FLOW OF DILUTE POLYMER-SOLUTIONS - CHAIN CONFORMATIONS AND DEGRADATION OF DRAG REDUCERS

A model of flowing solutions that takes into account the structure, orientation, and mechanism of action of drag reducers is analyzed. For each polymer chain that causes drag reduction (DR), the model assumes the existence of two kinds of sequences that interact with the flow in different ways. The resulting solution structure seems to agree with the available experimental evidence on DR. A theoretical analysis of conformational states is provided. Computer calculations for model chains show the effects of varying solvent quality, polymer concentration, and free volume in the system. The results of the computer work provide clear criteria for choosing drag reducers with high efficacy λ. The model is represented by equations in terms of the parameters that determine DR. Among other things, the theory provides a relation between the DR efficacy and time t, this for unary as well as multicomponent drag reducers. Calculations performed for a variety of DR agents in aqueous solutions show that the predicted λ(t) values agree with the measured ones within limits of the experimental accuracy. The parameters obtained can be used to optimize multicomponent DR agents. While our primary interest in the present paper is in polymers, it is at least possible that nonpolymeric drag-reducing agents act by a similar mechanism. © 1990, American Chemical Society. All rights reserved.