Pressure dependence of the propagation rate coefficient kp for vinyl acetate polymerizations in bulk and in solution of fluid CO2

The propagation kinetics of vinyl acetate (VAc) free-radical homopolymeriza tion in bulk and in solution of 40 Wt % CO2 have been studied by the PLP-SE C method at pressures up to 1500 bar. The molecular weight distributions of the polymer samples show well-resolved pulsed-laser-induced structure with at least two, in most cases even three, distinct inflection points. At the p and T conditions of this work, no difference is seen in propagation rate coefficients, k(p), of VAc in solution of carbon dioxide and in bulk. The activation volume for k(p), at 25 degreesC in both reaction media is DeltaV (#) = -(10.2 +/- 0.9) cm(3) mol(-1).