SILVERSON

The appropriate amount of biocide carrier composition needed to yield a specified dry film concentration of biocide was added to a fixed quantity of waterborne acrylic paint and premixed using a high-speed disperser. This dispersion was then transferred to a Silverson-type mixer to obtain a finer dispersion. At this stage the influence of addition of silica or zeolite on the physical/mechanical properties of the paint film was assessed, though only minor changes in properties were noted, which could be eliminated by appropriate adjustments to the paint formulation. 

Fig. 4.2 Silverson Homogenizer machine used for shearing liquid in water to form emulsions...

Stable aqueous emulsions were prepared consisting of vegetable oils and fatty acids, nonionic surfactants and deionized water, and prehomogenized with the Fisher Sonic Dismembrator and completed with the Silverson Flomogenizer (emulsifier turbine). 

Heavy Duty Laboratory Mixer Emulsifier, Model L4RT-A, Silverson Machines Ltd., Waterside Chesham, Bucks., England, HP5 1PQ. 

These particles require no activation, but can be made super-fine by stirring a 10% suspension in 0.1 M NaHCOs, pH 8.5-9, with a high-speed mixer (e.g., Silverson Laboratory Mixer-Emulsifier). 

Rotor-stator Silverson Model GX25 Production scale batch Maximum rpm 3600 2400 L (low viscosity) Emulsions dispersions. 

Fig. 6 Portable batch mixer on mobile hydraulic floor stand (Courtesy of Silverson Machines, Inc., East Long Meadow, Massachusetts).

The process employed Eor the preparation of a primary emulsion, high-speed mixers (e.g., Elado (Ystral), UltraTurrax or Silverson) may be used. For the secondary emulsion preparation, a low-shear mixing regime is required, in which case paddle stirrers are probably the most convenient. The mixing times, speed, and order of addition need to be optimised. 

Oil/water emulsions were prepared (28) by mixing dichlorodecane (DCD, volume fraction 1%) into a 5 x 10 M sodium dodecyl sulfate (SDS) solution with a Silverson homogenizer. The oil phase was a 70 1 mixture of DCD, which is characterized by an extremely low density contrast to water, and decane. 

IKAMASCHINENBAU TOKYO,UNIVERSITY SWANSEA,UNIVERSITY COLLEGE KARLSRUHE,UNIVERSITY SPRETEC FRYMA GUEDU CLEXTRAL SA SILVERSON... 

Tissue homogenates were prepared from laboratory stocks of mice, rats and Chinese hamsters and from human post mortem material using a Silverson mixer emulsifier. Cell lines of rodent and human origin were cultured by standard methods and homogenates were prepared by brief sonication of cell pellets. Haemolysates were prepared by freeze-thawing saline washed erythrocytes. 

Cooke M, Rodgers TL, Kowalski AJ (2012) Power consumption characteristics of an in-line silverson high shear mixer. AlChE J 58(6) 1683-1692... 

HaUa S, Paceka AW, Kowalskib AJ, Cookec M and, Rothmand D (2012) The effect of scale of liquid-liquid dispersion in line Silverson Rotor Stator Mixers. 14th European conference on mixing, Warszawa... 

Thus, emulsion formation is non-spontaneous and energy is required to produce the droplets. The formation of large droplets (few pm) as is the case for macroemulsions is fairly easy and hence high speed stirrers such as the Ultraturrax or Silverson Mixer are sufficient to produce the emulsion. In contrast the formation of small drops (submicron, as is the case with nano-emulsions) is difficult, requiring a large amount of surfactant and/or energy. 

Another popular rotor-stator design is the Silverson Machines or Ross type. The rotor is a radial impeller that rotates inside a stationary housing with slots as shown in Figure 8-3a. The rotor moves the fluid radially out of the mixer head through the slots or holes in the stator. Superimposed on the radial flow is a... 

Figure 8-3 Silverson Machines or Ross rotor-stator design (a) head assembly (b) general purpose disintegrating head (c) high-shear screen (d) slotted-screen disintegrating head.

Figure 8-5 Batch or semibatch rotor-stator assemblies (a) Silverson Machines batch mixer on hydraulic double-lift stand (b) IKA Works batch mixa-. (Myers, 1999, reproduced with permission of AIChE 1999.)...

Figure 8-7 Rotor-stator head geometry for the Silverson L4R batch rotor-stator mixer (a) side view (b) bottom view showing rotor (c) range of stator geometries.

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