SWOLLEN EMULSION POLYMERIZATION OF STYRENE WITH CETYL AND OR LAURYL ALCOHOL AS SWELLING AGENT

The kinetics of swollen emulsion polymerization of styrene was investigated. Two types of fatty alcohol, namely, cetyl alcohol and lauryl alcohol, were used as swelling agents in the presence of sodium dodecyl sulfate as emulsifier and potassium persulfate as initiator. The polymerizations were carried out in a magnetic-drive, sealed, cylindrical polymerization reactor, in nitrogen atmosphere. The effects of emulsifier concentration and the weight ratio of emulsifier to swelling agent on the variation of total monomer conversion with the polymerization time, average particle size, and the size distribution of the latex were examined. A significant decrease in the polymerization rate was observed at especially lower emulsifier concentrations in the presence of cetyl alcohol. The maximum average diameter of the latex with the sodium dodecyl sulfate-cetyl alcohol system was obtained as 0.30 mum. Lauryl alcohol was tried as a novel swelling agent. It was found that lauryl alcohol was an effective swelling agent without using sodium dodecyl sulfate. The latexes having average diameters of 1.0 mum and 0.67 mum (highly monodisperse) were obtained using 0.6 g and 2.0 g lauryl alcohol, respectively, at 300 mL of reaction volume. If it was used together with sodium dodecyl sulfate, the presence of lauryl alcohol did not cause any significant decrease in the polymerization rate as in the case of sodium dodecyl sulfate-cetyl alcohol system, but the average diameters of the latexes obtained with different sodium dodecyl sulfate-lauryl alcohol combinations were rather small compared to the sodium dodecyl sulfate-cetyl alcohol system at the same polymerization conditions.