Environment reinforced plastics

A wide variety of thermoplastics have been used as the base for reinforced plastics. These include polypropylene, nylon, styrene-based materials, thermoplastic polyesters, acetal, polycarbonate, polysulphone, etc. The choice of a reinforced thermoplastic depends on a wide range of factors which includes the nature of the application, the service environment and costs. In many cases conventional thermoplastic processing techniques can be used to produce moulded articles (see Chapter 4). Some typical properties of fibre reinforced nylon are given in Table 3.2. 

Occupational and environmental exposure to chemicals can take place both indoors and outdoors. Occupational exposure is caused by the chemicals that are used and produced indoors in industrial plants, whereas nonoccupa-tional (and occupational nonindustrial) indoor exposure is mainly caused by products. Toluene in printing plants and styrene in the reinforced plastic industry are typical examples of the two types of industrial occupational exposures. Products containing styrene polymers may release the styrene monomer into indoor air in the nonindustrial environment for a long time. Formaldehyde is another typical indoor pollutant. The source of formaldehyde is the resins used in the production process. During accidents, occupational and environmental exposures may occur simultaneously. Years ago, dioxin was formed as a byproduct of production of phenoxy acid herbicides. An explosion in a factory in... 

During the last half-century, aeronautics technology has soared, with plastics playing a major role. Lightweight durable plastics and reinforced plastics (RPs) save on fuel while standing up to forms of stress like creep and fatigue, in different environments. 

From ships to submarines to mining the sea floor, certain plastics can survive sea environments, which are considered more hostile than those on earth or in space. For water-surface vehicles many different plastic products have been designed and used successfully in both fresh and the more hostile seawater. Figure 2-55 is an example where extensive use is made using unreinforced and reinforced plastics meeting structural and nonstructural product requirements. Included are compartments, electronic scanners, radomes, optically transparent devices, food storage and dispensing containers, medical products, buoyant devices, temperature insulators, and many more. 

Fiber-reinforced plastics have varying degrees of resistance to adverse environments such as moisture, alkali, acid, and other chemicals. The degree of resistance depends on the fiber-resin system. Moisture absorption and chemical infiltration will be different for different fiber-resin systems. The degradation of composite materials may result from several factors ... 

Hojo, H., Tsuda, K. Effects of Chemical Environments and Stress on Corrosion Behaviors of Glass Fiber Reinforced Plastics and Vinyl Ester Resin, Proc., 34th Ann. Tech. Conf., Reinf. Plast./Compos. Inst., SPI, Sec. 13-B, 1979... 

Meinhardt, T.J., Young, R.J. Hartle, R.W. (1978) Epidemiologic investigations of styrene-butadiene rubber production and reinforced plastics. Scand. J. Work Environ. Health, 4 (Suppl. 2), 240-246... 

Federal environment regulations, 75-78 Feed-tray location in distillation towers, lo Fiberglass reinforced plastics (FRP), 436-437 Fibonacci search, 407 Fifo method for materials accounting, 148... 

Fig. 6 Processes of environment-conscious material design of precast lightweiht concrete reinforced with continuous fiber reinforced plastic (FRP) reinforcement...

Among thermoplastic resins used as the matrix in reinforced plastics, the largest tonnage group is the polyolefins, followed by nylon, polystyrene, thermoplastic polyesters, acetal, polycarbonate, and polysulfone. The choice of any thermoplastic is dictated by the type of application, the service environment, and the cost. 

These assumptions are not always justifiable when applied to plastics unless modification has occurred. The classical equations cannot be used indiscriminately. Each case must be considered on its own merits, with account being taken of such factors as the mode of deformation, the service temperature and environment, the fabrication method, and so on. In particular, it should be noted that the past traditional equations that have been developed for other materials, principally steel, use the relationship that stress equals the modulus times strain, where the modulus is constant. Except for thermoset reinforced plastics and certain engineering plastics, many plastics do not generally have a constant modulus. Different approaches have been used for the nonconstant situation some are quite accurate. The drawback is that most of these methods are quite complex, involving numerical techniques that are not attractive to designers. One method that has been widely accepted is this so-called pseudoelastic design method. In this method appropriate values of such time-dependent properties as the modulus are selected and substituted into the standard equations. 

Jones FR. Durability of reinforced plastics in liquid environments. In Pritchard G, editor. Reinforced plastics durability. Cambridge Woodhead 1999. pp. 70—110. 

ASTM is a worldwide organization that started in the 19th century with headquarters now in West Conshohocken, Penna. (suburb of Philadelphia), USA. It is recognized as a world authority on standards for testing all types of materials that includes plastics. Their annual books of ASTM Standards contain more than seven thousand standards published in sixty-six volumes that include different materials and products. There are four volumes specifically on plastics 08.01-Plastics I 08.02-Plastics II 08.03-Plastics III, and 08.04-Plastic Pipe and Building Products. Other volumes include information on plastics and reinforced plastics (KPs). The complete ASTM index is listed under different categories for the different products, types of tests (by environment, chemical resistance, etc.), statistical analyses of different test data, and so on. 

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