Dispersed Structure and Rheology of Lipophilized-Smectite/Toluene Suspensions

Okamoto, Masami; Taguchi, Hideyuki; Sato, Harumi; Kotaka, Tadao; Tochihara, Hiroshi

doi:10.1021/la990933c

Cited by 41 publications

(25 citation statements)

References 6 publications

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“…In our previous study [21] on lyophilized smectic clay-toluene suspensions, we observed this type of shear thinning feature of the clay particles in the rapid shear flow. Such a feature is strongly dependent on the shear rate in the dynamic measurements, because of the formation of the shear-induced alignment of the dispersed clay particles.…”

Section: Dynamic Oscillatory Shear Measurementssupporting

confidence: 53%

New Polylactide/Layered Silicate Nanocomposites, 6

Ray

Okamoto

2003

Macro Materials & Eng

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165

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The measurement of rheological properties of any polymeric material under molten state is crucial to gain fundamental understanding of the processability of that material. In the case of polymer/layered silicate nanocomposites, the measurements of rheological properties are not only important to understand the knowledge of the processability of these materials, but is also helpful to find out the strength of polymer‐layered silicate interactions and the structure‐property relationship in nanocomposites. This is because rheological behaviors are strongly influenced by their nanoscale structure and interfacial characteristics. In order to get this knowledge in the case of polylactide/montmorillonite nanocomposites, we have studied melt rheological properties of these materials in detail. On the basis of rheological data, we have conducted foam processing of pure polylactide and one representative nanocomposite by a newly developed pressure cell technique using carbon dioxide as a physical‐blowing agent.The time variation of the elongational viscosity of one of the intercalated polylactide/montmorillonite nanocomposites.magnified imageThe time variation of the elongational viscosity of one of the intercalated polylactide/montmorillonite nanocomposites.

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Section: Dynamic Oscillatory Shear Measurementssupporting

confidence: 53%

New Polylactide/Layered Silicate Nanocomposites, 6

Ray

Okamoto

2003

Macro Materials & Eng

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165

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confidence: 99%

Shear-Induced Aggregation Behavior in Lipophilized Smectite Clay/Styrene Suspension.

Okamoto

Sato

Taguchi

et al. 2000

J. Soc. Rheol., Jpn

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In a series of our studies on a synthetic smectic clay/organic monomer suspensions, 1) we have devoted to understanding of thixotropic behavior under shear flow. To understand this intriguing issue, we should follow directly an internal structural change of the suspensions under shear flow. In a recent attempt, a small-angle neutron scattering measurements in hectorite-type clay aqueous suspensions were carried out under in-situ shear conditions.2) It was reported that the spatial and orientational long-range anisotropic correlations between the plate-like particles were developed in the flow direction with low shear.Recently we constructed the rheo-optical device, smallangle light scattering apparatus under shear flow (Rheo-SALS), which enables us to perform time-resolved measurements of light intensity scattered from the internal structure developed under shear flow. We show here the preliminary results concerned with the long-range correlation and its evolution in the lipophilized smectite/styrene suspensions under shear flow.The lipophilized clay /styrene (10/90 w/w) suspension1) including small amount inhibitor was allowed to stand still in sealed grass tubes for 24 h and then was subjected to Rheo-SALS experiment and viscosity measurement at room temperature. Fig. 1 shows a schematic illustration of the apparatus: Plane polarized light normal to the Ox-axis (flow direction) from the laser source (λ=632.8nm, 5mW) was applied vertically to a parallel-plate type shear cell along the velocity gradient (Oyaxis) and the scattering profile was observed under Vv (depolarized geometry in which the optical axis of the analyzer was set parallel to that of the polarizer) and Hv (crosspolarized geometry with a perpendicular set to the two axes) optical alignment at azimuthal angle µ of 0°. The Vv and Hv scattering data were obtained in separate runs. The quantitative analysis of angular-dependence of scattering intensity is captured in the Oz-axis (neutral direction) by a 38 channel photodiode array (PDA: Hamamastu Photonics Co.) as a one-dimensional detector, which facilitated time-resolved measurement of light scattering profiles within the scattering angle θ range of 1.4 -30° with a time slice of 1/30s. The shear cell used is a transparent parallel-plate type made of quartz with 80mm diameter and 10mm thickness, which rotated by motor in revolution range of 0-3000 rpm and fixed a constant gap of 600 µm in this experiment, giving a imposed shear rate range of around 10 -1 -10 3 s -1 . Steady shear viscosity measurement was carried out on a Rheometrics Stress Rheometer (DSR200) with a cone-plate geometry of cone

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“…It has been reported that liophilized clay, such as Na-MMT intercalated with alkylammonium ions, can readily disperse into toluene. 16 In our system, we also obtained a slightly brown but nearly transparent suspension when organoclay was suspended in toluene. The following reports the chemical modification of the organoclay in toluene using trialkoxysilane.…”

Section: Modification Of Organoclaymentioning

confidence: 70%

Effects of organoclay modification on microstructure and properties of polypropylene–organoclay nanocomposites

Lee

Kim

Choi

et al. 2005

J of Applied Polymer Sci

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ABSTRACT:We prepared polypropylene nanocomposites based on a modified organoclay with isobutyl trimethoxysilane to investigate the effects of such modifications of organoclay on the microstructure and properties of the nanocomposite. The organoclay was preliminarily intercalated with distearyldimethylammonium bromide via an ion exchange before being grafted with silane. The morphology of the polypropylene-organoclay nanocomposites was characterized by wide-angle X-ray diffraction analyses and transmission electron microscopy. The modification of the edges of clay platelets with organic silane resulted in a more uniform dispersion of nonagglomerated tactoids, which consisted of several intercalated clay platelets. However, the unmodified organoclay led to a mixed morphology with both agglomerated and nonagglomerated tactoids. The grafting of the clay edges with organic silane also affected the linear viscoelastic properties of the nanocomposites in the melt state, which was shown to be sensitive to the interaction between the edges of clay platelets as well as to the interaction of the polymer with the platelet edges.

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Dispersed Structure and Rheology of Lipophilized-Smectite/Toluene Suspensions

Cited by 41 publications

References 6 publications

New Polylactide/Layered Silicate Nanocomposites, 6

New Polylactide/Layered Silicate Nanocomposites, 6

Shear-Induced Aggregation Behavior in Lipophilized Smectite Clay/Styrene Suspension.

Effects of organoclay modification on microstructure and properties of polypropylene–organoclay nanocomposites

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