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ANALYTICAL AND LABORATORY EQUIPMENT 23


The shear-rate depends on the circumferential speed and the size of the gap between the rotor and stator


Te oil droplets get finer and finer and eventually reach a size where they can form a stable emulsion. Te emulsifier will stabilise the emulsion to keep it from separating again. Te smaller the oil droplets are, the more stable the emulsion will appear.


Stirring


While the oil and water phase are homogenized the product is usually stirred at the same time to speed up the process and allow it to be most thoroughly mixed inside the reaction vessel. When the viscosity of the product rises it is of especially high importance to use scrapers on the stirring element inside the stirred vessels wall and bottom to keep the product in motion and move it back into the centre of the vessel and away from the walls. If other ingredients are added to a more viscous product these should be distributed evenly throughout the whole product. Tis is of particularly high importance when producing pharmaceutical products such as ointments, which contain an active ingredient.


Heating and cooling Heating and cooling allows the user to first heat up the oil phase, which could also be a wax that is solid at room temperature. Instead of heating the oil phase separately on a heating plate or magnetic stirrer, it can be performed right within the reactor-system.


At the end of the product’s formulation it is usually cooled down to room temperature. By using double-walled glass


reactor vessels it is easy and convenient to heat and cool the product with an oil- or water- thermostat, depending on what temperatures are required. If a thermostat is connected to a temperature sensor that is placed into the product inside the reactor, the temperature of the oil surrounding the product can be controlled in a way that the products temperature will be most exact.


Cosmetic products show a change in viscosity during the production process. Tese allow further interpretation of the products’ comparison to other batches, behaviour, stability and sensitivity to certain influencing variables that can be changed. Viscosity measurements


require removing sample material from the vessel during the process and do not allow a continuous interpretation. Te Eurostar control


stirrers allow monitoring of these changes during the actual process of producing


The LR.2ST is IKA’s all-rounder lab reactor


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