Biomedical Engineering Reference
In-Depth Information
10
5
(a)
30
C
32
°
C
33
°
C
34
°
C
35
°
C
36
°
10
4
C
37
°
C
38
°
C
39
°
C
42
°
C
°
10
3
10
2
10
1
0.1
1
10
100
ω
(rad
s
-1
)
G
'
(b)
10
3
G
”
10
2
G
”
∞
ω
10
1
10
0
G
'
∞
ω
2
30
°
C
-
42
°
C
10
-1
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
ω
a
(
T
) (rad
s
-1
)
(a) Dynamic complex viscosity |
η
*(
ω
)| and (b) master curve for the shear moduli with frequency
-
temperature superposition for poly[F127] (EG56®). Adapted with permission from Pham Trong
et al.(
2008
) © 2008 Elsevier.
Figure 6.15
formation retards the diffusion process. For lifetimes shorter than T
d
, the reversible
network resembles a permanent network; in the data shown in
Figure 6.15
the number
of elastically active chains derived from the plateau value of the storage modulus
increases slightly with temperature (vertical shift factor). According to the Tanaka and
Edwards classi
cation, the physical gel formed by the hydrophobic associations is
de
nitely a non-permanent network.
Another well-known example of a thermogelling solution is methyl cellulose (MC)
(Haque and Morris,
1993
;Desbriereset al.,
1998
;Li,
2002
). In contrast to Pluronics
copolymers, where solutions and gels are completely transparent, indicating homogeneous
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