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t
Figure 1.20 Relaxation after a step shear strain y0 [21 ]
O
Shear stress relaxation modulus G(t) (Figure 1.20 and Figure 1.21):
(1.54)
Dependence of storage modulus G' and loss modulus G" on frequency (Figure 1.22)
with sinusoidal shear strain y.
Sinusoidal and out-of-phase shear stress V.
where
l 9(*,s-?-r)
t
Figure 1.19 Retardation from steady shear flow [21] (shear stress T= Oat time f = 0)
7
x
Y = amplitude of shear
CO = angular frequency
t
(1.55)
(1.56)
The storage modulus G'{(0) characterizes the elastic behavior, whereas the loss modulus
G" depicts the viscous behavior of the melt subjected to periodic shear deformation.
X