Drag-Reduction Properties of Ultra-High-Molecular-Weight Polyacrylamide and Related Polymers

Abstract

The drag-reduction phenomenon has been the subject of intense interest and activity among scientists and engineers for the past decade. This phenomenon is observed when solutions of very small amounts of high-molecular-weight linear polymers are subjected to turbulent pipe flow. The resultant effect is that the pressure gradient required to move the fluid is substantially reduced at a given flow rate. Toms (1) gave the first clear description of this phenomenon in his study of the turbulent flow of poly(methyl methacrylate) in monochlorobenzene. Many investigators since then have confirmed such effects in aqueous solutions of guar gum, carboxy-methylcellulose, poly(acrylic acid), polyacrylamide, and poly(ethylene oxide). The bulk of the materials which have been tested to date are commercial samples, among which the poly(ethylene oxides) and polyacrylamides are the most widely used. These polymers are inexpensive, easy to handle and are extremely effective agents; for example, a 44 percent drag reduction is possible by the addition of 10 parts per million by weight (ppmw) of poly(ethylene oxide) of molecular weight 900,000 (2).