Non-Newtonian viscosity of concentrated polymer solutions

Abstract

We can say with assurance that the viscosity coefficient is the most sensitive parameter in relation to any possible changes in liquids and liquid mixtures. For example, this parameter can change at the change of concentration of polymer solutions in 12-15 decimal orders. Consequently, the study of viscosity of polymer solutions is very prolific.As Fox and collaborators (l) have already noted that for a satisfactory comprehension of flow processes it is necessary to know the influence of the numerous polymer characteristics such as molecular weight change, temperature, type of solvent and concentration upon viscosity.Prior to 1956 these data were meager and fragmentary. But from this date on the number of works dealing with concentrated polymer solutions has sharply increased. The Chair of Macromolecular Chemistry of the Ural State University devoted much of its attention to this problem. This communication is an attempt to summarize all the experimental data at our disposal.The works of a number of investigators show that the viscosity of low molecular liquids and their mixtures is determined by their structures (2). The same viscositystructure relation should be expected for polymer solutions.According to common notions the structure of any dispers system and polymer system, too, is in close connection with the initial Newtonian viscosity, which is the viscosity of a system with not desintegrated structure (3). Therefore, our early works were devoted to the investigation of the initial Newtonian viscosity of polyisobutylene (PI) and polystyrene (PS) solutions in a wide range of concentrations (4).The point of our interest was the influence of the solvent nature on the solution viscosity. It has a great importance because depending on the quality of solvent either interstructure swelling spontaneously followed by *) Paper presented at the Conference on Advances in Rheology, Glasgow, September 16-18, 1969. dissolution of polymer or intrastructure limited swelling are observed. Consequently, the structure of polymer may be desintegrated step by step by means of changing the quality of solvent and this affects the value of solution viscosity.Therefore, for each polymer the solvents were chosen with different thermodynamic affinity to this polymer (different goodness). The affinity was evaluated quantitatively by conventional methods (5).The results of measurements of the concentration dependence of the Newtonian viscosity are presented in fig. 1. It can be seen that the nature of the solvent affects the value of the initial Newtonian viscosity of concentrated polymer solutions in a different way, depending upon the flexibility of the polymer chain. For instance, the viscosity of a solution of non-polar flexible polymer (PI) depends little upon the nature of solvent. The maximal variation is of a decimal order.The viscosities of equiconcentrated PS solutions in different solvents differ on 2-3 decimal orders. The viscosities of acetylcellulose (AC) solutions in different solvents differ on 4 decimal orders. The maxi...

Viscosity of polyacrylonitrile solutions: The effect of the molecular weight

“…At a certain critical stress, the flow of solutions ceases and the spurt phenomenon is observed, that is, a sharp increase in the rate of flow due to the forced transition of the wall layers of solutions to the high elasticity state and loss of contact with measuring surfaces (with tran sition to slippage). The value of this stress for equicon centrated solutions is independent of molecular mass [24,25]. For the tested number of samples, these critical stresses are practically the same and amount to ~2.6 × 10 3 Pa.…”

Hydrodynamic Scaling of Viscosity and Viscoelasticity of Polymer Solutions, Including Chain Architecture and Solvent Quality Effects

“…The above results include several studies of a single polymer under different solvent conditions, notably results of Tager et al [41][42][43] on a single polyisobutylene and a single polystyrene, each in a series of solvents. From Table 2, for each polymer-solvent pair studied by Tager et al the hydrodynamic scaling form of eq 1 describes tolerably well the concentration dependence of .…”

“…Figure 4 presents 77/770 of 1.2 x 106-Da polyisobutylene in decalin, cyclohexane, CCI4, isooctane, and toluene at 25 °C, as measured by Tager et al [41][42][43] For this system, the behavior of 77/770 depends on the solvent. In decalin and cyclohexane, there is a solutionlike-meltlike transition near c[?7] 80 and 77/770 ~106, with meltlike behavior at larger [ ] and 77/770.…”

Approach to generalization of concentration dependence of zero‐shear viscosity in polymer solutions

“…This consideration is based on experimental results published in the form of a review5 of investigations for the period of [1957][1958][1959][1960][1961][1962][1963][1964][1965][1966][1967] and in some subsequent papers. [6][7][8][9][10][11][12] EXPERIMENTAL Though the investigated polymer systems and the experimental techniques have been described elsewhere, for the sake of completeness, these systems and the methods of investigation are described below.…”