LAUSR

Flow drag reduction with polymer additives has been studied and applied for many years. But degradation of the drag-reducing agent (DRA) is still not well understood. In this study, a new theory for the mechanism of DRA degradation is proposed: the degradation of polymers in flow drag reduction process is a first-order chemical reaction based on the molecular weight. A modified Arrhenius equation can be used to predict the chemical reaction constant. This brings physicochemical meaning to the previously empirical degradation coefficient k in existing correlations. We then conduct a series of flow drag reduction experiments with PEO (polyethylene oxide) of three different molecular weights in a double-gap rheometer to investigate the degradation phenomena. A new correlation is developed to predict the lifespan of DRAs. Predictions with this correlation agree with measured data with an average relative error of 15%, better than previous correlations. The results indicate validity of the proposed new mechanism of DRA degradation.