화학공학소재연구정보센터
Journal of Rheology, Vol.62, No.4, 845-867, 2018
Shear thinning in dilute and semidilute solutions of polystyrene and DNA
The viscosity of dilute and semidilute unentangled deoxyribonucleic acid (DNA) solutions, in steady simple shear flow, has been measured across a range of temperatures and concentrations. For polystyrene solutions, measurements of viscosity have been carried out in the semidilute unentangled regime, while results of prior experimental measurements in the dilute regime have been used for the purpose of data analysis, and for comparison with the behavior of DNA solutions. Interpretation of the shear rate dependence of viscosity in terms of suitably defined nondimensional variables is shown to lead to master plots, independent of temperature and concentration, in each of the two concentration regimes. In the case of semidilute unentangled solutions, defining the Weissenberg number in terms of a concentration dependent large scale relaxation time is found not to lead to data collapse across different concentrations. On the other hand, the use of an alternative relaxation time, with the concentration dependence of a single correlation blob, suggests the existence of universal shear thinning behavior at large shear rates. (C) 2018 The Society of Rheology.