Gas structural element

Shutov, F. A The gas-structure element and a new classification of plastic foams. All-Union Conference on Gas-Filled Polymers, Vladimir/USSR, 1974 (in Russian)... 

Berlin, A. A, Shutov, F. A. Gas-structure element of plastic foams. Second Internation Conference on the Mechanics and Technology of (Composite Materials. Varna, Bulgaria 1979... 

The gas structural element concept is more general than the cell concept. Indeed, similarly sized and shaped cells may form different types of GSE (due to different configurations and different intercellular space volume). On the other hand, a similarity of the GSE would indicate similar size and shapes of the cells as well as their walls, struts and the intercellular space (see Sect. 5.3). 

Fig. 2. Relationship between the volume ratio of open gas structural elements 3, and the volumetric weight y and volume ratio of gas Sg for rigid polyurethane foam (Grade PPU-3)...

Fig. 4. Schematic view of the gas structural element of rigid resol phenolic foam (sketch of microphotograph, magnification ISO times)...

Fig. 9. Possible types of structures for walls and struts of gas structural elements with the same length L, according to Harding...

In investigations of the structure and properties of disperse materials, particularly plastic foams, it is necessary to find out the distribution pattern of one phase in the material. It is simpler to consider the distribution of the gas phase in a solid body, i.e. the gas-filled cell distribution within a foam bulk] In their turn, the cells, as shown above, may be characterized by several parameters (size, shape, volume and surface area). The cell size distribution pattern is the most comprehensive characteristic of the dispersity of the gas structural elements of plastics. Furthermore, the cell size can, be determined by one of the methods which will be discussed below, and the foam dispersity is expressed in terms of the nominal cell diameter distribution function. 

GFRP glass fiber-reinforced plastic GSE gas structural element... 

In open cell structures the gas is air and for this reason they have a higher absorptive capacity of moisture, a higher gas and vapour permeability, less effective insulation capabilities for either heat or electricity, and a better ability to absorb and dampen sound. Eor any polymer composite, the proportion of open gas structural elements increases as the density of the foamed plastic decreases, because an increase in cell size means a decrease in the thickness of cell walls and ribs [60]. The combination of other advantageous physical properties with fair acoustic characteristics has led to the use of plastic foams in sound proofing [31]. 

The elements (X) in this group are two electrons short of a noble gas structure which they can achieve either by gaining or sharing electrons. The formation of the ion may require considerable amounts of energy thus for oxygen 650 kJ must be supplied for the reaction... 

Noble gas An element in group 18 at the far right of the periodic table, 31 anions, 38 cations, 38 characterization, 190 structures, 150-151... 

The experimental approach discussed in this article is, in contrast, particularly amenable to investigating solvent contributions to the interfacial properties 131. Species, which electrolyte solutions are composed of, are dosed in controlled amounts from the gas phase, in ultrahigh vacuum, onto clean metal substrates. Sticking is ensured, where necessary, by cooling the sample to sufficiently low temperature. Again surface-sensitive techniques can be used, to characterize microscopically the interaction of solvent molecules and ionic species with the solid surface. Even without further consideration such information is certainly most valuable. The ultimate goal in these studies, however, is to actually mimic structural elements of the interfacial region and to be able to assess the extent to which this may be achieved. 

The previous discussion has been limited to ions with noble-gas structure the same phenomena occur in the highly-charged elements of the subgroups, as can be seen from the values of the heats of formation of some of the oxides, Table XIX> where again the... 

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