Solution styrene polymerizations performed with multifunctional initiators

Abstract

This paper analyzes the performance of multifunctional initiators frequently used in the literature and in the industry for the production of polystyrene (PS). Polymerizations of styrene in ethylbenzene were conducted in batch at high temperatures (120°C) until conversions around 70%, as frequent in industrial sites. Polymerizations were conducted in glass test ampoules with different concentrations and types of initiators, parameterized in terms of the active oxygen concentration. The results showed that when used at similar active oxygen concentrations, the use of the tetrafunctional initiator tetrakis(tertbutylperoxy carbonate) can allow for the production of polymer resins with significant higher average molar masses with similar polymerization rates, which can be very useful at plant site for the modification of polymer grades. Besides, the results show that the decomposition of one peroxide group of the analyzed multifunctional initiators does not affect the rates of decomposition of the remaining ones significantly, as reaction proceeds as initiated by a monofunctional initiator. Finally, although described in previous styrene polymerization studies, the use of the trifunctional initiator 3,6,9‐triethyl 3,6,9‐trimethyl‐1,4,7 triperoxonane is difficult to justify in commercial units, given its very high half‐life time. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42609.

Mixing Effects in Continuous Free‐Radical Solution Copolymerization Tank Reactors: I—Characterization of Residence Time Distributions

“…These results suggest that addition of DVB provides chain transfer reactions, due to impurities present in the commercial mixture. Chain transfer reactions to impurities are responsible for the decrease of the average molecular weights, when compared with data obtained with similar initiator concentration and in the absence of DVB (presented by Mermier et al [39] ), as one can see in Figure 6. Figure 7 shows the evolution of molecular weight distributions in styrene polymerizations performed with 0.05 wt% of DVB.…”

“…Figure 7 clearly shows that this amount of DVB is sufficient to cause significant changes of the molecular weight distribution of the soluble fraction the final product. [39] Particularly, one must observe that bimodal molecular weight distributions can be obtained after addition of DVB to the reaction medium, indicating the successful incorporation of DVB into the polymer chains.…”