In this work unsaturated polyesters based on terephthalate
acid and isophthalic acid have been prepared by a two-stage process.
In the first stage the prepolymer bis(2-hydroxypropyl) terephthalate
(PTP1) was prepared and purified. PTPl was heated at
different temperatures within the range lSO-1800 C, and the changes
in molecular weight distribution, on heating, and the considerable
ester-interchanges were assessed by gel permeation chromatography
(GPC) and nuclear magnetic resonance spectroscopy (NMR). Similar experiments were performed with the prepolymer (P(TP)J provided by
Imperial Chemical Industries and the prepolymer bis(hydroxypropyl)
isophthalate (PIP1) which was synthesised and purified. GPC and
NMR were used to compare the temperature dependence of ester-interchange
and polycondensation in the three prepolymers.
In order to see the implications of the ester-interchange observed on the mechanism of the reaction between prepolymer and
maleic anhydride, unsaturated polyesters produced at various temperatures
in short reaction times have been fractionated by preparative GPC. High resolution 300 MHz proton NMR was used for the qualitative
and quantitative analysis of the unsaturated polyester and its fractions~
$tructures were assigned to the oligomeric compounds and
reaction mechanisms were outlined.
-Finally the products of the reaction of (PTP1), propylene glycol,
maleic anhydride (or fumaric acid) in various molar ratios were
examined by NMR and GPC, and their results were compared with a
study of unsaturated polyesters based on (P(TP)n) and (PIP1).
Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.