Nano-surface modification of several polymers by low-energy electron irradiation

Summary form only given, as follows. Nanosurface hardening of several polymers has been observed by high-fluence, low-energy electron beam irradiation. The energy of the electron beam is 50 keV and the fluence is 7 5 /spl times/ 10/sup 17/ electrons/cm/sub 2/. The hardness of the polymers is dramatically increased in near surface region less than 100 nm and reaches about 3 GPa, which corresponds to the hardness of stainless steel. The phenomena are observed for both the radiation-crosslinking polymers such as polyethylene and polystyrene and radiation-degrading polymers like polymethyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE). Both the Raman spectra and the FTIR spectra of the irradiated polymers show that the nanosurface hardening is caused by a transformation of the near surface polymer into an amorphous carbon.