Giant Reduction in Dynamic Modulus of -Carrageenan Magnetic Gels
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- 作者：Tetsu Mitsumata ; Kazuki Sakai ; Jun-ichi Takimoto
- 刊名：Journal of Physical Chemistry B
- 出版年：2006
- 出版时间：October 19, 2006
- 年：2006
- 卷：110
- 期：41
- 页码：20217 - 20223
- 全文大小：291K
- 年卷期：v.110,no.41(October 19, 2006)
- ISSN：1520-5207
文摘
Effects of magnetization on the complex modulus of 
-carrageenan magnetic gels have been investigated.The magnetic gel was made of a natural polymer, -carrageenan, and a ferrimagnetic particle, barium ferrite.The complex modulus was measured before and after magnetization of the gel by dynamic viscoelasticmeasurements with a compressional strain. The gels showed a giant reduction in the storage modulus of~107 Pa and also in the loss modulus of ~106 Pa due to magnetization. The reduction increased with increasingvolume fraction of ferrite, and it was nearly independent of the frequency. It was also found that the changein the modulus was nearly independent of the magnetization direction and irradiation time of the magneticfields to the gel. The magnetic gels demonstrating the giant reduction in the dynamic modulus showed alarge nonlinear viscoelastic response. It was observed that the magnetic gel was deformed slightly due tomagnetization. The observed giant complex modulus reduction could be attributed to the nonlinearviscoelasticity and deformation caused by magnetization. Magnetism, nonlinear viscoelasticity, and effectsof magnetization on the morphological and shape changes were discussed.
-carrageenan magnetic gels have been investigated.The magnetic gel was made of a natural polymer, -carrageenan, and a ferrimagnetic particle, barium ferrite.The complex modulus was measured before and after magnetization of the gel by dynamic viscoelasticmeasurements with a compressional strain. The gels showed a giant reduction in the storage modulus of~107 Pa and also in the loss modulus of ~106 Pa due to magnetization. The reduction increased with increasingvolume fraction of ferrite, and it was nearly independent of the frequency. It was also found that the changein the modulus was nearly independent of the magnetization direction and irradiation time of the magneticfields to the gel. The magnetic gels demonstrating the giant reduction in the dynamic modulus showed alarge nonlinear viscoelastic response. It was observed that the magnetic gel was deformed slightly due tomagnetization. The observed giant complex modulus reduction could be attributed to the nonlinearviscoelasticity and deformation caused by magnetization. Magnetism, nonlinear viscoelasticity, and effectsof magnetization on the morphological and shape changes were discussed.