Rheological test for the homogeneity of aqueous blends of associative polymer network and entangled linear polymer

Abstract

Linear viscoelastic behavior has been examined for the mixtures of a transient network and entangled linear polymers in aqueous solutions. We have found that the aqueous blends of hydrophobically ethoxylated urethane (HEUR) and sodium polyacrylate (PAANa) become transparent solutions and look homogeneous. To examine the molecular level homogeneity of this mixture, we analyze the linear viscoelastic spectra as functions of the volume fraction of PAANa, ϕP, at fixed HEUR concentrations, especially focusing on the plateau modulus, GN, mix of the mixtures. The increase in GN, mix by increasing ϕP is assumed to be due to the formation of the hetero-entanglement between HEUR and PAANa, and the contribution of the hetero-entanglement on the plateau modulus, can be estimated by using the Wu's model. We have obtained the result that all the data can be explained in terms of a single value, strongly supporting the view that the HEUR and PAANa chains are homogeneously mixed and interpenetrated each other in the mixed aqueous solutions.