Different from general polymer solutions

poly(vinyl alcohol) (PVA) aqueous solutions showed distinctive rheological behaviors caused by the hydrogen bonded networks

which include hydrogen bonding between polymer chains and water

intra and inter macromolecular hydrogen bonding.The steady shear curves sof PVA aqueous solutions with the concentration of 10 wt% indicated four regions with increasing shear rate

the first plateau

the first shear thinning region

the second plateau and the second shear thinning region.The experimental results combined with the scaling theory exhibited that the occurrence of the first shear thinning region owed to the inter-macromolecular hydrogen bonding while the arising of the second shear thinning region was due to the disentanglement of PVA chains.The decreasing of viscosity and hydration number of PVA aqueous solutions with introduction of sodium dodecyl sulfate (SDS) also demonstrated the rheological behavior of PVA aqueous solutions in low shear range mainly depended upon the inter-macromolecular hydrogen bonding.In addition

changes in alcoholysis degree and shearing history produced remarkable effect on hydrogen bonded networks

making different rheological responds for PVA aqueous solutions.Since PVA is a semi-crystalline polymer

spinodal decomposition could be observed in PVA aqueous solutions

resulting in the appearance of polymer-rich and polymer-poor phases.The longer aging time benefited the formation of hydrogen bonding and the phase separation of PVA aqueous solutions

causing the increase of viscosity during the shear recovery process upon decreasing shear rate.