scholarly journals Enhancing Thermal and Mechanical Properties of UHMWPE/HA Composite as Tibial Tray

2020 ◽  
Vol 20 (3) ◽  
pp. 597
Author(s):  
Yusuf Bramastya Apriliyanto ◽  
Sri Sugiarti ◽  
Sulistioso Giat Sukaryo
Keyword(s):  
Mechanical Properties ◽  
Gamma Irradiation ◽  
Gamma Rays ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Thermal And Mechanical Properties ◽  
Artificial Joints ◽  
Tibial Tray ◽  
Physical Strength ◽  
Ultrahigh Molecular Weight ◽  
Press Method

A bearing material in an artificial knee joint has to have good thermal and mechanical properties to prevent wear in order to be used as a tibial tray. Despite its well-known good properties, ultrahigh molecular weight polyethylene (UHMWPE) still needs to be modified to enhance its physical strength in its use in artificial joints. In this research, composites made from UHMWPE and hydroxyapatite (HA) were prepared by mechanical alloying and hot press method and their thermal and mechanical properties were modified using gamma rays. The composites were prepared using various HA loading ratios and irradiated using gamma rays at doses of 0, 25, 50, and 75 kGy. The effects of HA loading and gamma irradiation on thermal and mechanical properties were studied by various methods. The results showed that the addition of HA enhanced the hardness of UHMWPE by 8–15% and the maximum stress up to 38%. Gamma irradiation enhanced the crystallinity by 113–172%, the melting point by 0.6–0.7%, and decreased the break elongation of composites by 23–48%. Addition of polyvinyl alcohol (5% w/w) in composites reduced their rigidity by 16–47% and hardness by 3–9%.

Effect of Polyethylene Jacket on Swelling Behavior and Mechanical Properties of PVA Hydrogel Nucleus Pulposus Prosthesis

2011 ◽  
Vol 287-290 ◽  
pp. 2042-2045 ◽  
Author(s):  
Jin Gao ◽  
Wei Zhu ◽  
Xian Zhou ◽  
Xiao Gang Li
Keyword(s):  
Mechanical Properties ◽  
Nucleus Pulposus ◽  
Free Water ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Relaxation Property ◽  
Dsc Analysis ◽  
Equilibrium Water Content ◽  
Ultrahigh Molecular Weight ◽  
Pva Hydrogel ◽  
Dimension Ratio

New prosthetic nucleus which consisted of ultrahigh molecular weight polyethylene (UHMWPE) jacket and polyvinyl alcohol (PVA) hydrogel core was prepared and studied. The hydrogels with similar size were encased in polyethylene jacket of different dimension. Studies indicate that with the decrease of jacket dimension, swelling time of prosthetic nucleus increases, the equilibrium water content and volume change ratio decrease. Differential Scanning Caborimetry (DSC) analysis shows that increasing the jacket dimension results in a slight increase of non-freezable bond water and significant increase in free water. The prosthetic nucleus with larger jacket has better stress relaxation property due to the plasticization of non-freezable water. These results suggest that the dimension ratio of jacket to core at 1.19-1.35 is the most suitable for artificial nucleus pulposus

scholarly journals Co-Processing of [Fe(NH2trz)3](2ns)2 and UHMWPE into Materials Combining (Spin Crossover and High Mechanical Strength

Sci ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 66
Author(s):  
Manuel Baumgartner ◽  
Raphael Schaller ◽  
Paul Smith ◽  
Irene Weymuth ◽  
Walter Caseri
Keyword(s):  
Mechanical Properties ◽  
Coordination Polymer ◽  
Spin Crossover ◽  
Magnetic Transition ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
High Mechanical Strength ◽  
Flexible Films ◽  
Ultrahigh Molecular Weight ◽  
Crossover Behavior ◽  
Poor Solvent

The coordination polymer [Fe(NH2trz)3](2ns)2 exhibits the rare phenomenon of spin crossover in an attractive temperature range, i.e., somewhat above room temperature. Spin crossover in [Fe(NH2trz)3](2ns)2 is manifest by thermochromism, which is accompanied by a magnetic transition from diamagnetism to paramagnetism. However, [Fe(NH2trz)3](2ns)2 is brittle and difficult to process, which limits its use. In this study, we show that [Fe(NH2trz)3](2ns)2 can be co-processed with ultrahigh molecular weight polyethylene (UHMWPE), which possesses outstanding mechanical properties, particularly when tensile drawn. Therefore, [Fe(NH2trz)3](2ns)2–UHMWPE blends were gel-processed by extrusion, employing a relatively poor solvent, which has recently been shown to offer advantages compared to good solvents. Uniform and flexible films, ribbons and fibers with [Fe(NH2trz)3](2ns)2 fractions as high as 33.3% m/m were obtained that could be readily drawn. Spin crossover in the coordination polymer is retained in these materials, as evident from their thermochromism. The tensile strength and Young’s modulus of the blends exceed those of typical commodity polymers. Thus, the films, ribbons and fibers constitute a special class of multifunctional materials that combine the flexibility and excellent mechanical properties of drawn UHMWPE with the spin crossover behavior of [Fe(NH2trz)3](2ns)2.

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