Characterisation of the Surface and Structural ...

It is of vital importance that most medical devices are sterilised prior to use. However, sterilisation performed by ionising radiation can cause significant damage and degradation to polymers due to the energetic secondary electrons released from the primary irradiation event. In this present work, low density polyethylene (LDPE) was subjected to a commercial gamma irradiator and a high energy electron beam irradiator (combined 10/12MeV unit, 30KW). Characterisation was performed on the non-irradiated and irradiated LDPE samples by several analytical methods. X-ray diffraction (XRD) revealed that the percentage crystallinity and crystalline size had no significant alterations. Scanning electron microscope (SEM) imagery illustrated a rougher sample surface subsequent to electron beam irradiation at 400kGy which was perhaps attributed to oxidative degradation. In addition, the fracture behaviour of the cryofractured surface specimens was highly influenced by electron beam irradiation. Colorimetry was employed in quantifying the effects of electron beam and gamma ray processing on the colour changes of LDPE. This technique identified that the gamma ray process leads to more discolouration of the LDPE material, indicating that the electron beam process was more user friendly.