Replacement with Plastic

While this increase in thickness may have some disadvantages, (space 

In contrast to sheet metal, where the thickness is uniform, STX can be molded with sections of varying thickness. While it is always recommended in design of plastic parts that section thicknesses be uniform, it is always the first rule to be violated. It is this, very design flexibility that becomes advantageous, and designers are usually unable to resist the ability to strategically modify section thickness to meet the load or stress requirements. If stress, temperature, creep, impact or any other environmental conditions require a heavier or specific section thickness, it can be done within prevalent design parameters. 

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If metal in cars is replaced with plastics, the vehicle is lighter and more fuel efficient. The same applies to aircraft and spaceships. Nevertheless, polymers cannot replace all the metal, because they are not as tough. Even worse Plastics fatigue over time. Fatigue may, e.g., cause that after driving a year on cobblestone the spare wheel breaks through its well. 

Coatings for luggage exteriors must be durable. Typical compounds use 50-70 phr of DINP or DIDP, 10-20 phr calcium carbonate filler, colorants as required, 2-3 phr 5-7 p,m AZO, and 2-3 phr of a liquid activator-stabilizer. In almost all applications, DOP has been replaced with plasticizers of lower volatility. This is particularly true of automotive upholstery. DIDP blends with trimellitate plasticizers have become common use levels are typically about 80 phr, with 5-10 phr calcium carbonate, colorants as needed, 2-3 phr of 3 pm AZO, and 2-3 phr of activator-stabilizer. Lower residual odor is achieved with 3-5 phr 3 p,m OBSH instead. 

After the addition of the propyne the thermometer-gas outlet combination was replaced with a "cold finger" filled with dry-ice and acetone. The top of this reflux condenser was connected via a plastic tube with a cold trap (-75°C) containing 50 ml of dry THF. The cooling bath was removed and the conversion of propyne started... 

Textile. Textile bags are made from natural fibers such as cotton and burlap (see Fibers, vegetable). Burlap or Hessian cloth is woven from jute fibers. Because the supply of jute and, consequendy, its price have been uncertain for many years, textile bags gradually have been replaced by various combinations of textile components with plastic or paper, multiwaH paper bags, or plastic bags (see Textiles). 

Waterproof Finishes. Waterproofing results from coating a fabric and filling the pores with film-forming material such as varnish, mbber, nitroceUulose, wax, tar, or plastic. The materials may be appHed as hot melts, eg, waxes or some polymers, as solvent solutions, or as aqueous latexes. The continuity of the film provides the water resistance. Except for tents, tarpauHns, and covers, coated fabrics have been largely replaced by plastics, and by fabrics treated with water and oU repeUents that do not reduce permeabUity to air and water vapor. Eabrics are also commonly laminated to films, such that the total stmeture is waterproof (15), or in some cases water-resistant but breathable (16). 

It may also be replaced with new carbon and disposal of the exhausted carbon Most adsorbers are pressure vessels constructed in carbon steel, stainless steel or plastic. Large systems for drinking water are often eonstructed in concrete. In some cases, a moving or pulsed bed adsorber is employed to optimixe the use of the granular activated carbon. 

Finite-element techniques can cope with large, highly non-linear deformations, making it possible to model soft tissues such as skin. When relatively large areas of skin are replaced during plastic surgery, there is a problem that excessive distortion of the apphed skin will prevent adequate adhesion. Finite-element models can be used to determine, either by rapid trial-and-error modelhng or by mathematical optimisation, the best way of... 

Liquid membranes consist of an organic phase, which by its hydrophobic nature is relatively impermeable to ions. Originally organic solvents such as decanol were used in conjunction with a porous hydrophobic membrane. These have been replaced by plasticized polyvinyl chloride membranes which behave like liquids yet have improved mechanical properties Other polymers such as silicone, polyurethane and ururshi, a... 

This P -I type of response curve can also be easily shown to apply to a simple rigid-plastic mechanical system, in the manner shown in Figure 16 (see Refs. 15 and 22). Here, the spring in the system is replaced with a pure Coulomb friction element, with resisting force f, which is independent of displacement once the mass starts to move. All other symbols are defined above. 

Costs can be lowered with the use of newer types of pipes, insulating materials and excavation techniques. Plastic piping in long rolls is laid in plastic insulation and placed in narrow trenches. Using these techniques, hundreds of feet of pipe can be laid quickly. Metal radiators can also be replaced by plastic units. 

Pentaerythritol tetranitrate (PETN) is a colorless crystalline solid that is very sensitive to initiation by a primary explosive. It is a powerful secondary explosive that has a great shattering effect. It is used in commercial blasting caps, detonation cords, and boosters. PETN is not used in its pure form because it is too sensitive to friction and impact. It is usually mixed with plasticized nitrocellulose or with synthetic rubbers to form PBXs. The most common form of explosive composition containing PETN is Pentolite, a mixture of 20 to 50% PETN and TNT. PETN can be incorporated into gelatinous industrial explosives. The military has in most cases replaced PETN with RDX because RDX is more thermally stable and has a longer shelf life. PETN is insoluble in water, sparingly soluble in alcohol, ether, and benzene, and soluble in acetone and methyl acetate. 

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