The emulsion copolymerization of Styrene (Sty)-Butyl acrylate (BuA) was
carried out in a semibatch reactor with sodium lauryl sulphate (SLS) as surfactant and potassium persulphate (KPS) as initiator. The effects related to the distribution of the
monomer, the surfactant, and the initiator on the copolymer composition and the
overall behaviour of the reactor were thoroughly studied.
It was found that BUA rich initial charge increased the polymerization rate,
reduced the particle sizes, and minimized the composition drift. The experimental
data showed that the free unadsorbed surfactant in the reactor increased with
increasing the fraction of the BuA monomer initially charged in the reactor. This led
to an increase in the number of polymer particles and in return increased the
polymerization rate. In addition, cross-linked copolymer was obtained when the BuA
content was high indicating the possibility of gel effect which as well led to the
apparent increase in the polymerization rate. The water-solubilities of the monomers
did not affect the reaction kinetics or the copolymer composition. This was
demonstrated experimentally and by means of mathematical modeling.
Reducing the surfactant and the initiator concentrations showed the general
behaviour of lower polymerization rates and larger particle sizes. The copolymer
composition was not affected by the changes in the surfactant and the initiator
concentrations in the reactor. Feeding part of the initiator or the surfactant during the
semi batch stage while maintaining constant concentrations showed major effects on
the sizes and the numbers of the polymer particles, and the polymerization rate. This
is believed to be related to the change in the agitation intensity as a result of varying
the volume of the initial charge. No effects were observed on the copolymer
composition and the monomers mass fraction in the particles.
A Master's Thesis. Submitted in partial fulfilment of the requirements for the award of Master of Philosophy of Loughborough University.