Shear degradation of water‐soluble polymers. I. Degradation of polyacrylamide in a high‐shear couette viscometer

Abstract

Abstract This manuscript reports an experimental investigation of the mechanical degradation of polyacrylamide in aqueous solution using a high‐shear couette viscometer. Equilibrium molecular weight distributions (MWD) at various shear stresses were measured by gel permeation chromatography. Degradation data indicate that the MWD becomes narrower at higher shear stresses, in general agreement with Bueche's midpoint break theory. An empirical correlation of the critical molecular weight and degrading shear stress is presented. It has the form where M c is the critical molecular weight and τ is the degrading shear stress in dynes/cm 2 .