SURFACE MODIFICATION OF POLYSTYRENE BY GAMMA-RADIATION

The effect of gamma-radiation on the surface chemical properties of polystyrene was studied by ESCA and FT-IR. Gamma-radiation produces surface >C=O and C-O containing functional groups only, and also causes oxidation to depths >10 nm as detected by ESCA. FT-IR spectra showed that below the top few molecular layers ester, acid, and carbonyl groups of various types were present. The α,β-unsaturated carbonyl/acid groups form a higher proportion of the total carbonyls with increasing depth. Surface oxidation follows pseudo-first-order kinetics; the extent of interior oxidation is linear with dose.