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.

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A novel quadruple spinneret to produce dual-layer hollow fiber membranes by simultaneous spinning of two polymer solutions, using the dual precipitation bath technique is proposed. Hollow fibers aimed at gas separation processes were prepared in extrusion system specifically designed and built for this purpose. A polyurethane polymer was selected as the selective layer (outer-layer), while polyethersulfone was defined as the support (inner-layer). Activated carbon powder was added into the PU solution for further improvement of the transport properties. The hollow fibers showed good adhesion between the polymer layers and a defect-free selective layer. Representative results include a CO 2 /N 2 selectivity of 43.