Effect of electron beam irradiation and plastic deformation on molar mass of medical grade ultra-high molecular weight polyethylene

Separated and combined electron beam irradiation (as a sterilization procedure) and plastic deformation effects on the average molar mass of ultra-high molecular weight polyethylene (UHMW-PE) were studied. It was found, that both irradiation and deformation have a different impact on the polymer structure. With the growing irradiation dose the mass-average molar mass (Mm) of the polymer soluble fraction reduces and the amount of insoluble fraction (gel) increases. On the other hand, the plastic deformation of UHMW-PE alone may be considered as not involving any destruction of polymer macromolecules. The combined effect of these factors leads to different results in comparison to their separate action and depends on the sequence of the destructive impacts on the polymer. However independently of the sequence of both external factors their synergetic effect is observed for the degradation of UHMW-PE.