β Scribed by Moore, W. R. ;Murphy, M.
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Viscosities of dilute solutions of six fractions of polyvinyl acetate covering the molecular weight range 40,000 to 340,000 have been obtained using acetone, chlorobenzene, chloroform, dioxane, methanol, and toluene as solvents at temperatures in the range 18β67Β°C. There is some evidence for association of polymer in methanol and toluene. Intrinsic viscosities and values of the Huggins constant kβ² vary with solvent but the variation of kβ² is not always that expected from considerations of solvent power. Where comparison is possible, values of the constant K and exponent a in the expression [Ξ·] = KM^a^ are in reasonable agreement with other values. The variation of a with solvent is not always that to be expected from the variation of [Ξ·] with solvent. The variation with solvent of the swelling or expansion factor Ξ± in the expression [Ξ·] = Kβ²M^1/2^Ξ±^3^ is similar to that of the exponent a. Values of Kβ² vary somewhat with solvent. Values of [Ξ·] for acetone, chlorobenzene, chloroform, and dioxane decrease with increasing temperature, the reverse being the case with methanol and toluene. The variation of kβ² with temperature is the inverse of that of [Ξ·]. The exponent a increases with increasing temperature in all cases but that of toluene and values of K decrease. The swelling factor Ξ± increases with increase of temperature, and temperature coefficients of [Ξ·] seem to be primarily due to changes in the value of (rΜ~0~^2^/M), where rΜ~0~^2^ is the mean square unperturbed endβtoβend distance of the chains.
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