Study On The Preparation And Properties Of HDPE/UHMWPE/HA Composites

By means of melt blending process, the blend of high density polyethylene HDPE)/ultra high molecular weight polyethylene (UHMWPE) and the composite biomaterials of HDPE/UHMWPE/Hydroxyapatite (HA) were prepared respectively. The performances of composite on the mechanical properties, thermal stability, and rheological properties were evaluated. The crystal properties and non-isothermal crystallization kinetics were tested by differential scanning calorimetry (DSC) and microstructures were observed by scanning electron microscopy observation (SEM).By selecting UHMWPE resins with different molecular weight (M=200,350,600,900million), the blends of HDPE/UHMWPE were prepared separately. It indicates that the effects of UHMWPE with average molecular weight600million on the properties of HDPE blend are comparatively better. With the addition of UHMWPE, tensile strength, elastic modulus and heat distortion temperature (HDT) are increased. With the UHMWPE content increasing, the apparent viscosity of blend is declined with shear rate increasing, the apparent viscosity of the blend is more and more sensitive to the shear rate, and melt flow rate (MFR) is decreased rapidity.HDPE/UHMWPE/HA composites were prepared with HA and HDPE/UHMWPE blend with mass ratio90:10. With the HA content in HDPE/UHMWPE blend increasing, the tensile and flexure properties are increased preliminary and then decreased, meanwhile, the impact strength of the composites decreases because of brittle HA. The melt flow rate (MFR) values of composites are decreasing by the addition of inorganic particles. Thermal stability is decreased. By selectively using three kind of interfacial modifier (EPDM-g-MAH, HDPE-g-MAH, and POE-g-MAH) added into the HDPE/UHMWPE/HA composites, among which the effect of EPDM-g-MAH is relatively better. When the content of EPDM-g-MAH is around4phr and2phr respectively, the tensile strength and flexure strength of composites reaches the peak value, meanwhile, the impact strength increases remarkably at the same time and the agglomerate HA is reduced. However, the melt flow rate decreases with the content of EPDM-g-MAH increasing compared with HDPE-g-MAH.By addition of dispersant, the mechanical properties, MFR, and thermal stability of HDPE/UHMWPE/HA/EPDM-g-MAH composites are improved, the peak value appeares at the dispersant content of0.6phr. Considering the comprehensive performance, the modified effects of INT-40DHT are obvious.In non-isothermal crystallization kinetics experiment, Mo method had been calculated that it was suitable for HDPE/UHMWPE blend and the three composites containing EPDM-g-MAH, HDPE-g-MAH, and POE-g-MAH respectively. With the molecular weight of UHMWPE increasing, the crystallization rate of composites decreases, and the activation energy of crystallization increases. When adding POE-g-MAH, the crystallization rate is faster and the activation energy of crystallization of composites is lower than that of the other two ones, the HDPE-g-MAH is middle and the last one is EPDM-g-MAH.The composites of HDPE/UHMWPE/HA, HDPE/UHMWPE/HA/EPDM-g-MAH, and HDPE/UHMWPE/HA/EPDM-g-MAH/dispersant were analyzed by Jeziorny and Kissinger method. The results show that the addition of interfacial modifier and dispersant in the composites bring on the crystallization rate become faster and the activation energy of crystallization decreases.