Fe-Al-Mg-MMH/钠质蒙脱土分散体系触变性研究

研究了Fe-Al-Mg型混合金属氢氧化物(简称MMH)/钠质蒙脱土(简称MT)分散体系的触变性,发现在不同MMH/MT质量比(R)条件下,分散体系可分别呈现正触变性和负触变性.在所研究的R范围(0～0.091)内,随R增大,体系的触变性发生正触变性-复合触变性-负触变性的转化.考察了高速剪切分散后,测定粘度变化前的静置时间(ts)和测定粘度时的剪切速率(DL)对触变性的影响.探讨了各种触变性产生的原因,提出了“分散粒子-空间连续网络结构-密实聚集体”和“分散粒子-密实聚集体-密实聚集体簇”机理,较合理地解释了观察到的复合触变现象.

Studies on the Thixotropy of Ferric Aluminum Magnesium Hydroxide/Montmorillonite Suspension

The study on the thixotropy of aqueous dispersion consisting of ferric aluminum magnesium Hydroxide(Fe Al Mg MMH) possessing permanent positive charges and Na montmorillonite(MT) possessing permanent nagative charges is reported. It was found that the suspension studied may display positive thixotropy, negative thixotropy or complex thixotropy depending on the Fe Al Mg MMH/MT mass ratio( R ). Two kinds of complex thixotropy were found, one is that the system may display a positive thixotropic character and negative thixotropic character successively, and the other is that the system may display a negative thixotropic character and positive thixotropic character successively. In the studied range of R (0-0.091), with increasing R , the thixotropy of the suspension changes from positive thixotropy through complex thixotropy and then to negative thixotropy. The effects of rest time( t s) after cessation of high intensity and the low shear rate( D L) used at measuring viscosity on the viscosity change for Fe Al Mg MMH/MT suspension were examined. It was found that the suspension which shows negative thixotropy at low D L may display complex thixotropy, first negative thixotropic character and then positive thixotropic character, at high D L. The system which is negative thixotropy at low t s may display complex thixotropy at high t s. The mechanism of the thixotropy is discussed, and the change process of "dispersed particles steric continuous network structures over the whole system densed floc units" and "dispersed particles densed floc units clusters of densed floc units" is proposed to explain the complex thixotropic phenomenon observed.