In situ SAXS studies of structural relaxation of an ordered block copolymer melt following cessation of uniaxial extensional flow

Erica M. McCready, Wesley Roth Burghardt*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

A hexagonally ordered styrene-ethylene-co-butylene-styrene triblock copolymer melt is studied during and immediately following uniaxial extensional flow using small-angle X-ray scattering. Strips of polymer melt are stretched between counter-rotating drums inside an oven designed for in situ synchrotron studies. Previous study of this sample demonstrated deformation and reorientation of PS microdomains and identified a critical Hencky strain ∼0.2 at which the structure is dramatically disrupted. To further probe microstructural dynamics, we study relaxation behavior of structure and stress in samples stretched in the melt to various Hencky strains. Upon cessation of stretching below the critical strain, structural relaxation is strongly retarded; stretching to higher strain leads to more rapid relaxation. At all strains, microdomain orientation relaxation following flow is slower than relaxation of flow-induced deformation and mechanical stress. The extension rate dependence of the samples response is also explored; higher rates result in faster relaxation of both stress and structure.

Original languageEnglish (US)
Pages (from-to)264-271
Number of pages8
JournalMacromolecules
Volume48
Issue number1
DOIs
StatePublished - Jan 13 2015

ASJC Scopus subject areas

  • Organic Chemistry
  • Materials Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry

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