Novel Coupling of a Capacitive Probe with a Dynamic Vapor Sorption (DVS) Instrument for the Electrostatic Measurements of Powders

Abstract

Powders may become electrostatically charged due to friction. This phenomenon may lead to unusual outcomes such as increased cohesion, adhesion and poor flow. It is still a challenge to investigate the electrostatic properties of powders due to restrictions associated with existing methods. The objective is to present a novel coupling method with the Dynamic Vapor Sorption (DVS) instrument using a capacitive probe to measure the electrostatic potential of powders. The critical factors affecting measurements are defined to aid experimental design. The method was tested with glass beads tribocharged after contact with stainless steel to assess the feasibility of the setup via analysis of the repeatability and reproducibility of the data generated. The results obtained show that electrostatic measurements can be performed with minimum noise interference, short equilibration time of 15 min and high reproducibility based on 19 measurements. Stability of experimental conditions of ±0.1 °C and ±0.2% RH is achieved.

Evaluation of a new dispersion technique for assessing triboelectric charging of powders

“…This approach allowed the study of charge distribution in a bipolar system as a function of different process parameters. Recently, Smyth et al (2004), , Zhou et al (2013) and Biegaj et al (2016) employed a non-intrusive procedure involving an oscillating vibrating capacitive probe based on the method of Masuda et al (1995), to measure the contact potential difference and to investigate triboelectric chargeability of pharmaceutical powders under controlled environmental conditions. Kwok et al (2005), Telko et al (2007) and Ali et al (2008) used an Electrical Low Pressure Impactor (ELPI) to measure the triboelectric charging for aerosols.…”

Surface Chemistry and Humidity in Powder Electrostatics: A Comparative Study between Tribocharging and Corona Discharge

“…Triboelectrification of glass beads was measured using a capacitive probe method as reported previously. 50 Briefly, glass beads were stored in a conductive-grounded container under controlled environmental conditions (25 °C, 30–35% RH) for a minimum of 18 h before measurement. A U-shaped stainless steel spatula was used to charge and load particles into the measuring pan, as illustrated in Figure 8.…”