论文部分内容阅读
Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study is to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1 wt% ALN-loaded UHMWPE (UHMWPE-ALn ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALn ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALn ma. Tensile test and small punch test show that Youngs modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALn ma increase significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALn ma both decrease significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduce type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALn ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It is attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALn ma and UHMWPE-ALN, respectively. Moreover, EDS spectra reveal the more homogeneous distribution of ALN in UHMWPE-ALn ma compared to that of UHMWPE-ALN. In summary, mechanical activation is able to significantly increase the mechanical properties and wear resistance of UHMWPE-ALN. The main mechanisms of mechanical activation are that peeled-off layer and chain scission of UHMWPE particles improved the compaction and self-diffusion during compression molding, reducing two types of fusion defects. Aforementioned combines with the homogeneous distribution of ALN in UHMWPE-ALn ma will increase its mechanical and tribological properties. The present results show that mechanical activation is a potential strategy to improve mechanical and tribological properties of UHMWPE-ALn ma as an orthopeadic biomaterial for joint replacements.