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The antistatic effect: AEROXIDE® fumed alumina grades from Evonik control the electrostatic charge of powders


With fumed alumina, the electrostatic charge of powders can be controlled and the workability can be significantly improved. Evonik offers hydrophilic types under trade names AEROXIDE® Alu C, AEROXIDE® Alu 65, AEROXIDE® Alu 130 and a hydrophobic grade known as AEROXIDE® Alu C 805 for this purpose.


Many non-conductive powders tend to pick up electrostatic charges upon friction. This may happen e.g. when a polymer powder or granulate is pumped through a pipe or is moved in a mixer. The result is a charged powder sticking to the wall of the pipe or the mixer that cannot be transported further or emptied from the mixer. Small additions of AEROXIDE® fumed alumina grades typically less than 0.1% can result in neutralization of the charge and enable processing. This leads to more precise dosing of powders, better quality, and less downtime.
 
Many synthetic polymers have a high electron affinity and tend to charge negatively. Fumed alumina in contrast tends to pick up positive charges. Moreover, fumed alumina has very fine particles and can be easily dispersed in powders or granulates. Mixing a small percentage of AEROXIDE® fumed alumina with e.g. a polymer granulate results in dispersing the alumina on the surface of the polymer granulate and covering it. The opposite charge compensates and the granulate recovers flowability.
 
The application of AEROXIDE® Alu grades is very easy. Similar to the use as a flow aid it is sufficient to mix the alumina and the host powder with a suitable mixer such as a plough-share mixer, a paddle mixer or a ribbon blender. 
 
AEROXIDE® Alu grades for controlling electrostatic charges are often used in polymer powders. However, they can also be applied in many non-conductive powders or granulates as well. 
 
Detailed information on this subject can be found in the following technical information sheets: Flyer Plastics and Fact Sheet Plastics. more