Effect of Humidity on Charge Accumulation on Polymer-Air Interfaces under DC Stress

Paper in proceeding, 2022

Accumulation of charge on polymer-air interfaces stressed with DC voltage has been studied under variable relative humidity (RH). In the experiments, a flat polymeric sample was placed on a grounded copper plate and its open surface was charged by applying a DC voltage to a rod electrode positioned above its center. The charging took place inside a sealed box where relative humidity was fixed by inserting various saturated salt solutions at room temperature. During charging, surface potential distributions were measured at 15 min intervals using a capacitive probe. It was found that the charging became significant at 40% RH for positive polarity and at 51% RH for negative polarity. Above these values, the initial charging rate increased exponentially with relative humidity, and it was substantially greater for positive polarity.