Studies in concentrated solution properties of 1,4-cis-polybutadiene, polystyrene, and polychloroprene using viscometry as a tool

The zero shear viscosities of concentrated solutions of 1,4-cis-polybutadiene (PB), polystyrene (PS) and polychloroprene (PC) along with their fractions in single and mixed solvents were measured at different temperatures in good, poor, single and mixed solvent systems. The variation of zero shear viscosity with polymer concentration and solvent was studied. The temperature dependence of eta(0) for these three polymers in different solvent systems was expressed by well known Arrhenious-Frenkel-Eyring equation. The heat of activation of viscous flow (DeltaH(v)), the free energy of activation of viscous flow (DeltaG(v)) and entropy of activation of viscous flow (DeltaS(v)) were also evaluated. The values of DeltaG(v) and DeltaH(v) were found to be dependent on polymer concentration, nature of solvent and molecular weight. However, in case of PB, DeltaG(v) is independent of temperature for all the solvent systems under study. The entropy of activation of viscous flow was found to be zero and the results obtained are discussed on the basis of modem ideas of polymer structure.