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Thunga, M. ; Staudinger, U. ; Ganß, M. ; Weidisch, R. ; Knoll, K.
Influence of molecular weight on rheological properties of linear symmetric S-(S/B)-S triblock copolymers

Symmetric linear S-(S/B)-S triblock copolymers with 80 wt.-% of PS having a block composition of 20-60-20 and a S/B ratio of 70:30 in the middle block are studied with varying molecular weights. Increase in the molecular weights leads to a change in the morphology from disordered to ordered microphase separated structure, as characterised by TEM and SAXS. Two distinct glass transitions for PS- and PB-rich phases are observed from DMA measurements, which are due to phase separation at high molecular weights. Rheological studies (master curves) reveal an extended rubbery plateau and a delay in the terminal response with an increase in , whereas a terminal flow behaviour is observed for materials having a disordered nature at low molecular weights. A brittle-to-tough transition is observed from tensile tests with the increase in molecular weights.

Macromolecular Chemistry and Physics 210



Erschienen am
January 2009

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