Lightweight Structures

Class IV Large prime movers (i.e., drivers greater than 100 horsepower) mounted on relatively soft, lightweight structures. 

Waste products from a number of commercial processes can be used as cheap and readily available fillers for PCM. For example, lightweight structural materials may be obtained by filling various low-viscous resins with waste materials [4, 5]. Also by adding fillers to reprocessed polymers it is possible to improve their properties considerably and thus return them to service [6]. This method of waste utilization is not only economically feasible but also serves an ecological purpose, since it will help to protect the environment from contamination. The maximum percentage of the filler should in these cases be such as to assure reliable service of the article made from the PCM under specified conditions for a specified period of time. 

In the case of plastics, emphasis is on the way plastics can be used in these structures and why they are preferred over other materials. In many cases plastics can lend themselves to a particular field of application only in the form of a sophisticated lightweight stiff structure and the requirements are such that the structure must be of plastics. In other instances, the economics of fabrication and erection of a plastics lightweight structure and the intrinsic appearance and other desirable properties make it preferable to other materials. 

This rigid linear foam with closed cells was developed by ATC Chemicals Company to be used as the core in lightweight structural sandwich composites particularly intended for boatbuilding. SAN foams have ... 

Astrom, B.T., Department of Lightweight Structures, Royal Institute of Technology, Stockholm, Sweden... 

Foamed Sulfur (15, 1 8). By using additives and simple ma-chinery, sulfur can be turned into a foam that has very useful properties. Lighter than water, foamed sulfur can be used for building insulation, subbases for pavements, and perhaps lightweight structural members for housing and other small structures. 

Syntactic foams manufactured from hollow glass or silica microspheres and an epoxide, phenolic or other matrix resin represent a class of lightweight structural materials used for buoyancy purposes, insulation and packaging. The effect of silanes on the mechanical properties of syntactic foams at a nominal density of 0.35 g/cm3 is shown in Tables 14-16. The Proportional Limit is defined as the greatest stress which the foam is capable of sustaining without any deviation from proportionality of stress to strain (Hooke s Law). 

Stiff lightweight structures such as aircraft wings are made from sandwiches of continuous sheets filled with foams or honeycombs. Open porous structures can form frameworks for infiltration by other materials leading to application of biocompatible implants. Open pore structures are used as supports for catalysts. 

Magnesiiun Dolomite ([Mg,Ca]C03) Electrolysis of fused MgCb (obtained from brines) Lightweight structures (alloys) Sacrificial electrodes Flares, pyrotechnics, incendiary bombs... 

Outside of the sphere of interest in environmental science and technology that is occupied by activated carbons, the use of other forms of carbon is so broad that there are numerous instances where carbons contribute directly or obliquely to the development, protection, or maintenance of an environmentally friendly society. Examples include diverse applications in the field of medicine, where carbon is attractive, ceteris parihus, because of its compatibility with the human body—carbons are chemically and biologically inert the formation of strong, lightweight, structures that are resistant to chemical attack and can improve the efficiency of energy use and protection from thermal and acoustic emissions. 

Boron fibers possess good mechanical properties at low densities, which accounts for their use in composites for lightweight structures. Commercially obtainable boron fibers exhibit an elasticity modulus at room temperature of 400 Gpa, a tensile strength of 3-4 GPa and a thermal expansion coefficient from room temperature to 327°C of 4.9 10 /K. The maximum use temperature is 367°C, the elasticity modulus having dropped to 240 GPa at 627°C. 

Magnesium occurs widely in carbonate ores, but most Mg comes from salt brines and from the sea (Figure 22-5). Sea water is 0.13% Mg by mass. Because of its low density (1.74 g/cm ), Mg is used in lightweight structural alloys for such items as automobile and aircraft parts. 

Because of its relatively low density, aluminum is often used as a lightweight structural metal. It is often alloyed with Mg and some Cu and Si to increase its strength. Many buildings are sheathed in aluminum, which resists corrosion by forming an oxide coating. 

Ordered macroporous materials with pore sizes in the sub-micrometer range have applications in low-dielectric-constant materials and lightweight structural materials. Macroporous oxides such as silica, titania, and zirconia as well as polymers with well defined pore sizes in the sub-micrometer regime have been successfully synthesized.[166,167]... 

SPMs can now be found in commercial markets and specialty clothing due to their lightweight structure, liquid and aerosol repellent properties, and facilitation of moisture vapor transport. However, for military use, SPMs have limitations (Wilusz 2007). SPMs may act as liquid-repellents but may allow vapors to pass and therefore need an activated carbon layer to add extra protection capabilities. Moreover, military garments experience tremendous stress on a day-to-day basis. SPM-based ensembles are more susceptible to tearing as compared to activated carbon-based textile fabrics (Wilusz 2007). Optimizing the permselectivity of the membrane by surface modification or other such techniques is necessary to achieve a balance between comfort (e.g., moisture vapor transmission) and chemical vapor barrier properties. Furthermore, SPMs or membrane-carbon ensembles must possess acceptable mechanical strength to sustain daily military operations. 

Lithium is element number 3, a soft, silvery-white, solid element with a density of 0.535 g/cm3. It is the lightest of all metals and can be alloyed with other metals to make lightweight structural materials. 

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