POLYMERISATION OF VINYL ACETATE IN AQUEOUS EMUL5IFIER WITHOUT MICELLES

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dc.contributor.authorYETUNDE, OLUREMI MOSURO,
dc.date.accessioned2014-02-07T10:38:02Z
dc.date.available2014-02-07T10:38:02Z
dc.date.issued1983-06
dc.descriptionA thesis submitted to the Postgraduate School, Ahmadu Bello University, in partial fulfilment of the requirements for the degree of; MASTER OF SCIENCE in POLYMER SCIENCE AND TECHNOLOGY.en_US
dc.description.abstractThe effect of four different monomer and emulsifier concentrations and two different initiator concentrations on the kinetics of polymerisation of vinyl acetate at 55 + 0.05 oC, below the critical micelle concentration of sodium lauryl sulphate as emulsifier, using potassium persulphate as the initiator, and on some properties of the polymer samples produced have been studied. The form of the dependence of the rate of of polymerisation (R ), on the exponent of the emulsifier and initiator concentrations was also studied. The forms of the variation of limiting viscosity and Huggins• constant with (%) conversion of monomer to polymer were also studied. The rate of polymerisation of vinyl acetate under the conditions studied was appreciable, increasing with increase in the emulsifier concentration. The form of the dependence of rate on the exponent of emulsifier concentration on the rate of polymerisation was independent of monomer concentration but dependent on the initiator concentration. The rate of polymerisation decreased as the monomer concentration increased. Generally, polymerisation of vinyl acetate in the absence of micelles is explained as due to the combination of factors including partial solubility of vinyl acetate in water, agitation which allows for interaction of monomer molecules with the free radicals, and diffusion of free radicals from the aqueous to the monomer layer. Delay in the vi - action of these factors have caused an induction period to the polymerisation reaction. Limiting viscosity values for the polyvinyl acetate - methanol systems at 30 +/- 0,05 C were obtained and used to qualitatively describe the pattern of the dependence of polymer molecular characteristics mainly (molecular weight with branching) on the conditions of the polymerisation. Conclusions were drawn showing that molecular characteristics of the polymers produced at lower conversions of the monomer are significantly different from those at higher conversions. These properties, are also affected by emulsifier, monomer and initiator concentrations. Huggins constant was used as a measure of polymer-solvent interactions and an estimate of size of polymer backbone, degree of branching and length, as described qualitatively. Generally, the study shows that many of the results can not be explained in terms of the classical theories of emulsion polymerisation of vinyl monomers. - vii -en_US
dc.identifier.urihttp://hdl.handle.net/123456789/649
dc.language.isoenen_US
dc.subjectPOLYMERISATIONen_US
dc.subjectVINYL ACETATEen_US
dc.subjectEMUL5IFIERen_US
dc.subjectMICELLESen_US
dc.titlePOLYMERISATION OF VINYL ACETATE IN AQUEOUS EMUL5IFIER WITHOUT MICELLESen_US
dc.typeThesisen_US
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