Polymer flow, adsorption

Membrane extraction offers attractive alternatives to conventional solvent extraction through the use of dialysis or ultrafiltration procedures (41). The choice of the right membrane depends on a number of parameters such as tlie degree of retention of the analyte, flow rate, some environmental characteristics, and tlie analyte recovery. Many early methods used flat, supported membranes, but recent membrane technology has focused on the use of hollow fibers (42-45). Although most membranes are made of inert polymers, undesired adsorption of analytes onto the membrane surface may be observed, especially in dilute solutions and when certain buffer systems are applied. 

The discussion in the Introduction led to the convincing assumption that the strain-dependent behavior of filled rubbers is due to the break-down of filler networks within the rubber matrix. This conviction will be enhanced in the following sections. However, in contrast to this mechanism, sometimes alternative models have been proposed. Gui et al. theorized that the strain amplitude effect was due to deformation, flow and alignment of the rubber molecules attached to the filler particle [41 ]. Another concept has been developed by Smith [42]. He has indicated that a shell of hard rubber (bound rubber) of definite thickness surrounds the filler and the non-linearity in dynamic mechanical behavior is related to the desorption and reabsorption of the hard absorbed shell around the carbon black. In a similar way, recently Maier and Goritz suggested a Langmuir-type polymer chain adsorption on the filler surface to explain the Payne-effect [43]. 

Ionic polymers Adsorption on capillary wall With positively charged polymers, flow reversal... 

Malkin (1990) reviews the rheology of filled polymers and highlights the importance of yield stresses, non-Newtonian flow, wall slip and normal stresses in filled polymer flow. Details of the effects of particle shape, concentration and adsorption on these phenomena are discussed. 

Equation (1) can also be applied to describe the retained polymer after brine flush. The meaning of the first member on the right-hand side of Equation (1) is the same as during polymer flow. The C , member, however, has a different meaning. It also consists of two parts. The first part originates from the physical adsorption in... 

The brass die data in Figure 12.2 do not show a discontinuity in the flow curve, but rather approach the high-rate slip-dominated behavior smoothly. These data illustrate the significant role that can be played by the interfacial chemistry, which determines the degree of polymer chain adsorption and hence stress transmission through the melt at the surface. 

Lakatos et al. (1979) also studied the retention of HPAM in unconsolidated silica sand. The HPAM polymers used had a range of molecular weight of 0.7-4.8 X 10 and degree of hydrolysis of 0-40%. A silica sand of particle size 100-200 m and with a specific surface area between 0.1 (by mercury permeometry) and 0.18m /g (by krypton adsorption) was used to construct sandpacks 20cm long for all the polymer flow experiments. 

The first stage of polymer adsorption has been investigated by refleetometry [63]. The amount of poly(ethylene oxide) adsorbed on the sihea plate arises linearly with time and reaches the plateau section in 30-60 s. The initial rate of adsorption depends on the rate of flow and molecular mass of the polymer. Therefore, adsorption proeeeds in the diffusional field. The substitution of the polymer solution by solvent did not ehange the amount of adsorbed polymer. 

Polymer Retention, When a polymer flows through a porous sandpack or roek, there is usually a measurable amount of polymer retention. Retention is caused primarily by adsorption on the surface of the porous material and mechanical entrapment in pores that are small relative to the size of the polymer molecule in solution. >3 >38 In most cases, retention of polymers used in EOR applications is considered instantaneous and irreversible. This is not exactly true because small amounts of polymer can be removed from porous rock by prolonged exposure to water or brine injection. Usually, however, the rate of release is so small that it is not possible to measure the concentrations accurately. It is thus more ac-... 

This paper presents three experimental polymer floods showing the effect of inaccessible pore volume in the presence of varying amounts of adsorption. Results of these floods clearly show that about 30 percent of the connected pore volume in the rock samples used was not accessible to the polymer solutions. The changes required to include inaccessible pore volume in mathematical models of polymer flow and in field prediction methods are discussed. 

In the physical separation process, a molecular sieve adsorbent is used as in the Union Carbide Olefins Siv process (88—90). Linear butenes are selectively adsorbed, and the isobutylene effluent is distilled to obtain a polymer-grade product. The adsorbent is a synthetic 2eohte, Type 5A in the calcium cation exchanged form (91). UOP also offers an adsorption process, the Sorbutene process (92). The UOP process utilizes ahquid B—B stream, and uses a proprietary rotary valve containing multiple ports, which direct the flow of Hquid to various sections of the adsorber (93,94). The cis- and trans-isomers are alkylated and used in the gasoline blending pool. 

The present study investigates the adsorption and trapping of polymer molecules in flow experiments through unconsolidated oil field sands. Static tests on both oil sand and Ottawa sand indicates that mineralogy plays a major role in the observed behavior. Effect of a surfactant slug on polymer-rock interaction is also reported. Corroborative studies have also been conducted to study the anomalous pressure behavior and high tertiary oil recovery in surfactant dilute-polymer systems(ll,12). 

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