Fiber-filled suspension

An interesting observation with some non-newtonian mixtures is that at high shear they appear to violate the zero-velocity boundary condition at the wall. For multiphase fluids such as suspensions and fiber-filled polymers, this effect is believed to be the result of a thin layer near the wall that is depleted of particulates... 

A sustained industrial interest has been shown in fiber-filled polymers. When fibers are combined with a polymer matrix that provides cohesion, the fibers become the load bearing component of the composite, and enhance the strength and stiffness of the material. Many articles made from the fiber-reinforced composites are produced by injection molding or compression molding. The thermo-mechanical properties of the end-product highly depend on the fiber orientation distribution induced by the flow of fiber suspension during processing. Therefore, the flow of fiber suspensions needs to be understood in order to predict the fiber orientation distribution and its effects on the end properties of the products. 

Animal cell cultures that are initiated from cells removed directly from the animal are called primary cultures (Figure 2). Primary cultures include both explant cultures (i.e., cultures initiated from small pieces of intact tissue), as well as cultures initiated from preparations of individual or dispersed cells (obtained from intact tissue by mechanical or proteolytic dismption). Nerve fiber explant cultures in blood plasma were among the earliest types of tissue cultures (Harrison, 1907). Cells grow out from such tissue explants and form a single layer of cells completely filling the tissue culture vessel surface. Such cell cultures are called confluent monolayers. Confluent monolayers can then be treated with trypsin, so as to remove the individual cells from the culture vessel surface. The resulting cell suspension is then transferred into other culture containers, so that more viable monolayer... 

Because the first method is not always very satisfactory from the aesthetic standpoint and because of the limitations of the second, conservators have sought to expand their repertoire with alternative procedures. One possibility which has attracted recent interest is the use of a suspension of paper fibers to fill losses in a way that is analogous to the manufacture of paper. The paper pulp to be used for repairing an art work, for instance, can be obtained by the maceration of handmade rag-fiber paper in an ordinary food blender. 

Use of an appropriate cladding material will permit a fiber s core to etch faster than its clad. When such an etch is carried out on a fiber-optic bundle, the result is a bundle tip with one well per fiber. Remarkably, when the tip is brought into contact with a suspension of well-sized beads, self-assembly occurs to yield a bead-filled array. While this bulk self-assembly process is not really akin to the molecular assembly processes of current academic interest, the result is perhaps equally striking. The atomic force micrographs (AMF) shown in Fig. 7 reveal an etched bundle tip with 4-pm wells being filled by 3.5-pm polystyrene beads. Experience reveals that many types of bead material will self-assemble into etched bundle tips. 

The presence or absence of a yield stress is of great importance in the molding of filler filled or fiber reinforced polymers, and also for the physical stability of many industrial products. Casson proposed an equation describing the steady state shear flow properties of the suspensions of solid particles in Newtonian liquids (Casson, 1959), so as to easily evaluate yield stresses ... 

The method is used to follow the front in mold filling of a fiber suspension in... 

Sandler JKW, Kirk JE et al (2003) Ultra-low electrical percolation threshold in carbon-nanotube-epoxy composites. Polymer 44 5893 Sautereau H, Maazouz A et al (1995) Fatigue behavior of glass bead filled epoxy. J Mater Sci 30 1715 Schadler LS (2003) Polymer-based and polymer-fiUed nanocomposites. In Aja) PM, Schadler LS et al (eds) Nanocomposite science and technology. Wiley-VCH, Weinheim, p 380 Schmid CF, Klingenberg DJ (2000) Mechanical flocculation in flowing fiber suspensions. Phys Rev Lett 84 290... 

This relation is known as the Cox-Merz rule (Cox and Merz, 1958). When i](y) is not available, the Cox-Merz rule serves as a usefiil way to obtain t](y), especially for linear polymers (i.e., those without branching). When dealing with filled polymers, polymer blends, fiber suspensions, or highly branched polymers, the Cox-Merz rule may not hold. 

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