New Advances on the Mathematical Modeling of the Continuous Bulk Process for the Production of High-Impact Polystyrene Using Multifunctional Initiators

EMILIO BERKENWALD; GRACIELA MORALES; LAURA LAGANA; PABLO ACUÑA; JUAN MAFFI; DIANA ESTENOZ

Cancún

Simposio; XV Simposio Latinoamericano de Polímeros; 2016

SPM

In this work, new advances on the mathematical modeling of thebulk continuous HIPS process are presented. The modelconsiders a kinetic mechanism which includes thermal initiation,chemical initiation by sequential decomposition of amultifunctional initiator, propagation, transfer to monomer, transferto rubber, termination by combination and re-initiation, as well ashigh temperature crosslinking and oligomer generation reactions.The model is an extension from our previous publications, andconsists of three sub-models: i) a polymerization model usingmultifunctional initiators, which simulates the evolution of the mainpolymerization variables and the detailed molecular structure ofthe polymeric mixture (free polystyrene, residual polybutadieneand graft copolymer); ii) a devolatilization (DV) model, includingboth high-temperature kinetics and interfacial transportphenomena in a falling strand devolatilizer, which quantifies theeffect of this stage on the melt chemical composition andmolecular structure and; iii) a physical properties model based onstructure-properties relationships, which estimates a) Melt FlowIndex from mass and momentum balances in a plastometer andthe estimation of rheological characteristics of HIPS, b) SwellingIndex from thermodynamic phase equilibrium considerations inthe heterogeneous microstructure, and c) other physicalproperties from semi-empirical correlations such as impactresistance and elastic modulus. The model is adjusted andvalidated using new experimental data for bulk HIPS continuouspolymerization in a pilot-scale plant.