Chemistry Reference
In-Depth Information
swelling measurements obtained on unfilled and filled PDMS elastomers
to estimate the degree of adhesion between elastomer and filler parti-
cles.
117-119
The results differ greatly from those for nonadhering fillers, in-
dicating good bonding between the two phases. Resistance to separation
from the surface in such swelling tests does not contradict the chains
having considerable mobility
along
the surface.
In situ-generated silica fillers improve creep resistance and compress-
ion set in cyclic deformation.
120
The filled samples show very little com-
pression set (figure 9.7). Thermal stability also improves as reflected by
higher decomposition temperatures. (figure 9.8)
121
A possible mechanism
3.0
12.4%
2.5
2.0
19.4%
1.5
1.0
0%
0.5
0.0
0
20
40
60
80
Time, hours
Figure 9.7:
Effect of cyclic stress on unfilled PDMS and PDMS elastomers filled with in situ precipi-
tated silica: (∆) unfilled, (⚫) 12.0 wt % silica, (O) 19.4 wt % silica.
120
100
80
Comm-AE
60
40
A
Comm-MO
20
U
0
100
200
300
400
500
600
700
800
T (
C)
Figure 9.8:
Comparison of thermogravometric plots for PDMS networks that were unfilled (U), or
contained either in situ precipitated silica (A) or commercial fume silica (COMM-MO and
COMM-AE).
121
The heating was under nitrogen.
