Chemistry Reference
In-Depth Information
strains are typical for polymer materials in general and are due to intermo-
lecular bonds anharmonicity [46]. In Ref. [47], it has been shown that the
dependence
E
(
h
pl
) first part at
h
pl
≤500 nm is not connected with relaxation
processes and has a purely elastic origin. The elasticity modulus
E
on this
part changes in proportion to
h
pl
as:
=+
,
(30)
E
E
Bh
0
0
pl
where
E
0
is “initial” modulus, that is, modulus, extrapolated to
h
pl
=0, and
the coefficient
B
0
is a combination of the first and second kind elastic
constants. In the considered case
B
0
<0. Further Grüneisen parameter g
L
,
characterizing intermolecular bonds an harmonicity level, can be deter-
mined [47]:
B
E
11
1
0
0
,
(31)
g
≈− −
(
)
L
6 2
12
−
n
where n is Poisson ratio, accepted for elastomeric materials equal to ~
0.475 [36].
FIGURE 6.9
The dependence of reduced elasticity modulus
E
obtained in nano
indentation experiment on plastic strain
h
pl
for nanocomposites BSR/TC.
