Papers by Keyword: Ultra-High Molecular Weight Polyethylene

Abstract: Ultra-high molecular weight polyethylene (UHMWPE) has been used as a bearing material in total joint replacements due to its excellent mechanical properties and biocompatibility. The acetabular cup in total hip replacement and the tibial component in total knee replacement is widely fabricated from UHMWPE. The use of UHMWPE in total joint replacements is well established, and the goal is to improve its mechanical properties, wear resistance, and oxidation resistance. The quality and life span of the artificial joints can be further increased by enhancing the relevant mechanical properties of UHMWPE. The addition of filler material to UHMWPE is an effective way to enhance its relevant properties. In this study, relevant properties of UHMWPE were enhanced by incorporating an appropriate filler. Reduced Graphene Oxide (rGO) was selected as a filler material as it improves mechanical properties, wear resistance, toughness, and thermal stability. Graphene oxide (GO) was synthesized by Modified Hummer’s Method (MHM), and it was thermally reduced to obtain rGO. The synthesized GO was characterized by Fourier Transform Infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD) which confirmed the accurate synthesis. The reduction of GO was validated by the disappearance of (OH) broad peak in the FTIR analysis. The rGO/UHMWPE nanocomposite was prepared by adding 0.7 wt.% of rGO employing the solvent mixing method. The morphology of the composite was validated by Scanning Electron Microscopy (SEM). Tensile and Izod Impact tests were performed on the samples which showed an increase in tensile strength of 33.2% and the impact strength increased by 140.5%. The rGO/UHMWPE nanocomposite with greater tensile and impact strength is an excellent candidate to produce orthopedic implants with superior properties.

Abstract: This study investigates the ballistic resistance of composite plates composed of a silicon carbide (SiC) strike face and ultra-high molecular weight polyethylene (UHMWPE) layers against 7.62 mm NATO caliber projectiles using Ansys Explicit Dynamics. Five ballistic plate samples were numerically modeled, featuring 40 to 60 UHMWPE layers and a 4 mm SiC strike face. The simulation assessed the plates' response, including backface signature, bullet penetration depth, absorbed kinetic energy, and deformation mechanisms. The findings revealed that increasing the UHMWPE thickness reduces both the backface signature and bullet penetration depth. Plates with 50 to 60 layers of UHMWPE met level III NIJ standards, demonstrating lower backface signatures and bullet penetration compared to those with 40 or 45 layers. Thicker UHMWPE layers were associated with reduced deformation, with the plate featuring 60 layers of UHMWPE and an overall thickness of 25 mm emerging as the optimal configuration for level III ballistic protection.

Abstract: In this work, studies have been conducted on the treatment of ultrahigh molecular weight polyethylene (UHMWPE), which is one of the structural materials used in the endoprostheses, with atmospheric pressure plasma in high-purity argon and helium. For this purpose, an installation consisting of a high-voltage pulsed generator, voltage and current measuring devices and a reaction quartz chamber with electrodes, in which UHMWPE samples were placed, was developed and constructed. It is shown that processing under certain conditions in Ar plasma and He at atmospheric pressure leads to the appearance of terminal double bonds in the structure of the processed polyethylene, as evidenced by the appearance of a peak of 880 cm^-1, in the attenuated total reflection IR spectrum. This peak is observed both for samples treated in helium and argon plasma. The formation of such bonds is a consequence of the generation of active radicals in the UHMWPE surface layer under plasma treatment, which, during recombination, also form intermolecular crosslinking, thereby increasing the strength characteristics of the material as a whole. The modification of the surface of the treated samples begins within the first minute of processing and reaches its peak values 10-20 minutes after treatment in plasma.

Abstract: The main aim of this paper is to study and analyze methods of predicting the serviceability and lifespan of ballistic armors made of a high-strength polyethylene ultra-high molecular weight (UHMWPE) fibers composites. Experimental tests were conducted on the accelerated use of composite ballistic inserts in lab to predict the durability; changes in the ballistic, physical, and mechanical properties occurring due to accelerated conditions of use. Data of following ageing simulation methods under controlled environment was used. 1-Application of mechanical load to the insert, 2-application of mechanical load and temperature cycle treatment to the product and 3-applying mechanical load, temperature cycle and immersion in liquid solution simulating human sweat to the test product. It was revealed that mechanical loading, temperature cycling, and the solution simulating human sweat incites the degradation and disintegration of the polyethylene material. To evaluate the correlation between the natural ageing process and the simulated one, ballistic insert samples were also examined under natural conditions for 5, 7, 9 and 13 years. Ansys Workbench Explicit Dynamics (R1 2020) and Solidworks (2018) were used to model and simulate the ballistic impact on standard product as well as accelerated aged samples. Experimental testing data was used in simulation and results were compared to analyze the ageing behavior of composite armor.

Abstract: A comparative analysis on structure, mechanical and tribological properties of a multicomponent extrudable polymer composites "UHMWPE + 17 wt. % HDPE-g-SMA + 12 wt. % PP" fabricated by i) FDM (fused deposition modeling) as well as hot pressing of ii) powder mixture, and iii) granules of the same composition has been conducted. It is shown that UHMWPE composites obtained by the 3D–printing over a complex of tribomechanical properties (wear resistance, friction coefficient, elastic modulus, yield point, tensile strength, elongation at break) are comparable with those of composites fabricated by compression sintering of granules (this is associated with formation of more homogeneous permolecular structure, first of all, due to the compounding with the help of a twin-screw extruder) and significantly exceed those for hot pressing of powder mixtures. The obtained results allow one to recommend this composite for manufacturing complex shape products for tribotechnical application at employing 3D-printing technologies.

Abstract: Geopolymer are being considered for a variety of application including formation of ceramics. The addition of Ultra High Molecular Weight Polyethylene as binder in geopolymer based ceramic is purposely to enhance the strength and toughness of the ceramic materials. This paper aims to study the relation of density and flexural strength of geopolymer based ceramic with addition of Ultra High Molecular Weight Polyethylene as binder. Geopolymer were synthesized by fixing the NaOH molarity, Na₂SiO₃/NaOH and solid to liquid ratio at 12 M, 0.24 and 1.0 respectively. Geopolymer in a powder form with addition of various content of UHMWPE (2 wt.%, 4 wt.%, 6 wt.%, 8 wt.% ) were pressed into pellets followed by sintering at 1200 °C. The highest flexural strength of geopolymer based ceramics was achieved at sintering temperature of 1200 °C which is 92.1 MPa with a lowest density of 1.88 g/cm³.

Abstract: In connection with the huge range of ultra-high molecular weight polyethylene (UHMWPE) grades, the choice of a particular brand is a difficult task. Rational choice of the polymer matrix is a necessary condition for the increase in reliability and service life of products, and consequently, for the efficiency of using these composite materials. The given article presents the results of tests on stress-strain properties of GUR-2122, 4113, 4120, 4130, 4150, 4170 and GHR-8020 ultra-high molecular weight polyethylene grades. GUR-4150 UHMWPE is chosen as the polymer matrix on the base of the test results. It is shown that the friction coefficient of the polymer composite material is reduced even with the modification of UHMWPE with nanodispersed thermally expanded graphite (TEG) in amount of 0.001-0.5 mass%. It is established that the rate of mass wear decreases by 3-4.3 while maintaining the stress-strain properties of the composites at the level of the initial UHMWPE. Polymer composite materials with an improved set of performance indicators are developed.

Abstract: The results of the research of the resistance of reinforced polymeric composite materials to hydro-abrasive action are presented. Hydro-abrasive wear research was carried out on a specially developed device that makes it possible to study the wear resistance of materials and coatings under impact conditions of loosely suspended abrasive particles simulating the flow of a hydro-abrasive medium. Composites based on polyester resin and polyurethane reinforced with ultra-high molecular weight polyethylene (UHMWPE) fibers and glass fibers were chosen as the objects for the study. An analysis of the intensity and nature of wear of these composites in compared with structural steel, UHMWPE and polyurea was carried out.The analysis of the obtained research results shows that UHMWPEis the most resistant to hydro-abrasive effects. However, the high cost and variation of the traditional technology of manufacturing composite products using UHMWPE as a lining material shows the advantage of using composite materials reinforced with oriented UHMWPE fibers.

Abstract: Ultra-high molecular weight polyethylene (UHMWPE) is a tough semi-crystalline polymer employed widely as a bearing material in total joint replacements. The micromechanical model has been presented that predicts stiffness of UHMWPE as an aggregate of crystalline inclusions (lamellae) embedded in a rubbery matrix of amorphous polymer chains. The differential scheme was chosen for its ability to represent the interaction between an inclusion and the matrix. Numerical simulations show that increasing lamellar thickness results in less stiffness, less shear stress imposed on the lamellae, indicates that thick lamellae are desirable for UHMWPE materials utilized in total joint replacement bearings.

Abstract: This paper studies the influence of work conditions, difference compression load and counterface roughness, on UHMWPE under abrasive wear test without lubrication according to GOST 426-77. It was found that the formation of deep and wide furrows on worn surface and abrasive intensity increased when the number of grit grade was decreased (average grit size increase). The behavior of abrasive wear can be classified as follows: the first characteristic volume loss quickly increases in the beginning of running time about 5-15 minutes, which is referred to as “run-in” wearing stage; the second characteristic volume loss regularly increases after running time about 15 minutes, which is approaching to “steady-state” wearing stage. In addition, the abrasive wear intensity increase with increasing compression load and/or decreasing number of grit grade (average grit size increase). The results of this research can be applied to abrasive applications in mechanical engineering.