THE INFLUENCE OF MECHANICAL DAMAGING ON THE LIFETIME OF POSITRONS IN ULTRAHIGH-MOLECULAR POLYETHYLENE

摘要

We study the influence of damaging of ultrahigh-molecular polyethylene [(PE-UHMW) Chiru-len?1120] applied, among other materials, in the production of hip endoprostheses on the spectra of positrons lifetime in this material. Polyethylene samples were damaged by the impacts, rolling friction, and collisions with metal balls in a planetary mill. The changes in the parameters of the spectra of positrons lifetime related to the annihilation of orthopositronium (o-Ps) were analyzed depending on the mechanical energy transferred to the sample. On the basis of the Eldrup-Tao model, the changes in the radii of voids in which positroniums are formed and annihilated and the changes in the degree of filling of the space atoms in the examined polymer were determined.