Emulsion polymerization of butadiene, 2. Polymerizations with sodium dodecyl sulfate

Abstract

Abstract The emulsion polymerization of butadiene was investigated with sodium dodecyl sulfate as emulsifier, and the results were compared with those obtained with the industrial‐grade emulsifier Dresinate 214. Limited coagulation was observed in both cases, caused by the high ionic strength of the aqueous phase. Sodium dodecyl sulfate was found to be a better stabilizer than Dresinate 214. The average rate per particle in interval II (corresponding to the linear portion of the conversion vs. time curve) depends strongly on particle size, but not on recipe parameters used to vary the final particle diameter, such as the type and amount of emulsifier and ionic strength. The dependence of particle number per volume of water N on initiator ([I]) and emulsifier concentration ([E]) is usually expressed as the exponent in the empirical relationship N ∼ [I] x · [E] y . Promoting coagulation by increasing the ionic strength decreases x towards zero, while y increases sharply. Increasing [I] at constant [E] and constant ionic strength induces limited coagulation, presumably because the rate of emulsifier adsorption becomes insufficient.