Mixing protocol

A series of mixing experiments were conducted using two pass mixing protocols rather than the multipass processes as described in the previous references. Five grades of carbon black (N-121,... 

A large concentration gradient was so established by having a mixing protocol different to the symmetrical flow mode (for details, see [164]). Simulation results basically agree with the experimental findings. 

Fig. 7.2 The top figure indicates a mixing protocol of mixing by stretching-cutting-stacking, yielding 2n+1 layers after n steps, in this case, n — 1. The bottom figure shows a stretching-folding bakers transformation yielding 1+2 layers, in this case, n — 2.

Figure E7.2 compares a stepwise increase in interfacial area in simple shear flow with optimal initial orientation, and simple shear flow where, at the beginning of each step, the interfacial area element is placed 45° to the direction of shear. The figure shows that, whereas in the former case the area ratio after four shear units is 4.1, in the latter case the ratio is 6.1, with a theoretical value of 7.3 when the 45° between the plane and direction of shear is maintained at all times. We note, however, that it is quite difficult to generate steady extensional flows for times sufficiently long to attain the required total elongational strain. This is why a mixing protocol of stepwise stretching and folding (bakers transformation) is so efficient. Not only does it impose elongational stretching, but it also distributes the surface area elements over the volume.

Fig. 7.7 Sample particle trajectories in a twin vortex flow. The agitator location is set by the amplitude, which is 0.5 (i.e., it is at midpoint between the center and the perimeter) and marked by the crosses. The dimensionless period for each vortex is 0.5. The mixing protocol is to activate one agitator for a period of time and then switch to the other agitator. [Reprinted by permission from H. Aref, Stirring Chaotic Advection, J. Fluid Meek, 143, 1-21 (1984).)...

Fig. 7.9 Eccentric coaxial cylinders or journal bearing configuration. In the mixing protocol, the cylinders rotate alternately in the clockwise and counterclockwise directions.

While the procedure shown in Scheme 4 [26], Hke the original method, introduces much of the diversity (i. e., up to three variable positions) off the solid phase, thereby limiting the combinatorial potential available for split-and-mix protocols, another recently described scheme [30] builds up the diversity in a stepwise manner on the solid phase, which simpHfies the logistics for automated library production. Intermediates may also be used to access thiohydantoins (see Scheme 6). 

The library of 140 pyrrole-3-carboxamides was synthesized following the split-mix protocol with 14 primary amines and 10 a-bromo-ketones as variable building blocks. In the first step Rink-Amide-AM-PS resin was acetoacetylated at —15 °C by addition of di-ketene to the resin suspended in CH2CI2. After 0.5 h at —15 °C and 2 h at room temperature the resin was washed and dried. A negative Kaiser test proved the complete conver-... 

EMAA ionomer (0-30 parts) dispersed phase particle size vs. interfacial modifier concentration / emulsification curves / effects of mixing protocol / also blends containing PP in place of HDPE Favis, 1988... 

Favis [1994] and Willis andFavis [1988] prepared compatibilized PA blends with PP and carboxylic acid-functionalized EMAA ionomer. Blends containing 90-10 parts PA-6, 0-30 parts EMAA ionomer, and 10-90 parts PP were combined in an internal mixer at 250°C and characterized by torque rheometry and SEM. Dispersed phase particle size vs. interfacial modifier concentration was determined. Emulsification curves were constructed. Effects of mixing protocol on blend properties were studied. Blends were also prepared containing HOPE in place of PP. 

PA-6 (80-70) or PA-66 / SMA (0-10) / SB core + MMA shell impact modifier (20) or BA core + MMA shell SSE at 240-280°C / torque rheometry / mechanical properties / ductile-brittle transition temperatures / TEM / effects of mixing protocol Lu etal., 1996, 1993... 

PA-6 (100-0) / ABS (0-100) / imidized acrylate copolymer with various acid + anhydride concentrations (0-20) SSE at 240°C / TEM / torque rheometry / mechanical properties vs. compatibilizer content, functionalization level, rubber cone, and mixing protocol / ductile-brittle transition temperatures Majumdar et al., 1994 b... 

---