Cumene Hydroperoxide in Redox Emulsion Polymerization

Abstract

retardation-namely, by the use of mixtures of normal and tertiary mercaptans and by an increase in the sodium hydroxide content of the system.The role of mercaptan in a recipe, such as given in Table I, is a dual one.It acts both as a chain initiator and as a chain transfer agent. The data in Table VI suggest that a DDM content of from 0.075 to 0.2 part should be sufficient to function as an initiator and that a tertiary mercaptan could then be used as modifier. This was verified in pilot plant experiments and found to be a practical method of overcoming retardation by ammonia. Measurements of Mooney viscosity of rubbers produced with ammoniaretarded recipes indicated that ammonia has little if any effect on the modifier activity of tertiary mercaptans. Thus, it appears that retardation affects initiation and not chain transfer.The effect of increasing the sodium hydroxide content of the recipe above that required to give a pH of 10 is interesting. Without ammonia (part A, Table VIII), the conversion is quite constant up to a sodium hydroxide content of 0.50 part. Some precoagulum appeared in the reaction vessel at higher conversions with the highest alkali concentration. In the presence of 200 p.p.m. ammonia, however, the increase in rate of conversion was very marked. At 16 hours, with 0.512 part sodium hydroxide, a conversion of 90.0% was obtained (Figure 4). This is about 15% higher than was expected without ammonia. The results indicate that, under these conditions, ammonia is a polymerization accelerator rather than a retarder. To verify this rather surprising observation the experiments reported in part C of Table VIII were conducted. The ammonia content was varied in two series of experiments, one with, and the other without, sodium hydroxide. The now familiar retardation was observed in the absence of sodium hydroxide but an increase in rate with increase of ammonia up to 200 p.p.m., followed by an extremely pronounced retardation, was obtained in the presence of sodium hydroxide. The data are plotted in Figure 5. LITERATURE CITED(1) Baker, W. O., Bell Laboratories, to Office of Rubber Reserve, private communication, 1942. (2)

Emulsion Polymerization

“…Table 4-1 shows a typical recipe for an emulsion polymerization [Vandenberg and Hulse, 1948]. This formulation, one of the early ones employed for the production of styrene-1,3-butadiene rubber (trade name: GR-S), is typical of all emulsion polymerization systems.…”

“…The main components are the monomer(s), dispersing medium, emulsifier, and water-soluble initiator. The dispersing medium is the liquid, usually water, Vandenberg and Hulse [1948].…”

Redox recipes. II. Redox recipes in alkaline medium initiated by the system cumene hydroperoxide–iron–sugar at 30°

“…From experiments carried out in the absence of iron ( Fig. 15) it may be concluded that a large proportion of the CHP is consumed by di- (1) no Fe(N0&.9HzO; (2) 0.0022 part of Fe(N03)8*9Hz0; (3) 0.009 part of Fe(N03)3. ~H z O ; (4) 0.036 part of Fe(N03)3*9HzO; (5) 0.144 part of Fe(NO3)s9HzO.…”

“…~H z O ; (4) 0.036 part of Fe(N03)3*9HzO; (5) 0.144 part of Fe(NO3)s9HzO. (1) no irop, no salt; (2) 0.036 part of Fe(N03)3.9Hz0, 0.5 part of KzSO4; (3) 0.036 part of Fe(N03)3.9H20, 0.5 part of Na4PzOr10Hz0; (4) no iron, 1 part of Na4P&-1OHzO.…”

“…With 5 parts of Aerosol AY (the corresponding amyl ester), small and poorly reproducible rates were obtained. This is because the amount of Aerosol AY charged was in the neighborhood of the critical concentration of this detergent.12 (1) L-sorbose (1 part); (2) fructose (1 part); (3) invert sugar (1 part); (4) glucose (3 parts); (5) glucose (1 part).…”