Corresponding state relations for the viscosity of moderately concentrated polymer solutions

Abstract

SynopsisCorresponding state relationships are considered for good (toluene) and &solvents. The polymers investigated are polystyrene, polymethyl methacrylate, and a copolymer of approximately 49 mole-% of methyl methacrylate with styrene. The choice of the reduced variables q a p ( c [~] ) and c / y permits the construction of master curves, characteristic of a given polymer-solvent system over a wide range of molecular weights. The concentration parameter y varies with the degree of polymerization less rapidly than CO, the concentration for overlap of average coils, particularly in the good solvent. Here y is independent of temperature. In cyclohexane, y is proportional to the critical concentration for phase separation. The existence of such universal relations results in an explicit form for the coefficients of the power series expansions of the viscosity as a function of c. In particular the parameter kt is predicted to be a slowly decreasing function of molecular weight in the good solvent, but to be almost independent in cyclohexane. This is in accordance with recent observations for polystyrene fractions below 50,000. However, the scatter in the experimental data does not permit a quantitative comparison. Moreover, the results must be sensitive to polydispersity and depend on higher moments of the distribution, as is indicated by the relation between y and thc critical concentration.

Fluorescence excitation spectroscopy of polystyrene near the critical concentration c*

“…[20][21][22] The equation used to calculate c* was based on the MarkHouwink equation and is given by b Calculated from fluorescence excitation spectra as described in the text.…”

“…For each polymer studied, a stock solution of the highest concentration measured (approximately double the calculated value for c* at 208C based on the Mark-Houwink equation [5][6][7]20,21 ) was prepared in a 50 mL volumetric flask, and aliquots of this solution were transferred using graduated pipettes into 10 mL volumetric flasks and diluted to the mark with solvent.…”

Newtonian Viscosity of Dilute, Semidilute, and Concentrated Polymer Solutions

“…Simha and co-workers [Simha, 1952;Utracki and Simha, 1963;Simha and Somcynsky, 1965;Simha and Chan, 1971;Utracki and Simha, 1981] Comparison of experiment versus a scaling analysis according to Eq. (1.100) indicates that hard-sphere scaling works reasonably well for theta and subtheta conditions [Simha, 1952;Simha and Chan, 1971;Utracki and Simha, 1981], but breaks down for good solvents.…”

The effect of solution surface tension on aroma compound release from aqueous xanthan solutions

“…The different concentration regimes (dilute, semi-dilute and concentrated) were evaluated using the Utracki and Simha approach. 16 Table 1 indicates the characteristic critical concentrations C* and C** delimiting the three concentration domains described above.…”