Laser Diffraction at elevated temperatures
Powders dispersed in liquids can behave differently at process temperature and room temperature and could have different particle size distributions. Therefore it might be necessary to know the particle size distribution at higher temperatures.

A special setup is developed to investigate samples at higher temperatures up to 85 °C. The setup is made by placing the 1L dispersion tank with reinforced PVC tubes, which could handle higher temperatures. These tubes are thicker than the standard tubing and have gold-painted screws that are used to attach them to the instrument (measurement cell). In front of the tank, a tripod holding a temperature sensor and a heating element (350W) are placed in the liquid in the dispersion unit. Both the sensor and heating element are controlled by a temperature controller. The measurement cell is isolated with Styrofoam and the tank’s surface (where the liquid is visible) is also packed with Styrofoam, which is tailored in both cases.

When performing the measurements, approx. 1 liter of the dispersant is placed into the tank (minimum level of the heating element should be achieved).

This is stirred and pumped through the system as the background is checked. Then the dispersant is heated by turning the heating on with the temperature regulator.

The system is stabilized by letting it heat for half an hour after reaching the required temperature.The background is measured.

The sample is heated to the required temperature with a stirring/heating plate. The sample is then homogenized with a top stirrer and an aliquot of the sample is transferred into the 1 liter tank. When the required obscuration is obtained, the sample is measured and the particle size distribution at a higher temperature is obtained.

Our conclusion of the week:
Our setup, with reinforced PVC and precise temperature control up to 85 °C, enables accurate laser diffraction measurements, unveiling the dynamic particle size distribution of powders in a liquid at elevated temperatures.

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