Temperature Adjusted Material Densities

DIPPR Project 882 is organized to develop, maintain and make available to its sponsors a computer databank of selected and evaluated physical, thamodynamic and transport properties for binary mixtures. The properties include viscosity, thermal conductivity, mutual-diffusion coefficient, excess volume and density, surface tension, critical temperature, pressure and density and the solubility of sparingly soluble materials. The data from the original literature have been compiled in their original units. Computer routines have been developed to provide the data in SI units for final dissemination. Assessments of the imprecisions and inaccuracies for each of the variables (temperature, pressure, composition and property) are made, and the results have been screened and adjusted, where applicable, to be consistent with the pure component data calculated from a variety of reliable sources. The data may be drawn from electronic database as tables and plots of the experimental data in the original or SI units. 

An illustration of time-temperature (t-7) superposition procedure for shifts in creep compliance, D(t). Adjustments for any change in the material density are ignored... 

In each case, the pressure is mainly fixed by the density and quite insensitive to temperature. A consequence of this is that, when a new nuclear reaction (e.g. helium-burning) sets in in degenerate material, the additional heat cannot be taken up (as it would be in an ideal gas) by expansion and there is a thermal runaway (Mestel 1952). The temperature rises very strongly until it becomes high enough for the degeneracy to be removed, and the star adjusts to a new structure with lower central density. 

Nanocrystalline materials have received extensive attention since they show unique mechanical, electronic and chemical properties. As the particle size approaches the nanoscale, the number of atoms in the grain boundaries increases, leading to dramatic effects on the physical properties and on the catalytic activity of the bulk material. Nowadays, there is a wide variety of methods for the preparation of nanocrystalline metals such as thermal spraying, sputter deposition, vapor deposition and electrodeposition. The electrodeposition process is commercially attractive since it can be performed at room temperature and the experimental set-up is less demanding. Furthermore, the particle size can be adjusted over a wide range by controlling the experimental parameters such as overvoltage, current density, composition, and temperature (see Chapter 8). 

Notice that transformation from a crystalline phase to presumably metastable amorphous phases is called amorphization. It is very promising to use for making of adjustable stores hydrogen fuel phenomena that is called polyamorphism. This term meaning that the pure material can exist in more than one amorphous state. In principle, the abovementioned mechanism of density jumps at polyamorphic transition of ice allows to obtain reversible accumulation of methane inside cellular nanostructures of cryogenic amorphous ice. It is important that the degree of accumulation can be sharp adjusted by pressure and temperature. 

The continuous pre-foamer normally consists of an open stirred tank with baffles. The raw material is fed by an adjustable feed screw near the container bottom. Steam is introduced at the bottom of the pre-foamer. The EPS beads move slowly upwards during pre-foaming and discharge into the fluidized bed via the overflow. The foam density attained depends on the residence time in the pre-foamer, which is adjusted by the feed screw or the weir height. High foam densities (>30g/l) require temperature control by air addition. For low bulk densities (special, <15 g/1), the material pre-foamed once is pre-foamed again, after temporary storage. 

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