Elasticity retention

The high strength and high-elasticity retention over a wide range of temperatures imparts HNBR with a good retention of dynamic behavior. Stein et al. [120] have... 

The foregoing is an equilibrium analysis, yet some transient effects are probably important to film resilience. Rayleigh [182] noted that surface freshly formed by some insult to the film would have a greater than equilibrium surface tension (note Fig. 11-15). A recent analysis [222] of the effect of surface elasticity on foam stability relates the nonequilibrium surfactant surface coverage to the foam retention time or time for a bubble to pass through a wet foam. The adsorption process is important in a new means of obtaining a foam by supplying vapor phase surfactants [223]. 

A good compilation of the functions of fats in various food products is available (26). Some functions are quite subtle, eg, fats lend sheen, color, color development, and crystallinity. One of the principal roles is that of texture modification which includes viscosity, tenderness (shortening), control of ice crystals, elasticity, and flakiness, as in puff pastry. Fats also contribute to moisture retention, flavor in cultured dairy products, and heat transfer in deep fried foods. For the new technology of microwave cooking, fats assist in the distribution of the heating patterns of microwave cooking. 

Grease Retention, Wrinkle Resistance, and Durable Press. On bending or creasing of a textile material, the external portion of each filament in the yam is placed under tension, and the internal portion is placed in compression. Thus, the wrinMe-recovery properties must be governed in part by the inherent, tensional elastic deformation and recovery properties of the fibers. In addition to the inherent fiber properties, the yam and fabric geometry must be considered. 

The important properties of the rubbers are their temperature stability, retention of elasticity at low temperatures and good electrical properties. They are much more expensive than the conventional rubbers (e.g. natural rubber and SBR) and have inferior mechanical properties at room temperature. 

Figure 4.70. GF PB T examples of elastic modulus retention (%) versus low temperatures (°C)...

In general, at low latex dosage levels, the creep strain and creep coefficient of latex modified concrete and mortar are considerably smaller than those of ordinary cement cement, mortar and concrete [94, 98]. The low creep is probably due to the low polymer content which may not affect the elasticity, but increases the strength by improving the binding capacity of the matrix as well as providing better hydration through water retention in the mortar and concrete. The coefficient of thermal expansion at about 9-10 x 10 is very similar to that of concrete, which is 10 x 10 6 [87, 94, 99]. 

Some specimens have withstood over 500 cycles. Untreated specimens of these concretes commonly failed the test at approximately 80 cycles. The elastic modulus criterion (less than 60% of original by resonant frequency analysis) was used to determine failure. Specimens often failed the test with no visible cracking or spalling. Strength retention in these specimens was usually high (50% or more). 

Non-reserve polysaccharides seem to function in biological tissues through the part they play in cohesion, the retention of water and salts, the physical organization, and the elasticity and general texture. Polysaccharide conformation and association, as well as chemical structure, are obviously involved in the control of such properties. The polysaccharide-polysaccharide interactions considered in this Section can be regarded (in the nomenclature of protein biochemistry) as showing secondary, tertiary, and quaternary structure.4W>2W8 The... 

Retention of elongation reaches a maximum at 35 to 50% copolymer content. Higher butadiene content in the copolymer gives increased softness and elasticity. According to experimental data, the copolymer with 37% acrylonitrile has optimal efficiency in handling, homogeneity, and mechanical properties. This composition corresponds to a molar ratio of 1.5 mole of butadiene to 1 mole of acrylonitrile. 

PVC has a unique ability to be compounded with a wide variety of additives, making it possible to produce materials that range from flexible elastomers to rigid compounds, that are virtually unbreakable with a notched Izod impact greater than 0.5 J/mm at —40 C, that are weatherable with good property retention for over 30 years, as well as compounds that have stiff melts and litde elastic recovery for outstanding dimensional control in profile extrusion, and also low viscosity melts for thin-walled injection molding. 

The deformation appears as a surface bump that can be detected during the read operation because the intensity of light reflected back to the detector will be different from that reflected from a flat area. Erasure is effected by exposure to a second laser beam at 780 nm. Here, light is absorbed by the dye in the retention layer but not the expansion layer the retention layer is softened, and the elastic energy stored in the expansion layer restores planarity to the laminated structure. 

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