The swellings of P. V. C. films having thermal bridging are measured in acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, cyclohexanone, tetrahydrofuran and the mixtures of these ketones and CS2. From these results, the parameters of the polymer-solvent interaction μ are calculated and the minimum values of μ are found by adding CS2 in acetone, methylethyl ketone, methylisobutyl ketone and acetophenone, but the small μ's values are increased by adding CS2 in cyclohexanone and tetrahydrofuran solutions.The viscosities of the dilute solution of P. V. C. in methylisobutyl ketone, acetophenone and cyclohexanone are measured. From these results the values of _??_η_??_ and k′ (in Huggin's equation _??_ )are calculated. In comparing the _??_η_??_, k′ and μ, it is obvious that _??_η_??_ of cyclohexanone solution is larger than _??_η_??_ of acetone, methyl ethyl ketone, methyl isobutyl ketone and acetophenone solution, k′ and μ of cyclohexanone solution are smaller than those of the ketone solutions, and those of methylisobutyl ketone and acetophenone solution are almost the same.