Some studies on tertiary hexadecyl mercaptan as a modifier in butadiene-styrene copolymerizations.

Tertiary hexadecyl mercaptan was investigated as a modifier in the emulsion copolymerization of butadiene and styrene. This mercaptan disappeared slowly during the first 50-60 per cent of the polymerization but underwent a rapid increase in rate of disappearance thereafter. This rapid rate of disappearance at high conversion cannot be accounted for on the basis of changing styrene content during polymerization or upon mercaptan addition to the polymer double bonds. Changes in viscosity of the polymer during polymerization were studied. A decrease was observed in the same conversion range where the rate of the mercaptan disappearance increased. Tertiary hexadecyl mercaptan was applied to the preparation of relatively homogeneous polymers of different composition and molecular size. On the basis of the modifier reaction theory polymers of various compositions but of the same molecular weight were prepared and studied. It was found that the viscosity decreased and the solubility increased with an increase in the styrene content of the polymer