Bulk High-Impact Polystyrene Process, I: Partitions of Tert-Butyl Peroctoate and Styrene in Blends containing Polystyrene and a Rubber

Abstract

In relation to the bulk high-impact polystyrene process, this work investigates the partition between phases of styrene and an initiator: tert-butyl peroctoate. A Flory-Huggins model was applied for predicting the phase separation point and the partitions of styrene and tert-butyl peroctoate. For blends of styrene, polystyrene, and a styrene-butadiene diblock copolymer, the model provides reasonable predictions of a ternary equilibrium diagram. For blends of styrene, polystyrene, polybutadiene, and tert-butyl peroctoate, the partition of tert-butyl peroctoate was measured at 25 °C. At emulated conversions of 13% or lower, equilibrium was reached after 1 h of mixing time. For the higher molar masses and conversion of 16%, equilibrium was not reached after 24 h of mixing time. To fit the equilibrium measurements, the solubility parameter of tert-butyl peroctoate was adjusted.