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Schlegel, R. ; Wilkin, D. ; Duan, Y. ; Weidisch, R. ; Heinrich, G. ; Uhrig, D. ; Mays, J.W. ; Iatrou, H. ; Hadjichristidis, N.
Stress softening of multigraft copolymers

The hysteresis behaviour of multigraft (MG) copolymers, with a polyisoprene backbone and polystyrene (PS) side chains, was investigated by applying a modified softening model proposed by Elías-Zúñiga, which uses an approach of Ogden and Roxburgh. The model was combined with the non-affine tube model of rubber elasticity of Kaliske and Heinrich. Four parameters are obtained: chemical and physical cross-link moduli (Gc, Ge), the number of statistical segments between two successive entanglements (ne/Te) and a softening parameter (b). The model was proven to be valid by a comparison with other methods evaluating hysteresis behaviour. The characterization of the multigraft copolymers revealed a branch point and molecular architecture dependence of the softening parameter. b was low for tetrafunctional MG copolymers with cylindrical microdomains, and it was further reduced for a spherical morphology and for more complex molecular architectures. The magnitude of b also depends on the PS arm molecular weight for hexa- and tetrafunctional multigraft copolymers.

Source
Polymer 50

Pages
6297-6304

DOI
http://dx.doi.org/10.1016/j.polymer.2009.10.026

Published
December 2009
 
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