Absolute propagation rates in emulsion polymerization. II. Butadiene in hydroperoxide‐polyamine systems

Abstract

Abstract A study has been carried out on the emulsion polymerization of butadiene, using the “peroxamine” recipe at low temperatures in an attempt to evaluate the absolute propagation rate, according to the theory of Smith and Ewart, from a determination of the rate of polymerization per particle of latex. Unlike the persulfate‐mercaptan system previously reported, the hydroperoxide‐polyamine systems show a polymerization rate per particle which is independent of all variables other than temperature. Hence this system behaves according to case 2 of the Smith‐Ewart treatment, where the number of free radicals per particle is approximately 1/2. On this basis it is possible to calculate a value for the absolute propagation rate constant for butadiene, as follows: k p = 1.2 × 10 8 e −9300/ RT l./mole/sec. This value in turn leads to an evaluation of the absolute rates of some other reactions involving the butadiene radical, such as cross‐linking, chain transfer, and copolymerization. It agrees with the current data on absolute rates for other monomers and with present‐day theories concerning the effect of conjugation on radical‐monomer interaction.