Synthesis and characterization of HDA/NaMMT organoclay

Minerals, 2020

In this work, the effect of layer charge density of Na-montmorillonite (Na-MT) and carbon chain length of alkyl ammonium on the structure and gel property of organo-montmorillonite (organo-MT) was studied by using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TG) analysis, contact angle test, molecular dynamics (MD) simulation, and gel apparent viscosity determination experiment. The results of XRD show that Na-MT with lower layer charge density is easier to swell after intercalation of alkyl ammonium, and the basal spacing of organo-MT increases with the increase of carbon chain length. The results of FTIR show that the absorption bands at 2924 cm−1 and 2853 cm−1 shift towards low frequency region with the increase of carbon chain length, and the absorption bands at 515 cm−1 and 463 cm−1 move towards high frequency region when the layer charge density increases. The mass loss of organo-MT evidently increases with the increase of layer charge density...

Minerals, 2020

In this work, a series of comparative studies for the effect of the nine commercially available cationic, amphoteric and nonionic surfactants on the structure and wettability of the montmorillonite based organoclays were performed. The pristine and modified clays were characterized by X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and water contact angle (CA) measurements. It has been observed that the maximum basal spacing and the hydrophobicity of the organoclays increased with the alkyl chain length and chain number of the surfactant. It was found out that this effect is most pronounced when using cationic surfactants. The maximum value of contact angle corresponded to the organoclay obtained using di(hydrogenated tallow) ammonium chloride (DDA). The outcomes of this study are important and relevant to the preparation of effective organoclays for geotechnical, petroleum and polymer nanocomposite applications.

Applied Clay Science, 2011

Eight carefully selected organoclays from monoalkyl-to tetraalkylammonium type were prepared from a sodium-saturated b2 μm fraction of Jelšový Potok bentonite (Slovakia). Four samples contained 1-4 octylammonium chains, from monooctylammonium (1C8) to tetraoctylammonium (4C8). Two cations had chains with 16 carbons each, hexadecylammonium (1C16) and dihexadecyldimethylammonium (2C16). Two cations contained a benzene ring, either without reactive bonds (benzyltrimethylammonium, C10) or with a double bond in 4-vinylbenzyl-trimethylammonium (C12). The d 001 values depended on the size and structure of the organocation. The height of the interlayer space in the 1C8-4C8-Mt series increased from 0.45 to 1.68 nm. 2C8 cation opened the interlayer space more than 1C16; 2C16 was more effective than 4C8. Expansion of only 0.55 nm was obtained with C10 and C12. Mass losses between 150 and 800°C in N 2 flow were 13-38% for 1C8-4C8-Mt and 40% for 2C16-Mt. Infrared (IR) spectra were similar for 1C8-4C8-Mt but different for the samples with 16 C and 32 C atoms due to altered ratios of CH 3 and CH 2 groups. Downward shift of the CH 2 stretching bands with increasing size of the alkylammonium cation suggest that alkyl chains adopt more ordered structure. The suitability of the prepared materials to be used as fillers for polymer nanocomposites was assessed according to rheological measurements of dispersions in solvents taking solubility parameters as primary factors for comparison of particular solvent and polymer.

Applied Clay Science, 2013

Rheological properties of the organoclays prepared by cation exchange reaction of Indian bentonite with quaternary ammonium compounds viz. Hexadecyltrimethylammonium bromide, N-cetylpyridinium chloride and Stearyldimethylbenzylammonium chloride have been investigated. The basal spacing, particle size and bulk density of organoclays were affected by the chain length and/or carbon content (organic density) of quaternary ammonium compounds. The rheological behavior study revealed that all the toluene-organoclay-dispersions exhibited shear-thinning flow behavior, degree of shear-thinning, stability of the gel structures and yield stress. The incorporation of a mixture of 5 vol.% of H 2 O in methanol as polar activator studied in the range of 33 to 100 wt.% of organoclay reinforced the rheological properties, viscosity and gel volume, and the degree of shear-thinning, stability of the gel structures and yield stress of the toluene-organoclay-dispersions. The organoclays with polar activator having 65 wt.% concentration exhibited optimum rheological reinforcement. The rheological properties were found to be more enhanced by ultrasonication relative to conventional stirring/shearing. Power-law and Casson equations have been used to describe the rheological properties of toluene-organoclay-dispersions.

Journal of Applied Polymer Science, 2013

In this study, nanocomposites based on linear low density polyethylene (PE) and organomodified montmorillonites (MMTs) have been processed without adding any other polar compatibilizer such as maleic anhydride grafted PE. We evidence the beneficial effect on the state of dispersion of an imidazolium-based MMT compared to traditional commercial organoclays, one of which being its alkylammonium equivalent. Transmission electron microscopy observations and melt rheology are used to characterize the state of dispersion of clay in the polymer matrix. Thinner primary particles and lower interparticle distances are obtained with the imidazolium-based MMT. This result is attributed to a higher initial gallery spacing which favors delamination phenomena. As a consequence, the dispersion state of this organoclay is much more sensitive to changes in the mixing shear rate, contrarily to the commercial ones.

American Journal of Applied Sciences, 2009

Problem statement: Sodium Montmorillonite (Na-MMT) has been modified via cation exchange reaction using Fatty Hydroxamic Acids (FHAs) synthesized from palm oil as a surfactant to produce organoclay which is used to prepare polymer nanocomposites. Approach: Basal spacing, functional groups identification and thermal stability of this Organo-Montmorillonite (OMMT) were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA) respectively. Elemental analysis was also used to know the composition of OMMT. Cation Exchange Capacity (CEC) was also investigated in this study. Results: The (XRD) results showed that the basal spacing of the treated clay with FHA increased to 31A. The highest d-spacing was observed at 1.8 CEC. FTIR spectra illustrate that FHA compound was successfully intercalated into the clay layers. Tthermogravimetric analysis showed that the thermal decomposition of organoclay occurs in four steps. Con...

Journal of physics, 2015

In this paper we characterized at first, the rheological behavior of the bentonite suspensions and the aqueous solutions of polyethylene oxide (PEO), then we were investigated the influence of this polymer in a water-based drilling fluid model (6% of bentonite suspension). The objective is to exhibit how the non ionic polymer with molecular weight 6x10 3 g/mol. of varying concentration mass (0.7%, 1%, 2% et 3%) significantly alter the rheological properties (yield stress, viscosity, loss and elastic modulus) of the bentonite suspensions. The rheological measurements made in simple shear and in dynamic on the mixture (water-bentonite-PEO), showed rheological properties of bentonite suspensions both in the presence and absence of non-ionic polymer. The PEO presents an affinity for the bentonite particles slowing down their kinetic aggregation. The analysis by X-rays diffraction also allowed understanding the structure of this mixture. It had revealed the intercalation between of the clay platelets on one hand, and the links bridges assured by the chains of polymer between bentonite particles beyond a critical concentration in PEO on the other hand. The Herschel-Bulkley rheological model is used for the correlation of our experimental results.

Clays and Clay Minerals, 2013

Several detailed studies have been done on the characterization of organoclays and the type of structures developed when they interact with alkylammonium molecules. Few published contributions exist, however, on the distribution of surfactant within the organoclays and the mechanism by which they are intercalated. Also, although X-ray photoelectron spectroscopy (XPS) is a suitable technique for the study of the surface characteristics of organoclays, very few such XPS studies have been carried out. With the aim of contributing to a better understanding of the intercalation process, a series of organoclays was synthesized using a montmorillonite and the cationic surfactant hexadecyltrimethylammonium bromide (HDTMABr), with an increasing surfactant load of between 0.2 and 4.0 times the cation exchange capacity of the starting clay. By means of XPS, zeta potential, and thermal analysis techniques, distinguishing the strongly interacting fraction from the weakly interaction fraction of the adsorbed surfactant molecules was possible. Adsorption isotherms of each of these processes were constructed and then adjusted using the Langmuir and Dubinin-Radusquevich adsorption models. Three types of interaction between the surfactant and the clay were identified and described qualitatively and quantitatively. Two of these interactions, strong and weak, involved the hexadecyltrimethylammonium cation (HDTMA +). The third was a weak interaction involving the ion pair HDTMA + Br À. The results of this study may be useful for the comprehensive design of organoclays with specific physicochemical properties according to the application for which they are destined.

2012

Polymer/layered-silicate hybrid nanocomposites have attracted strong interest in today's materials research, as it is possible to achieve impressive enhancements of material properties compared to the pure polymers. This study aim is to modify the clay surface using ion exchange and surfactant methods before proceeding with fabrication of polymer nanocomposites. The polymer that used is Polylactic acid (PLA) because of its biodegradability characteristic. Organoclay will characterize by using Atomic Adsorption Spectrometry (AAS) and Fourier Transform Infrared Spectroscopy (FTIR). PLA-Nanocomposites were prepared by using solution casting and characterized by X-Ray Diffraction Analysis (XRD), Scanning Electron Microscopy (SEM). AAS analysis showed there is a transition metal ion in the interlayer of sodium montmorillonite (MMT) and it is confirmed with SEM analysis. The FTIR analysis for surfactant organoclay shows the presence of TEOS surfactant in the organoclay properties. The XRD analysis proved that the modification happens by the increasing of clay interlayer basal spacing. The XRD analysis for PLA-Nanocomposites showed that PLA is intercalated the interlayer gallery of organoclay to similar extents and also increased the d-spacing. The structure of polymer nanocomposites that came out of this research is intercalated and exfoliated nanocomposites.

The effects of NaC1 and CaC12 on the colloid stability and rheological properties of Na-and Ca-montmorillonite dispersions were studied. The distribution of cations between the surface and the bulk phase was determined. For both of monocationic montmorillonite, the critical coagulation concentration were 250 mmol NaC1/dm 3 and 2 mmol CaC12/dm 3. The changes in the Bingham yield stresses of Na-and Ca-montmorillonite dispersions as functions of the NaC1 and CaC12 concentration could be explained in terms of the surface excess amount and equilibrium concentration of the cations, the second electroviscous effect and the formation of a gel structure.