Monomer addition policies for copolymer composition control in semicontinuous emulsion copolymerization

✍ Scribed by Gurutze Arzamendi; Jose M. Asua

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 890 KB
• Volume: 38
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1989.070381106

✦ Synopsis

The effect of various monomer addition policies on the composition of a copolymer synthesized by semicontinuous emulsion copolymerization, using monomers with widely different reactivity ratios, was studied by mathematical simulation. Three policies were considered. In the first, both monomers are added under starved conditions. In the second, the reactor is initially charged with all of the less reactive monomer plus the amount of the more reactive monomer needed to initially form a copolymer with the desired composition. Subsequent addition of the remaining monomer is made at a flow rate that ensures the formation of a copolymer of constant composition. In the third, the initial charge is the same as in the previous case with subsequent addition of the remaining monomer at a constant feed rate. The copolymer composition obtained under starved conditions was almost constant in the cases where low feed rates were used. However, this led to long process times. For the second policy, a mathematical model was developed to calculate the necessary addition rate of the more reactive monomer, that ensured the production of a copolymer of constant composition. It was found that the resulting process time was one third of that corresponding to the starved process. When variations in the copolymer composition were allowed, the third addition policy might prove to be a good alternative to the second addition policy because of its shorter process time and the advantage of working with a constant feed rate.