Polymeric materials polypropylene

The yams in these cloths are composed of soUd polymeric material (polypropylene, polyester, pofyamide, etc.). Cloths of diflerent patterns are produced on the loom by varying the manner in 4iidi the warp and weft yams are woven together. The warp yam is stretched in the machine or longitudinal directian and the weft yam lies at right angles to the warp. Yams are usually cylindrical, although other shapes are available. 

F. Molesky in Recent Advances in Flame Retardamy of Polymeric Materials, Stamford, Coim., 1990 F. Molesky, "The Use of Magnesium Hydroxide for Flame Retarded Low Smoke Polypropylene," Polyolefins IHInternational Conference, Feb. 24,1991, Houston, Tex. 

One of the most important reactions in the chemical industry is the cracking (removing hydrogen) of paraffins to form olefins. Olefins are essential starting materials for many common products that we all use, particularly plastics. The simplest olefin is ethylene, which can be polymerized (reacted many times with itself) to give po/yethylene used for bottles, dishware, film, etc. The next higher olefin, propylene, can be polymerized to polypropylene used in the manufacture of rugs, toys, kitchenware, and many other plastic objects. Note that the names of olefins end in -ene, which denotes the presence of a double bond in the compound. 

Uses Used in the petroleum industry to make so-called alkylate for improved octane gasoline. Large quantities are polymerized to polypropylene for carpeting, upholstery, ropes, and other uses. Used in the chemical industry as a starting material for many large-volume chemicals such as acetone, acrylonitrile, and propylene oxide. 

Several manufacturers introduced products amenable for this solid-supported LLE and for supported liquid extraction (SLE). The most common support material is high-purity diatomaceous earth. Table 1.8 lists some commercial products and their suppliers. The most widely investigated membrane-based format is the supported liquid membrane (SLM) on a polymeric (usually polypropylene) porous hollow fiber. The tubular polypropylene fiber (short length, 5 to 10 cm) is dipped into an organic solvent such as nitrophenyl octylether or 1-octanol so that the liquid diffuses into the pores on the fiber wall. This liquid serves as the extraction solvent when the coated fiber is dipped... 

The best known aspect, and the first one to find commercialization in the direct fluorination area, was the fluorination of polymer surfaces. This Lagow-Margrave invention, trademarked Fluorokote, involved many types of polymeric materials in various forms e.g., polyethylene bottles, polypropylene objects, and rubber gloves. Polyethylene bottles are easily given fluorocarbon surfaces (>0.1 mm), and this has been commercialized. Air Products has at least 20 licenses for what is known as their Aeropak process and Union Carbide has a Linde Fluorination process as well. Applications in chemical, pharmaceutical, and cosmetic storage are widespread. 

In starting a residue analysis in foods, the choice of proper vials for sample preparation is very important. Available vials are made of either glass or polymeric materials such as polyethylene, polypropylene, or polytetrafluoroethylene. The choice of the proper material depends strongly on the physicochemical properties of the analyte. For a number of compounds that have the tendency to irreversible adsorption onto glass surfaces, the polymer-based vials are obviously the best choice. However, the surface of the polymer-based vials may contain phthalates or plasticizers that can dissolve in certain solvents and may interfere with the identification of analytes. When using dichloromethane, for example, phthalates may be the reason for the appearance of a series of unexpected peaks in the mass spectra of the samples. Plasticizers, on the other hand, fluoresce and may interfere with the detection of fluorescence analytes. Thus, for handling of troublesome analytes, use of vials made of polytetrafluoroethylene is recommended. This material does not contain any plasticizers or organic acids, can withstand temperatures up to 500 K, and lacks active sites that could adsorb polar compounds on its surface. 

The surface of polymeric materials such as polypropylene (PP), PS, polyacrylonitrile (PAN), and nylon was oxidized by immersing them in aqueous solution of oxidizing agents such as potassium peroxy disulfate under nitrogen purging at high temperatures [14]. Graft polymerization of water-soluble monomers such as AAm, methacrylic acid, and 3-aminopropyl methacrylate has been frequently performed in aqueous solution with the use of ceric ion, for instance, at... 

Ceramic materials, including sapphire, have been used extensively in HPLC pumps for more than 20 years as pistons and check valve components. These materials have also been used to construct heads because of their good chemical stability. The use of ceramics is limited, however, because of high cost and brittleness. Although many systems have one material as the primary construction material, the wetted surfaces of a pumping system can contain several other materials. Therefore, for material-sensitive applications, all the materials in the HPLC eluent flow path should be considered. Materials that may be encountered are polymeric materials for pump seals such as fluoropolymers, polypropylene, and Teflon sapphire pump pistons and check valve seats ruby check valve balls Kalrez, KelF, or ceramic washers and spacers polymer-based transducer components and in older systems connections and joints made with silver solder. 

Kuran, W., Polypropylene Oxide) , in The Polymeric Materials Encyclopedia, CRC Press, Boca Raton, 1996, Vol. 9, pp. 6656-6662. 

Bertelli, G., Goberti, P., Marchini, R., Camino, G., and Luda, M.P., Combined melamine/mineral fillers as fire retardants for polypropylene, Proceedings from 6th European Meeting on Fire Retardancy of Polymeric Materials (FRPM 97), Lille, France, 1997, p. 34. 

In general, ionic liquids tend to be non-corrosive towards most metallic and polymeric materials that would normally be encountered in electroplating or electropolishing situations so there is no reason why they could not be simple drop-in replacements for aqueous systems. The majority of plating plants are constructed from polymers such as polyethylene, polypropylene, nylon and PVC, ail of which are stable in the majority of ionic liquids. 

Membrane polymeric materials for separation applications are made of polyamide, polypropylene, polyvinylidene fluoride, polysulfone, polyethersulfone, cellulose acetate, cellulose diacetate, polystyrene resins cross-linked with divinylbenzene, and others (see Section 2.9) [59-61], The use of polyamide membrane filters is suggested for particle-removing filtration of water, aqueous solutions and solvents, as well as for the sterile filtration of liquids. The polysulfone and polyethersulfone membranes are widely applied in the biotechnological and pharmaceutical industries for the purification of enzymes and peptides. Cellulose acetate membrane filters are hydrophilic, and consequently, are suitable as a filtering membrane for aqueous and alcoholic media. 

The discovery of homogeneous metallocene catalysts in the 1980s was a very important milestone in polymer technology. With these catalysts the plastic industry is poised to move into an era of an entirely new range of polymeric materials with several specific advantages. From the initial discovery in the 1980s, close to five billion dollars is estimated to have been invested by several large chemical companies in research and development. In a relatively short time, this has resulted in approximately fifteen hundred patent applications Close to 0.5 million tons of metallocene-catalyzed polypropylene is expected to be manufactured by the year 2003. 

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