Positron annihilation lifetime spectroscopy studies of irradiated poly(propylene-co-ethylene)/poly(ethylene-co-vinyl acetate) blends

The positron lifetimes and Doppler broadening of the annihilation line are measured in poly(propylene-co-ethylene) (PPE)/poly(ethylene-co-vinyl acetat e) (EVA) blends containing 10, 30, 50 acid 60 wt% PPE before and after irra diation with fast electrons. On the basis of the values of the longest-live d ortho-positronium component in lifetime spectra the radii of the free-vol ume holes in amorphous regions of the blends are calculated. A sharp decrea se of the values of the free-volume holes radii is established for PPE cont ent in the range 30-50 wt%, The study of the irradiated samples showed that at low electron doses (up to 100 kGy) a crosslinking process prevails whil e at higher doses the net effect of irradiation is scission of polymer chai ns. Comparison is made of the results obtained by positron annihilation spe ctroscopy (PAS) and wide angle X-ray diffraction (WAXD). (C) 2000 Elsevier Science Ltd. All rights reserved.