Void volume considerations related

It is of interest to relate the void volume as calculated from water adsorption volume to the framework density of the zeolites—i.e., the density of the zeolite structure with no consideration of the nonframework atoms (cations and water). The framework density may be expressed in terms of grams per cubic centimeter or in terms of the number of tetrahedra per unit volume of 1000 A3. A plot of the framework density for zeolites of known structure vs. the void fraction, Vf, as determined from water... 

The sulfur sorbent that has received the most attention is limestone because of its widespread availability and low cost. Unfortunately the conversion of limestone to calcium sulfate results in a volumetric increase, and it can be readily shown (8 ) that for particles that do not permit volumetric expansion on reaction the maximum conversion attainable is about 59 percent (the value is dependent on the specific volumes of reactant and product). This constraint can be avoided by use of dolomite, since the MgO is not sulfated and the void volume produced by the decomposition of MgCO and CaCO is sufficient to permit complete calcium utilization, but at the expense of an added weight of sorbent and added energy requirement for calcination. The above conclusions follow from consideration of the stoichiometric relations ... 

Dendrimers have attracted considerable attention in the polymer field over the past two decades as they have been recognized as the most important macromolecules possessing tunable internal packing density, void volumes, solvent-dependent size, branching dimensions, and surface functionalities. Since the first report of a dendrimer-like molecule in 1978 [33], significant progress has been made in the dendrimer chemistry. A large number of dendrimer compositions (families) and dendrimer surface modifications have been reported. A plethora of applications related to controlled release of pharmaceuticals have been reported. Currently, there are two widely studied dendrimer families, namely the Tomalia-type polyamidoamine (PAMAM) dendrimers and the Frdchet-type polyether dendrimers. PAMAM dendrimers are the first complete dendrimer family to have been synthesized. 

The measurement of the bulk density of powders in no exception to the general situation outlined above, but it is so fundamental to their storage, processing, and distribution that it does merit particular consideration. The bulk density of a powder is its mass divided by the bulk volume it occupies. The volume includes the spaces between particles and the envelope volume of the particles themselves. The spaces between particles are denoted as porosity or voidage, and can be defined as the volume of the voids within the bulk volume divided by the total bulk volume. Bulk density and porosity are related by... 

---