Drag reduction by collapsed and extended polyelectrolytes

I REPORT experiments on drag reduction by saline solutions of a partially hydrolysed polyacrylamide (PAMH) showing the effect of macromolecule conformation. The extreme collapsed and extended PAMH conformations also simulate the deportment of linear random-coiling macromolecules in solution, and of high aspect ratio fibres in suspension; and they indicate a possible relationship between the mechanisms of drag reduction produced by these additives. © 1975 Nature Publishing Group.