Chemistry Reference
In-Depth Information
The MWD of cis-1,4-polyisoprene obtained under the aforementioned
experimental conditions, q
w
(M), were considered through the equation
q
w
(M)=
)=∫
∞
0
Y(b)Mb
2
exp(-Mb)db
where β is the probability of chain termination and ψ(β) is the distribution
of active site over kinetic heterogeneity, M is current molecular weight.
As was shown previously [9] Eq. (1) is reduced to the Fredholm inte-
gral equation of the first kind, which yields function ψ(β) after solution
via the Tikhonov regularization method. This inverse problem was solved
on the basis of an algorithm from [9]. As a result, the function of the dis-
tribution over kinetic heterogeneity in ψ(lnβ)-lnM
coordinates with each
maximum related to the functioning of AC of one type was obtained.
3.3 RESULTS
After mixing of the components of the titanium catalyst, depending on its
formation conditions, particles 4.5 μm to 30 nm in diameter, which are
separated into three arbitrary fractions, are formed (Table 3.1).
During the formation of catalyst C-1 via method 1, the fraction com-
posed of relatively coarse particles, fraction I constitutes up to 85% (Fig.
3.1). In method 2, the hydrodynamic action on the titanium catalyst formed
under similar conditions results in an increase in the content of fraction II.
Analogous trends are typical of catalyst C-2. The catalyst modification
with piperylene additives, catalyst C-3, is accompanied by the disappear-
ance of fraction I and an increase in the content of fraction II (Fig. 3.1),
as was found during the hydrodynamic action on C-1. The hydrodynamic
action on a two-component catalyst is equivalent to the addition of piper-
ylene to the catalytic system. The preparation of catalytic complex C-3 via
method 2 results in narrowing of the particle size distribution of fraction
II owing to disintegration of particles 0.50-0.85 μm in diameter (Fig. 3.1).
The reduction of the catalyst exposure temperature to −10°С (catalyst C-4)
is accompanied by further disintegration of fraction II (Fig. 3.1
)
. In this
case the content of particles 0.19-0.50 μm in diameter decreases to 22%
with predominance of particles 0.15-0.18 μm in diameter. The formation
of C-4 via method 2 results in additional dispersion of particles of fraction
II, with the content of particles 0.15-0.18 μm in diameter attaining 95%.
