| Abstract: | Studies of the polymerisation of butadiene in the presence of carbon tetrabromide in bulk and emulsion systems have shown that in both systems telomers are the first products of reaction. These consist of between 4–10 butadiene units with terminal allylic bromine and tribromomethyl groups. However, the fact that the telomers function as chain transfer agents through the terminal tribromomethyl group to produce diallylic bromine terminated low molecular weight polymers is unique to the emulsion system. Telomers prepared in bulk and emulsion have been isolated, characterised and the kinetics of their formation studied. Kinetic analysis has indicated that at low molecular weights an increase in polymerisation rate with increasing carbon tetrabromide concentration is predicted, but it is postulated that the telomer itself can initiate polymerisation. Telomers formed in either bulk or emulsion have been studied as chain transfer agents in the polymerisation of butadiene in emulsion at 60°C. Polymerisation rate decreases with increasing amount of chain transfer and it is postulated that degradative chain transfer plays a role in the polymerisation. A simplified kinetic scheme for retarded polymerisation has been developed to analyse the results. It is postulated that radical termination is by cross termination of growing polymer radicals with telomer radicals. |
