Viscosity of semi-dilute polymer solutions

Abstract

We report viscosity measurements on semi-dilute solutions (c* < c < 10 %). The viscosity variation is independent of the glass transition temperature of the undiluted polymer and consistent with monomer friction proportional to the solvent viscosity. With concentration, the following variations were observed : — for PIB-toluene, η r ∼ c4.1, close to de Gennes' viscosity theory, — for PS-benzene and PIB-cyclohexane, ηr ∼ c4.6 which seems to be influenced by local statistics in the chains, — for semi-dilute θ solvent conditions, ηr ∼ c5 which could be interpreted using de Gennes' theory of reptation and mean field theory of elasticity. With molecular weight we observe : ηr ∼ M3.1w in agreement with reptation model. However temperature scaling laws do not seem to be applicable. The interpretation of the temperature dependence of the viscosity remains open question.