WATER DIFFUSION IN POLYETHYLENE MODIFIED BY ION IRRADIATION

Water diffusion in polyethylene (PE) modified by irradiation with 40 k eV Ar+ ions to fluences of 1 x 10(12) to 1 x 10(15) cm(-2) was studied . The diffusion experiments were performed in a temperature interval f rom 25 to 100 degrees C and for diffusion times of up to 3 h. The wate r incorporated was detected by infra-red spectroscopy, microgravimetry and by measuring contact angles. Maximum water uptake observed for th e ion fluence of 1 x 10(13) cm(-2) may be connected with an increase i n free volume fraction and oxidative processes in the PE surface layer modified by ion irradiation. For higher ion fluences, the available f ree volume is reduced owing to carbonization and crosslinking of the p olymer and, accordingly, the water content decreases. The water incorp orated in PE is mostly in the form of isolated molecules. At elevated temperature rediffusion of water is observed. (C) 1998 Elsevier Scienc e Limited. All rights reserved.