ELASTIC PROPERTIES - Fractal Mechanics of Polymers - page 42

FIGURE 3.3 The experimental (1 ÷ 4) and calculated according to the Eq. (3.10) (5 ¢ 8)
dependences of elasticity modulus E on sharp notch length a for HDPE at testing temperatures
293 (1.5), 313 (2.6), 333 (3.7) and 353 K (4.8) [13].

Let us note, that the exponent b t is a function of structure fractal dimen-
sion d f [22]:

1
d

. (3.12)

b =

t

f

Since j cl depends on strain rate (testing temporal scale) then the indi-
cated structural parameter is dependent on the time order parameter and for
it one can write [23]:

exp t

0

φφ t = -

f

,

(3.13)

cl cl

0

c φ is the value j cl at t f = 0 (the greatest attainable theoretically one),
t f is time up to fracture, t 0 is relaxation time.
In Fig. 3.4 , the comparison of experimental and calculated according to
the Eq. (3.13) values j cl and

where

0

c φ , respectively, is adduced, which shows their
good correspondence. This means, that at impact loading of HDPE with de-
vitrificated amorphous phase a its definite part mechanical vitrification oc-
curs, the fraction of which increases at testing temporal scale reduction [21].

T