POLYMETHYL METHACRYLATE: A STUDY OF ITS FORMATION AND MOLECULAR WEIGHT DISTRIBUTION.

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Date
1983-10
Authors
MOSAKU, OLUFUNMILAYO IRENE
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Abstract
The kinetics of the emulsion polymerisation of methylmethacrylate using potassium persulphate as initiator and sodium lauryl sulphate (SLS) as emulsifier has been studied at two different temperatures, with four different emulsifier concentrations, and two different initiator concentrations. Sigmoid shaped conversion - time curves were obtained, the steep parts of which are linear. The slopes of these were taken as a measure of the rate of polymerisation, and increase with emulsifier and initiator concentrations and with temperature. The intrinsic viscosity and hence molecular weight of the polymer samples were determined from dilute solution viscosity measurement and found to be considerably high for the polymethylmethacrylate c"71 c o obtained while polymerising below the critical micelles concentration of the emulsifier. Molecular weight increased with increase in emulsifier concentration particularly at lower initiator concentration. Molecular weight also increased with increase in temperature. Futhermore molecular weight per unit conversion increased with emulsifier concentration, decreased with initiator concentration and increase in temperature. Huggins constant also suggested a ipoor PMMA acetone interaction* The polymer samples were characterised by the fractional precipitation method. Two distinct fractions were obtained for each polymer sample produced while polymerising (MMA) below the cmc of (SLS). The molecular weight distribution curve is sigmoidal and indicates polydispersity in the polymer molecular weight. The degree of polydispersity increased with increases in percentage conversion, emulsifier concentration, initiator concentration and temperature of polymerisation of the monomer.
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A. thesis submitted to the Postgraduate School, • Ahmadu Bello University, Zaria, in partial fulfillment of the requirements for the degree of Master of Science in Polymer Science and Technology. DEPARTMENT OF CHEMISTRY, FACULTY OF SCIENCE, AHMADU BELLO UNIVERSITY, ZARIA - NIGERIA.
Keywords
POLYMETHYL,, METHACRYLATE,, FORMATION,, MOLECULAR WEIGHT,, DISTRIBUTION.
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