Semibatch Acrylic Acid Polymerization Controlled by Redox Initiation

CÁCERES, GERARDO; GUTIERREZ, CAROLINA G; MINARI, ROQUE J.; VEGA, JORGE R.; GUGLIOTTA, LUIS M.

Bahia Blanca

Congreso; IX Congreso Argentino de Ingeniería Química; 2017

Low molar mass Poly(acrylic acid) (PAA) is generally obtained by radical polymerization of acrylic acid (AA) in aqueous solution, using thermal initiators and chain transfer agents (CTA). This strategy is not enough to reach the low molar masses required for the final product to act as a dispersant. In this work, the semibatch polymerization of AA at 45 ºC was considered, using potassium persulfate (KPS) and sodium metabisulfite (KPS / NaMBS), or KPS and sodium hypophosphite (KPS / NaHP) as redox initiators to produce PAA of low molar mass (MM). These initiation systems enables to obtain PAA with Mn ≈ 2.0 KDa, relatively narrow MMD (Mw/Mn≈2), and a low branching degree (BD) per molecule. Typically, the polymerization reactions reach an almost complete conversion (≥ 94%), and both NaMBS and NaHP also behave as CTA. Results indicate that the two couple redox allow obtaining polymers with acceptable deflocculant capacities