Degree of expansion

The potential to use only a central nozzle or the need to build in a manifold have a fundamental bearing on the design and cost of the mould. This choice depends primarily on  

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Thermal Properties. Refractories, like most other soHds, expand upon heating, but much less than most metals. The degree of expansion depends on the chemical composition. A diagram of the thermal expansion of the most common refractories is shown in Figure 1. 

Determination of Relative EfSciences of Explosives By The Method of Equivalent Charges From the Degree of Expansion In a Trauzl Bomb , ZhPMTF No 2, 116-19 (1960) CA 55, 20434 (1961) 121) V.K. Bobolev ... 

It is necessary to check that this degree of expansion is possible within pipe... 

Combination of the Perrin function, p often referred as the frictional ratio due to shape with the frictional ratio (f/fo) enables the degree of expansion of the molecule (vh/ w ) to be estimated, where Vh, (cw / g) is the volume of the swollen molecule (Polysaccharide or protein + associated solvent) per unit mass of polysaccharide and v is the partial specific volume (essentially the anhydrous molecule) ... 

Arguably, the appearance, particularly the degree of expansion of a loaf, is not especially important as bread is sold by weight. In practice consumers prefer well-risen and well-shaped loaves. 

The upper limit of gas velocity for particulate expansion is termed the minimum bubbling velocity, umb. Determining this can present difficulties as its value may depend on the nature of the distributor, on the presence of even tiny obstructions in the bed, and even on the immediate pre-history of the bed. The ratio umb/umf, which gives a measure of the degree of expansion which may be effected, usually has a high value for fine light particles and a low value for large dense particles. 

The trends observed here continue with the addition of more configurations we decided that a point of diminishing returns was reached at four configurations, and therefore, established that degree of expansion for more exhaustive investigation. 

Near the surfactant region the crystalline or lamellar phase is found. This is the region one finds in hand soaps. The ordinary hand soap is mainly the salt of fatty acid (coconut oil fatty acids or mixtures [85%] plus water [15%] and some salts. X-ray analyses have shown that the crystalline structure consists of a layer of soap separated by a water layer (with salts). The hand soap is produced by extruding under high pressure. This process aligns the lamellar crystalline structure lengthwise. If the degree of expansion versus temperature is measured, the expansion will be found... 

Since the degree of expansion of the polymer coils is directly dependent on the solvating power of the solvent, under otherwise comparable conditions, both a and [q] provide a measure of the goodness of a solvent high values of a and [q] (at constant molecular weight and temperature) indicate remarkable coil expansion and therefore a good solvent. Low values of a and [q] indicate a bad solvent. For example, the values a for poly(vinyl acetate) in methanol and acetone are 0.60 and 0.72, respectively. 

For chromophores that are part of small molecules, or that are located flexibly on large molecules, the depolarization is complete—i.e., P = 0. A protein of Mr = 25 kDa, however, has a rotational diffusion coefficient such that only limited rotation occurs before emission of fluorescence and only partial depolarization occurs, measured as 1 > P > 0. The depolarization can therefore provide access to the rotational diffusion coefficient and hence the asymmetry and/or degree of expansion of the protein molecule, its state of association, and its major conformational changes. This holds provided that the chromo-phore is firmly bound within the protein and not able to rotate independently. Chromophores can be either intrinsic—e.g., tryptophan—or extrinsic covalently bound fluorophores—e.g., the dansyl (5-dimethylamino-1-naphthalenesulfonyl) group. More detailed information can be obtained from time-resolved measurements of depolarization, in which the kinetics of rotation, rather than the average degree of rotation, are measured. For further details, see Lakowicz (1983) and Campbell and Dwek (1984). 

One of the first applications of biodegradable materials is based on the cooked, extruded, and expanded starch known from the food and chemical sectors (Fig. 14.23). Starch is cooked with water in the extruder and chemically modified as necessary or mixed with plasticizers, then expanded to a starch foam and dried. The extrudate is ground so that the functional properties thus created can be used in the food/chemicals sector. The foamed, cut, and dried extrudate is the end product for loose-fill packaging applications. The degree of expansion is a measure of the foam texture. It increases strongly with product temperature at the die, helped by a higher specific mechanical energy input. However, both measures increase the water-solubility of the product. 

When a solid plastic is expanded to moderately lower its density, it is called a structural foam. Bone and wood are natural structural foams, which benefit from this moderate degree of expansion. Most plastic materials can similarly be expanded during melt processing, and also gain many benefits as a result. 

Plastics with solid densities of 0.9-1.2 are generally expanded 13-25 percent, giving foamed densities of 0.75-0.9. At this modest degree of expansion, they look and perform like solid products. 

A study of the effects of several different plasticisers on the density, elasticity and degree of expansion of foams, produced from different PVC plastisols, has been reported (120). A three-dimensional and high resolution quantitative image technique has been proposed for the investigation of the internal microstructure of foams. This provides a tool to study the relationships between foam structure and physical properties (18). 

The results are reported of a study of the effects of several plasticisers on the density, elasticity and degree of expansion of foams produced from different PVC plastisols containing either 44 parts of chalk and 52 parts of plasticiser or 60 parts of chalk and 66 parts of plasticiser. Plasticisers employed were di-iso-heptyl phthalate, DOP, butyl benzyl phthalate, dioctyl adipate, dodecyl benzene or combinations thereof. 9 refs. EASTERN EUROPE YUGOSLAVIA... 

Temperature gradients. These gradients produce cracks in rocks as a result of expansion-contraction cycles. The degree of expansion-contraction is dependent on the individual thermal expansion coefficients. Interestingly, it is believed that ancient civilizations took advantage of the expansion-contraction cycle of water/ice to split rocks apart for decorative and construction purposes. 

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