UBC Theses and Dissertations
The control of molecular size in emulsion polymerized styrene Broadhead, Ronald Leslie
The effect of increment addition of monomer, during the emulsion polymerization of styrene, upon the molecular homogeneity of polystyrene has been investigated. This procedure results in a polymer containing large amounts (greater than 60%) of benzene insoluble material indicating that there is a considerable degree of cross-linking during the process. A small amount of the product (less than 20%) exhibits a fair degree of homogeneity with respect to the molecular weight. Low molecular weight polystyrene can be obtained by the use of mercaptan modifiers. The mercaptan appears to be carried into the reaction loci by the styrene during the early stages of the polymerization. Later, the effectiveness of the modifier is governed by diffusion through the aqueous phase.
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