Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 5, pp. 877−881.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © D.G. Lin, E.V. Vorob’eva, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 5, pp. 848−852.
AND POLYMERIC MATERIALS
Contact Oxidation of Inhibited Polyethylene on Copper
at Nonuniform Antioxidant Distribution
D. G. Lin and E. V. Vorob’eva
Skorina Gomel State University, Gomel, Belarus
Received October 3, 2010
Abstract—The oxidation resistance of polyethylene ﬁ lms in which the antioxidant is concentrated exclusively
in the surface layer of the polymer or in the layer contacting with the support was studied. Speciﬁ c features of
oxidation of polyethylene ﬁ lms with heterogeneous distribution of an amine (Neozon D) or phenolic (Irganoks
1010) antioxidant on a catalytically active copper support were examined in relation to the kind of the antioxidant.
Oxidation of polyethylene (PE) ﬁ lms in contact with
active metals is accompanied by transfer of compounds
of the support metal into the bulk of the polymer [1, 2].
The transferred metal-containing compounds, which
are hydrated or nonhydrated carboxylates , catalyzed
oxidative transformations in polymers [2, 4]. To suppress
the polymer oxidation and reduce the catalytic effect of
the transferred metals, antioxidants (AOs) are introduced
into polymers. AO-containing polymers have a longer
induction period of oxidation (IPO), which depends on the
activity of the metal support contacting with the polymer
being oxidized. Replacement of a passive support by an
active support, as a rule, makes IPO of polymer ﬁ lms
shorter , although in certain cases deviations from this
trend are possible. For example, the contact of the copper
support with PE inhibited by an amine AO, Neozon D, is
accompanied by an increase in the AO performance .
Similar effect was observed in oxidation on zinc supports
of PE ﬁ lms containing a phenolic AO, Irganoks 1010 .
Oxidation of polymer ﬁ lms in air occurs throughout
the ﬁ lm thickness nonuniformly. The surface layer of
the sample is the most affected, because in this layer the
oxygen supply to the reaction zone and the removal of
gaseous products of oxidative transformations are the
easiest. In the bulk of the ﬁ lm, the oxidation is mainly
hindered by a decrease in the oxygen partial pressure in
going to deeper layers. In addition, the oxidation progress
is affected by the nature of the metallic support, which can
intensify the polymer oxidation. As a result, two zones
of intense oxidation of the polymer arise in such ﬁ lms:
one zone in the surface layer of the sample and another
zone in the layer adjacent to the support. Depending on
the temperature, time, and other service conditions, the
rates of oxidative transformations in these zones can
differ signiﬁ cantly.
The above-presented scheme of the oxidation prog-
ress throughout the sample depth becomes considerably
complicated on introducing an AO into the polymer. If
the support is inactive, localization of the oxidation in the
surface layer of the ﬁ lm leads to accelerated consump-
tion of AO in this part of the sample. Then the diffusion
of AO to the reaction zone becomes the decisive factor.
If the AO is sufﬁ ciently mobile, it migrates from deep
layers of the sample to the zone of intense consump-
tion of AO, and the autocatalytic mode of the polymer
oxidation is not attained for some time. Then, as the AO
is consumed, the oxidation becomes autocatalytic (ﬁ nal
step) throughout the sample volume. With an active
support, the AO inhibits the oxidation in two local zones
simultaneously: in the surface layer of the polymer and