Key fiber properties

Introduction General Construction Basic Principles of Operation Key Fiber Properties Fiber Manufacturing ... 

The bulk properties of regenerated cellulose are the properties of Cellulose II which is created from Cellulose I by alkaline expansion of the crystal stmcture (97,101) (see Cellulose). The key textile fiber properties for the most important current varieties of regenerated cellulose are shown in Table 2. Fiber densities vary between 1.53 and 1.50. 

The / -transition is a key feature and trademark in silks (Craig, 2003), whether the final product (Fig. 7) will be a high-performance fiber or will have other functions (Craig, 1997). The role, functionality, and diversity of each silk raise the interesting question whether selection pressures on the final fiber properties are mirrored (at, ultimately, the molecular level) in the precursor liquid proteins. Figure 8 shows SRCD spectra of six of the... 

One key requirement in the commercial production of fibers is to control fiber diameters within narrow ranges of the target. Another is to control the internal structure of the fiber, particularly the orientation of the polymer molecules. It is this orientation along the fiber axis that controls the morphology, and hence the fiber properties, such as dye uptake, shrinkage and tensile strength. 

Table VI compares the key properties of these two types of thermotropic polymers category by category. The samples compared had the same melting ranges, but were very different in reduced viscosities and solubility characteristics. The data compared were those processed under the most favorable conditions. Interestingly enough, the as-spun fibers from the polyester-carbonate can be heat-treated more efficiently than those fibers (of same tenacity) spun from the polyester. Both of them gave fiber properties far superior to those of nylons and polyethylene terephthalate. These two classes of polymers also had comparative properties (such as tensile strength, tensile modulus, flex modulus, notched Izod impact strength) as plastics and their properties were far superior to most plastics without any reinforcement.

There are many options and elegant methods for the dyeability modification of polypropylene fiber. The key to success is the cost, fiber properties, and color durability. With further research and market evaluation, it is quite hopeful that the dyeing problem of polypropylene fiber will be successfully resolved in the near future. 

Enzymes today are key strategic ingredients for washing and cleaning formulations. Enzymes not only remove stains but also improve textile fiber properties. 

Table 1 lists some key production and compositional details for a variety of SiC-based fiber types of current interest and availability as CMC reinforcement. The polymer-derived types range from first-generation fibers with very high percentages of oxygen and excess carbon, such as Nicalon and Tyranno Lox M, to the more recent near-stoichiometric (atomic C/Si 1) fibers, such as Tyraimo SA and Sylramic. For the CVD-derived types, such as the SCS family with carbon cores, the only compositional variables in the SiC sheaths are slight excesses of free sihcon or free carbon. Table 2 lists some of the key physical and mechanical properties of the SiC fiber types in their as-produced condition, as well as estimated commercial cost per kilogram, all properties important to fiber application as CMC reinforcement. These SiC fiber properties in Tables 1 and 2 are in most part those published by the indicated commercial vendors. It should be noted that the Sylramic fiber... 

A key material property of powders and fibers in particular is the specific surface area. The extent of adsorption from the vapor and liquid states on a solid surface is determined in part by the specific surface area of the solid. Typically, to determine the specific surface area, a gas adsorption isotherm is measured for example, the adsorption of nitrogen is measured on the substrate of interest at 77 K, the boiling point of nitrogen. The experimental isotherm is then analyzed by the BET (Brunauer, Emmett and Teller) model [42,43] to determine the monolayer capacity of the substrate. The specific monolayer capacity multiplied by the cross-sectional area of the adsorbed gas molecule gives the specific surface area. Amorphous silica gel may have a specific area of 200-300 mVg while carbon fibers may have a value of around 0.1 mVg. 

While textile processing previously included almost always three to four successive steps to achieve a 3D structure, from fiber to the yam and then from the yam to the surface and volume arrangement, one more recent way to achieve this is 3D printing and 3D deposit of the fibrous component. Even if it is not the only way to obtain desired and optimized stmctures, it points out the willingness to control all the key parameters of fibrous stmctures. Orientation, distribution, and square density of fiber is aimed to be controlled, as well as the fibers properties themselves, their interlacing pattern, at aU scale levels. 

For a wide range of apphcations, composites reinforced with continuous fibers are the most efficient structural materials at low to moderate temperatures. Consequently, we focus on them. Table 5.3 presents room-temperature mechanical properties of unidirectional polymer matrix composites reinforced with key fibers E-glass, aramid, boron, standard modulus (SM) PAN (polyacrylonitrile) carbon, intermediate modulus (IM) PAN carbon, ultrahigh modulus (UHM) PAN carbon, ultrahigh modulus (UHM) pitch carbon, and ul-trahigh thermal conductivity (UHK) pitch carbon. The fiber volume fraction is 60 percent, a typical value. 

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