6533b872fe1ef96bd12d3755

RESEARCH PRODUCT

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The intrinsic viscosities, [η], for the ternary systems alkane (1)/2-butanone (2)/poly(dimethylsiloxane) (PDMS)(3), with the alkanes decane, dodecane and hexadecane, are determined at 20,0°C. The constants a of the Mark-Houwink equation and the constant of the unperturbed dimensions, KΘ, of the polymer are evaluated over the whole composition range of the binary solvent mixture. [η] shows a pronounced maximum at intermediate compositions as found in cosolvent mixtures. In these cosolvent mixtures, the numerical values of KΘ are higher than in the single-component solvents, because the cosolvent mixtures correspond to a mixed solvent with an excess free energy, GE ≥ 0, the increase in KΘ being only moderate though. A new procedure taking into account ternary interactions, to evaluate the intrinsic viscosity in ternary systems from GE values is proposed. The influence of ternary interactions through a constant (1–2aχ) is also investigated. From these new expressions the constant of the apparent polymer unperturbed dimensions, K, and (1–2aχ) are calculated and compared with those directly evaluated from second virial coefficients.