Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 7, pp. 1333−1335.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
A.A. Tarasenko, A.V. Gribanov, I.P. Dobrovol’skaya, Yu.N. Sazanov, V.A. Lysenko, 2010, published in Zhurnal Prikladnoi Khimii,
2010, Vol. 83, No. 7, pp. 1225−1227.
Speciﬁ c Features of Processes in Carbonization of Fibers Based
A. A. Tarasenko
, A. V. Gribanov
, I. P. Dobrovol’skaya
Yu. N. Sazanov
, and V. A. Lysenko
St. Petersburg State University of Technology and Design, St. Petersburg, Russia
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Received March 24, 2010
Abstract—Speciﬁ c morphological changes in polypyromellitimide ﬁ bers in carbonization at temperatures of up
to 900°C are considered.
It was noted in early studies [1–3] concerned with
the thermal stability of a ﬁ ber-forming polymer,
polyacrilonitrile (PAN), that the nitrogen atom
plays a key role in the formation of both the starting
polymer and its cyclic precursor used to produce
carbon ﬁ bers. Another class of nitrogen-containing
polymers on which the role of nitrogen atoms in the
formation of carbonized structures can be traced are
polyheteroarylenes. Typical representatives of this
class of polycondensation polymers are polyimides
and, in particular, polypyromellitimide (PPMI), known
in the industry as a unique highly heat-resistant and
solid material (polyimide PM, PIPM, arimide ﬁ ber
VM, Kapton, and other trade names).
In a number of communications mostly devoted
to the heat resistance of PPMI, data were reported
on changes of service characteristics of polyimide
materials subjected to high-temperature treatment until
both carbonization and graphitization.
Since the publication of the ﬁ rst profound monograph
about polyimides , studies of these polymers and
primarily of their thermal properties and behavior in
a wide temperature range have been extensively reported.
A close attention was given to the thermooxidative
destruction of technical-grade polyimides in the
monograph . Thermal characteristics of more than 100
polyimides with different structures were determined
and considered in . In the later monographs [7–12],
numerous examples of how polyimides can be used
in practice were presented, with the unique ability
of polyimide materials and articles to operate under
thermally extreme conditions invariably emphasized.
These and other studies of the 1980s–1990s not only
recorded certain characteristics of thermal resistance and
thermal stability of polyimides, but also paid attention
to the possibility of their carbonization. One of the ﬁ rst
indications that polyimides undergo thermochemical
transformations to give carbon structures was provided
by determining the coke number (carbonized residue)
upon thermal treatment of these polymers at temperatures
higher than 600°C [13–16].
As regards PPMI structures in which nitrogen is
directly incorporated, this is, in the ﬁ rst place, a ﬁ ve-
membered imide ring coupled, on one side, with the
benzene ring of pyromellitic acid, and on the other, with
the diamine moiety of PPMI via a N–C bond. It should
be noted that the nitrogen atom is of key importance in
the course of the two-stage synthesis of polyimide from
the starting materials and the initiating role of nitrogen
begins from the ﬁ rst stages of synthesis of this polymer.
As also in the case of PAN, the nitrogen atom executes
in the ﬁ rst, low-temperature stage of formation of
a heat-resistant polymer a structural function by creating
a nitrogen-containing pyromellitic heteroring. From the