Semibatch Aqueous-Solution Polymerization of Acrylic Acid: Simultaneous Control of Molar Masses and Reaction Temperature

MINARI, R.J.; CÁCERES MONTENEGRO, G; MANDELLI, PAOLA; YOSSEN, M.M.; GONZÁLEZ SIERRA, M.; VEGA, J.R.; GUGLIOTTA, L.M.

MACROMOLECULAR REACTION ENGINEERING

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2011 p. 223 - 231

1862-832X

The isothermal (60 ºC) semibatch polymerization of non-ionized acrylic acid (AA) was investigated with the aim of producing polyacrylic acid (PAA) of controlled molar masses, at complete AA conversion, and under safe conditions. The proposed strategy mainly consists in initially loading a dissociative initiator (potassium persulphate: KPS) and feeding the AA at a constant feed rate along the reaction, for simultaneously controlling the polymerization rate and the produced molar masses. PAA of intermediate number-average molar masses ( ), in the range 1×104 - 2×105 g/mol, was produced through an adequate selection of both the KPS concentration and the AA feed rate. For a given KPS concentration, PAA of lower was obtained when reducing the AA feed rate. For long AA dosification times (240 min) and large KPS concentrations, transfer to polymer reactions caused PAA polydispersities higher than 4. In all experimental conditions, backbiting reactions were confirmed by 13C NMR. A simple mathematical model was developed to help interpret the experimental results.