Mathematical Model for the Bulk Polymerization of Styrene Chemically Initiated by Sequential and Total Decomposition of the Trifunctional Initiator Diethyl Ketone Triperoxide

EMILIO BERKENWALD; CECILIA SPIES; JORGE CERNA CORTÉS; GRACIELA MORALES; DIANA ESTENOZ

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 2012 vol. 128 p. 776 - 786

0021-8995

This work experimentally and theoretically investigates the use of the symmetrical cyclic trifunctional initiator diethyl ketone triperoxide (DEKTP) in the bulk polymerization of styrene (St). The experimental work consisted on a series of isothermal batch polymerizations at different temperatures, 120 and 130°C, with different initiator concentrations: 0.005, 0.01 and 0.02 mol/L. A mathematical model was developed in order to predict the evolution of the reacting chemical species and the produced molecular weights distributions (MWDs). The kinetic model includes chemical and thermal initiation, propagation, transfer to the monomer, termination by combination and re-initiation reactions. Simulation results predict the concentration of di- and monoradicals as well as polymeric chains, characterized by the number of undecomposed peroxide groups. Experimental results show that, at reaction temperatures of 120-130°C, DEKTP initiation produces an increase in polymerization rates and average molecular weights, depending on the initiator concentration, due to sequential decomposition of the initiator molecule. The mathematical model was adjusted and validated using the experimental data. Theoretical predictions are in excellent agreement with the experimental results. Also, an optimum initiator concentration was observed to achieve high polymerization rates and high molecular weights simultaneously. For polymerization temperatures of 120 -130°C the optimum concentration was 0.01 mol/L.