EVALUATION AND CHARACTERIZATION OF CHEMICALLY MODIFIED POLYMERS AS SECONDARY-ELECTRON EMITTERS

Measurements of secondary electron emission coefficient and surface work function phi are reported for polyacrylonitrile (PAN) and polytetrafluoroethylene (PTFE) in the virgin and chemically modified forms. A single pulse method was used for SEE measurements and a retarding field method for estimating the work function. Doping of PTFE with alkali metals (Na and Li) and pyrolysis of PAN at 300 degree C led to an increase in the surface conductivity. The processing of the surface effectively increased the SEE yield in these polymers. Electrical conductivity and XPS results were used to explain the chemical structures of modified polymers.