Chemistry Reference
In-Depth Information
temperature. To discuss the temperature dependence of
crit.
and
n
, it is necessary
to estimate the exact values of
crit.
and
n
. Figure26 shows the tan at different
versus plots for the CB-24-2/Varnish-1 suspensions at different temperatures.
From the -independent tan point,
crit.
and
n
values can be determined. The
crit.
(c
gel
) value is 0.131 (22.0 wt%), 0.118 (20.1wt%), 0.106 (18.2%), and 0.086
(15.0wt%) at 30C, 40C, 50C, and 60C, respectively. The corresponding
critical relaxation exponent
n
was
n
=0.71, 0.76, 0.80, and 0.83 at 30C, 40C,
50C, and 60C, respectively. The critical gel concentration shifts to low and the
corresponding tan values became large with elevating temperature. Figure 27
shows temperature dependence of the critical exponent
n
for four kinds of
CB/Varnish-1 suspensions. The critical exponent
n
increased with elevating
temperature, irrespective of CB species.
Figure 26. Plots of tan against CB volume fraction for the CB-24-2 suspensions at
various angular frequencies (0.1, 0.398, 1, 3.98, 10, 39.8 and 100 rad s
1
). (a) 30C, (b)
40C, (c) 50C, and (d) 60C.
crit.
is the critical gel concentration [31].
