Studies in Polymerization. IV. The Velocity Constants in the Polymerization of p-methoxystyrene

The velocity constants in the polymerization of p-methoxystyrene have been determined at 0°C by the method described in part I. The activation energies could not be measured directly. Comparison of the results with those for styrene suggests that the differences are due to mesomeric stabilization of the radicals by the p-substituent. The relation between intrinsic viscosity and molecular weight of the polymer has been studied by the method of part II. The results conform to the Houwink (1940) viscosity law, with an exponent 0⋅66, almost identical with that for polystyrene. If the Houwink equation is written in the form [η] = CP¯α, C is the same for solutions of both polymers in their respective monomers.