Reduction, drag, conformations

Balakrishnan C, Gordon RJ (1975) Influence of molecular conformation and intermolecular interactions on turbulent drag reduction J Appl Polym Sci, 19 909... 

Dschagarowa E, Mennig G (1977) Influence of molecular weight and molecular conformation of polymers on turbulent drag reduction Rheol Acta 16 309... 

The development of processing strategies in which the interaction between fluid motion and microstructural conformation can be used for (a) the development of microstructured materials with desired macroscopic properties and (b) active control of the flow itself, as in drag reduction and fluidized bed stabilization. 

The mechanical stability of polymers was related to the polymer s conformation in some of the earlier drag-reduction studies. Above a critical stress, degradation was faster the more contracted and entangled the polymer s conformation (5-7). In petroleum applications the mechanical instability of synthetic relative to carbohydrate polymers was well-recognized. The relative stability problems (possibly related to DUEVs (8)) encountered in the use of high molecular weight hydrolyzed poly(acrylamide) (HPAM) led to the development of an inverse-emulsion polymerization technique (9). (Current research directions using this technique are discussed in Chapter 9.)... 

The subject of Chapter 4 (originally the third lecture) is the problem of the reduction of turbulent losses by polymer chains in a solvent. The topic appears to be especially intricate in view of the coupling between the hydrodynamic aspects of turbulent flow and the viscoelastic behavior of chains in strongly perturbed conformations. The lecture followed closely a paper Towards a scaling theory of drag reduction published in 1986 by Professor de Gennes in Physica which is here reprinted by permission of the publisher. Because this lecture is the most tentative (and difficult) part in the series we have put it in the last chapter. 

Our research group has been intensively studying the behavior of polyampholytes in aqueous media of moderate electrolyte content for applications in petroleum recovery, drag reduction, water remediation, and formulation of pharmaceuticals, coatings, and cosmetics. For each application, selection of appropriate comonomers and synthetic techniques can lead to desired conformational behavior under external conditions of pH, temperature, shear stress, and electrolyte concentration. 

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