Kinetic Investigation of Styrene Free Radical Polymerization by Using Binary Mixtures of Monofunctional Initiators

Polymerization of styrene in presence of two monofunctional initiators is studied kinetically in an ampoule scale. Polymerizations were ceased at different conversions for each ampoule while the temperature was increased almost linearly during the reaction. Three different initiator mixtures were used. The first mixtures were composed of benzoil peroxide (BPO) and t-butyl perbenzoate (TBPB) with various molar ratios and temperature programs. The second and third series were performed on mixtures of BPO and α,α'-azobisisobutyronitrile (AIBN) and AIBN with TBPB, respectively. The experimental results for these series revealed thatincreasing the percentage of TBPB in the initiator mixtures at the same reaction temperature intervals enhanced polymerization rate and molecular weight of the resulting polymers. On the other hand the results from the second series indicated that reducing AIBN in the mixture would have reduction effect on the reaction temperature intervals while both conversion and the polymer molecular weight are increased.