ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 8, pp. 1312!1315. + Pleiades Publishing, Inc., 2006.
Original Russian Text + I.P. Dobrovol’skaya, M.V. Mokeev, Yu.N. Sazanov, A.V. Gribanov, T.E. Sukhanova, 2006, published in Zhurnal Prikladnoi
Khimii, 2006, Vol. 79, No. 8, pp. 1326 !1329.
AND POLYMERIC MATERIALS
Variation of Supramolecular Structure of Heat-Resistant
Polyimide Films during Thermal Treatment
I. P. Dobrovol’skaya, M. V. Mokeev, Yu. N. Sazanov,
A. V. Gribanov, and T. E. Sukhanova
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Received April 21, 2006
Abstract-Variation of the supramolecular structure of heat-resistant polyimide films in the course of high-
temperature treatment was studied by X-ray diffraction analysis and NMR spectroscopy in solids.
A wide range of practical applications of polyimide
(PI) films in various branches of industry arouses un-
remitting scientific interest in carbonization of poly-
imides. It was shown  that high-temperature treat-
ment of polyimides yields crosslinked carbo- and het-
erocyclic structures. These chemical transformations of
macromolecules favor formation of structures having
a series of new characteristics and also leads to a high
carbon residue in carbonization (up to 50370%). Sub-
sequent publications have shown  that the char-
acteristics of carbonized polyimides depend on the
chemical structure of the initial polymer, its supra-
molecular structure, conditions of thermal treatment,
and other process parameters. A study of variations
of the supramolecular structure of polyimide films in
the course of their thermal treatment can give addi-
tional data both on thermochemical processes and on
expected properties of composite materials based on
In this study, we examined variations of the supra-
molecular structure of heat-resistant films based on
polyimide PM during thermal treatment and the in-
fluence of the chemical structure of the polyimide on
the type of these variations.
The PI PM films were prepared from a solution of
polyacrylic acid (PAA), with the subsequent thermal
imidization. The film thickness was 20 mm. Pyrolysis
was performed in the dynamic mode in an inert medi-
um; the heating rate was 20 deg min
The studies by scanning electron microscopy were
performed on a Tesla BS-350 electron microscope;
X-ray diffraction measurements, on a DRON-1.5 and
KRM devices (Kratky collimation; Cu
C NMR spectra in solids were recorded at room
temperature on a Bruker CXP-100 spectrometer using
the magic angle spinning (MAS) and cross-polariza-
tion (CP) techniques.
The pyrolysis kinetics of the PI PM films was
studied at 500oC and keeping time of 1 and 6 h.
The large-angle X-ray diffraction patterns of
the initial PI PM films and films pyrolyzed at various
temperatures are shown in Fig. 1. The broadening of
Fig. 1. Large-angle X-ray diffraction patterns of PI PM
films: (1) initial and (236) pyrolyzed at various tempera-
tures. Heat treatment temperature, oC: (2) 500, (3) 550,
(4) 600, (5) 750, and (6) 850. (I) Intensity and (2q) angle.