Handbook of Solvents - George Wypych - ChemTech - Ventech!

248 Valery Yu. Senichev, Vasiliy V. Tereshatov
Table 5.1.1. Modification of δ 2 j values during stages of computation
Polymer
j=1 j=2 j=3 j=4
δ 2j , (MJ/m 3 ) 1/2
polydiene urethane epoxide 17.64 17.88 17.78 17.8
polydiene urethane 17.72 18.17 17.93 17.82
poly(butylene glycol) urethane 19.32 18.89 18.95 18.95
poly(diethylene glycol adipate) urethane 19.42 19.44 19.44 -
where:
δ2 j value of δ2 at the given stage of computation
By sorting of all experimental points into a defined amount of intervals (for 30-50
points it is more convenient to take 5-6 intervals), it is possible to calculate δ2 for each interval
separately. The current average weighted value (contribution of δ2 is defined), obtained
for each interval, is proportional to the amount of points in the interval according to the following
formula:
k 1
δ = ∑ δ
M
m
2j 2k
k
k=
1
[5.1.17]
where:
k = 1,2,.... k, number of intervals
mk number of points in k-interval
M the total number of points
j stage of computation.
The shaping of subarrays of points is made in the following order, ensuring that casual
points are excluded: 1) account is made in a common array of points of δ2 and χS(RT/V1) i;2)
partition of a common array into a population
of subarrays of χS(RT/V1) in limits defined
for elimination of points not included
in intervals and points which do not influence
consequent stages of computation, 3)
reductions of intervals in each of the
subarrays (this stage may be repeated in
some cases).
At the each stage the sequential approximation
to constant value of χS(RT/V1) is produced in a separate form, permitting
one to take into account the maximum number
of points. The procedure gives a sequence
of values δ2 j as shown in Table
5.1.1.
In still other methods of evaluation, 22
Figure 5.1.2. Dependence of equilibrium swelling of
crosslinked elastomer of polyester urethane (1) and
polybutadiene nitrile rubber (2) on the volume fraction of
acetone in the toluene-acetone mixture. [Adapted, by per- the solvents are selected so that the solubilmission,
from V.V. Tereshatov, V.Yu. Senichev,
A.I. Gemuev, Vysokomol. soed., B32, 412 (1990)]
ity parameter of polymer occupies an inter-