Dispersion of organically modified clays within n-alcohols

Tran, Ngoc Quang; Dennis, Gary R.; Milev, Adriyan; Kannangara, G. S. Kamali; Williams, Paul J.; Wilson, Michael; Lamb, Robert N.

doi:10.1016/j.jcis.2005.11.008

Cited by 24 publications

(16 citation statements)

References 17 publications

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“…The results of the simulated systems presented here agree with experimental findings in their individual components, i.e., the structure and geometry of the pure clays, the structure and energetics of ethanol, and the structure of the organic cations, all of which validates the force field parameters used in the simulations. Specifically, the d-spacing of the MMT-Q C simulated to be 18.7 Å for the unsolvated case is in excellent agreement with the only available experimental value 35,36 discrepancysimulated results showing that the MMT-Q C system swells in ethanol, whereas the experimental results show it does notcan be attributed to the fact that the macroscopic dynamics of swelling have not been simulated, and it is this phenomenon that is measured experimentally, as discussed by the authors of these studies. The experimental results of Burgentzléet al 35 lead to the conclusion that macroscopic swelling leading to dispersion does not solely correspond to intercalation of solvent molecules between individual clay layers; rather, swelling without dispersion can occur in the absence of intercalation, when the solvent molecules occupy the spaces between clay particles (or tactoids) to form gel-like structures.…”

Section: ■ Discussionsupporting

confidence: 79%

“…In the present case, with a typical dipole length of about 1.5−1.6 Å, this should induce parallel ordering of ethanol at the clay mineral surface, which is exactly what was observed in this study, confirming experimental findings. 24,36 The overall similarity of results between MMT and HCT obviates the need to continue with both clay minerals; hence, from this point onward only MMT and VMT are considered. Although all three clay minerals swell easily in water, they all have energy barriers to swelling in ethanol, and given the importance of this solvent to the polymer industry the addition of a surfactant to reduce this initial energy barrier is a possible solution to overcome the energy barrier to swelling and dispersion.…”

Section: ■ Resultsmentioning

confidence: 99%

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Understanding the Swelling Behavior of Modified Nanoclay Filler Particles in Water and Ethanol

et al. 2015

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Clay−polymer nanocomposite materials have gained much attention owing to their low weight ratio of filler to reinforcement properties, delivering lightweight yet resilient materials with excellent barrier properties to gas diffusion. An important process in their production is clay exfoliation, as maximum reinforcement and improvement of barrier properties occur when the clay mineral platelets are fully separated and dispersed through the polymer matrix with a preferred orientation. In this study we examine clay swellingthe first step leading to exfoliationusing molecular dynamics to generate solvation energetics, swelling curves, and atomic density profiles of three types of clay mineralsmontmorillonite, vermiculite, and hectoritewith interlayer Na + cations and/or three quaternary ammonium surfactants in water and ethanol. Analysis based on the provided simulations can help to distinguish between favorable and unfavorable swelling profiles of mineral/surfactant/solvent systems and therefore guide further research into this complex field. ■ INTRODUCTIONSince the early 1990s, when first introduced by Toyota, clayreinforced plastics, or clay−polymer nanocomposite (CPNC) materials, have attracted much attention owing to their superior performance and additional properties relative to conventionally filled (e.g., glass fiber) plastics. The term "nanocomposites" arises owing to the clay filler particles having at least one size domain in the nanometer region. Clay minerals are defined by Guggenheim and Martin as "phyllosilicate minerals and minerals which impart plasticity to clay and which harden upon drying or firing". 1 This typically refers to the fraction of soils with particle size of a layer thickness lower than 2 μm. As individual montmorillonite clay mineral layers are only 10 Å (1 nm) thick, these kind of clay minerals have a very high aspect (breadth to thickness) ratio. At relatively low filler loadings, polymers reinforced with clay minerals gave rise to similar mechanical properties for CPNCs as composites with much higher conventional filler loadings. 2 Initially, it was considered that the nanoscale size of these clay minerals conferred unique properties to the CPNC material. However, in time it became apparent that the strongly bound polymer interfacial layers on the clay mineral allowed CPNC materials to be placed within conventional composite theory. 3 In addition, owing to the preferred orientation and overlap of the highly anisotropic clay mineral platelets, CPNC materials were found to have far superior barrier properties to gas diffusion and better thermal stability compared to the pure polymers, or conventional composites, accelerating their deployment in packaging applications. The dramatically increased usage of plastic-based packaging materials over the last few decades together with future consumption predicted to increase even further 4 have served to stimulate the industry to provide new, more efficient barrier solutions 5−7 with the potential to further extend the usage of CPNC mate...

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Section: ■ Discussionsupporting

confidence: 79%

Section: ■ Resultsmentioning

confidence: 99%

Understanding the Swelling Behavior of Modified Nanoclay Filler Particles in Water and Ethanol

et al. 2015

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“…The delaminated clay possesses no long-range order along the stacking direction. Delamination of smectites has also been studied in organic media [8,20]. Recently we have shown that the delamination of organosmectite in nitrobenzene can be used as a technique for the separation of organosmectite from other mineral impurities [21].…”

Section: Introductionmentioning

confidence: 99%

Interstratification of trioctahedral and dioctahedral smectites through delamination and costacking

Venugopal¹,

Ravishankar²,

Rajamathi³

2008

Journal of Colloid and Interface Science

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“…For the purpose of maximizing the thermal conductivity of a thermal paste, it is conventional to use thermally conductive constituents at high proportions, e.g., zinc oxide in the amount of 72.8%. 23 Both thermal conductivity and conformability help the performance of a thermal paste. The workability and conformability of a thermal paste diminish with increasing conductive filler content, although the thermal conductivity of the paste increases with increasing filler content.…”

Section: Design Of Thermal Interface Materialsmentioning

confidence: 99%

Electrically Nonconductive Thermal Pastes with Carbon as the Thermally Conductive Component

Lin

Howe

Chung

2007

Journal of Elec Materi

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Electrically nonconductive thermal pastes have been attained using carbon (carbon black or graphite) as the conductive component and ceramic (fumed alumina or exfoliated clay) as the nonconductive component. For graphite particles (5 lm), both clay and alumina are effective in breaking up the electrical connectivity, resulting in pastes with electrical resistivity up to 10 13 WÁcm and thermal contact conductance (between copper surfaces of roughness 15 lm) up to 9 · 10 4 W/m 2 Á°C. For carbon black (30 nm), clay is more effective than alumina, providing a paste with resistivity 10 11 WÁcm and thermal contact conductance 7 · 10 4 W/m 2 Á°C. Carbon black increases the thermal stability, whereas either graphite or alumina decreases the thermal stability. The antioxidation effect of carbon black is further increased by the presence of clay up to 1.5 vol.%. The addition of clay (up to 0.6 vol.%) or alumina (up to 2.5 vol.%) to graphite paste enhances the thermal stability.

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Dispersion of organically modified clays within n-alcohols

Cited by 24 publications

References 17 publications

Understanding the Swelling Behavior of Modified Nanoclay Filler Particles in Water and Ethanol

Understanding the Swelling Behavior of Modified Nanoclay Filler Particles in Water and Ethanol

Interstratification of trioctahedral and dioctahedral smectites through delamination and costacking

Electrically Nonconductive Thermal Pastes with Carbon as the Thermally Conductive Component

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