ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 6, pp. 1010!1014. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + G.N. Gubanova, A.I. Grigor
ev, Yu.N. Sazanov, A.V. Novoselova, A.V. Gribanov, G.N. Fedorova, A.A. Kutin,
T.E. Sukhanova, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 6, pp. 971!975.
AND POLYMERIC MATERIALS
Cyclization and Carbonization of Anionic Polyacrylonitrile
in the Presence of Carbon Nanofibers
G. N. Gubanova, A. I. Grigor
ev, Yu. N. Sazanov, A. V. Novoselova,
A. V. Gribanov, G. N. Fedorova, A. A. Kutin, and T. E. Sukhanova
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Received April 3, 2008
Abstract-Composites based on anionic polyacrylonitrile and carbon nanofibers were studied by X-ray
diffraction, differential scanning calorimetry, thermal gravimetric analysis, and electron microscopy.
The effect of carbon nanofibers on the specific features of cyclization and carbonization of anionic
polyacrylonitrile at temperatures of to 550oC was studied.
Studying the cyclization and carbonization of
polyacrylonitrile (PAN) in the presence of various
modifiers and fillers is a topical task, because PAN-
based composites and their carbonization products
are widely used in many fields of engineering and
industry [1, 2].
It is known that PAN carbonizates and PAN-
based composites occupy a leading place among
polymeric carbon materials because of the high car-
bon residue, reaching 60% . In the initial step
of carbonization of PAN and its composites in
the temperature range 4003550oC, the major path-
way of thermal transformations is cyclization. It
is accompanied by a large heat release, frequently
leading to the polymer degradation and carbon loss.
The magnitude of the exothermic effect and the cy-
clization temperature can be decreased by using
PAN copolymers or by introducing various modify-
ing additives [4, 5].
Studies of the mechanisms of cyclization and
carbonization of PAN are performed with polymer
samples synthesized by both radical and anionic
polymerization [6, 7]. It was shown in  by thermal
analysis, IR spectroscopy, and mass spectrometry
that PAN synthesized on anionic initiators (a-PAN)
is a convenient model for studying the initial step
of carbonization, as it does not contain residual
amounts of the catalyst, oxidants, and other com-
ponents present in PAN prepared by radical poly-
merization. Previous studies of a-PAN in the tem-
perature range 203300oC have shown the absence
of impurities and volatile low-molecular-weight cy-
clization products .
Carbon nanoadditives (nanofibers, carbon nano-
tubes, fullerenes, shungite, etc.) find growing use
for modification of polymeric materials. These
additives have high specific surface area and exhibit
unique mechanical and conducting properties.
Introduction of carbon nanoadditives into polymers
can improve their physicomechanical characteris-
tics, enhance the heat resistance, and raise the car-
bon residue .
The goal of this study was to examine in more
detail specific features of the cyclization and carbo-
nization of composites of anionic polyacrylonitrile
with carbon nanofibers.
As object of study we used powdered a-PAN
synthesized with anionic catalysts by the proce-
dure described in . For thermochemical tests
we took samples with a molecular weight M
~20000. For the modification of a-PAN, we used
carbon nanofibers (CNFs) prepared by pyrolysis
of methane, using NiO as catalyst .
posites of a-PAN with CNFs were prepared by
Carbon nanofibers were prepared at a laboratory of
Tambov State Technical University.