Chemistry Reference
In-Depth Information
Williford [87] proposed, that the value
d
I
of multifractal corresponded to
its surface dimension (the first subfractal) - either sample surface or fracture
surface. For this supposition checking the authors of Ref. [73] calculate a
fracture surface fractal dimension for brittle (
duc
fr
d
br
fr
d
) and ductile (
) failure
types according to the equations [40]:
10(1 )
73
+
n
n
br
fr
d
=
(4.50)
-
and
2(1 4 )
12
+
n
n
.
(4.51)
d
duc
fr
=
+
duc
fr
d
In Fig. 4.20, comparison of the temperature dependences of
d
I
,
and
br
f
d
for PC is adduced. As one can see, at low
T
(
T
< 373 K) the value
d
I
corresponds to
br
fr
d
well enough and at higher temperatures (
T
> 383 K) it is
duc
fr
d
. In Fig. 4.20, the shaded region shows the temperature range
corresponding to the brittle-ductile transition for PC [73]. It is significant
that this interval beginning (
T
= 373 K) coincides with loosely packed ma-
trix devitrification temperature
T
'
g
, which is approximately 50 K lower than
polymer glass transition temperature
T
g
[18], for PC equal to ~423 K [88].
close to
FIGURE 4.20
Comparison of the temperature dependences of informational dimension
d
I
(1), fractal dimensions of fracture surface at brittle
fr
d
(3) failure for PC.
The temperature range of brittle-ductile transition is shown by shaded region [73].
br
fr
(2) and ductile
duc
d
