BULK THERMAL COPOLYMERIZATION OF STYRENE AND ACRYLIC ACID IN CONTINUOUS FLOW REACTIONS

Abstract

<p>This thesis contains two parts. The first involves the theoretical modelling of bulk, thermal, homo- and copolymerizations of styrene with another vinyl monomer in continuous flow stirred tank and tubular reactors. The second involves an experimental study of such polymer production in pilot plant scale reactors. Kinetic modelling fundamentals, applicable assumptions and their implications are discussed. Three series of experimental runs were performed in a 1.4 liter stirred tank reactor. The experimental conditions were in the range of 200 to 300 C with residence times of 15- 60</p> <p>minutes. The first set was done with pure styrene to verify the current styrene kinetic model and provide more detail on the formation of oligomers. Two additional series of experiments were performed with two different comonomer compositions. The monomers were styrene and acrylic acid. Parameter estimation and model verification were attempted with all data. The parameter estimation results are necessarily uncertain due to the low number of experiments possible with pilot plant work and the low variance of the responses obtained in experimentation on high temperature systems. The kinetic mechanism initiation, oligomer formation supported in this work describing styrene thermal and polymer production are Trimer formation is suppressed in the copolymerization of styrene with acrylic acid. This is due to the reaction of acrylic acid monomer with the thermal initiation intermediate, thus preventing rearrangement to trimer species.</p> <p>Trimer formation is accelerated by the addition of chlorine radical to the reaction. This radical reacts with the intermediate to produce chlorinated trimer species and prevents macroradical formation. The addition of a tubular reactor was found to severely increase polymer oil fraction and decrease molecular weight, with only a minor productivity increase.</p> <p>It is believed thermal degradation is <em>very </em> significant in determining molecular weights at temperatures greater than 280 c.</p>