Reinforced Plastic Successes

The business climate of the 1990s is different from the past. Factors such as increased competition, a global marketplace, rapid technical shifts, and greatly compressed product life cycles constantly open new opportunities for plastics in general and reinforced plastics in particular. Reinforced plastics have become widely accepted for particular appHcations because they offer a combination of design, performance, and economic benefits to the user. These materials have had a proven record of success since the 1940s. 

Fracture mechanics techniques, of the type described in Section 2.21.6 have been used very successfully for fibre reinforced plastics. Typical values of K... 

H = History if a plant has used material successfully for many years, and the staff members know its strengths and limitations, how to weld it, etc., hesitate before making a change. For example, a fiberglass-reinforced plastic had given excellent service for many years when another composite from the same company, with the same name but a different number, was used instead, it failed overnight. 

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. 

There are no simple rules of thumb in defining the cost of reinforced plastic components. Their successful use has resulted from proper design, utilizing the benefits these materials offer, process selection, tooling cost advantages that fit the production needs, and consideration of life cycle economics. Each existing application illustrates the cost-performance advantage of reinforced plastic over the traditional material that is displaced. 

Usually these products are oxidizers, and considerable success has been established over the years in small cooling systems, with mixed oxidizers of differing ratios, available as slow-release tablet (puck) and stick forms [such as l-bromo-3-chloro-5,5-dimethylhydantoin (BCDMH)]. These solid products are usually retained in a GRP (glass-reinforced plastic) or PVC (polyvinyl chloride) tank, often called a brominator. ... 

A third interesting aspect of this story is that Du Pont s aramide fiber was not specifically the result of market-driven research. When this fiber was patented in 1971 there was no commercial application in view. However, within ten years, three varieties of Kevlar fiber were commercialized by Du Pont for dozens of reinforced plastic applications in radial passenger tires, belts, in protective clothing, such as gloves or ballistic and flak vests, in ropes and cables in racing kayaks and canoes, and in commercial aircraft. Thus the Kevlar fiber by no means resulted from the functional, bottom-up, approach which is sometimes considered as a major characteristic of materials science. The aramide fiber resulted from the traditional style of industrial research which was successful in the plastic era and confirms the leadership of chemistry in materials technologies. 

The new dress-cap substrate material should be either fiber-reinforced plastic (FRP) or Type 316 stainless steel. Being a nonmetallic insulator, FRP would eliminate any possibility of galvanic corrosion. Type 316 stainless steel demonstrates good passivity in urban atmospheres and has been successfully used in contact with copper.1... 

The tubular reverse osmosis device is shown in Figure 4.10. The tube serves as the pressure vessel and the membrane is installed inside the tube. Tubes with inside diameters of % and 1 inch have been used. Uniformly porous fiberglass reinforced plastic tubes have been used and nonporous but perforated copper, stainless steel and fiberglass tubes have also been successfully used. The membrane can be bonded to the tube in which case it is cast in situ or the membrane can be loose. The loose membrane is cast in sheet form and a cylindrical section is formed and placed in the tube. Packing densities for the Vi-inch diameter tube are about 100 square feet per cubic foot and about 50 square feet per cubic foot for the 1-inch diameter tube. 

Following the success of ISO 10,350 [34] on comparable data for materials selection for plastics, it was agreed in 1996 to prepare two parts. Part 1 covers unreinforced plastics and plastics reinforced by fibers shorter than 7.5 mm. and Part 2 covers reinforced plastics w ith fibers greater than 7.5 mm. These database standards quote the appropriate international standard, normally ISO as discussed above. The original standard has been adopted widely leading to a greater use of the referenced ISO standards. The wide range of material properties found in composite materials requires that the correct method (e.g.. Part 4 or 5 of ISO... 

Limited at first to the inspection of metallic components, it was later demonstrated that high-frequency magnetic fields causing eddy current production could be applied to the testing of composites containing conductive fibers, or a certain amount of graphite [108.109], Eddy current testing has been successfully applied in the detection and characterization of defects in carbon fiber reinforced plastics (CFRP) panels, helicopter rotor blades, truck tires, and more [110-112]. 

The widespread use of GRP for marine vessels of less than 60 m length suggests that there is a high level of confidence in the ability of laminates to perform in service. The materials are nevertheless not without problems. This chapter will consider their response to the marine environment and will note any features of design and manufacture which may compromise the performance. The resulting emphasis on potential difficulties should be balanced by considering the obvious and numerous successes of reinforced plastics vessels in marine applications. 

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