Chemistry Reference
In-Depth Information
FIGURE 5.2
The optical microphotographs, showing ZD evolution in PASF film, received
from solution in chloroform, at sample strain growth Enlargement 18´ [23].
Lately the large attention is given to macromolecular entanglements
fluctuation network influence on crazes formation process in polymers [20].
Much less is known about entanglements network influence on shear defor-
mation zones (ZD) formation processes, which by their essence are crazes,
without microvoids. The authors of Ref. [21] fulfilled quantitative estima-
tion of such influence on deformation processes in ZD on the example of
polyarylatesulfone (PASF) samples in the form of films with a sharp notch.
In this analysis two models of macromolecular entanglements network were
used: of binary hooking's [20] and cluster ones [22]. The PASF films were
prepared with the aid of nine various solvents that allows their structure
wide enough variation [21].
In Fig. 5.2, ZD evolution at sample strain increase for PASF film, pre-
microphotographs of ZD surfaces and elastically deformed part of sample
(Figs. 5.3a and 5.3b, respectively) are adduced. As it follows from the com-
parison of Figs. 5.3a and 5.3b, in ZD considerable drawing of polymer is
observed - globules as if “floating” in the deformed material. The draw ratio
in ZD l
ZD
can be determined as follows [24]:
r
r
+
d
p
l
=+
1
ln
,
(5.6)
ZD
-
d
p
