Study On Vitamin E Diffusion Modified Irradiation Crosslinked UHMWPE/GO Composites And Its Tribological Properties

At present,irradiation crosslinking,adding Graphene Oxide(GO)and vitamin E(VE)have been widely used in the study of enhanced modification of ultrahigh molecular weight polyethylene(UHMWPE).Irradiation crosslinking and addition of GO can significantly improve the mechanical properties and wear resistance of UHMWPE,and VE doping can improve the oxidation resistance of UHMWPE.However,the presence of VE in the irradiation process can reduce the crosslinking degree of UHMWPE materials,resulting in the decrease of its mechanical properties and wear resistance.Therefore,in order to maintain good mechanical properties and wear resistance of irradiated UHMWPE materials and to further improve their antioxidant properties,GO/UHMWPE composites were prepared by hot pressing,and gamma ray irradiation was used to modify the samples by irradiation crosslinking.Finally,the diffusion of VE solution was diffused into the surface of the matrix and homogenized.The effects of VE diffusion modification on the structure,mechanical properties and biological tribological properties of radiation crosslinked GO/UHMWPE composites were studied.The diffusion mechanism of VE on the surface of the sample was analyzed and the diffusion kinetics equation was established.The friction and wear mechanism of the sample in the simulated biological environment was discussed.The specific research content and main conclusions are as follows:(1)The diffusion rule of VE in different UHMWPE composites was studied by VE solution immersion and homogenization treatment,and the diffusion equation was derived.The results show that the soaking temperature(80?,100?,120?)and soaking time(2h,4h,8h,16 h,32h)affect the diffusion of VE.The optimum soaking temperature and time are 120? and 32 h,in this condition,the diffusion quantity of VE in UHMWPE is 6%,and the diffusion depth is 280?m;irradiation cross-linking and addition of GO hindered the diffusion of VE into the UHMWPE matrix;Under the same conditions,the diffusion of VE in the irradiated GO/UHMWPE composite was 0.5%,and the diffusion depth was 70?m.(2)The effects of VE diffusion modification on the thermal properties,gel content,water absorption,contact angle and surface energy of different UHMWPE composites were studied by DSC,gel content,water absorption,contact angle and accelerated aging test.The results showed that after VE diffusion modification,the crystallinity of UHMWPE decreased by 2.3%,the melting point and crystallinity of other materials had no obvious change;VE diffusion modified treatment reduced the gel content of different materials after irradiation;meanwhile,VE diffusion modification increased the oxidation resistance of different UHMWPE composites and reduced their oxidation index.(3)The effect of VE diffusion modification on the mechanical properties of different UHMWPE composites was studied through ball indentation hardness,scratch test and small punch test.The results show that VE diffusion modified treatment reduces the hardness,scratch resistance,peak load and modulus of elasticity of UHMWPE,and the change of the mechanical properties of the other three kinds of materials is consistent with that before soaking in VE solution.(4)The effect of cross shear on the biotribological properties of UHMWPE composites after VE diffusion was studied by friction and wear tester.The results show that VE diffusion modification reduces the friction coefficient and wear rate of different UHMWPE composites,and improves their biotribological properties.