1070-4272/04/7703-0493C2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 3, 2004, pp. 493! 496. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 3,
2004, pp. 499! 502.
Original Russian Text Copyright + 2004 by Smirnov, Tubolkin, Britov, Nikolaev, Bogdanov.
AND POLYMERIC MATERIALS
Activating Mixing in Modification of Rubbers in Solution
B. L. Smirnov, A. E. Tubolkin, V. P. Britov, O. O. Nikolaev, and V. V. Bogdanov
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received February 4, 2003
Abstract-The applicability of the previously developed principles of activating mixing to modification of
rubbers in solutions was tested, and a process was developed for mechanochemical modification of cis-1,4-
polyisoprene in rotary pulsation apparatus.
Activating mixing can significantly intensify pro-
cesses involved in production of synthetic rubber.
Among such processes are distribution of catalyst
suspensions in the monomer and solvent prior to
polymerization, deactivation, stabilization, activation,
and washing. Activating mixing may be of particular
importance in chemical modification of rubbers in the
step of polymer preparation (these processes will be
considered below for modification of cis-1,4-polyiso-
prene as example).
Progress of studies on rubber modification allowed
development of commercial brands of modified cis-
1,4-polyisoprene (SKI-3-01 and DKI-3-OK rubbers).
Their production involves reactions with aromatic
C-nitroso compounds. Nitroso derivatives are widely
used as modifying agents, stabilizers, and promoters
of the interaction of rubber with carbon black in the
course of preparation of rubber stocks and vulcani-
zates. Among numerous C-nitroso amines and nitroso
compounds tested as modifying agents, much promise
is shown by p-nitrosodiphenylamine (PNDPA) owing
to a wide spectrum of its modifying effect and insig-
nificant contribution of side reactions to the molecular
structure of the final product.
The diphenylamine fragment, which can bind to the
polymeric chain via nitrogen atom, shows antioxidant
properties; therefore, PNDPA can act not only as
modifier, but also as stabilizer .
It is very interesting to prepare cis-oligoisoprene
with nitroso amine groups (SKI-3-NA) formed by
reactions of high-molecular-weight cis-1,4-polyiso-
prene (SKI-3) with nitroso compounds. The reaction
of cis-1,4-polyisoprene with PNDPA in solution in-
volves successive and parallel addition of the nitroso
compound dimer, cleavage of the resulting tetrahydro-
oxadiazole ring, and branching of the polymeric chain
with the participation of double bonds and groups
The use of SKI-3-NA in preparation of tire stocks
not only improves such propertiers of tires as heat and
ozone resistance but also considerably enhances the
fatigue resistance, stability in prolonged vulcanization,
and tear resistance-the parameters responsible for the
quality and service characteristics of large tires. Never-
theless, no high-capacity process for production of
SKI-3-NA have been developed up to now.
We noted recently  that rotary pulsation appara-
tus (RPA) show much promise in modification of
polymers using activating mixing. This fully concerns
the modification of SKI-3. The use of activating mix-
ing opens wide prospects for the process intensifica-
tion and improvement of the product quality.
The goals of this study are to analyze the possibili-
ties of modifying rubbers under conditions of activat-
ing mixing and to reveal qualitative and quantitative
correlations between the criteria of mechanochemical
transformations and criteria describing the external
mechanical field acting on a material.
We used the substances required for development
of a process for modification of isoprene rubber:
solutions of cis-1,4-polyisoprene in hexane of various
concentrations, solutions of p-nitrosodiphenylamine
sodium salt of various concentrations, phosphoric
acid (grades A, B), and other solvents (isopentane,
Modification of isoprene rubber was performed on
an installation schematically shown in Fig. 1.
The starting components for modification of iso-
prene rubber were prepared as follows. First, we pre-