Abstract: NVP was grafted onto surface of polyurethane to prepare TPU-g-PVP copolymer by ⁶⁰Co-γ irradiation. Fourier transform infrared spectroscopy(FT-IR) and scanning electron microscope(SEM)were used to characterize the copolymer structure, and the absorbed dose，solvent composition，NVP content，and the solution pH value were studied. It showed that the grafting ratio of the copolymer increased with increasing radiation dose and NVP content，it had a higher grafting ratio with ethanol content of 60%in neutral and alkaline conditions. Hydrophilic and lubrication performance test showed that the hydrophilicity and luhricity of the copolymer increased significantly with increasing grafting ratio. The optimum process conditions for this system were: ethanol 60%，pH 7，NVP 20%，and irradiation dosel0 kGy, the grafting ratio may reached 20%.

Key words: γ irradiation grafting;polyurethane, N-vinyl pyrrolidone, hydrophilicity, luhricity