In this paper, the non-isothermal differential scanning calorimetry
(DSC) was employed to investigate the cure process and to determine the kinetic
parameters of the curing reaction of the unsaturated polyester resin catalyzed
with promoter-cobalt(II)octoate and free-radical initiators. The initiators
were formed by the oxidation process of acetylacetone with 60% hydrogen peroxide
in the presence of the catalyst-sulphuric acid and the solvents: propano-1,2-diol
or the mixture of propano-1,2-diol and hydroxypolyether TG 500. As a reference,
the typical curing system containing ethyl methyl ketone hydroperoxide (Luperox)
and promoter was used.
It was found that the cure process of the
unsaturated polyester resin with the new initiators/cobalt(II)octoate was
described through lower maximum peak temperatures (Tmax)
and lower values of the total heat of the curing reaction (ΔHR) in comparison with Luperox/cobalt(II)octoate.
The computed values of activation energies were in the range of 40.8–44.9
and 80.4–87.6 kJ mol–1 for unsaturated
polyester resin cured with the new initiators/cobalt(II)octoate. The values
of activation energies were little lower or comparable to those obtained when
Luperox/cobalt(II)octoate system was used (45.8 and 82.3 kJ mol–1).