All the different methods available for sterilization of biomedical
devices are likely to produce modifications of the surface properties.
The use of heat (steam), radiation (b electrons or g photons) or
chemicals (mostly ethylene oxide) is known to affect the mechanical
and optical properties of polymers [9,10]. Radiation, especially
g-rays, has been shown to induce chain scission leading to mechanical
and thermal degradation effects [11]. Steam sterilization,
carried out in a temperature range of 120e130 C, probably does
not affect the molecular structure of polymers, but it leads to postcrystallization
and physical ageing effects [12]. Chemical sterilizing
agents can potentially make medical grade plastics toxic [13] and
can provide insufficient sterility on polymers [9,10]. Modern alternative
sterilization processes such as electron irradiation, UV irradiation
and the application of ozone are still not widespread, but all
of the three methods are known to induce the formation of radicals
in polymers, which might result in similar degradation effects as
the g eradiation [9].