ISSN 0018-1439, High Energy Chemistry, 2018, Vol. 52, No. 3, pp. 257–262. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © Yu.A. Olkhov, S.R. Allayarov, I.A. Frolov, 2018, published in Khimiya Vysokikh Energii, 2018, Vol. 52, No. 3, pp. 234–238.
Influence of Gamma-Irradiation and Thermal Annealing
on Molecular–Topological Structure
of Tetrafluoroethylene–Ethylene Copolymer
Yu. A. Olkhov, S. R. Allayarov*, and I. A. Frolov
Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia
Received March 29, 2017
Abstract⎯The molecular–topological structure of a tetrafluoroethylene copolymer with ethylene after
γ-irradiation and thermal annealing has been studied. The pseudo-network structure of the copolymer
contains, in addition to the amorphous block, crystalline segments of macromolecules in the role of
branching sites. Topologically, the diblock structure of the copolymer after thermal annealing at 538 K
is transformed into a three-block structure with the appearance of a high-temperature amorphous block.
Irradiation of the copolymer with γ-rays to a dose of 150 kGy does not lead to appreciable changes in its
Keywords: tetrafluoroethylene–ethylene copolymer, thermal annealing, thermomechanical analysis, molec-
ular topological structure
An ethylene–tetrafluoroethylene copolymer
(ETC) has excellent properties that distinguish it from
other fluorinated thermoplastics [1–5]. It has high
mechanical strength, hardness, elasticity, wear resis-
tance, and radiation resistance. The mechanical prop-
erties of ETC are less temperature-dependent than
those of polytetrafluoroethylene or a tetrafluoroeth-
ylene–hexafluoropropylene copolymer, which are
also among most widely used perfluorinated copoly-
mers. It should be noted that the thermal stability of
ETC is close to the stability of the tetrafluoroeth-
ylene–hexafluoropropylene copolymer, but some-
what lower than that of polytetrafluoroethylene. How-
ever, unlike polytetrafluoroethylene, ETC is easy to
process into products using the popular extrusion
method, which significantly reduces the cost of pro-
duction from it. Like polyvinylidene f luoride, ETC
has a higher radiation resistance than polytetrafluoro-
ethylene or the tetrafluoroethylene–hexafluoropro-
pylene copolymer . The combination of these prop-
erties makes ETC a very attractive material for use in
the nuclear industry and other areas where radiation
can be encountered.
It is known  that the thermal treatment of fluo-
rine-containing copolymers is widely used in their
production and manufacturing articles from them to
impart the necessary properties to these materials.
However, the effects of heat treatment on the molecu-
lar–topological structure of ETC have not been inves-
The purpose of this work was to study the molecu-
lar–topological structure of γ-irradiated and ther-
mally annealed ethylene–tetrafluoroethylene copoly-
mer by thermomechanical spectrometry.
Commercial ethylene–tetrafluoroethylene copo-
lymer of the Ftoroplast F-40 brand manufactured by
the Kirovo-Chepetsk Chemical Plant was used in the
study. Thermomechanical analysis (TMA) was carried
out according to the procedure described in papers on
the application of thermomechanical spectrometry to
the analysis of fluorine-containing polymers [7, 8].
One of the measured TMA quantities is the change in
the linear dimension of a sample between the substrate
and the probe. The analysis was terminated after
reaching the temperature of steady-state molecular
flow. The accuracy of the TMA method was analyzed
in . The accuracy of temperature measurements in
the thermostat unit was ±0.05 K. The error in deter-
mining the molecular mass (MM) was less than 10%.
The other characteristics were reproduced within error
limits of ±5 to 10%.
The copolymer was irradiated with
C γ-rays on a
Gammatok-100 source at a dose rate of 0.15 Gy/s.
Thermal treatment (annealing) of the copolymer was