Chemistry Reference
In-Depth Information
a
b
LCE2
ac
relaxation
20
3.0
5CB
ac
relaxation
15
N
PN
2.5
N
I
LCE1
ac
relaxation
10
5
2.0
307
308
309
-10
0
10
T
(K)
T
-
T
PN-N
(K)
Fig. 5
C
p
(
T
) and
C
p,eff
(
T
) profiles for the I-N transition of a pure 5CB liquid crystal (a) and
corresponding profiles for the PN-N transition of two liquid-crystalline elastomers, one with
below-critical (LCE1) and one with supercritical (LCE2) behaviour (b). Note that the data sets
in (b) have been shifted along the
y
-axis for clarity. The data are plotted versus
T
-
T
PN-N
for a direct
comparison.
T
PN-N
denotes the phase-transition temperature obtained from the
C
p
data
C
P
(
T
)
1
st
order transition line
Widom line
Critical point
S
(
T
)
G
Fig. 6
T
-
G
(temperature-field) phase diagram for a system that exhibits first-order transitions
(
solid line
) that are terminated at a single critical point of the water-vapour type. The supercritical
evolution emanates further from the critical point along a Widom line (
dashed line
). The heat-
capacity
C
p
and order-parameter
S
temperature profiles corresponding to different
G
values are
shown in the graph. The
dotted lines
represent the discontinuity in the
C
p
(
T
) and
S
(
T
) profiles,
corresponding to the phase-coexistence region in which the latent heat is released
Search WWH ::
Custom Search