Superior electrets of polychlorotrifluoroethylene (Aclar)

A polymer film of Aclar (PCTFE) is corona-charged above room temperature and its charge stability for different charging temperatures is studied using thermally stimulated currents (TSC). Negative charging is found to be more efficient. Analysis of the TSC curves shows that Aclar charged at 135 degrees C has three times more charge in deep traps than Teflon charged at 180 degrees C. Since Aclar also has better mechanical and moisture barrier properties, it makes a superior electret for most practical applications. High-temperature corona charging with subsequent quenching is much faster and hence a valuable method for commercial production of long-lived electrets.