Porosity void volume

Sinter = 0.35 (interpellet porosity, void volume fraction for the entire packed reactor, dimensionless)... 

The bulk density corresponds to the mass of proppants that fill a unit volume and includes both proppant and porosity void volume. 

There are two common types of membrane material microporous and homogeneous. Microporous materials are manufactured from hydrophobic polymers such as polytetrafluoroethylene or polypropylene, which have a porosity (void volume) of about 70% and a pore size of less than 1 pm. Because of the nonpolar, water-repellent properties of the film, water molecules and electrolyte ions are cxciuded from the pores gaseous molecules, on the other hand, are free to move in and out of the pores by effusion and thus across this barrier. Typically, the thickness of microporous membranes is about 0.1 mm. 

This flux expression is based on the pore cross section only for the second expression on the right-hand side, we have assumed ideal gas behavior. For a pellet/bead/membrane of porosity/void volume fraction and pore tortuosity factor of T , the gas species flux based on the total cross section of the pellet/bead/membrane is... 

Specific gravity is the most critical of the characteristics in Table 3. It is governed by ash content of the material, is the primary deterrninant of bulk density, along with particle size and shape, and is related to specific heat and other thermal properties. Specific gravity governs the porosity or fractional void volume of the waste material, ie. 

A macroporous polystyrene-divinylbenzene copolymer is produced by a suspension polymerization of a mixture of monomers in the presence of water as a precipitant. This is substantially immiscible with the monomer mixture but is solubilized with a monomer mixture by micelle-forming mechanisms in the presence of the surfactant sodium bis(2-ethylhexylsulfosuccinate) (22). The porosity of percentage void volume of macroporous resin particles is related to percentage weight of the composite (50% precipitant, 50% solvent) in the monomer mixture. 

Porosity of a separator is defined as the ratio of void volume to apparent geometric volume. High porosity is desirable for unhindered ionic current flow. 

Micropores are invisible to the naked human eye thus for outsiders it is always surprising that separators of typically 60 percent porosity (i.e., 60 percent void volume, 40 percent solid material) present the impression of a compact, hole-free, nontransparent sheet. 

The functional dependence of jD on Reynolds number has been the subject of study by many investigators [e.g., Thodos and his co-workers (77, 78), and Wilson and Geankoplis (79)]. A variety of equations have been proposed as convenient representations of the experimental data. Many of these correlations also employ the bed porosity (eB) as an additional correlating parameter. This porosity is the ratio of the void volume between pellets to the total bed volume. 

Geometrical factors - structure, void volume and porosity will affect the filler s ability to be wetted by the rubber into which it is incorporated. The shape of the particle will depend on the crystal structure of the mineral being used. 

A number of other parameters can be calculated from true, bulk, and tap density measurements. These include void volume, porosity, bulkiness, and compressibility. 

The total porosity (e) is a combination of the void volume and the pores within the particles [5,62]. It can be calculated using volume measurements ... 

It is noteworthy that porosity is remarkably independent of the dimensionality. For a given PS, the volumetric porosity sv (void volume/total volume) in 3D space is equal to the interfacial porosity sA (void area/total area, measured on a representative cross section) in 2D and the linear porosity sL (void interval/total length, measured on a representative traverse line) in ID [96] ... 

The lowest theoretical interparticular volume of perfectly packed uniformly sized spherical beads is calculated to be about 26% of the total available volume. In practice, even the best packed columns still contain about 30-40% void volume in addition to the internal porosity of the beads. The problem of interparticular volume does not exist in systems in which a membrane is used as the separation medium. Both theoretical calculations and experimental results clearly document that membrane systems can be operated in a dead-end filtration... 

In order to understand monolithic supports and the effects of polymerization parameters, a brief description of the general construction of a monolith in terms of microstructure, backbone and relevant abbreviations is given in Fig. 8.1 [63, 64]. As can be deduced therefrom, monoliths consist of interconnected microstrac-ture-forming microglobules, which are characterized by a certain diameter dp) and microporosity (gp). In addition, the monolith is characterized by an inter-microglobule void volume sfj, which is mainly responsible for the backpressure at a certain flow rate. The sum of gp and g directly translates into the total porosity gf. 

Porosity is one of the most important properties of a stationary phase, since it severely inflnences the chromatographic colnmn performance, the speed of separation, as well as the specific surface area and consequently loading capacity. Porosity refers to the degree and distribution of the pore space present in a material [114], Open pores indicate cavities or channels, located on the surface of a particle, whereas closed pores are situated inside the material. The sum of those pores is defined as intraparticular porosity. Interparticular porosity, in contrast, is the sum of all void volume between the particles. According to their diameter, pores have been internationally (lUPAC) classified as follows [114] ... 

In a powder bed the void volume is defined as the volume not occupied by solids. Further, the porosity p is defined by... 

In many areas of powder technology the need to measure the powder volume or density often arises. For example, powder-bed porosities in permeametry, volume specific surface area, sample cell void volumes as well as numerous other calculated values all require accurately measured powder densities or specific volumes. It is appropriate, therefore, to introduce some discussion of powder density measurements. 

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