Premium
The influence of the solvent upon the low shear viscosity of styrene–acrylonitrile copolymer solutions
Author(s) -
Blanks R. F.,
Shah B. N.
Publication year - 1978
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1978.070220408
Subject(s) - copolymer , acrylonitrile , styrene , materials science , solvent , viscosity , polymer chemistry , shear (geology) , shear viscosity , polymer science , chemical engineering , composite material , chemistry , polymer , organic chemistry , engineering
This paper describes the results of an experimental investigation concerning the effect of polymer–solvent thermodynamics on low‐shear viscosity of copolymer soltions. Thermodynamic parameters and low‐shear solution viscosities were measured for solutions of polystyrene homopolymer and styrene–acrylonitrile copolymers in four solvents: benzene, dioxane, methyl ethyl ketone, and dimethylformamide. The thermodynamic quality of a solvent for a polymer is characterized by free‐energy‐of‐mixing parameters. These quantities are: the Flory‐Huggins thermodynamic interaction parameter χ, the second virial coefficient (from light scattering), the intrinsic viscosity, and the polymer expansion factor. The thermodynamic interaction between a solvent and a polymer in solution influences the rheological behavior of the system. At low concentrations of polymer in solvent, the low‐shear solution viscosity is larger in a good solvent than in a poor solvent. In solutions of higher concentration, the reverse may be true and the viscosity is often significantly larger in a poor solvent than in a good one. These results are not predicted quantitatively by existing theory. The parameters in existing viscosity correlation techniques are found to be solvent dependent. The so‐called entanglement concentrations for polymer solutions are not unique for a particular polymer but are related to the free energy of mixing polymer with solvent.