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Giant Complex Modulus Reduction of κ ‐Carrageenan Magnetic Gels
Author(s) -
Mitsumata Tetsu,
Nagata Akiyasu,
Sakai Kazuki,
Takimoto Junichi
Publication year - 2005
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200500405
Subject(s) - magnetization , materials science , barium ferrite , dynamic mechanical analysis , magnetism , nuclear magnetic resonance , modulus , elastic modulus , ferrite (magnet) , composite material , dynamic modulus , condensed matter physics , polymer , magnetic field , physics , quantum mechanics
Summary: Effects of magnetization on the complex modulus of κ ‐carrageenan magnetic gels have been investigated. The magnetic gel was made of a natural polymer, κ ‐carrageenan, and a ferromagnetic particle, barium ferrite. The complex modulus of the magnetic gel was investigated by dynamic viscoelastic measurements with a compressional strain. It was first observed that the magnetic gels showed giant storage modulus reduction ≈10 7 Pa before and after magnetization. The reduction was nearly independent of the frequency, and it increased with increasing the volume fraction of the ferrite. The maximum reduction in the storage modulus reached 14.9 MPa which corresponds to 76.5% of the modulus before magnetization. It was also found that the change in the modulus was nearly independent of a magnetization direction. Magnetism and morphology of the magnetic gels were also presented.Strain dependence of the storage modulus at 1 Hz for κ ‐carrageenan gel (□) and its magnetic gel before (○) and after (•) magnetization ( ϕ = 0.39). The geometry of magnetization and strain directions is perpendicular.