1070-4272/05/7805-0765+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 5, 2005, pp. 765!768. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5,
2005, pp. 779!782.
Original Russian Text Copyright + 2005 by Zakharov, Berlin, Monakov.
Decrease in Content of Insoluble Fraction in cis-1,4-Polyisoprene
in Formation of Titanium Catalyst in Turbulent Flow
V. P. Zakharov, Al. Al. Berlin, and Yu. B. Monakov
Bashkir State University, Ufa, Bashkortostan, Russia
Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, Russia
Institute of Organic Chemistry, Ufa Scientific Center, Russian Academy of Sciences, Ufa,
Received October 14, 2004
Abstract-The effect caused by using a tubular prereactor of the diffuser3confuser design operating in the
turbulent flow mode on the content of the insoluble gel fraction in cis-1,4-polyisoprene obtained on a Ti/Al
catalyst is studied.
SKI-3 large-scale synthetic isoprene rubber is syn-
thesized on Ti/Al Ziegler!Natta catalysts on the basis
of the cis isomer and is used primarily in production
of tires, conveyer belts, and other industrial and
medical goods. Performance of goods manufactured
from cis-1,4-polyisoprene and their application areas
are controlled to a considerable extent by the molecu-
lar characteristics of the macrochains, particularly, by
the content of the insoluble fraction (gel fraction) in
the polymer, which may be as large as 20!30% .
Rubber stocks based on cis-1,4-polyisoprene with de-
creased insoluble fraction can be processed by mold-
ing, and SKI-3-based rubber stocks with low gel frac-
tion content demonstrate better adhesiveness and
lower shrinkage .
Muzhai et al.  suggested that formation of the
gel fraction in stereoregular polymerization of dienes
on Ziegler!Natta catalysts is initiated by secondary
cationic reactions involving the macrochain at the
solid surface of the heterogeneous catalyst. Most like-
ly, these reactions are intra- and intermolecular inter-
actions between the double bonds of the ready poly-
mer chain and also chain propagation. At the same
time, we have demonstrated previously that, in poly-
merization of isoprene on TiCl
, the use
of a tubular turbulent prereactor installed before the
bulk polymerizer with longer residence time affects
the catalyst particle size distribution, particularly,
reduces the particle size in the catalytically active
precipitate. Evidently, this alters the insoluble fraction
content in cis-1,4-polyisoprene, allowing development
of a procedure aimed at decreasing the gel fraction
content in isoprene rubber and improving performance
characteristics of the products.
Therefore, in this study we examined the effect of
the stereoregular polymerization procedure, namely,
of the formation of the TiCl
a turbulent flow provided by the use of a tubular tur-
bulent prereactor of the diffuser!confuser design on
the content of the insoluble fraction in cis-1,4-poly-
The experimental setup for isoprene polymerization
was described elsewhere . The starting reactants
were purified by standard methods accepted in stereo-
regular polymerization on Ziegler!Natta catalysts.
In the experiments we varied the process procedure,
the polymerization conditions remaining unchanged.
Method no. 1 simulated the traditional industrial
polymerization process. Separately prepared solutions
of the catalytic system [binary TiCl
ternary (modified) TiCl
(piperylene as a modifier was introduced in the cata-
lytic complex solution at the stage of its preliminary
keeping)] kept for 30 min at 273 K and of the mono-
mer were directly introduced into the apparatus (flask)
with gentle stirring.
Method no. 2. The preliminarily kept catalytic sys-
tem and the solvent were mixed in a tubular apparatus
operating in the turbulent flow mode. Then the cata-
lyst solution was fed to a stirred vessel. The monomer
was added with gentle stirring.
Method no. 3. Separately prepared solutions of
were mixed in the tubular
apparatus. The fast formation of the catalytically
active precipitate proceeded in a turbulent flow, fol-
lowed by keeping for 30 min with gentle stirring in
the vessel at 273 K. Finally, the monomer was added.