Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 4, pp. 701−707.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.G. Fazlitdinova, V.A. Tyumentsev, E.P. Mayanov, S.A. Podkopaev, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84,
No. 4, pp. 666−672.
AND POLYMERIC MATERIALS
Effect of Thermomechanical Treatment Modes
on Nanostructure Formation in Thermally Stabilized
A. G. Fazlitdinova, V. A. Tyumentsev, E. P. Mayanov, and S. A. Podkopaev
Chelyabinsk State University, State Educational Enterprise for Higher Professional Education, Chelyabinsk, Russia
Received June 11, 2010
Abstract—Structure of the crystalline component of a polyacrylonitrile fiber was studied in isothermal
thermomechanical treatment by comparing X-ray diffraction data at various temperatures and mechanical loads
of thermal stabilization.
Carbon ﬁ bers with high elasticity-strength character-
istics are produced by thermal stabilization of polyacry-
lonitrile (PAN) ﬁ bers, followed by a high-temperature
thermomechanical treatment. The oxidative thermal
stabilization of the starting ﬁ ber is one of the most im-
portant stages of the technological process, which af-
fects how the ﬁ nal structure of the carbon ﬁ ber is formed
and is accompanied by chemical reactions of cycliza-
tion, dehydrogenation, and oxidation [1–7]. As a result,
a new nanostructure of thermally stabilized ﬁ bers is
formed within the starting PAN ﬁ ber at temperatures of
Speciﬁ c features of chemical transformations of the
material in the stage of thermal stabilization have been
the subject of a rather large number of publications [3–
16]. It has been shown that thermal stabilization modes
(temperature, gas medium, stretching load) strongly af-
fect properties of the precursor and carbon ﬁ ber [10–13].
The fundamental aspects of how the structure of
PAN is transformed into that of a thermally stabilized
ﬁ ber have been studied by diffraction methods [2–7, 15,
16]. Important additional data on structural parameters
of PAN in various stages of its transformation to the
structure of a thermally stabilized ﬁ ber can be furnished
by texture studies of ﬁ bers and analyses of the proﬁ le of
a diffraction peak providing information about the ﬁ ne
structure of the material.
In our study, we examined in detail by means of
X-ray diffraction analysis speciﬁ c features of how the
structure of a polyacrylonitrile ﬁ ber is transformed
into that of a thermally stabilized ﬁ ber in the course of
isothermal treatment in air under various thermal and
stretching mechanical impacts.
The study was performed on PAN ﬁ bers (5 wt %
methyl acrylate) fabricated using dimethylsulfoxide.
The thermal stabilization was carried out in isothermal
conditions at temperatures of 255, 265, 275, and 285°C
(the complex ﬁ ber was transferred in 2 s to a preliminary
heated furnace) in air under a permanent stretching
load of 0.2, 0.6, or 1.0 g tex
. The temperatures were
maintained to within ±1°. In the course of a thermo-
mechanical treatment (TMT), changes in the length of
the complex ﬁ ber, l/l
, were monitored (l
and l are the
initial and running ﬁ ber lengths, respectively).
The structure of the ﬁ bers was studied with a D8
ADVANCE X-ray diffractometer (ﬁ ltered Cu
tion, Diffric Plus software package, proﬁ le analysis by