Nonporous structure

Treatment of the open-framework materials at high vacuum and 70 °C results in collapse of the pores that are readily visible in the X-ray crystal structure (Fig. 13) and a nonporous structure (surface area[Pg.267]

Symmetric polymeric membranes possess a uniform pore structure over the entire thickness. These membranes can be porous or dense with a constant permeability from one surface to the other. Asymmetric (also sometimes referred to as anisotropic) membranes, on the other hand, typically show a dense (nonporous) structure with a thin (0.1-0.5 pm) surface layer supported on a porous substrate. The thin surface layer maximizes the flux and performs the separation. The microporous support structure provides the mechanical strengdi. 

Linde silica is of special interest because, for a nonporous material, it has an unusually high area, 180 sq. m./g. A very small particle size obviously accounts for its extensive area in spite of its nonporous structure. The duplicate isotherm determinations plotted in Fig. 27... 

Pick s law is the simplest description of gas diffusion through a nonporous structure, i.e. 

Scheme 5 Schematic illustration of conversions observed in Cu-mhsa system. Assembled structure containing inclusion molecules change to amorphous by the removal of the guest molecules. Exposure to organic vapor does not reconstruct the initial structure but lead to another nonporous structure.

In general, there are two different types of bipolar plate technologies one based on metal and the other based on graphite as a conductive component. The latter can be pure (expanded) graphite or a graphite composite material containing a polymer binder. Metal plates offer excellent electrical and thermal conductivities and they can be machined to very small thicknesses. Additionally, they do not tend to form cracks or break even at small thicknesses and their nonporous structure offers good gas... 

Porosity. Fabric porosity also affects the thermal insulation characteristics of fabrics (Fan et al., 2000). Generally, a fabric with a highly porous structure can trap more air than one with a lower or nonporous structure. The air trapped inside the fabric increases its thermal insulation. 

The molten core material settled onto the reactor vessel bottom head and was not cooled significantly by water during the relocation. Thermal analyses indicated that lower-head temperatures exceeding 1520 F (1373°C = 1100 K) would have occurred if the molten material had settled onto the lower head as a cohesive, nonporous structure. The lower head would have failed due to creep rupture at such temperatures. Since this did not occur, the debris on the lower head must have had... 

Just like in the case of Si, and for the same reasons (better resistance to strain apposite for enhanced ionic and electronic diffusion), porous material has improved electrochemical properties with respect to nonporous structures. In particular, mesoporous mono-phasic anatase Ti02 spheres of uniform particle size (ca. 400 nm) encompassing an average crystallite size of 14 nm was synthesized... 

---