ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 7, pp. 1181!1185. + Pleiades Publishing, Inc., 2006.
Original Russian Text + E.A. Sergeeva, T.P. Safiullina, O.P. Shmakova, I.N. Bakirova, L.A. Zenitova, 2006, published in Zhurnal Prikladnoi Khimii, 2006,
Vol. 79, No. 7, pp. 1193!1197.
AND POLYMERIC MATERIALS
Structure of Castable Polyurethanes Filled
with Aluminum Oxide
E. A. Sergeeva, T. P. Safiullina, O. P. Shmakova,
I. N. Bakirova, and L. A. Zenitova
Kazan State Technological University, Kazan, Tatarstan, Russia
Nizhnekamsk Chemical Engineering Institute, Nizhnekamsk, Tatarstan, Russia
Received March 24, 2006
Abstract-The structure and properties of castable polyurethanes with different content of the aluminum
oxide filler were studied by X-ray diffraction, electron microscopy, and determination of the apparent
Previously  we developed SKU-OM castable
polyurethanes (PUs) with high content of aluminum
oxide (AO), filler which is a waste from petrochemi-
cal industry. The relative elongation and elasticity of
PUs do not decrease, and their elastic modulus and
especially hardness increase after introduction of AO,
unlike the use of conventional fillers. The increase in
the hardness with preservation of the strength suggests
that AO is a reinforcing filler for PUs.
To determine the mechanism of this influence of
AO filler on PUs, we studied the structure of PUs
filled with AO by X-ray diffraction and electron
microscopy and determined the apparent cross-link
density of PUs in a wide temperature range.
We studied monolithic SKU-OM castable PUs pre-
pared from oligoethylene glycol adipate (OEA) with
M ~ 2 010
and a mixture of 2,4- and 2,6-toluene
diisocyanate (TDI) taken in an 80 : 20 molar ratio
(OEA : TDI molar ratio 1.0 : 1.6) . Active AO with
the particle size of 5320 mm (substandard desiccant)
was used as the filler.
X-ray diffraction analysis of PUs was performed on
a DRON-2.0 automated diffractometer (CuK
tion with l = 1.54178 A) in the Bragg3Brentano sym-
metrical recording mode .
The morphology of the initial and filled PUs was
studied by high-resolution transmission electron mi-
croscopy using self-shadow-cast replicas. To deter-
mine the structural relief, the samples were etched in a
high-frequency electrodeless discharge plasma [4, 5].
The apparent cross-link density was determined by
the Clough3Gladding procedure on an axial compres-
sion relaxometer . 506-mm cylindrical samples
were tested in the range 253170oC. The apparent
cross-link density n
/V (mol m
) was calculated by
/V = A/RTS,
where A is the slope of the linear portion of the F vs.
dependence; F is the loading (N); h
is the initial sample height (m); h is the equilibrium
height of the deformed sample after a 15-s exposure
(m); R is the universal gas constant (8.314 Jmol
T is the temperature (K); and S is the initial cross-sec-
tion area of the sample (m
The X-ray pattern of PU is typical for an amorph-
ous polymer (Fig. 1, curve 1).
The interplanar spacing of the amorphous sample
(4.371 A) is not a characteristic value but lies in the
range typical for amorphous rubbers . In addition,
as we showed previously , PUs prepared at
NCO : OH > 1.6 do not crystallize.
As determined by X-ray analysis, two AO samples
differ not only in the water content but also in the
crystal structure (Fig. 2). This unexpected result is
caused by preparation of these desiccants and is