Miniature internal mixers

The tolerance allowed on mass of ingredients is fairly tight at 1% generally but down to 0.02g for sulphur and accelerators. For miniature internal mixers this reduces even further to 0.002g. There are limits on the difference between the sum of the masses of the ingredients and the final mass of the mixed batch of between + 0.5% and - 1.5%. Carbon black is required to be conditioned before use to remove moisture but it seems curious that this is not required for other fillers. 

Standard mills can be used that have diameters of about 150 to 155 mm. The rolling speed should be about 0.4 rad/s, with the ratio between the fast and slow roll at 1.4 to I. The standard internal mixers used should be about 1550-1600 cm in volume. If smaller volumes are required, the miniature internal mixer to be used should have a capacity of... 

For either reactive or non-reactive blends in an extruder, internal mixer, or a miniature cup-and-rotor mixer, similar morphological features were observed. Initially, during melting, the polymers were stretched into sheets and ribbons, which broke into fibers, then in turn into drops. One reason that may explain the reported differences in morphology is the concentration of the dispersed phase — 5 vol% was used by the first authors, whereas > 20 wt% by the latter. More detailed information of this, as well as on the topic discussed in the following part, will be found in Chapter 9 Compounding Polymer Blends. 

One of the most successful mixers used in research laboratories is the internal batch mixer (Thermo-Haake Corp., Karlsruhe, Germany and Madison, WI, and Brabender, South Hackensack, New Jersey both produce versions of this mixer). This mixer produces structures similar to those created when the material is later processed by conventional industrial methods such as twin-screw extrusion. This mixer requires an approximate sample mass of 50g, which may be quite excessive for newly synthesized or specialty materials. Therefore, we created and tested a miniature version of this mixer. 

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