Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 5: New Materials
CPP 5.6: Vortrag
Montag, 25. Februar 2008, 11:30–11:45, C 230
Relaxation and cyclic deformation behaviour of multigraft copolymers — Ralf Schlegel1, •Roland Weidisch1, Ulrike Staudinger1, and Jimmy W. Mays2 — 1Institute of Materials Science and Technology (IMT), Friedrich-Schiller-University Jena, Löbdergraben 32, D-07743 Jena, Germany — 2Department of Chemistry, University of Tennessee, Knoxville, USA
Multigraft copolymers consisting of a polyisoprene (PI) backbone chain and several grafted polystyrene (PS) arms form microphase separated morphologies in which the hard phase (PS) is coupled directly by chemical bonds to the soft rubbery phase. As shown in recent work PI-PS multigraft copolymers exhibit higher strains at break as well as lower residual strains in comparison to commercial triblock thermoplastic elastomers [Zhu06]. In this study the materials have been characterized by cyclic deformation (hysteresis measurements) and relaxation tests. Stress strain curves of the materials have been characterized by applying models of rubber elasticity. It could be observed that the mechanical properties in relaxation and during the hysteresis are significantly influenced by the unctionality and the number of branch points β. In addition the morphology impacts the mechanical behaviour. At low PS-contents at about 16 - 19 wt.-% tetrafunctional multigraft copolymers exhibit a spherical morphology and the values for the modulus increase with β, whereas they decrease in multigrafts with a PS content of about 23 - 25 wt-% forming a cylindrical morphology.
[Zhu06] *Zhu, Y.; Burgaz, E.; Gido, S.P. Macromolecules, 2006, 39, 4428-4436