Interdigital multilamination micromixer

In the case of Y- or T-shaped micromixers, a decrease in the channel width to shorten mixing time leads to a decrease of production volume per unit time. To solve this problem interdigital multilamination micromixers have been developed. In this type of micromixer, two fluids are separated into many small narrow streams, which are arranged to contact each other alternately. The mixing takes place at interfaces of such sub-streams by molecular diffusion. The IMM (Institute of Microtechnik Mainz) single... 

In interdigital multilamination micromixers, the small thickness of the lamellae leads to short diffusion paths, resulting in fast mixing. Further thinning of the liquid lamellae should lead to shorter diffusion paths and faster mixing. The IMM single mixer applied this concept by shrinking the channel width in the slit. A further extension of this concept leads to the... 

Numerical simulations of styrene free-radical polymerization in micro-flow systems have been reported. The simulations were carried out for three model devices, namely, an interdigital multilamination micromixer, a Superfocus interdigital micromixer, and a simple T-junction. The simulation method used allows the simultaneous solving of partial differential equations resulting from the hydrodynamics, and thermal and mass transfer (convection, diffusion and chemical reaction). 

Superfocus interdigital multilamination micromixer can achieve better control than a macrobatch reactor, and the PDI obtained is very close to the theoretical limiting value of 1.5. As the characteristic dimension of the microdevice increases the reactive medium cannot be fully homogenized by diffusion transport before leaving the system, resulting in a high PDI and a loss in control of the polymerization. 

Hessel, V., Numerical simulation of polymerization in interdigital multilamination micromixers. Lab Chip 5(9) (2005) 966-973. 

Fig. 4 Flow microreactor system for controlledAiving cationic polymerization of vinyl ether initiated by SnCL. M interdigital multilamination micromixer, R microtube reactor...

The effects of mixing in radical polymerization of MMA are interesting [168]. The use of a 5 mm static mixer leads to fouling in the reactor. In contrast, the use of an interdigital multilamination micromixer with 36 lamellae of 25 pm thickness results in a reduction in fouling. This numbering-up approach enables production of 2,000 tons per year without the fouling problem [169]. 

Continuous nitroxide-mediated block copolymerization of n-butyl acrylate (first monomer) and styrene (second monomer) can be performed using two serial 900-p m inner diameter stainless steel microtube reactors (Fig. 29) [215]. For the second polymerization process, the influence of mixing was examined by changing micromixers. The use of a high-pressure interdigital multilamination micromixer (HPIMM) provided by the Institut fiir Mikrotechnik Mainz (Mainz, Germany), can significantly reduce the polydispersity index = 1.36, 120°C) compared... 

Figure 4 Micromixers, (a) Interdigital structure of a multilamination micromixer. (b) Principle of split-and-recombine static micromixers. (Source IMM.)...

As industrial relevant Friedel-Crafts reaction, the synthesis of Bisphenol-F, a material for epoxy resin, from phenol and formaldehyde was chosen [57]. This reaction involves formation of higher order condensates such as tris-phenols. To minimize the latter, the molar ratio of phenol to formaldehyde is set to a very high value (30-40), which is more than 15 times larger than the amount theoretically necessary. Three types of micromixers were used. These are a T-shaped mixer with 500 pm inner diameter, a multilaminating interdigital micromixer with 40 pm channels and a so-called self-made K-M micromixer with center collision mixing. 

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