Impact polyester fiber

The surface of the synthetic polymers can be modified by chemical, physical, and enzymatic methods (Figure 4.1). Chemical modification requires harsh reaction due to which strength properties of polymers get affected. Zeronian and Collins (1989) reported a 10-30% weight loss in polyester fibers after chemical treatment. Additionally, chemical treatments are difficult to control and have negative impacts on the enviromnent. 

In very simple terms, a filter fabric intercepts a particle moving along a gas stream. When a particle impacts a fiber in the filter, the fiber does not get out of the way and the particle cannot go around the fiber. The gas stream, of course, can go around the fiber. The particle has mass and thus cannot follow the gas stream. Very small and light particles can be influenced by the bombardment of gas molecules, changing their path until they bump into the fiber and are trapped. Then there is also electrical entrapment when fibers in the fabric and dust particles carry opposite charges. In this case particles are attracted to the fiber and are trapped there. Fabrics made of cotton, polypropylene, nylon, polyester, Nomex, Teflon, glass, and wool are used as filters. 

Polyester fibers are frequently used in combination with cellulose fibers and fabric chips to produce impact-resistant PF molding compounds. In combination with glass fibers, they increase the impact strength of reinforced UP molding materials as required. 

Uses Building block/modifier for polyester fibers, polyamides, urethane elastomers modifier (increases flexibility, impact resist., toughness, hydrolytic stability) for industrial coatings (automotive, coil, textile, leather, wood lacquers)... 

The oversupply of polyester fibers and the trend toward casual dress has had a negative impact on the cellulose acetate textile market. Use in plastics applications has also declined. Worldwide demand for fiber declined at the rate of 9% per year for the period 1996-2001. It is estimated that the decline will continue at the rate of 3% per year during the period 2001-2006. 

Diallyl phthlates (DAP) and diallyl isophthlates (DAIP) are the principal thermosets in the allyl family, with DAP used predominantly. They are used for glass-preimpregnated cloth and paper that must undergo a heat, time, and pressure cycle to produce parts. Molding compounds are reinforced with fibers to improve their mechanical and physical properties. Glass fibers impart mechanical performance, acrylic fibers provide improved electrical performance, polyester fibers enhance impact resistance, and other fibers and fillers can impart different performance traits. 

Ceramic powders Mica flakes Molybdenum disulfide Nano-clay Polyester fibers Antioxidants Antistatics Preservatives Processing aides Fungicides Smoke suppressants Foaming agents Viscosity modifiers Clarifiers Impact modifiers Odor reducers... 

Not all synthetic polymers are used as fibers Mylar for example is chemically the same as Dacron but IS prepared in the form of a thin film instead of a fiber Lexan is a polyester which because of its impact resistance is used as a shatterproof substitute for glass It IS a polycarbonate having the structure shown... 

Rayon is unique among the mass produced man-made fibers because it is the only one to use a natural polymer (cellulose) directly. Polyesters, nylons, polyolefins, and acryflcs all come indirectly from vegetation they come from the polymerization of monomers obtained from reserves of fossil fuels, which in turn were formed by the incomplete biodegradation of vegetation that grew millions of years ago. The extraction of these nonrenewable reserves and the resulting return to the atmosphere of the carbon dioxide from which they were made is one of the most important environmental issues of current times. CeUulosic fibers therefore have much to recommend them provided that the processes used to make them have minimal environmental impact. 

THPOH—Ammonia—Tris Finish. By far the most effective finish for polyester—cotton textiles was a system based on the THPOH—NH treatment of the cotton component either foUowed or preceded by the appUcation of Tris finish to the polyester component. This combined treatment appeared to be effective on almost any polyester—cotton blend. A large amount of fabric treated in this way was sold throughout the United States and much of the rest of the world. Shortly after the introduction of Tris finishing, Tris was found to be a carcinogen. Most of the Tris treated production was in children s sleepwear, and this created a situation in which almost aU chemical fire-retardant-treated textiles were unfairly condemned as dangerous. Manufacturers mshed to replace chemically treated textiles with products produced from inherently flame-resistant fibers. Nowhere was the impact more severe than in the children s sleepwear market. New, safer materials have been introduced to replace Tris. Thus far none has been as completely effective. 

Other reinforcements that may be used in the substrate layers of decorative laminates and throughout the stmcture of industrial laminates are woven fabrics of glass or canvas and nonwoven fabrics of various polymeric monofilaments such as polyester, nylon, or carbon fibers. Woven and nonwoven fabrics tend to be much stronger than paper and have much more uniform strength throughout the x—y plane. They greatly enhance properties of laminates such as impact and tear strength. 

Mechanical Properties. Properties of typical grades of PBT, either as unfiUed neat resin, glass-fiber fiUed, and FR-grades, are set out in Table 8. This table also includes impact-modified grades which incorporate dispersions of elastomeric particles inside the semicrystalHne polyester matrix. These dispersions act as effective toughening agents which greatly improve impact properties. The mechanisms are not fiiUy understood in all cases. The subject has been discussed in detail (171) and the particular case of impact-modified polyesters such as PBT has also been discussed (172,173). 

Hexamethylphosphoramide (HMPT), 185 HFBPA-based poly(arylene ether)s, 362 HFCs. See Hydrofluorocarbons (HFCs) High-impact polystyrene (HIPS), 219 High-melting polymers, 33 High-melting-point fiber-forming polyesters, 19... 

Nylon was the first commercial polymer to make a substantial impact on the textile industry, but polyesters now comprise the largest segment of the market for synthetic fibers. In fact, polyesters account for 40% of the more than 4 billion kilograms of synthetic fibers produced in the United States each year. The leading polyester, by far, is poly(ethylene terephthalate), or PET. This polymer is made from terephthalic acid and ethylene glycol in an acid -alcohol condensation reaction ... 

Typically, polyester resins are used for high-end applications that require excellent electrical and thermal resistance. When dimensional stability under load is more critical, glass fibers are incorporated to increase the heat distortion temperature and the stiffness of the part. Examples of glass fiber reinforced parts include electrical housings, electrical adapters, computer components, telephone housings, and light bulb sockets. When impact modified, polybutylene terephthalate can be injection molded to make car bumpers. 

A major aspect of polymer, in particular polyester, production is the manufacturing of fibers for textile and technical applications. This section deals with the impact of the production conditions on the fiber quality. The following discussion will be mainly based on PET fibers, but by and large the problems, phenomena and their solutions are generally relevant to the production of other polymer filaments. 

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