Equivalent mechanical properties of X-ray and E-beam cross-linked vitamin E blended ultrahigh molecular weight polyethylene.

The influence of X-ray cross-linking compared with electron beam cross-linking on the mechanical and thermal properties of UHMWPE blended with 0.1 wt% vitamin E was investigated. Two X-ray doses (80 and 100 kGy) and two irradiation temperatures (RT: room temperature; 100 °C: warm) were considered. The reference was Vitelene® a vitamin E stabilized UHMWPE cross-linked with 80 kGy e-beam at 100°C. Uniaxial tensile and small punch testing were conducted. The Izod impact strength and the thermal properties were determined. The yield, ultimate tensile strength and elongation were 21.7 MPa, 48 MPa, and 393% for Vitelene® and 21.7 MPa, 47 MPa, and 402% for X (80 kGy)-warm, respectively. The peak load, ultimate displacement, and work to failure accounted for 63 N, 5.7 mm and 331 mJ for Vitelene® and 65 N, 5.6 mm, and 322 mJ for X (80 kGy)-warm respectively. The Izod impact strength of Vitelene® amounted to 81 kJ/m2 , that of X (80 kGy)-warm to 82 kJ/m2 . Crystallinity of both was 52%. The melt temperature of Vitelene® was 140 °C, that of X (80 kGy)-warm 139°C. In conclusion, using the same irradiation temperature (100 °C) and dose (80 kGy), the different radiation sources e-beam and X-rays resulted in equivalent thermal and mechanical properties.