Material balance expressions polymers

See Figure 1.2. A component balance can be expressed in mass units, and this is done for materials such as polymers that have ill-defined molecular weights. Usually, however, component A will be a distinct molecular species, and it is more convenient to use molar units ... 

Material Balances. The material (mass) balances for the ingredients of an emulsion recipe are of the general form (Accumulation) = (Input) - (Output) + (Production) -(Loss), and their development is quite straightforward. Appendix I contains these equations together with the oligomeric radical concentration balance, which is required in deriving an expression for the net polymer particle generation (nucleation) rate, f(t). 

Equation (2) requires the concentration profile of the VOC in the polymer melt that can be calculated from the material balance in the polymer melt. Assuming that the convective flux is negligible, Eq. (3) expresses this balance, where D is the diffusion coefficient of the volatile in the polymer matrix. 

A displacement experiment was conducted where a 50-ppm xanthan solution in 15,500 ppm NaCl was injected into a Clashach sandstone core to determine the amount of polymer retained. The Clashach sandstone is more than 99.5% quartzitic and has a low concentration of clays. Consequently, retention by adsorption is expected to be low. Table 5.63 summarizes polymer concentration data from this run when 0.995 PV of polymer solution was injected followed by 0.938 PV of brine. The PV of the core was 303 cm, and the porosity was 0.175. Assuming that polymer retention was irreversible, use material-balance calculations to estimate the amount of polymer retained. The length of the core was 100 cm, and the cross-sectional area was 17.35 cm. Express the polymer retention as mg/g of rock. The density of the solid matrix may be taken as 2.65 g/cm. ... 

The first is answered by introducing relative reactivities. The second is approached by the Alfrey-Price Q-e scheme. To express the relationship of polymer composition to the monomer composition from which it is being formed, we go back to the kinetic scheme of Section 4.4. If we can assume that we achieve a steady-state population of chain radicals that grow to high molecular weight, the material balances for various species are few and simple for a binary system. 

In the case of RO membranes, the Hilderbrand s solubihty parameter (SP) of a polymeric material can be used to select suitable polymeric materials. It has also been used for the study of PV membranes. The solubility parameter expresses the nature and magnitude of the interaction force working between molecules between the permeant molecule and the molecules of the membrane material [8]. The SP of polymers, from which RO membranes with excellent performance have been prepared, are between 24 and 35. In this range the membrane material hydrophobic/hydrophihc ratio is well balanced a low SP reflects hydrophobicity of the polymer, whereas hydrophifrcity is associated with a high SP value. 

---