(60n) New Advances in the Mathematical Modeling of the Continuous Mass Processes for the Production of Rubber-Toughened Styrene Polymers

The bulk copolymerization of styrene and acrylonitrile in the presence of PB and SBR using the bifunctional initiator Luperox-331 M80 (L331) was theoretical and experimentally investigated. A mathematical model for the continuous bulk production of ABS is presented. The model was developed on the basis of our previous publications [1,2], and considers: i) the use of multifunctional initiators, ii) the modeling of the devolatilization stage, and iii) the influence of the rubber composition in the industrial quality variables. The model allows the prediction of conversion and other global chemical species, grafting efficiency, and molecular weights along the train reactor as well as final product properties such as molecular weights distributions (MWD), melt flow index (MFI), swelling index, and residual monomer content. The model was adjusted and validated with experimental data.

Eight different reactions for ABS production were carried out in a pilot plant varying the rubber composition and structure (SBR and PB). The pilot plant comprised the main stages of an industrial HIPS process: dissolution, prepolymerization, finishing and devolatilization. Samples were taken in order to determine conversion by gravimetry, residual monomer content by RMN, MFI in an extrusion plastomer, molecular weight distributions by Size Exclusion Chromatography, morphology by Transmission Electron Microscopy, and Impact Resistance (IR) by Izod Impact Testing . Final Mw of the range of 2.1-2.3 10⁵ g/mol were measured and a considerable improvement in the IR was observed when using a mixture of SBR and PB.

A good agreement between measurements and simulations was obtained. The model is an useful tool for control and optimization of the industrial production process.