Viscosity of polyacrylonitrile solutions: The effect of the molecular weight
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The copolymer of acrylonitrile with methyl acrylate and itaconic acid (93: 5.7: 1.3) is synthesized via free-radical copolymerization. For solutions of the initial copolymer and its 12 fractions in dimethyl sulfoxide, viscosities are measured in a wide shear-stress range. The viscosity behavior of 10% solutions is examined in more detail, and the rheological studies of several fractions are performed in the concentration interval from 5 to 20%. All solutions exhibit weak non-Newtonian behavior. This makes it possible to determine the zero-shear viscosity. The dependences of this viscosity on the number-average and weight-average molecular masses for the equiconcentrated solutions obey an exponential law with the same exponent, equal to 2.3. The macromolecules of copolymers are inclined toward association. For low-molecular-mass fractions, this effect is the most pronounced.
KeywordsMolecular Mass Polymer Science Series Itaconic Acid Methyl Acrylate Molecular Mass Distribution
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