Mechanisms of decrease in fatigue crack propagation resistance in irradiated and melted UHMWPE.
Adhesive/abrasive wear in ultra-high molecular weight polyethylene (UHMWPE) has been minimized by radiation cross-linking. Irradiation is typically followed by melting to eliminate residual free radicals that cause oxidative embrittlement. Irradiation and subsequent melting reduce the strength and fatigue resistance of the polymer. We determined the radiation dose dependence and decoupled the effects of post-irradiation melting on the crystallinity, mechanical properties and fatigue crack propagation resistance of room temperature irradiated UHMWPE from those of irradiation alone. Stiffness and yield strength, were largely not affected by increasing radiation dose but were affected by changes in crystallinity, whereas plastic properties, ultimate tensile strength and elongation at break, were dominated at different radiation dose ranges by changes in radiation dose or crystallinity. Fatigue crack propagation resistance was shown to decrease with increase in radiation dose and with decrease in crystalline content. Morphology of fracture surfaces revealed loss of ductility with increase in radiation dose and more detrimental effects on ductility at lower radiation doses after post-irradiation melting.
Oral
Ebru
E
Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, GRJ 1206, Boston, MA 02114, USA.
Malhi
Arnaz S
AS
Muratoglu
Orhun K
OK
D003080:Cold Temperature; D003460:Crystallization; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D044367:Phase Transition / Q000528:radiation effects; D011095:Polyethylenes / Q000737:chemistry* / Q000528:radiation effects*; D013718:Tensile Strength
D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene