带相反电荷胶体颗粒混和悬浮体的流变学性能

研究了带相反电荷的粘土颗粒和MMH(铝、镁混合金属氢氧化物)颗粒形成的混和悬浮体的流变学性能,考察了盐对混合体系流变学性能的影响.结果表明,当粘土质量分数为1%时,悬浮体为牛顿型流体;当质量分数升至2%时,悬浮体表现出固体的弹性响应;特定粘土含量的悬浮体中,随着MMH量的增加,混合体系的屈服值和弹性模量亦增加,表明凝胶结构增强.向混合体系中加入NaCl,弹性模量、屈服值和粘度等流变参数均降低.与单组分粘土悬浮体或MMH悬浮体相比,双组分混合体系的结构恢复很快.

Rheological Properties of Mixed Suspensions Containing Oppositely Charged Colloidal Particles

The rheological properties of single-component clay dispersions and clay/MMH mixed dispersions containing oppositely charged colloidal particles have been investigated. As the clay concentration is increased, the clay suspensions develop from the newtonian form of flow behavior to a yielding type of response. At w(clay) is between 2%-4%, upon addition of MMH to clay dispersions, the magnitude of yield value and storage modulus increase monotonically, indicating enhanced gel strength. Adding NaCl to clay/MMH mixed suspensions causes the decrease of storage modulus, yield values and apparent viscosities. In the structural recovery measurements, the time dependence of viscoelastic properties of clay/MMH mixed dispersions shows only very small variations of the storage moduli over 3 h, in contrast to unusual thixotropic properties of aqueous single-component dispersions of laponite or MMH. The above results are interpreted based on attractive electrostatic interactions between clay and MMH particles due to their opposite charges, similar to the edge( )/face(-) interactions in single-component clay dispersions under a low pH value.