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CPP: Chemische Physik und Polymerphysik
CPP 11: POSTER Disperse Polymer Systems
CPP 11.32: Poster
Tuesday, March 28, 2006, 17:00–19:00, P3
Influence of molecular weight on rheological properties of linear symmetric S-(S/B)-S triblock copolymers — •Mahendra Thunga1, Ulrike Staudinger1,2, Bhabani K. Satapathy1,2, Roland Weidisch1,2, and Konrad Knoll3 — 1Leibniz Institute of Polymer Research, Hohe Str. 6, 01069 Dresden, Germany — 2Institute of Materials Science and Technology, Friedrich-Schiller-University Jena, Löbdergraben 32, 07743 Jena, Germany — 33BASF AG, D-67056 Ludwigshafen, Germany
The influence of molecular weight on morphology, rheology and mechanical properties of a symmetric linear S-S/B-S type triblock copolymer has been studied. The morphology reveals that the size of dispersed PS (hard) phase is narrowed down with the increase in molecular weight from 110 to 156 kg/mol. On further increasing the molecular weight to 200 kg/mol phase separation is observed with the formation of lamellar morphology. The rheological studies reveal that storage modulus and complex viscosity are strongly influenced by their relative molecular weights. An increase in molecular weight leads to an extended rubbery plateau and the terminal region is narrowed down. A transition from Newtonian to non-Newtonian flow in the low frequency regime could be observed with the increase in molecular weight along with an increase in the order-disorder transition temperature. DMA and DSC measurements reveal that the increase in the molecular weight from 165 to 200 kg/mol has lead to two distinct transition points for PS rich phase and PB rich phase due to the macrophase separation.