1070-4272/04/7704-0633 C 2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 4, 2004, pp. 633!638. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 4, 2004,
Original Russian Text Copyright + 2004 by Britov, Bogdanov, Nikolaev, Tubolkin, Lebedeva.
AND POLYMERIC MATERIALS
Preparation of Compounds of Epoxy Resins
with Low-Molecular-Weight Carboxyl-containing
Rubbers by Activating Mixing
V. P. Britov, V. V. Bogdanov, O. O. Nikolaev,
A. E. Tubolkin, and T. M. Lebedeva
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received February 4, 2003
Abstract-A process was developed for preparing adhesives from a low-molecular-weight carboxyl-contain-
ing rubber and an epoxy resin with different oligomer ratios. The process involves the chemical reaction of
the components under conditions of activating mixing.
To develop a process for preparing and modifying
compounds under conditions of activating mixing, we
chose as objects to be studied epoxy oligomers (EOs)
and low-viscosity carboxyl-containing rubbers. This
choice was governed by the following facts.
(1) Mixing of epoxy oligomers and low-viscosity
carboxyl-containing rubber can initiate their chemical
(2) These materials have low viscosity, and, in this
case, it is especially difficult to provide the strain
energy density required to initiate a chemical reaction.
(3) Blends of epoxy polymers with rubbers are of
large practical interest as adhesives.
Epoxy oligomers exhibiting high adhesive power
are still important for practice, despite the development
of new types of adhesives. However, the properties of
the existing epoxy adhesives, in particular, their shock
resistance and elasticity, do not fully meet the re-
quirements of modern engineering. These characteris-
tics are improved by modifying EOs with liquid rub-
bers [13 4]. The modification process is based on the
high reactivity of carboxy group toward epoxy groups.
Modification of EOs with liquid rubbers is per-
formed by the following procedures: (1) addition of
a curing agent to a blend of EO with a rubber, pre-
pared by mechanical mixing; (2) copolymerization of
epoxy and rubber oligomers, which occurs simulta-
neously with curing of the epoxy resin at 120 or 150oC
(hot curing); (3) preliminary reaction (esterification)
between epoxy groups of the resin and carboxy groups
of the rubber, followed by curing of the resulting
copolymer at room temperature .
In preparation of compounds by the first procedure,
there is no chemical reaction of the rubber with the
epoxy matrix, which does not allow high mechanical
characteristics of the compound to be attained. How-
ever, prolonged heating enhances the cracking resis-
tance owing to changes in the phase interaction of the
In preparation of compounds by the second proce-
dure, important factors are the selectivity and activity
of the functional groups of the rubber, which are nec-
essary for formation of chemical bonds between the
Of particular interest is the third procedure for EO
modifcation. On mixing of epoxy and rubber oligo-
mers, followed by heating for 2 h at 150oC, a non-
catalytic reaction of the carboxy and epoxy groups
occurs to yield a hydroxy ester.
The other procedures ensuring the required proper-
ties of the materials are more difficult to perform in
practice because of the sophisticated equipment re-
quired and prolonged process.
Analysis of these methods from the process view-
point reveals the following contradiction: Mechanical
mixing is the simplest and the most convenient proce-
dure, but it does not ensure the required properties of
the compound because of the absence of a chemical re-
action between the components. Irrespective of a par-
ticular procedure of compound preparation, mixing is