High-Speed Mixers

Procedure. Add A to B usiag an efficient, high speed mixer. Put emulsion through homogenizer to obtain very small particle (ca 2—4 -lm) particle size and a high emulsion stabiHty. 

Dry-Blending. Most plasticized PVC powders are prepared by a dry-blend process in which the plasticizers, stabilizers, pigments, and additives are absorbed on the porous PVC particles at elevated temperatures while they are being agitated in a high speed mixer. Thermosetting powders are almost never prepared by this process. 

Physical Properties. The egg is composed of three basic parts shell, whites (albumen), and yolk. Each of these components has its own membranes to keep the component intact and separate from the other components. The vitelline membrane surrounds the yolk, which in turn is surrounded by the chala2iferous layer of albumen, keeping the yolk in place. Egg white (albumen) consists of an outer thin layer next to the shell, an outer thick layer near the shell, an inner thin layer, and finally, an inner thick layer next to the yolk. Thick layers of albumen have a higher level of ovomucin in addition to natural proportions of all the other egg white proteins. This ovomucin breaks into shorter fibers when the egg white is blended on a high speed mixer (3), or when the egg white ages. Viscosity is gready reduced when the egg white is blended in this way. 

High-Speed Mixers High-speed mixers include continuous-shaft mixers and batch high-speed mixers. Continuous-shaft mixers have blades or pins rotating at high speed on a central shaft. Both horizontal and vertical shaft designs are available. Examples include the vertical Schugi mixer (Fig. 20-84) and the horizontal pin or peg... 

PVC resin, plasticizers, and additives are weighed according to the recipe and mixed in a high-speed mixer. This mixture is then processed at 140-I80°C for a certain period of time to form the preplasticized PVC. The TPU is then added and further blending is performed until completion, depending on each case. 

To an 8-L beaker a solution of 3.78 g (0.630 mol) of ethylene diamine and 0.126 mol of potassium hydroxide in 4.5 L of distilled water are added and stirred with a high-speed mixer. To this, 12.79 g (0.634 mol) of terephthaloyl chloride dissolved in 1 L of methylene chloride (a safer solvent is THF) is added and stirred for 10 min. The suspension is filtered and washed twice with methanol. After drying, the polymer has an of 1.0 as measured in 96% sulfuric acid (0.5% solution at 30°C). The melting temperature of the polymer is 455° C. 

Iron flake powder and polystyrene beads had been blended in a high-speed mixer. The mixture ignited and binned rapidly when discharged into a polythene bag. Rapid oxidation of the finely divided metal and/or static discharge may have initiated the fire. No ignition occurred when the iron powder was surface coated with stearic acid. 

Mixing Conventional Conventional High speed Tweedy high speed mixer or similar... 

Wet Process. About 5 kg of each meal were slurried in 25 1 of 0.02% NaOH for 1 hr at room temperature. The mixture was stirred with a high speed mixer (Polytron) until a uniform slurry was obtained (Figure 2). The yellowish suspension was passed through a... 

Most plastics e.g. polyolefins and polystyrenes and their derivatives such as ABS (acrylonitrile-butadiene-styrene) and SAN (styrene-acrylonitrile) are supplied by the manufacturers in ready-to-use form with most of the above-mentioned stabilizers or simply need to be additionally stabilized with other additives, e.g. antistatic agents and HALS stabilizers, as required. On the other hand, in the case of other materials (e.g. PVC) it is the end user who adds the additives, pigments or preparations. This is normally done on fluid or high-speed mixers, although in the past gravity mixers or tumble mixers were also used. The mixture is then homogenized on mixing rolls, kneaders, planetary extruders or twin-screw kneaders and further processed. 

There are a number of mixing and processing techniques which have been used successfully to color granulated or powdered polyolefin with pigments or pigment preparations. Powders, for instance, are processed primarily with high-speed mixers, while granulated types respond better to slower mixers. 

Lipid microparticles and nanopellets for oral use were first described by Speiser [11]. Nanopellets are prepared by dispersing melted lipids with high-speed mixers or via ultrasound techniques. Lipospheres developed by Domb are also prepared from dispersed lipids by stirring and sonication [12]. These preparations may contain a high degree of microparticles, which thus excludes an intravenous injection. For other routes of application (e.g., peroral administration), these microparticles might not be a serious problem. Furthermore, the dispersions may be contaminated by metal shed. With optimized conditions, however, mean particles sizes of 1(X) to 200 nm are possible [13]. 

Fig. 18. Schematic diagram of non-fluxing high-speed mixer...

The important concept for scale-up is the principle of similarity (1-6). When scaling up any mixer/granulator (e.g., planetary mixer, high-speed mixer, pelletizing dish, etc.), the following three types of similarity need to be considered geometric, kinematic, and dynamic. Two systems are geometrically similar when the ratio of the linear dimensions of the small-scale and scaled-up system are constant. 

Figure 5 Power consumption profile of a high-speed mixer (Collette-Gral 751) with peak and level detection. Source From Ref. 8.

Usteri M, Leuenberger H. Agglomeration of binary mixtures in a high speed mixer. Int J Pharm 1989 55 135-141. 

In order to rescue the amounts necessary to be added, PS-encapsulated Mg(OH)2 has been prepared. In a high speed mixer Mg(OH)2 was dispersed together with 3-(methacryloxy)propyltri-methoxysilane in acetone solution. After drying, the powder was encapsulated with PS by polymerizing styrene in the mixer. It is believed that the thus modified Mg(OH)2 can be more finely divided in the HIPS matrix an in this way better flame retardancy at lower levels of Mg(OH)2 is achieved (22). 

Mix 2 mL of the RIP solution with 2 mL of Freund s complete adjuvant and emulsify, using a high-speed mixer. 

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