The yield stress of model waxy oil after incorporation of organic montmorillonite

To study the influence of organic montmorillonite (OMMT) on the yield stress of the model waxy oil (LMO) under dynamic cooling, OMMT was prepared through ion exchange of the sodium montmorillonite with dimethyldioctadecylammonium chloride (DOAC). The incorporation of OMMT lead to a great reduction of the yield stress, which could be explained by the inhibition effect of OMMT on the wax gelation. For 100 ppm OMMT loading, the yield stress reduced by 74.1% at 36 °C. The inhibition effect was realized through decreasing the wax crystallinity, reducing the crystal dimension and introducing the electrostatic repulsion between the crystal particles. The role of thermal history on the yield stress was also studied. Compared with the pure LMO, the OMMT-doped LMO showed different dependence level on the thermal history, but similar trend with that. High testing temperature and short holding time facilitated a lower yield stress. Due to the presence of different shear stress during cooling, the cooling rate showed a complicated effect on the yielding process.