Mathematical Modeling of Molecular Weight Distributions in Suspension Polymerization of Vinyl Chloride by Probability Generating Functions

CASTOR JR., CARLOS A.; SARMORIA, CLAUDIA; ASTEASUAIN, MARIANO; BRANDOLIN, ADRIANA; PINTO, JOSÉ CARLOS

MACROMOLECULAR THEORY AND SIMULATIONS

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2014 vol. 23 p. 500 - 522

1022-1344

This paper presents a mathematical model to describe the evolution of the molecularweight distribution (MWD) in vinyl chloride (VCM) free-radical suspensionpolymerizations performed with a bifunctional initiator, 1,3-di(2-neodecanoylperoxyisopropyl) (DIPND). The model yields, as a function of time, themass balances for the distinct phases, the monomer conversions, the number- andmass-average molecular weights and the complete MWD of both the growing anddead polymer chains. In order to describe the MWD, the model uses probabilitygenerating functions (pgf) to transform the infinite mass balance equations thatdescribe the evolution of the distribution into a reduced and finite set of modelequations. The set of pgf-transformed model equations is then solved and invertednumerically. Numerical validation of the proposed numerical scheme was successfullyperformed with help of published experimental data. As shown throughout manyexamples, as the dynamics of the molecular weight distributions in vinyl chloridesuspension polymerizations is controlled by chain transfer to monomer, the molecularweight distributions of the final polymer resin is little sensitive to the presence of thelinear symmetrical bifunctional initiator.