A Model of the Rheological Behavior

The linear viscoelastic behavior of the pure polymer and blends has already been described quantitatively by using models of molecular dynamics based on the reptation concept [12]. To describe the rheological behavior of the copolymers in this study, we have selected and extended the analytical approach of Be-nallal et al. [13], who describe the relaxation function G(t) of Hnear homopolymer melts as the sum of four independent relaxation processes [Eq. (1)]. Each term describes the relaxation domains extending from the lowest frequencies (Gc(t)) to the highest frequencies (Ghf( )), and is well defined for homopolymers in Ref [13]. 

Let us describe the different relaxation domains for the copolymers in the study  

For the copolymers these expressions will be the same as for the homopolymer. 

We have seen previously that the diblock and triblock copolymers do not exhibit reptation in the terminal domain. Therefore, the terminal relaxation process in Benallal s model has been modified in the case of diblock and triblock copolymers and their blends  

In this domain, the expression of the relaxation modulus is Eq. (11), which also leads to a distribution of relaxation times which is much broader than the spectrum of linear species. 

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