Chemistry Reference
In-Depth Information
80
Brittle
60
Tough
Elastometric
40
20
0
0.8
1.0
1.2
1.4
R/Si
Figure 9.13:
The hardness of a silica-PDMS composite as a function of the molar ratio of alkyl groups
to silicon atoms.
397
Reproduced by permission of Springer Verlag.
10
500
8
400
6
300
200
4
a
100
2
b
40
0
0
0
10
20
30
Wt % PDMS
Figure 9.14:
Dependence of two estimates on the impact strength on the amount of PDMS in PDMS-
modified SiO
2
glasses.
403
The impact strengths were obtained from: (a) the Charpy pendu-
lum impact test and (b) the falling-weight impact test.
glasses with PDMS contents ranging from 0 to 65 wt %. Only samples
with relatively high ceramic content were sufficiently brittle to be studied
in this manner. The larger the amount of PDMS used, the higher the
impact strength.
For PDMS-modified SiO
2
glasses, structural analysis shows that this
hybrid material exhibits localized phase separation of the PDMS compo-
nent, even though OH-terminated PDMS can be successfully incorpo-
rated into the SiO
2
network by chemical bonding. The PDMS component
