The viscosity of organic liquid suspensions of trimethyldococylammonium-montmorillonite complexes

Abstract

An organophilic bentonite was prepared by means of a reaction of natural Na-montmorillonite with trimethyldococylammonium which has an especially long n-alkyl chain. The addition of trimethyldococylammonium to montmorillonite was in the range 0.25–3.0 times the cation exchange capacity (CEC) of the clay (i.e. 0.23–2.82 mmol/g clay). The particle morphology in organic liquid suspensions of organoclay complexes was studied by measuring the viscosity based on Eyring’s rate process and Robinson’s relative sediment volume. In toluene, montmorillonite with 1.17 mmol/g clay trimethyldococylammonium (1.25 times the CEC) had the largest specific gel volume, relative sediment volume, and K-factor. The results of the stoichiometry for trimethyldococylammonium-montmorillonite show that practically all of the quaternary ammonium was adsorbed to montmorillonite. Maximum half widths of 001 reflections from X-ray diffraction patterns were obtained in the range 0.74–1.17 mmol/g clay, indicating a disordered arrangement of the organic cation molecules intercalated between the layers. Appreciable shifts to lower-frequency regions in the Fourier transform infrared absorption spectra as a result of CH2-stretching vibrations were observed with increasing amounts of the organic cation. When increasing the amount of organic cation added to the clay from 0.94 to 1.41 mmol/g clay, a large shift occurred to the lower-frequency side, approaching the frequency of the organic cation alone. This indicates that the interaction between adjacent hydrocarbon chains becomes progressively stronger, due to van der Waals attraction, with increases in the amount of organic cation. Interactions of the alkyl chains in trimethyldococylammonium-montmorillonite complexes with irregularly distributed and randomly arranged alkyl chains between the silicate layers were weak, and, as a result, solvation with external organic liquids occurred and gel formation developed through macroscopic swelling of the organoclay.

Combined Effect of Pressure and Temperature on the Viscous Behaviour of All-Oil Drilling Fluids

“…Then, above the threshold temperature, particle associations might undergo an increase in the effective volume. Thus, an increase in volume fraction leads to an increase in yield stress value, as has been observed by other authors for clay suspensions (Minase et al, 2008). Interestingly, this particular behaviour has been recently reported by Wu et al (2012), who also suggested an increase in the effective volume fraction with increasing temperature for particulate dispersion in non-aqueous media.…”

The structure and properties of OMt prepared by a synergistic modification strategy using the emulsifier OP-10 and hexadecyltrimethylammonium chloride as comodifiers

“…In rubber or plastic materials, OMt not only is required to have good dispersion and peeling properties but also needs good heat resistance to meet the processability requirements [6]. Excellent thermal stability and good rheological properties are indispensable for the wide use of OMt in oil-based drilling fluid [7,8]. Therefore, it is desirable to prepare advanced OMt with controllable surface polarity, excellent thermal stability, good dispersion, and peeling properties.…”

Influence of aqueous phase volume fraction, organoclay concentration and pressure on invert-emulsion oil muds rheology

“…Organoclay addition to a solvent leads to the formation of a gel-like microstructure, which depends on the characteristics of the interchangeable organic ions, the nature of the solvent, as well as the interactions between organoclay and solvent [5,6]. The resulting microstructure, formed as a consequence of the swelling capacity of organoclays in non-aqueous media, may result in shear-thinning characteristics and viscoplasticity, even at low clay concentrations [7][8][9]. Generally, these rheological properties are desirable in drilling fluids, as has been pointed out elsewhere [10].…”