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Suwardie, Herman; Yazici, Rahmi; Kalyon, Dilhan M.; Kovenklioglu, Suphan

doi:10.1023/a:1004423411227

Cited by 16 publications

(1 citation statement)

References 21 publications

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“…By conducting shear-flow experiments, they observed work-hardening in the very low shear rate region, stress oscillation in the high shear rate region, as well as yield behavior. Suwardie et al [28] observed viscoplasticity, plug flow, wall slip and flow instabilities associated with axial migration of the low viscosity binder under an imposed pressure gradient for ceramic suspension with 50% by volume of silicon carbide in a wax binder.…”

Section: Introductionmentioning

confidence: 99%

Stable and Unstable Capillary Flows of Highly-Filled Epoxy/Nickel Suspensions

Zhou

Sancaktar

2008

Journal of Adhesion Science and Technology

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Epoxy/nickel adhesives can be used as integrated circuit (IC) packaging materials due to their lower cost than epoxy/silver adhesives with acceptable electrical conductivity. In this study, stable and unstable capillary flows of highly-filled epoxy/Ni suspensions were investigated with and without cure at room temperature, via the capillary rheometry and syringe extrusion. Variations of the bulk electrical conductivity in these processes were discussed as well. Axial filtration of the polymer binder occurs under a static pressure for a cured epoxy/Ni system, Epon 815 C/Ni/diethylenetriamine (DETA) adhesive with 50 wt% of Ni in the syringe, resulting in an unstable flow and a cross-sectional filler concentration or electrical conductivity gradient. In dynamic capillary extrusion, lower resin viscosity and apparent shear rates enhance the flow instability and filtering of polymeric binder for epoxy/Ni suspensions with 75 wt% of Ni, thus facilitating a change in bulk electrical conductivity during processing. With increasing shear rates, both average force and force oscillation frequency increase. Incorporation of Ni nanopowder promotes a stable flow, yet the occurrence of agglomerates somewhat nullifies this advantage. Additionally, different rheological behaviors result as cure proceeds with different resins. Also, occurrence of the agglomerates leads to flow instability during processing with cure.  Koninklijke Brill NV, Leiden, 2008

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Section: Introductionmentioning

confidence: 99%

Stable and Unstable Capillary Flows of Highly-Filled Epoxy/Nickel Suspensions

Zhou

Sancaktar

2008

Journal of Adhesion Science and Technology

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Periodic fluid extrusion and models of digesta mixing in the intestine of a herbivore, the common brushtail possum (Trichosurus vulpecula)

et al. 2005

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The digesta in four gut compartments (proximal and distal halves of small intestine, caecum, and proximal colon) of a wild hindgut fermenting herbivore, the common brushtail possum (Trichosurus vulpecula), were investigated by rheometry and permeametry. Digesta from all compartments were highly viscous and exhibited shear-thinning. Apparent viscosity was positively related to dry matter content, and increased from proximal small intestine to colon. Dynamic rheological measurements showed that in small intestinal digesta the elastic modulus was greater than the viscous modulus and their ratios were characteristic of weak gels, indicating that digesta could sustain compression. The apparent viscosity of distal small intestinal digesta was markedly lower when measured by capillary viscometry than by rotatory viscometry, indicating that plug flow was likely to be facilitated by lubrication from a peripheral layer of less viscous fluid; i.e., there was an augmented plug flow. Permeametry showed that fluid was extruded from all digesta on compression at physiological pressures, that there was significant permeability of proximal and distal small intestinal digesta, but that digesta became progressively compacted during permeation, with a concomitant reduction in permeability as dry matter content increased. It is proposed that conditions within the small intestine differ from those of an ideal plug flow reactor as radial mixing and turbulence cannot occur. Instead, we suggest that segmentation and peristalsis aid radial mixing of the fluid phase by compressing the solid phase, with extrusion of fluid through the digesta plug. This extrusion may be followed by resorption of fluid back into the plug when the elasticity of the solid phase of digesta is Hookean, thus aiding the mixing of secreted enzymes with insoluble substrates within the plug.

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