Chemistry Reference
In-Depth Information
1
s
bss
=
l
,
(2.21)
-
l
r
where s
l
is stress at loading moment, sl
r
is stress later definite time of relax-
ation proceeding.
FIGURE 2.10
The dependence of ratio
E
/
E
∞
on temperatures difference (
T
g
-
T
) for PC(1),
PAr (2) and HDPE (3). For HDPE the temperatures difference (
T
m
-
T
) was used [47].
Within the frameworks of the considered mechanisms of structural relax-
ation it was to be expected, that clusters size decrease at testing temperature
T
growth should be facilitate process, proceeding according to the mecha-
nism II and, consequently, the correlation between 1/b and clusters function-
ality
F
was expected (let us remind, that segments number per one cluster is
to be correct and the value 1/b extrapolates to one at
T
g
[49, 59], that is, at
clusters complete thermofluctuation decay [19].
Hence, the cluster model of polymers amorphous state structure allows
to identify structural relaxation mechanisms in them. In the case of glassy
loosely packed matrix relaxation process is realized by conformational reor-
ganizations in this structural component (mechanism I) and in the case of its
devitrification - clusters mutual motions (mechanism II).
