Fiber end-use applications

Fiber end-use applications include (2) ready-to-wear, active-wear, intimate apparels, inner linings where stretch-recovery, softness, hand, and drape are the key attributes (2) carpets where resiliency, newness retention, stain resistance, and low static generation provide values over currently used materials in some market segments (3) automotive and home upholstery utilizing the easy dyeing, stain resistance, stretch-recovery properties. Within a short period of time since the polymer s commercialization, PTT ready-to-wear stretch apparels (52) and resilient floor coverings had already appeared in the market (since 1999). 

The reinforcement of rubbers using nylon, rayon, vinyl, and polyester fibers was reported by various authors [10,58,73-75]. Because of the design flexibility and suitable end-use applications, high-performance fibers such as glass, carbon, and aramid also find extensive applications in short fiber-reinforced mbbers. A brief description of some of the major high-performance fibers commonly used in short fiber-rubber composites is given below ... 

Qualification of different cellulose sources for the various end use applications is determined on the basis of purity, molecular size, and a-cellulose content, a-cellulose refers to the portion of cellulose insoluble in 18% aqueous sodium hydroxide. Whereas the content of noncellulosic polysaccharides has proven to be a hindrance to the clarity of cellulose esters (determined as haze in otherwise clear films), a-cellulose content is important for the spinnability of cellulose solutions into regenerated fibers, and for viscosity characteristics of cellulose ethers. Molecular weights play an important role in various cellulose ethers. 

As stated above, the modification to achieve these results is usually achieved by mixing a polymer with other polymers, both organic and inorganic materials including additives, metal powders, glass fibers, and other materials to match the end-use application. 

Figure 9.19 Prototypes developed for various end-use applications (a) Motorbike airfilter made up of sisal/PP composites at 30% fiber loading left side shows the front view while right side shows the back view with metallic inserts (b) Ecofriendly Garment Hangers made out of Sisal/PP composites at 20% fiber loading (c) Gas Guiding paper for offshore oil drilling for application below 100 °C made out of Banana Glass/PP hybrid composites (d) Automotive Hinge Component made of Banana Glass/PP hybrid composites.

Samuels [183,184] has conducted extensive studies on the relations between structural states and properties. His studies have been carried out on both polypropylene films and polypropylene fibers. According to Samuels, each fabrication process, test, and end-use application involves a deformation, and all these steps cause a change from an initial structural state to a final one. His view was that the initial and final structural states will always lie between that of the undeformed polymer and the final state just before fracture. These states are specified by the relative amounts of crystalline and amorphous materials present and by their orientation and are attainable by different fabrication paths. In addition to /c and /am, Samuels used an / average for correlating properties. The definition of/av is given by ... 

Uses AntioxidanL stabilizer for PP film, PE, polyamides, polyesters, POM, PU, PVC, PS, cellulosics, mbbers, EPDM, adhesives, fiber applic., talc, food-grade polymers processing and end-use applic. in food-pkg. adhesives... 

Modifications of the surface properties ofman-made fibers play a dominant role in several end-uses. Via a variety of application processes it is possible to treat manmade fibers with fluorine gas. The electronegativity of flouorine is 4.0eV the highest of all elements. In particular, the siuface activity of yams can be increased considerably by incorporating fluorine atoms. As part of this investigation some polymers and fiber types for diverse end-uses were tested (Table 17.1). All end-use applications for these yams have important surface function requirements, e.g., for tire yams the adhesion to mbber is very important while for tarpaulins it is the adhesion to PVC. Textile and medical applications with different end-use characteristics were also considered. The modifications attempted to this investigations did not influence other properties such as tenacity, elongation, or shrinkage. 

Polyethylene (PE) and polypropylene (PP) exemplify a class of materials called polyolefins. Composites based on these resins are relatively new by the standards of those early materials of construction. Recent efforts to use these types of materials combine inherent cost-effectiveness with a wide spectrum of end-use applications as film, fiber, and moldings. The impetus for this remarkable development is attributed to the ease of polyolefin manufacture with effective production and purification of the monomers from a variety of sources, ongoing improvements of the catalyst, and large well-controlled polymerization units. Consequently, a strong market demand for good performance and cost-effective materials have spurred a multibillion dollar industry. 

Polypropylene is a very versatile polymer. It has many properties that make it the polymer of choice for various applications (e.g., excellent chemical resistance, good mechanical properties and low cost). There are many ways in which the mechanical properties of polypropylene can be modified to suit a wide variety of end-use applications. Various fillers and reinforcements, such as glass fiber, mica, talc, and calcium carbonate, are typical ingredients that are added to polypropylene resin to attain cost-effective composite mechanical properties. Fibrous materials tend to increase both mechanical and thermal properties, such as tensile strength, flexural strength, flexural modulus, heat deflection temperature, creep resistance, and sometimes impact strength. Fillers, such as talc and calcium carbonate, are often used as extenders to produce a less-costly material. However, some improvement in stiffness and impact can be obtained with these materials. 

Traditionally, material design requirements that suit such demanding end-use applications have been limited within the domain of engineering plastics based on polyamide 6 or 66, polyester alloys, and polyacetal type resins. However, as described in Chapter 1, glass fiber-reinforced polypropylene (GFRP) composites continue to gain a market share in automotive molded parts. 

DuPont cites applications in world team tennis T-shirts and athletic socks, golfing apparel and New York Police Department bicycle patrol clothing. The fabrics contain fibers described by DuPont as tetra-channef Dacron . Synthetic fibers are produced with different cross-sectional shapes depending on the extrusion technology (e.g. melt, solvent or wet spun) and the end-use application. The cross-sections of these fibers contain four lobes, thus the description tetra-channef. The theory is that these channels provide for the wicking of perspiration away from the skin surface towards an outer layer of fabric, which in turn absorbs the liquid. DuPont s claims for the performance of CoolMax fabrics are given in Table 10.1. 

Because membranes applicable to diverse separation problems are often made by the same general techniques, classification by end-use application or preparation method is difficult. The first part of this section is, therefore, organized by membrane structure preparation methods are described for symmetrical membranes, asymmetric membranes, ceramic and metal membranes, and liquid membranes. The final two subsections cover the production of hollow-fine-fiber membranes and membrane modules. 

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