Rheology of schizophyllan solutions in isotropic and anisotropic phase regions

Yapeng Fang, Makoto Takemasa, Keiko Katsuta, Katsuyoshi Nishinari

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

In this paper, we discuss the rheological properties of aqueous solutions of a rigid triple-helical polysaccharide, schizophyllan (SPG), in isotropic, biphasic, and fully anisotropic phases. Both steady shear and dynamic rheological behaviors reveal remarkable changes when SPG solutions pass through the three phases. The steady shear flow exhibits shear thickening at low shear rates for anisotropic SPG liquid crystalline samples, which is attributed to the shear-induced cholesteric to nematic transformation. The first normal stress difference and transient rheological experiments demonstrate that director tumbling is absent or negligible in SPG liquid crystals in the range of examined shear rates. Additionally, the stress relaxation of SPG liquid crystals after flow cessation shows an inverse relation between the relaxation time and preshear rate, as expected by Larson and Mead's theory [Larson and Mead (1989)]. Small amplitude oscillation measurements following flow cessation show decreasing complex modulus with time for SPG liquid crystals, which is probably related to an increase of molecular orientation after flow cessation. The evolutions of complex modulus after flow cessation are discussed in terms of chain persistence length.

Original languageEnglish
Pages (from-to)1147-1166
Number of pages20
JournalJournal of Rheology
Volume48
Issue number5
DOIs
Publication statusPublished - 2004 Sep
Externally publishedYes

ASJC Scopus subject areas

  • Mechanics of Materials
  • Computational Mechanics
  • Physics and Astronomy(all)

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