Polypropylene fiber, synthetic chemical fibers

Fibers from synthetic polymers make up approximately 80% of the total production of chemical fibers in Germany and about 90% worldwide (2000). The most important synthetic fibers are polyamide (Wulfhorst, 1997), polyester (Tetzlafi", 1997), and polyacrylonitrile (Wulfhorst, 1998). Because of their very specific properties, polyvinyl chloride (Koch, 1968), polytetrafluoroethylene, polyolefin fibers (such as polyethylene and polypropylene) (Wulfhorst, 1989b), and polyvinyl alcohol are used mostly for technical textiles. At the end of this section, an overview is given of synthetic polymers featuring the chemical structures, specific properties, and various applications (Table 2.7). The physical characteristics of chemical fibers from synthetic polymers are summarized later in Table 2.8. 

The plastics industry and all the products made from plastics are almost entirely dependent on chemicals extracted or produced from hydrocarbons. This includes not only the familiar materials such as polyethylene, polypropylene, polyvinyl chloride (PVC), epoxies, nylon, polyesters, polycarbonate. Teflon and Plexiglas, but also includes a large portion of materials made from rubber and a diverse group of other materials formulated from polymers such as tape, glue, ink, waterproofing, wax, and polishes. Virtually all the synthetic fibers used in textile products, Orion , Dacron , Nylon and polyesters are made from polymers based on hydrocarbons. 

In 2002, the world production of polymers (not including synthetic fibers and rubbers) was ca. 190 million metric tons. Of these, the combined production of poly(ethylene terephthalate), low- and high-density polyethyelene, polypropylene, poly(vinyl chloride), polystyrene, and polyurethane was 152.3 million metric tons [1]. These synthetic, petroleum-based polymers are used, inter alia, as engineering plastics, for packing, in the construction-, car-, truck- and food-industry. They are chemically very stable, and can be processed by injection molding, and by extrusion from the melt in a variety of forms. These attractive features, however, are associated with two main problems ... 

Membrane filters are used to remove particulates from samples and solvents prior to HPLC analysis and also for the preparation of liquid samples, where no solvent is used. Typical materials of construction for membrane filters are usually synthetic polymeric materials, although natural substances, such as cellulose, and inorganic materials, such as glass fibers, are also used acrylic copolymer, aluminum oxide, cellulose acetate, glass fiber, mixed cellulose esters, nitrocellulose, nylon, polycarbonate, polyester, polyether sulfone, polypropylene polysulfone, PTFE, PVC, etc. The compatibility of the polymeric material with the solvents used must be a great concern of their different chemical properties. 

The natural polymers mentioned above are synthesized and grown into fibers by nature. Cotton, wool and silk are some examples. Wood is produced similarly, but not being in a form suitable for use as a textile fiber, it must be chemically modified to produce an appropriate solution, which can then be extruded into a fiber. Rayon and cellulose acetate are examples of this pro-cess.1 Synthetic materials, on the other hand, must be first polymerized into chains, by finking small molecules together end to end, and then extruded into fibers. Chains are built by either a condensation or an addition process. Nylon and polyester are examples of polymers synthesized by condensation, whereas polyethylene, polypropylene, acrylic and polytetrafluoroethylene (Teflon ) are some examples of polymers prepared by the addition process. 

In using this new approach, conventional corona treatment is combined with injection in a reactive medium of microcapsules in aerosol form. Chemical nanotreatment or coating occurs when the aerosol condenses on the substrate at low temperature, resulting in a durable effect (most likely due to the formation of covalent bonds). An improved antistatic behavior is also obtained on textile substrates. Application is possible on both natural and synthetic fibers, as well as on thermosensitive hydrophobic substrates such as polypropylene and polyethylene. 

A modified polymer, also called a semisynthetic polymer, is a natural polymer compound treated by a chemical reaction. The world s first man-made polymer material—cellulose nitrate—was made from natural cellulose, such as cotton or cotton cloth, that was treated with concentrated nitric acid and concentrated sulfuric acid. A synthetic polymer is a polymer compound synthesized by small molecular weight compounds through chemical methods. Examples of synthetic polymer materials are plastics such as polyethylene, polypropylene, and polyvinyl chloride and fibers such as polyester, nylon, and other synthetic fibers. 

When a synthetic fiber is stretched or drawn, the molecules in most cases will orient themselves in crystalline areas parallel to the fiber axis, although crystalline areas in some chain-folded polymers such as polypropylene can be aligned vertical to the fiber axis. The degree of crystallinity will be affected by the total forees available for chain interaction, the distance between parallel chains, and the similarity and uniformity of adjacent chains. The structure and arrangement of individual polymer chains also affects the morphology of the fiber. Also, configurations or optical isomers of polymers can have very different phys-ieal and chemical properties. 

Geotextiles are produced using synthetic fibers or yams commonly made from polypropylene or polyester. These materials do not absorb water or support the growth of fungus or mildew, are chemically resistant to pH levels 1—14, and are stable up to 150°C. Geotextiles made of these materials have a life expectancy of more than 200 years when they are buried. If the geotextile is to be exposed for more than about... 

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