Abstract
The unperturbed molecular dimensions of dextran samples (of different molecular weights) have been evaluated in ethylene glycol solutions from viscosity measurements at 25°C, 30°C, 35°C, 40°C and 45°C. The unperturbed dimension, K 0, has been determined from extrapolation methods, i.e, Kurata–Stockmayer–Fixman (KSF), Berry and Inagaki–Suzuki–Kurata (ISK) equations. The hydrodynamic expansion factor, α η , as well as the unperturbed root-mean-square end-to-end distance, 〈 r 2〉 0 1/2, found for dextran samples in ethylene glycol solutions, indicated that the polymer coils are contracted as the temperature is raised from 25°C to 45°C. The long-range interaction parameter, B, was also evaluated and a significant decrease is found for the dextran/ethylene glycol system between 25°C and 45°C. The theta temperatures, Θ, were determined as 328.53, 328.02 and 325.93 K from the temperature dependence of the interaction parameter, respectively.
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