Equation 11-28 also applies to a wire or fiber [58]. 

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