Viscosities of dilute solutions of polyvinyl acetate

Abstract

Abstract 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 18–67°C. There is some evidence for association of polymer in methanol and toluene. Intrinsic viscosities and values of the Huggins constant k ′ vary with solvent but the variation of k ′ 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 [η] = 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 [η] with solvent. The variation with solvent of the swelling or expansion factor α in the expression [η] = K′M 1/2 α 3 is similar to that of the exponent a . Values of K ′ vary somewhat with solvent. Values of [η] for acetone, chlorobenzene, chloroform, and dioxane decrease with increasing temperature, the reverse being the case with methanol and toluene. The variation of k ′ with temperature is the inverse of that of [η]. The exponent a increases with increasing temperature in all cases but that of toluene and values of K decrease. The swelling factor α increases with increase of temperature, and temperature coefficients of [η] seem to be primarily due to changes in the value of ( r̄ 0 2 / M ), where r̄ 0 2 is the mean square unperturbed end‐to‐end distance of the chains.