Bulk High‐Impact Polystyrene Process, 1

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.magnified image

Instability of styrene/polystyrene/polybutadiene/polystyrene‐b‐polybutadiene emulsions that emulate styrene polymerization in the presence of polybutadiene

“…This indicates a small preference of the monomer toward the upper PB-rich phase irrespective of conversion and also whether or not it included the BC. The partition coefficients of Exps 1 L and 1 H without BC are very close to previous determinations by Rigler et al [31], Ludwico and Rosen [34], and Luciani et al [3] for St/PS/PB blends. Clearly, the K St values are little affected by the presence of the BC; and this seems reasonable, remembering that the St partition between the homopolymers is close to unity.…”

“…For volume fractions of PS in the PS‐rich phase between 0.001 and 0.5, the volume ratio of St in the PB‐rich and PS‐rich phases varied between 1 and 1.10, respectively. Ludwico and Rosen [34] and Luciani et al [3] also determined the partition of St in St/PB/PS blends. As before, the monomer exhibited a slight preference toward the PB‐rich phase; and the St partition coefficient was seen to slightly increase with increasing PS concentrations [34, 3].…”

“…The room temperature is required to avoid the thermal polymerization of St that occurs at 708C or higher. Ternary phase diagrams of St/ PS/PB blends at room temperature have been developed to estimate the approximate phase volumes and compositions along a bulk HIPS process without rubber grafting [3]. So far, thermodynamic equilibrium diagrams that include the GC have not been reported.…”

A Mathematical Model of the Bulk Copolymerization of Styrene and Acrylonitrile in the Presence of Polystyrene‐block‐Polybutadiene

“…[16,[34][35][36][37][38][39][40][41] Experimental studies involving blends that emulate the bulk process have shown that low molar mass species, such as monomer, chain transfer agent, and initiators, are evenly partitioned between the phases when the system has reached thermodynamic equilibrium. [38][39][40][41] These uniform distributions have justified the use of homogeneous models at conditions where phase separation has already occurred. Heterogeneous models consider the polymerization taking place in 2 phases that instantaneously reach thermodynamic equilibrium.…”

Mechanisms and Conditions that Affect Phase Inversion Processes. The Case of High‐Impact Polystyrene

“…Depending on the rubber particle size and the number of occlusions, two typical morphologies are usually identified: a “salami morphology” (large rubber particle with several occlusions) or a “core–shell morphology” (relatively small rubber particle with only one large occlusion). These structures provide the material with improved mechanical properties in comparison with general purpose PS.…”