Electrostatic measurements

Electrostatic charging is an unwanted phenomenon in many industrial applications e.g., the problematic of polymer particle agglomeration and adhesion to a fluidized bed reactor wall is still unresolved in today’s polymer industry. It is known that several processes and phenomena are responsible for the adhesion of materials. We are using two instruments to study electrostatic phenomena:

 

Charge decay measurement

This setup (JCI 155v5 Charge Decay Test Unit) allows us to charge polymer sample (powder or film) negatively or positively by corona discharge. Corona charge deposition simulates practical charging events. Applied corona discharge is created by high voltage needle electrode. The needle electrode can be subjected to voltages up to ±10 kV.

Figure 1: Detail view of “field mill” and Charge decay test unit 155v5.

Faraday cup measurement 

Faraday Pail is capable to measure a nett quantity of charge placed into the pail. The pail is not very deep when compared to its diameter (a height to diameter ratio is about 0.63), so the top level of inserted sample must be kept low to ensure that all charge introduced into pail couples to the pail. The sensitivity of the measuring unit ranges to 200nC. Triboelectrification of the sample (polymer particles) could be done by different methods (shaking in the vessel, rolling on the ramp, charged by corona discharge, …).