Charge generation on dielectric surfaces

Measurements have been made of the charge density produced on dielectric surfaces by contact with metals of known difference in work function in vacuo. The injected charge density is dependent on the metal work function and, therefore, described by electron transfer for all the materials examined. Values of work function are presented for PVC, 4·85 ev; polyimide, 4·36 ev; PTFE, 4·26 ev; polycarbonate, 4·26 ev; PET, 4·25 ev; polystyrene, 4·22 ev; and nylon 66, 4·08 ev. The positions of some of these materials in the familiar `triboelectric series' are readily described by their work functions.