6533b827fe1ef96bd1286d85

RESEARCH PRODUCT

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Taking into account the dependency on molar mass of the viscometric interaction parameter B, the modified Stockmayer-Fixman-Burchard equation ([η]/M1/2) = KΘ + C″ · A2 · M1/2 is obtained. It relates the intrinsic viscosity, [η], to the second virial coefficient, A2, and to the unperturbed dimensions parameter, KΘ, with C″ being a constant. Hereupon, KΘ can be determined from [η] and A2 data of any binary (solvent/polymer) and/or ternary (solvent 1/solvent 2/polymer) system, BPS and/or TPS. Because of the scarcity of reliable sets of [η] and A2 values mostly for TPS, the application of the above equation to obtain KΘ coefficients rests limited. This limitation can be surmounted by an A2 evaluation from [η] data and trial KΘ values through two-parameter theories taking into account the interpenetrating factor between chains, ψ, as evaluated from the Flory-Krigbaum-Orofino (FKO) theory, from a modified FKO theory, or from the Kurata-Yamakawa theory. An interative process is followed until coincidence between assumed and evaluated KΘ values is reached. The method has been applied to the KΘ evaluation from [η] with literature data for diverse BPS and TPS of polystyrene, poly(methyl methacrylate), poly(dimethylsiloxane), poly(2-vinylpyridine) and poly(1-vinyl-2-pyrrolidone), with the respective KΘ values 7,5 · 10−2, 5,8 · 10−2, 8,2 · 10−2 and 6,4 · 10−2, 7.2·10−2 and · 6,4 · 10−2 mL · mol1/2 · g−3/2 being obtained. Moreover, a single C″ value, mainly C″ = 0,52, holds for all five polymers.