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