Fiber content

It is determined by extraction of the resin system in a soxhlet apparatus with a suitable solvent such as butanone (note that dicy is not soluble in butanone). If any crosslinking of the resin system has occurred, then it will be necessary to use the H2SO4/H2O2 digestion system. 

---

The Textile Eiber Product Identification Act (TEPIA) requires that the fiber content of textile articles be labeled (16). The Eederal Trade Commission estabhshed and periodically refines the generic fiber definitions. The current definition for a polyester fiber is "A manufactured fiber ia which the fiber-forming substance is any long-chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxyUc acid, including but not restricted to terephthalate units, and para substituted hydroxyben2oate units."... 

Considerable effort is being made (ca 1993) to develop satisfactory flame retardants for blended fabrics. It has been feasible for a number of years to produce flame-resistant blended fabrics provided that they contain about 65% or more ceUulosic fibers. It appears probable that blends of even greater synthetic fiber content can be effectively made flame resistant. An alternative approach may be to first produce flame-resistant thermoplastic fibers by altering the chemical stmcture of the polymers. These flame-resistant fibers could then be blended with cotton or rayon and the blend treated with an appropriate flame retardant for the ceUulose, thereby producing a flame-resistant fabric. Several noteworthy finishes have been reported since the early 1970s. 

Compositions of the four oilseeds are given in Table 2. All except soybeans have a high content of seed coat or hull. Because of the high hull content, the cmde fiber content of the other oilseeds is also high. Confectionery varieties of sunflower seed may contain up to 28% cmde fiber on a dry basis (8). Soybeans differ from the other oilseeds in their high protein and low oil content. AH these oilseeds, however, yield high protein meals when dehuUed and defatted. 

Techniques for efficiently and economically measuring the other important characteristics, ie, length, strength, and position of weakness in the fiber, are now in commercial use. Existing color-measuring equipment can be used to measure the color (whiteness or yellowness) of washed wool, but accurate measuring of colored-fiber content remains a problem (5,8). 

The overall objective of research under way as of ca 1997 is to develop a system of sale by description for fine and medium wools whereby the buyer is presented only with measured data on the principal characteristics of the raw wool, as well as an assessment of the less important characteristics by an independent skilled appraiser (8). A scheme for assessing the risk of the presence of colored fiber content in greasy wool has been proposed which depends on production parameters and on the age and sex of the sheep (5). Instmmentation and computer algorithms for the measurement of style and handle... 

The choice of a particular mining method depends on a number of parameters, typically the physical properties of the host matrix, the fiber content of the ore, the amount of sterile materials, the presence of contaminants, and the extent of potential fiber degradation during the various mining operations (33). However, most of the asbestos mining operations are of the open pit type, using bench drilling techniques. 

The annual production of DDG is over one million tons. Most of it is used ia animal feed. However, increa sing quantities are being sold as food iagredients because of its excellent nutrient and fiber content. 

AOAC Method 985.29for TDF. This AO AC method (3), referred to as the method of Prosky and co-workers (4), was cited in the Nutritional Labeling and Education Act of 1990 as the general analytical approach for food labeling of dietary fiber content. The method has undergone several modifications for IDE and for the primary fractions, SDE and IDE. 

Dyeing procedures vary according to the fiber content of the textile material and the equipment to be used. Examples of basic carrier dyeing procedures are as follows. 

Faser-gehalti m. fiber content (Paper) fiber yield, -gewebe, n. fibrous tissue fibrous texture, -gips, m. fibrous gypsum, -haut,/. (Anat.) fibrous membrane, faserig, a. fibrous, fibery, fillamentous, stringy. 

Aside from type of claim (fiber dominant or interfacet matrix dominant), the efficiency of surface treatments depends noticeably on the fiber content within the composite. At a fiber content of 30 vol%, tensile strength increases by 10% and shear strength increases by about 100% (Fig. 12). In contrast to modified fibers where shear strength rises with increasing fiber content, the chart, after having reached a maximum, shows a... 

Figure 11 Wohler chart of silanized and unsilanized jute reinforced epoxy-resin composites at different moisture contents (R = O.l f,est = 10 Hz fiber content = 40 vol%) [12].

Figure 12 Dependence of tensile strength and shear strength of PP-flax composites on fiber content and on surface treatment. (-) untreated flax (-) flax pretreated with hostaprime HC5.

Figure 13 Influence of coupling agents and fiber content on the characteristic values of kenafreinforced recycled PE at room temperature (dry state) and after exposure in boiling water (wet-state) [57].

Figure 18 Tensile strength of B.M.C. molded plastics as dependent on their fiber content. %fibers = g fibers/100 g UP resin.

Table 12 Tensile Strength and Young s Modulus of Sisal, Flax, and Glass Fiber MTs with a Fiber Content of 40% (weight) [60]...

Tests by Roe et al. [63] with unidirectional jute fiber-reinforced UP resins show a linear relationship (analogous to the linear mixing rule) between the volume content of fiber and Young s modulus and tensile strength of the composite over a range of fiber content of 0-60%. Similar results are attained for the work of fracture and for the interlaminate shear strength (Fig. 20). Chawla et al. [64] found similar results for the flexural properties of jute fiber-UP composites. 

Figure 20 Influence of fiber content by volume on tensile strength. Youngs modulus, work of fracture, and interlaminate shear strength of one-dimensional jute fiber-reinforced UP resins [63].

Fiber content = 50% by vol., linen weave, cable direction = testing direction. 

Figure 22 Influence of fiber content on flexural strength and fracture toughness of (O) softwood-cement composites and ( ) hardwood-cement composites (air-cured) [78].

Fiber content (wt%) Flexural strength (MPa) Fracture toughness (kJ/m ) ... 

When used as substitutes for asbestos fibers, plant fibers and manmade cellulose fibers show comparable characteristic values in a cement matrix, but at lower costs. As with plastic composites, these values are essentially dependent on the properties of the fiber and the adhesion between fiber and matrix. Distinctly higher values for strength and. stiffness of the composites can be achieved by a chemical modification of the fiber surface (acrylic and polystyrene treatment [74]), usually produced by the Hatschek-process 75-77J. Tests by Coutts et al. [76] and Coutts [77,78] on wood fiber cement (soft-, and hardwood fibers) show that already at a fiber content of 8-10 wt%, a maximum of strengthening is achieved (Fig. 22). 

Fiber content (wt%) Tensile strength (MPa) Young s modulus (MPa) Elongation at break (%) Tear strength Hardness (shore-D) (kN/m) Tension set (%) Density (g/cm )... 

Figures 10-101, lO-lOJ, and 10-1 OK indicate the process flow patterns for single tube units and for multiple corrugated tubes in a single plain shell. These units are suitable for heating or cooling process fluids containing high pulp or fiber content or suspended particulates. The heat transfer coefficients are improved when compared to plain tubes as the turbulence improves the performance. The units can be arranged in multiple shells for parallel or series flow. The manufacturers should be contacted for details.

Fig. 7-19 Example of the effect on thermal conductivity by varying the glass fiber content (by weight) in RPs.

The CLTE is an important consideration if dissimilar materials like one plastic to another or a plastic to metal and so forth that are to be assembled where material expansion or contraction is restricted. The CLTE is influenced by the type of plastic (liquid crystal, for example) and RP (particularly the glass fiber content and its orientation). It is especially important if the temperature range includes a thermal transition such as Tg. Normally, all this activity with dimensional changes is available from material suppliers. 

---