Chemistry Reference
In-Depth Information
FIGURE 7.7
The dependence of fracture strain ef
f
on bromine-containing monomer contents
C
B
for B-PES (1) and hypothetical polymers, having
S
= 30.7 (2), 22 (3) and 18.7 Å
2
(4) [43].
Let us consider further the strength (fracture stress) sf
f
of copolymers B-
PES. The value sf
f
can be estimated theoretically according to the following
relationship [46]:
56
€
‚
M
MM
r
5
s
=× -
1, 4
1 0
1
e
, Pa,
(7.12)
„
…
f
†
‡
e
n
where r is polymer density,
M
e
is molecular weight of polymer chain part
between entanglement nodes,
M
is average number molecular weight of
polymer.
The value
M
e
ca
n
be determined from the Eqs. (1.4), (1.5) and (1.11)
combination. Since
M
>>
M
e
[42], then in the first approximation the mem-
M
ber
1
-
e
in the Eq. (7.12) can be neglected and the Eqs. (1.4), (1.5),
M
n
(1.11) and (7.12) gives (for high-molecular polymers):
5/6
φ
5
cl
s
=×
1, 4
1 0
, Pa,
(7.13)
f
2
N SC l
A
∞
0
Let us note, that the side groups influence on sf,
f
, in contrast to ef,
f
, has
unequivocal effect, namely, sf
f
reduction in virtue of simultaneous D growth
