Aerospace industry performance

Boron filaments are formed by the chemical vapor deposition of boron trichloride on tungsten wire. High performance reinforcing boron fibers are available from 10—20 mm in diameter. These are used mainly in epoxy resins and aluminum and titanium. Commercial uses include golf club shafts, tennis and squash racquets, and fishing rods. The primary use is in the aerospace industry. 

Boron Trichloride. Approximately 75—95% of the BCl consumed iu the United States is used to prepare boron filaments by CVD (7). These high performance fibers are used to reinforce composite materials (qv) made from epoxy resius and metals (Al, Ti). The principal markets for such composites are aerospace industries and sports equipment manufacturers. 

Eor more demanding uses at higher temperatures, for example, in aircraft and aerospace and certain electrical and electronic appHcations, multifunctional epoxy resin systems based on epoxy novolac resins and the tetraglycidyl amine of methylenedianiline are used. The tetraglycidyl amine of methylenedianiline is currently the epoxy resin most often used in advance composites. Tetraglycidyl methylenedianiline [28768-32-3] (TGALDA) cured with diamino diphenyl sulfone [80-08-0] (DDS) was the first system to meet the performance requirements of the aerospace industry and is still used extensively. 

In the late 1970s, Kirchhoff at Dow Chemical Company developed the use of benzocyclobutenes in polymer synthesis and modification. These efforts culminated in 1985 with the issuance of the first patent describing the use of benzocyclobutene in the synthesis of high-molecular-weight polymer.27 Similar work that involved a thermosetting system based on Diels-Alder cycloaddition between terminal benzocyclobutene and alkyne groups,28,29 was reported separately and independently by Tan and Arnold.28 Since these initial discoveries, the field of benzocyclobutene polymers has expanded rapidly and benzocyclobutene chemistry constitutes the basis of a new and versatile approach to the synthesis of high-performance polymers for applications in the electronics and aerospace industries.30... 

Adhesives and sealers can be an important part of a total corrosion protection system. Structural bonding procedures and adhesives for aluminum, polymer composites, and titanium are well established in the aerospace industry. Structural bonding of steel is gaining increasing prominence in the appliance and automotive industries. The durability of adhesive bonds has been discussed by a number of authors (see, e.g., 85). The effects of aggressive environments on adhesive bonds are of particular concern. Minford ( ) has presented a comparative evaluation of aluminum joints in salt water exposure Smith ( ) has discussed steel-epoxy bond endurance under hydrothermal stress Drain et al. (8 ) and Dodiuk et al. (8 ) have presented results on the effects of water on performance of various adhesive/substrate combinations. In this volume, the durability of adhesive bonds in the presence of water and in corrosive environments is discussed by Matienzo et al., Gosselin, and Holubka et al. The effects of aggressive environments on adhesively bonded steel structures have a number of features in common with their effects on coated steel, but the mechanical requirements placed on adhesive bonds add an additional level of complication. 

Observations for cured epoxy resins and resins derived from 1,2-polybutadlene crosslinked with t-butylstyrene are reported. These resins find applications in aerospace industry, including high performance, Kevlar 49, filament wound, pressure vessels on Skylab and the Space Shuttle. 

Propellant compositions are also used in numerous "gas generator" devices, where the production of gas pressure is used to drive pistons, trigger switches, eject pilots from aircraft, and perform an assortment of other critical functions. The military and the aerospace industry use many of these items, which can be designed to function rapidly and can be initiated remotely. 

Resin type Performance Processing Cost Aerospace industry Automotive industry... 

Perhaps the biggest thrust for the development of high performance polymers over the next 10 years will be in the aerospace industry where materials will be required for a fleet of high speed civil transports (supersonic transports). At a speed of Mach 2.4, an aircraft surface temperature of about 150 to 180°C will be generated. The life requirement of materials at these temperatures will be about 60000 hours. Many different types of materials such as adhesives, composite matrices, fuel tank sealants, finishes and windows will be needed. These materials must exhibit a favorable combination of processability, performance and price. The potential market for these materials total several billions of US dollars. 

A growing specialty application for acrylonitrile is in the manufacture of carbon fibres. These are produced by pyrolysis of oriented polyacrylonitrile fibres and are used to reinforce composites for high-performance applications in the aircraft, defence and aerospace industries. Other minor specialty applications of acrylonitrile are in the production of fatty amines, ion exchange resins and fatty amine amides used in cosmetics, adhesives, corrosion inhibitors and water-treatment resins (Brazdil, 1991). 

More recently, we have seen other new plastics arrive, including such exotic, high performance materials as the polybenzimidazoles, polyoxadiazoles, polyperfluorotriazines, polyphenylenes, and such inorganic materials as the boron polymers, the metalloxanes, and the polysilazanes, to name only a few. These exotic materials are mostly development products today, they are very expensive and will undoubtedly find their first uses, if any, in the aerospace industry which requires the high performance offered by these materials and can afford to pay for them. Some of these new materials will become commercial successes, others will not. 

Harmonic number (h) refers to the individual frequency elements that comprise a composite waveform. For example, h = 5 refers to the fifth harmonic component with a frequency equal to five times the fundamental frequency. If the fundamental frequency is 60 Hz, then the fifth harmonic frequency is 5 x 60, or 300 Hz. The harmonic number 6 is a component with a frequency of 360 Hz. Dealing with harmonic numbers and not with harmonic frequencies is done for two reasons. The fundamental frequency varies among individual countries and applications. The fundamental frequency in the U.S. is 60 Hz, whereas in Europe and many Asian countries it is 50 Hz. Also, some applications use frequencies other than 50 or 60 Hz for example, 400 Hz is a common frequency in the aerospace industry, while some AC systems for electric traction use 25 Hz as the frequency. The inverter part of an AC adjustable speed drive can operate at any frequency between zero and its full rated maximum frequency, and the fundamental frequency then becomes the frequency at which the motor is operating. The use of harmonic numbers allows us to simplify how we express harmonics. The second reason for using harmonic numbers is the simplification realized in performing mathematical operations involving harmonics. 

The nadimide and maleimide end-capped oligomers belong to the family of thermosetting telechelic oligomer precursors of thermostable networks shown in Fig. 1. These products were developed in order to fulfill the requirements of the aerospace industry in the domain of high performance adhesives and matrices for laminates. 

Compared to the carboxylated nitrile elastomer additives, the use of thermoplastics has primarily been focused on the aerospace industry. On a cost per pound basis, the two-phase nitrile additives offer the best combination of property improvement without negative impact. The thermoplastic additives, however, may offer better high-temperature performance, but they are more difficult to formulate and to process as adhesives. As a result, the cost of these adhesives is generally much higher than that of other toughened epoxy mechanisms. 

In the aerospace industry, too, there is an increasing demand for high-performance electrical insulation with a high degree of tire safety and light weight. Here the trend is for foamed fluoroplastics. FEP is attractive for this purpose. Fuel-tank seals are made predominantly from special perfluoroelastomers. 

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