Interdiffusion of Polyvinyl Acetate with a Series of Solvents

The Lamm scale method has been used to follow the interdiffusion of polyvinyl acetate with ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and triacetin at 30°C, and with acetone at 20°, 30°, and 40°C. For all these systems the mutual diffusion coefficient attains a maximum value at intermediate polymer concentrations. At a given concentration and temperature the D(c) values are largest with acetone and much the smallest with triacetin, although the relative variation in D(c) over the concentration range is actually largest with the latter. The general variation of D(c) with concentration can be plausibly interpreted in terms of the mass flow-intrinsic diffusion concept introduced by Hartley. For the system acetone—polyvinyl acetate the calculated energy of activation for the diffusion is nearly constant at 1 kcal in the concentration range 0 to 40 grams polymer per 100 cc of solution but then rises rapidly to 10 kcal at 90 grams polymer per 100 cc.