Flow Instability of Poly(vinyl alcohol)/Dimethyl Sulfoxide Solution under Steady Shear

摘要: The effects of solution temperature and molecular weight on the rheological responses poly(vinyl alcohol) (PVA) semidilute solutions (13 g/dL - 19 g/dL) in dimethyl sulfoxide (DMSO) have been studied using PVA with two different number-average degrees polymerization (P n ): 1700 4000. For experiments dynamic shear, a P showed rather simple Newtonian fluid behaviour, whereas that 4000 exhibited non-Newtonian shear thinning behaviour. Steady rheology suggested lower were fluids, which is consistent results. However, an abrupt decrease viscosity at high rates was observed for higher temperatures, such as 30 °C 50 °C. At temperatures 70 90 °C, behaviour without any further complications flow instability. fact plays critical role controlling instability DMSO strongly suggests there exist enhanced inter-chain interactions by hydrogen bonding chains beyond chain entanglements, particularly low temperatures. Therefore, it important to consider both entanglements order process causing undesirable