Relationship between structures and rheological properties of plate-like particle suspensions

• The relationship between structures and rheological properties of three plate-like particle suspensions are studied.
• Liquid crystalline phase is observed in OMMT/SO, GO/SO but absent in Kaolin/SO.
• Negative ΔN is found in the three plate-like particle suspensions.
• Tumbling and rotation motions of OMMT sheets lead to negative ΔN in OMMT/SO.
• Vorticity alignment of GO or Kaolin clusters induces negative ΔN.

The structures and rheological properties of three different plate-like particle suspensions, i.e., organically-modified montmorillonite (OMMT), graphene oxide (GO) and Kaolinite (Kaolin) in silicone oil (SO), are explored. Since the interactions between plate-like particle and SO are different, the dispersion states of these particles in SO are different. OMMT particles disperse relatively well in SO, and small clusters exist in GO/SO suspensions, but larger aggregates are found in Kaolin/SO suspensions. Moreover, liquid-crystalline ordering structure is found in both OMMT/SO and GO/SO suspensions, while it is absent in Kaolin/SO suspensions. Negative normal stress differences (ΔN) are observed during shear in all three plate-like particle suspensions, however, the mechanisms of the negative ΔN might be different. It can be further inferred that the negative ΔN in OMMT/SO suspensions results from the tumbling and rotating motions of OMMT sheets, while for GO/SO or Kaolin/SO suspensions, the negative ΔN results from the vorticity alignment of large GO clusters and Kaolin aggregates.

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