Internal Pressure and Free Volume of Polymer Solutions of Poly Vinyl Acetate

Ultrasonic studies have been widely used to know more about the properties of the polymer solutions. Ultrasonic velocity, density and viscosity of polymer solutions of Poly vinyl acetate were measured at different temperatures ranging from 35°C to 55°C. The internal pressure (π_i) and free volume (V_f) of the solutions are computed. At a given concentration, the variation of π_i and V_f due to a change in temperature can be represented by the relation, π_i V_f^x=k where k is a constant and x is the slope of the straight lines. In all the systems, the above equation was checked thus signifying the importance of internal pressure and free volume in fixing the polymer solutions thermodynamically.