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化学学报
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化学学报 ›› 2006, Vol. 64 ›› Issue (15): 1543-1547. 上一篇    下一篇

研究论文

低固相含量SiO2分散体系流变性研究

伍秋美*, 阮建明, 黄伯云, 周忠诚, 邹俭鹏   

  1. (中南大学粉末冶金国家重点实验室 长沙 410083)
  • 投稿日期:2005-11-04 修回日期:2006-03-16 发布日期:2006-08-14
  • 通讯作者: 伍秋美

Study on the Rheological Behavior of SiO2 Dispersions with Low Volume Fraction

WU Qiu-Mei*, RUAN Jian-Ming, HUANG Bai-Yun, ZHOU Zhong-Cheng, ZOU Jian-Peng   

  1. WU Qiu-Mei*, RUAN Jian-Ming, HUANG Bai-Yun, ZHOU Zhong-Cheng, ZOU Jian-Peng
  • Received:2005-11-04 Revised:2006-03-16 Published:2006-08-14
  • Contact: WU Qiu-Mei

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以甘油(GL)和聚乙二醇(PEG)为分散介质, 研究了低体积分数(Φ＜8%)的SiO2分散体系的稳态和动态的流变性能, 发现体系都具有可逆的剪切变稀和剪切增稠现象. 在剪切速率大于临界剪切速率(γ.＞γ.c)时, 体系具有明显的剪切增稠现象, 而当γ.＜γ.c, GL体系只有轻微的剪切变稀现象, PEG体系剪切变稀现象却很明显. 在动态试验中考察了模量以及损耗角正切tg δ随剪切应力(σ)的变化. 在所研究的应力范围内, 体系中耗能模量G"都大于储能模量G', tg δ大于1, 体系主要表现为粘性. 用“粒子簇”生成机理能较好地解释这种剪切变稀和剪切增稠现象, 即剪切变稀是由于连续的空间网络结构被破坏, PEG体系剪切变稀现象较GL体系明显应该与PEG高分子链的松弛以及体系中较少的氢键有关; 剪切增稠是由于粒子簇的生成引起的.

关键词: SiO2分散体系, 流变性, 剪切增稠, 机理

The rheological behavior of fumed silica dispersions in glycerol (GL) and polyethylene glycol (PEG) have been studied under steady and oscillation shear. The reversible shear-thinning and shear-thickening behaviors have been observed. The two dispersions all show obvious shear-thickening when the shear rate is higher than the critical rate (γ.＞γ.c), but when γ.＜γ.c, the GL system only shows slightly shear-thinning behavior, while the PEG system shows shear-thinning comparatively more obviously. The storage modulus G', loss modulus G" and tg δ have also been studied through oscillation stress shear. The magnitude of G" is larger than that of G' and tg δ＞1 for both of the systems in the range of stress studied, which shows that the systems mainly possess the viscous properties. Through “clustering” theory, the shear-thinning and the shear-thickening behaviors can be explained. The shear-thinning is due to the breakage of the steric continuous network structure and that the degree of the shear-thinning of the PEG system is larger than the GL system is due to the less number of the hydrogen bonds and the laxation of the PEG chains; the shear-thickening is caused by the formation of the clusters.

Key words: silica dispersion, rheological property, shear-thickening, mechanism