Microstructure string

Figure 2.15 Schematic and photograph of the microstructured string reactor [39]...

FIG. 1.7 Some of the microstructures produced by the self-association behavior of diblock copolymer solutions. The figure illustrates the (a) spherical, (b) cylindrical, and (c) lamellar structures (among others) that are possible in such solutions. Each diblock polymer chain consists of strings of white beads (representing one type of homopolymer) and strings of black beads (representing the second type of homopolymer). (Redrawn from A. Yu. Grosberg and A. Khokhlov, Statistical Physics of Macromolecules, AIP Press, New York, 1994.)... 

FIGURE 16,17 Microstructure of sintered AI2O3 showing a string of pores detached from the grain boundary and left within a large grain, 3 gm in size. 

Droplet Microstructure and String Stability in Sheared Emulsions Role of Finite-Size Effects... 

We have studied the effects of mixture composition on droplet microstructure (5), and summarized these results in the form of a rich morphology diagram (Figure 3) in the parameter space of mass fraction and shear rate. Formation of strings of the suspended phase was observed over a broad composition window. At each composition, experiments were stopped when strings were formed. We also found a non-transient moiphology where we saw arrangement of the droplets in ordered pearl-necklace chain structures. 

Shish-Kebab structure shish-k3- bab n. A term borrowed from the broiling kitchen to designate a polymeric microstructure in which the random-coil chain of an amorphous polymer (shish) has been interlaced with crystalline cross-segments (kebab) produced by shearing the polymer in the molten condition or in solution. The string-of-lumps microstructure so resembles the edible dehcacy that its borrowed name seems quite apt. Ehas HG (1977) Macromolecules, vols 1—2. Plenum Press, New York. 

Of course, not all multiphase microstructured reactors are presented in Table 9.1. Either because they have attracted (too ) little interest, because they may have been qualified as microreactors in spite of their overall size but caimot be considered as microstmctured , or because they combine several contacting principles. Examples are a reactor developed by Jensen s group featuring a chaimel equipped with posts or pillars, thus resembling more a packed bed but with a wall-coated layer of catalyst [20], and a string catalytic reactor proposed by Kiwi-Minsker and Renken [21], that may applied to multiphase reactions. 

Non-Newtonian behavioitr can be allowed for in the Krieger-Dougherty formalism by allowing K to vary with the shear-rate. The justification for this is the formation at higher shear stresses of a more ordered microstructure, involving strings or layers of particles, characterized by a different value of shear stress r on the crowding factor can be represented by an equation of die form... 

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