Structure and dynamic viscoelastic properties of acylated chitosans in the melt state

Zhengang Zong, Hideki Yamane, Masaoki Takahashi, Rika Hayashi, Yoshiharu Kimura, Daisuke Tatsumi, Takayoshi Matsumoto

研究成果: Contribution to journalArticle

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Rheological properties of acylated chitosans with various acyl lengths were measured in the melt state. The acylated chitosans have two rheological transitions corresponding to rather abrupt decreases in viscoelastic functions and an abrupt drop in the height of plateau of the storage modulus. These transition temperatures become lower with increasing length of side chains. The time-temperature superposition principle was applied to dynamic viscoelastic functions for acylated chitosans. The time-temperature superposition fails for acylated chitosans with shorter acyl length. However, for an acylated chitosan with the longest acyl length, the viscoelastic data can be superposed into three separated master curves in different temperature ranges. Wide-angle X-ray diffraction measurements indicate that acylated chitosans have a layered structure. Temperature dependencies of d-spacing attributable to this layered structure indicate two transitions, whose temperatures reasonably correspond to those of the rheological transitions, exist. When the temperature exceeds the lower transition temperature, the d-spacing increases with increasing temperature, and the transition temperatures decrease with increasing length of side chains. The decreases of dynamic viscoelastic functions are associated with the layer spacing changes. It is suggested that the abrupt decrease of the plateau height is caused by the interchain movement of molecules or reorganization of the structure.

元の言語英語
ページ(範囲)41-46
ページ数6
ジャーナルNihon Reoroji Gakkaishi
28
発行部数1
DOI
出版物ステータス出版済み - 2000
外部発表Yes

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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