ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 6, pp. 995!998. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + N.I. Polezhaeva, A.A. Nefedov, L.A. Kruglyakova, I.V. Polezhaeva, V.A. Fedorov, 2007, published in Zhurnal Prikladnoi
Khimii, 2007, Vol. 80, No. 6, pp. 1021!1024.
AND POLYMERIC MATERIALS
Kinetics of Thermal Oxidative Degradation
of a Polyester Resin and of Its Formulation
with Diethyldibenzylammonium Bromide
N. I. Polezhaeva, A. A. Nefedov, L. A. Kruglyakova,
I. V. Polezhaeva, and V. A. Fedorov
GOU VPO Siberian State Technological University, Krasnoyarsk, Russia
Received September 21, 2006; in final form, January 2007
Abstract-The kinetics of thermal oxidative degradation of a polyester resin and of its formulation with
diethyldibenzylammonium bromide was studied. The rate constants of the thermal decomposition were
This study further examinates the developed for-
mulations of low-temperature noncorrosive solder
creams based on a polyester resin modified with rosin
and quaternary ammonium salts [1, 2].
The temperature and time limits of the working
capacity are important characteristics of polymers.
These limits are determined by the occurrence of
physical or chemical transformations of polymers .
A thermal analysis can be performed in isother-
mal and dynamic modes. In the first case, the thermal
degradation is monitored at a constant temperature,
which allows comparison of the degradation rates of
various materials at a given temperature. This mode
is suitable when the working temperature range of
a material is known.
To estimate the heat resistance of a material, it is
necessary first to determine the temperature ranges
of the occurrence of transformations that irreversibly
alter the chemical nature of the polymer. This is done
using dynamic thermal analysis.
The parameters of thermal oxidative degradation of
a polyester resin (sample no. 1) and its formulation
with diethyldibenzylammonium bromide (DEDBAB)
(sample no. 2) were determined by dynamic thermo-
gravimetry . For more accurate determination of
the temperatures at which the samples start to decom-
pose, we recorded along with the TG curves the DTG
and DTA curves (Figs. 1a, 1b). Experiments were per-
formed with an MOM Q-1000 derivatograph (Hun-
gary) in the programmed-heating mode. Samples
(0.05 g) were heated in a platinum crucible in air
at rates of 5 and 10 deg min
. The sensitivities were
as follows: balance, 100 mg; DTA galvanometer, 1/3;
DTG galvanometer, 1/10.
When heated in air, sample no. 1 decomposes
in three steps in the interval 803 600oC (Fig. 1a).
The first step (803250oC) involves removal of the re-
sidual solvent and free volatile components boiling in
this range: water formed in the course of the resin
synthesis, residual alcohol, and unsaponifiable sub-
stances. The second step (3103 400oC) involves endo-
thermic decomposition of the polyester resin and si-
multaneously occurring exothermic oxidation of a part
of the products formed [1, 3, 5]. The third step is
characterized by a complex exothermic effect with
characteristic temperatures of 420 (onset of exothermic
peak corresponding to the oxidation in the DTA curve)
and 540oC. The strong peak at 540oC corresponds
to oxidation of the gaseous products released in
the course of the thermal decomposition of the poly-
ester resin [1, 3, 5].
Sample no. 2, when heated in air, decomposed in
three steps in the interval 1003560oC (Fig. 1b).
The first step (1003220oC) is of the same origin as for
sample no. 2. The second step (2503 400oC) involves