Chemistry Reference
In-Depth Information
FIGURE 7.11
The dependences of fracture stress sf
f
on
K
st
value for sulfur-containing
epoxy polymers. 1 - calculation according to the Eq. (7.13); 2 - the experimental data [49].
Hence, the offered techniques of limiting mechanical characteristics
calculation allow stress and strain of fracture (strength and deformability)
estimation on the basis of two independent parameters only:
T
g
and
S
. Let
us remind, that value
T
g
is determined by the ratio of two molecular charac-
teristics [48]:
12
≈
, K.
S
T
147
(7.16)
g
C
∞
The value
T
g
can be estimated theoretically as well (for example ac-
cording to the group contributions method [52]). A cross-linked polymers
molecular characteristics change in curing process is necessary to account
for polymers with different cross-linking density (or
K
st
variation) at their
deformation-strength properties prediction.
Let us consider in the present chapter conclusion the fractal analysis of
amorphous glassy polyamide (phenylone) and particulate-filled nanocom-
posites on its basis fracture in compression tests. The experimental data
show that elastic bodies can be destroyed by brittle mode at compression.
In addition the fracture has often columnar character and body division on
vertical columns is formed by cracks, propagating in uniaxial compression
