Ultra-high Molecular Weight Polyethylene Composites Research Articles

Optimization through combined compromise solution and weight determination through SHANNON-ENTROPY for multi criteria decision making in tribological testing of ultrahigh molecular weight polyethylene nano-composite in SBF environment and compression testing with it’s invitro analysis

Aluminium oxide and graphene reinforced with ultrahigh molecular weight polyethylene (UHMWPE) composites offer significant potential for prosthetic and implant applications due to their unique combination of properties. In this article, a series of aluminium oxide and graphene reinforced with ultrahigh molecular weight polyethylene (UHMWPE) composites were successfully fabricated through compression moulding. The average hardness of all the composites was observed to be higher than the UHMWPE (6.1 Hv). Composite U-15A-5 G was found to be the hardest with hardness of 10.5 Hv owing to strong bond between Al2O3 and UHMWPE. The compression strength of the U-15A-5 G material was about 81.936 MPa, which is 40.9% better than the pure UHMWPE. The compression modulus was about 330 MPa which is 22.2% higher than neat UHMWPE. Composite samples were tribo tested under simulated body fluid (SBF) lubricating environment. Using combined entropy-COCOSO method it was found that 50 mm/s speed, 200N load and 5% graphene are the optimum tribological parameters. with Cof of 0.04 and wear rate of 4.8745*10−4 mm3/Nm. Microstructure analysis indicated that long-range structured lamellar structures and microfibers were created between the crystals with the assistance of graphene layers. Apatite layer was also found on the sample. The apatite layer included phosphate and carbonate ions, which is good for in vitro bioactivity on polymeric films. This composite is a good candidate for prosthetics and implant components.

Mechanical and bio-tribological behaviours of UHMWPE based composites for prosthetic hip joint implant application

Ultra-High Molecular Weight Polyethylene (UHMWPE) composites reinforced with talc, graphite (GRP), and multi-walled carbon nanotubes (MWCNTs) were evaluated for their physical, mechanical, and bio-tribological performances for their application as acetabular liner material for prosthetic hip implant. Addition of 15 wt% of talc to UHMWPE reduced its friction coefficient and wear by approximately 30 % and 54 %, respectively. The addition of 0.5 wt% of MWCNT increased the coefficient of friction by about 6 % with drastic reduction in the wear (∼ 45 %). Hardness and elastic modulus were higher for the composites. Wear mechanism involved plastic deformation and the formation of protuberances.

Effect of Nitrate Acid Treated Dolomite on the Tensile Properties of Ultra-High Molecular Weight Polyethylene (UHMWPE) Composites

Ultra-High Molecular Weight Polyethylene (UHMWPE) polymers have been used in biomedical applications due to its biocompatibility, durability, toughness and high wear resistance. To enhance the mechanical properties, various types of minerals are commonly utilized as fillers in UHMWPE. One of the minerals is dolomite, which has been recognized as a valuable mineral with versatile applications, particularly in the field of biomedical applications. This paper presents the tensile properties of UHMWPE composites that filled with dolomite and treated-dolomite at various filler loading (i.e., 1-5 wt.%). Nitric acid and diammonium phosphate were used to treat the dolomite. From the results, the peaks of the FTIR spectrum displays carbonate (CO3–2), phosphate (PO4–3) and hydroxyl (OH–) groups in the ct-dolomite powder sample while the XRD pattern reveals that using dolomite treated with 1M nitric acid resulted in the presence of calcium hydroxide phosphate (Ca10(PO4)5(OH)) and MgO. For tensile strength, UHMWPE/ct-dolomite composites show better tensile strength than the pure UHMWPE composites. Treated improve the dolomite filler and resulted in significantly better matrix-filler interfacial interactions and improve the properties.

Insights into synergic antioxidant effects for vitamin E and sugar alcohol stabilized ultrahigh molecular weight polyethylene composites for artificial joints

Oxidation resistance is strongly necessary for the use of crosslinked ultrahigh molecular weight polyethylene (UHMWPE) in artificial joints. The hybrid antioxidant strategy emerged as a promising alternative to the single rival that relies on vitamin E (VE). The goal of this study was to investigate the universality of the antioxidant synergy between VE and sugar alcohol (SA). Three types of SA, including D-sorbitol, maltitol and erythritol, were employed to cooperate with VE. Compared to the use of VE alone, these hybrid antioxidants generally enabled the corresponding UHMWPE composites with prolonged oxidation induction time (OIT) and increased crosslink density. The correlation between OIT and crosslink density of VE/SA-stabilized UHMWPE composites showed low attenuation. The applicability of the hybrid antioxidants to protect UHMWPE against oxidation was further demonstrated using the in vitro clinically relevant accelerated aging. Among the used SA, D-sorbitol exhibited the strongest ability to enhance the synergetic efficiency. The possible mechanism was revealed from the following aspects: the number of secondary hydroxyls per molecular mass and the molecular polarity determined via polarity parameter calculation. These findings provide significant insights for fabricating UHMWPE bearing materials with superior comprehensive performance and extended service longevity.

Effect of γ irradiation and Vitamin-E on the thermal and mechanical properties of graphene/nanodiamond reinforced hybrid UHMWPE nanocomposites

This work focus on solving the problems of fabricating inadequate prosthetic joint from mechanical perspective in total joint replacement. Ultra high molecular weight polyethylene (UHMWPE) composites with different weight fractions of Graphene (Gr) and Nanodiamond (ND) nanoparticles (0.2–0.5 wt %) were prepared by high pressure compression molding. The effect of vitamin E (vit E) and gamma irradiation at 50 kGy and 100 kGy doses on the structural and thermal properties of UHMWPE composites were investigated through swell ratio test, fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical properties including tensile, flexural, impact test, nanoindentation and micro scratch were studied and the fractured surfaces were analyzed under scanning electron microscope (SEM). Influence of gamma irradiation on UHMWPE composites shows better crosslinks and crystallinity in the polymer matrix. The nano-composites shows significant improvements in various mechanical properties compared to the 0.5 wt % vitamin-E + UHMWPE composite, with a 23 % increase in Young's modulus, a 21 % increase in flexural strength, a 24 % increase in hardness, and a 17 % increase in impact strength. The results shows that 100 kGy gamma irradiated composites exhibited better results. Composite with 0.5 wt % vit E + 0.3 wt % Gr + 0.5 wt % ND shown significant improvement in structural, thermal and mechanical properties.

Tribological Characterization of UHMWPE Composites Reinforced with MoS2 and Graphite: A Comparative Study

This study presents a comprehensive analysis of the microstructural, physical and tribological properties of Ultra-High Molecular Weight Polyethylene (UHMWPE) composites reinforced with micro MoS2 and nano Graphite. Microstructural evaluations through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) reveal intriguing insights into the morphology and elemental composition of the reinforcement materials. SEM images unveil the nanoscale hexagonal lattice structure of nano graphite, affirming its suitability for composite applications. EDAX spectra confirm the purity of both nano graphite and micro MoS2, reinforcing their efficacy as reinforcement agents.Density assessments illustrate an increase in composite density with rising reinforcement percentages for both materials, attributed to their inherently higher densities. This increase in density is complemented by reduced porosity, signifying improved packing efficiency within the composite.Wear evaluations under various load and speed conditions elucidate the tribological behaviour of the composites. UHMWPE composites with micro MoS2 exhibit reduced wear rates, frictional forces, and coefficient of friction (COF) compared to neat UHMWPE, emphasizing the effective lubricating properties of MoS2. Conversely, UHMWPE composites with nano graphite outperform micro MoS2 counterparts across all parameters, showcasing superior wear resistance and friction reduction. This is attributed to nano graphite's lamellar structure, which facilitates enhanced lubrication and reduced friction.

Recent Advances in Ballistic Resistance of Lightweight Metal Sandwich Cores

Sandwich construction has proven to be an excellent low-density multifunctional design for a wide range of applications in ballistic protection, energy absorption, and thermal insulation. Based on the bulletproof effect of each layer of the sandwich structure, this paper expounds and summarizes the material properties that can be used as each layer. The mechanical and ballistic properties of ultra-high strength aramid (Kevlar) and ultra-high molecular weight polyethylene (UHMEPE) composites and the ballistic properties of mixed fibers of these two materials versus the mechanical properties of single fiber materials, the mechanical properties, chemical stability and other properties of aluminum and magnesium alloys, the effects of heat treatment and coating treatment on the ballistic properties of aluminum alloys, and finally the energy absorption properties of several common core materials structures are compared.

Graphene oxide versus graphite and chemically expanded graphite as solid lubricant in ultrahigh molecular weight polyethylene composites

Graphene oxide (GO), chemically expanded graphite (CEG) and graphite were evaluated as solid lubricant for ultrahigh molecular weight polyethylene composites. Under dry conditions, the addition of all solid lubricants increased the coefficient of friction by up to 38%. For the composites corrugated stick–slip features were observed which correlate with a decrease in matrix degree of crystallinity. GO had the lowest effect on the crystallisation, resulting in the lowest relative increase in friction coefficient of only 13%. Under water lubrication, GO, CEG and graphite were equally effective in reducing friction and wear. The highest friction for the neat matrix was found to be due to a transfer film, which was suppressed by the addition of the solid lubricants.

Tribological analysis of ultra-high molecular weight polyethylene composites with boron carbide micro and nanoparticles

The goal of this study is to investigate the tribological and morphological changes obtained by addition of boron carbide (B4C) micro and nanoparticles into Ultra High Molecular Weight Polyethylene (UHMWPE/B4C). In this work, UHMWPE was reinforced with B4C micro, nano (powder) and nanoparticles prepared using pulsed laser irradiation in liquid by solvent mixing (SM). Subsequently, the mixtures were compression molded at 180 °C and 15 MPa for 15 min, then cooled for 5 min at different concentrations (0, 0.1, 0.3, and 0.5 wt%) to evaluate the thermal, mechanical, and tribological behavior of these composites. Studies on changes in the structural and morphological characteristics of the composite samples were carried out by means of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The microhardness and scratch hardness of the composites were measured using a diamond indenter revealing nanoparticles outperformed micro-particles in both properties. In addition, the tribological behavior of the hot-pressed composite structures was analyzed via a scratch test machine using a normal load of 10 N and a ball-on-disk tribometer with a normal load of 30 N. As a result, the wear resistance of the composite revealed significant improvement up to a certain amount of particles. The coefficient of friction was also reduced. Worn surface analyses were done on the composite using the confocal and scanning electron microscopy (SEM), indicating various wear mechanisms such as delamination, micro-cutting, micro-plowing, and groove-formation. The composites showed low wear rates and were correlated with scratch hardness.

Low-velocity impact performance of ultra-high molecular weight polyethylene/aramid-polyester core-spun yarn hybrid composites

The impact resistant composite has excellent energy absorption efficiency, but the structure and material selection of the composite have great influence on its energy absorption. In order to explore the effect of structure on the energy absorption of Ultra-high molecular weight polyethylene (UHMWPE) composites and the application potential of new aramid core-spun yarn and new polyester core-spun yarn in impact resistant composites. The UHMWPE composites with different fiber orientations and stacking sequences structure, as well as the new hybrid composites containing aramid core-spun yarn and polyester core-spun yarn were tested by low-velocity impact test and scanning electron microscope (SEM) observation. The differences of energy absorption of UHMWPE composites with different structures and the advantages of the new hybrid composites were analyzed. The results show that the energy absorption of the 45°/0°/90°/−45° UHMWPE composite is 15% and 86% higher than that of the 0°/90°/0°/90°UHMWPE composite and the 0°/90°/45°/−45° UHMWPE composite, respectively, which is the best structure among the three composites. The energy absorption performance of the composites introduced with aramid core-spun yarn and polyester core-spun yarn were improved by 223% and 202%, respectively, so that the energy absorption performance was significantly improved by new yarns.

Towards hybridization of ultra-high molecular weight polyethylene composites by thermally sprayed alumina: Feasibility and bond strength assessment

Composite materials are increasingly inescapable in engineered systems in various industrial fields, given their high strength to weight ratio for increasing autonomy, reducing energy consumption and enhancing mechanical strength of high added value products. However, their out-of-plane resistance could be improved by multimaterial assembly for structural hybridization. The purpose of this study is to explore the possibility of upgrading the shock resistance of UHMWPE Tensylon® by alumina coating. Thermal spraying was used for alumina deposition on UHMWPE and bond strength assessment of the obtained assembly was performed by Laser Adhesion Test (LASAT). During experiments, free surface velocities of specimens were recorded by the use of Photonic Doppler Velocimetry (PDV) allowing relevant observations complementary to optical observations. From the PDV analysis and cross section observations by microscopy, a diagnostic of the decohesion of the interface is proposed. The study shows the possibility of assembling alumina on UHMWPE to strengthen its shock resistance and makes now possible the improvement of the study of deposition process parameters thanks to LASAT evaluations.

Multi-length scale strengthening and cytocompatibility of ultra high molecular weight polyethylene bio-composites by functionalized carbon nanotube and hydroxyapatite reinforcement

The mechanical properties, such as hardness and elastic modulus, of ultra-high molecular weight polyethylene (UHMWPE) composites for acetabular cup liner are improved by adding hydroxyapatite (HAp) and carbon nanotubes (CNT). However, the weak adhesion of HAp (H) and CNT (C) with UHMWPE (U) limits the enhancement of mechanical properties. Thus, the surface of these reinforcements is silane-treated to improve the adhesion with polymer via Si–O and C=O bonds, as evidenced from spectroscopy techniques. An increased dispersion and interfacial adhesion of functionalized HAp (fH) and CNT (fC) with the polymer matrix is confirmed by nearly two-fold increased reinforcement fraction (Rf: 0.55) of U-10 wt% fHAp-2 wt.% fCNT (U10fH2fC) in comparison to U-10 wt% HAp-2 wt.% CNT (U10H2C). Additionally, Voronoi Tessellation (VT) on SEM micrographs of U10H2C and U10fH2fC revealed the dispersion of functionalized CNTs in U10fH2fC with a center-to-center distance of 0.076 μm, which is 74% higher for unfunctionalized CNT in U10H2C. The multilength scale strengthening of the UHMWPE matrix is confirmed from atomic level modification via functionalization of fillers which effectively adhered to the polymer chain on a micro-scale level. A uniform distribution of CNTs rendered increased crystallinity (+28%) of U10fH2fC, which in turn resulted in significant improvement in bulk mechanical properties (18%, 49%, and 12% increased hardness (148.1 MPa), elastic modulus (3.51 GPa) and tensile elastic modulus (219.8 MPa), respectively) in comparison to that of U10H2C. Functionalized-HAp/CNT reinforced UHMWPE composites maintained its cytocompatibility in the MTT test and fluorescence microscopy, affirming their potential employment as acetabular cup liners for hip joint arthroplasty.

Recycled carbon fibers as an alternative reinforcement in UHMWPE composite. Circular economy within polymer tribology

The increasing demand of carbon fiber reinforced polymers over the last few decades has brought attention to critical aspects such as disposal, environmental impact, and cost of production. Therefore, adopting a circular economy approach focused on improving efficiency is an enticing alternative nowadays. This investigation is focused on the mechanical and tribological characterization of ultra high molecular weight polyethylene (UHMWPE) composites reinforced with virgin (vCF) and recycled carbon fibers (rCF) under water lubricated conditions. An improvement of 208% in Young’s modulus, 105% in ultimate tensile strength and 146% in hardness for the samples with 30%wt rCF, compared to pure UHMWPE, was observed. Reductions of up to 62% in coefficient of friction and 32% in wear rates for 10 wt% CF composites were obtained, facilitated through the formation of a transfer film, which was present on the countersurfaces. The results of this project show that the composites containing recycled fibers exhibit a comparable performance to their virgin counterparts. An economical evaluation estimated possible monetary savings of 910.2 M€ in a time span from 2022 to 2026 by using rCF in composite production, providing arguments for the use of rCF reducing the environmental impact and cost without compromising performance.

Natural Computing-Based Designing of Hybrid UHMWPE Composites for Orthopedic Implants

The current study deals with the design of ultra-high molecular weight polyethylene (UHMWPE) composites by integrating various micro and nanoparticles as reinforcements for enhanced performance of acetabular cups in hip prostheses. For the design, a data-driven design approach was implemented, exploiting natural computing techniques such as Artificial Neural Network (ANN) and Genetic Algorithm (GA). Experimental data related to UHMWPE reinforced with carbon nanotube, graphene, carbon fiber, and hydroxyapatite were gathered from the published works of previous researchers. To study the relationship between the volume fraction and the morphology of the particles with the tribological and mechanical properties of the composites, ANN modeling and sensitivity analyses were used. Optimization of the properties was done with the developed ANN models as objective functions in order to find the optimal combinations of reinforcements, which helps to achieve enhanced tribo-mechanical properties of the composites. This natural computing approach of designing the UHMWPE composites paved a way for experimentation.

무거운 하중 조건에서 PAO40@SiO2/UHMWPE 복합체의 마찰특성 연구

Ultra-high molecular weight polyethylene (UHMWPE) is widely applied in heavy-loading conditions like bridge bearings, so the high hardness, high compression strength and good friction and wear properties of modified UHMWPE are needed. The PAO40@SiO₂ microspheres (PSM)/UHMWPE composites were prepared, and the hardness, compression strength and heavy-loading tribology properties were investigated. The result shows that the specimens with PSM have higher hardness and compression strength than pure UHMWPE. The friction coefficient and the wear rate show the tendency that decreases first and then increases with the rising of PSM content, and lower values were reached with 9 wt% PSM. PSM could improve the tribology properties by the way of both the formation of oil lubrication and the strengthen of transfer film, while the aggregation of PSM fragments would work against. The research could provide a reference for the design of self-lubricating materials under heavy load conditions such as bridge bearings.

Prediction of shear deformation and thickness gradients in deep-draw forming of ultra-high molecular weight polyethylene

Ultra-high molecular weight polyethylene (UHMWPE) composite armor offers a high level of lightweight protection. In the manufacturing of complex curvature UHMWPE based protective materials, UHMWPE composites are transformed from flat sheet stock to a near net shape complex curvature preform through deep-draw forming. The development of a deep-draw forming process model is critical for predicting UHMWPE sheet deformation during processing and knowing the fiber orientations at each location in the entire final part. This work introduces a robust methodology to model the deep-draw forming process. The model is validated by comparing critical output with experimental results for multiple UHMWPE materials and over a range of part thicknesses. A hemispherical geometry is used to demonstrate the methodology. A homogenization strategy for grouping sheets is presented and validated, which is critical for keeping computational times manageable. The influence of the material in-plane shear response, a critical model input, is investigated. The model developed in this work represents a valuable tool for selecting deep-draw forming parameters and accelerates the evaluation of new and emerging UHMWPE materials for application in manufacturing complex curvature protective armor.

Self-heating effect on ultra-high molecular weight polyethylene fibres and composites

This paper investigates the self-heating effect observed during testing ultra-high molecular weight polyethylene (UHMWPE) fibres and their composites, in particular Dyneema® SK76 fibres and Dyneema® HB26 laminates. Monotonic and cyclic tests were carried out at strain rates between 0.00833 s−1 and 250 s−1, frequencies up to 20 Hz, and different mean stress, amplitude stress and stress ratios to evaluate the self-heating effect developing in the materials. Measurements of the specimen’s temperature were carried out using a thermochromic liquid crystal paint and an infrared sensor. Experimental results showed that the temperature increased during fibre testing by as much as 13.2 ± 0.2 °C and, even though the maximum temperature was below the melting temperature of the material, melting was observed. Tension-tension cyclic tests showed that the fatigue life of the coupon specimens significantly depended on the testing conditions. In some cases, the measured temperature was as high as 102 ± 1 °C. Depending on the fatigue parameters, the laminates showed two different types of failure modes: mechanical or thermal. Hence, it is important to take into account self-heating effects when designing engineering parts reinforced with UHMWPE fibres.

Functional Ultra-High Molecular Weight Polyethylene Composites for Ligament Reconstructions and Their Targeted Applications in the Restoration of the Anterior Cruciate Ligament.

The selection of biomaterials as biomedical implants is a significant challenge. Ultra-high molecular weight polyethylene (UHMWPE) and composites of such kind have been extensively used in medical implants, notably in the bearings of the hip, knee, and other joint prostheses, owing to its biocompatibility and high wear resistance. For the Anterior Cruciate Ligament (ACL) graft, synthetic UHMWPE is an ideal candidate due to its biocompatibility and extremely high tensile strength. However, significant problems are observed in UHMWPE based implants, such as wear debris and oxidative degradation. To resolve the issue of wear and to enhance the life of UHMWPE as an implant, in recent years, this field has witnessed numerous innovative methodologies such as biofunctionalization or high temperature melting of UHMWPE to enhance its toughness and strength. The surface functionalization/modification/treatment of UHMWPE is very challenging as it requires optimizing many variables, such as surface tension and wettability, active functional groups on the surface, irradiation, and protein immobilization to successfully improve the mechanical properties of UHMWPE and reduce or eliminate the wear or osteolysis of the UHMWPE implant. Despite these difficulties, several surface roughening, functionalization, and irradiation processing technologies have been developed and applied in the recent past. The basic research and direct industrial applications of such material improvement technology are very significant, as evidenced by the significant number of published papers and patents. However, the available literature on research methodology and techniques related to material property enhancement and protection from wear of UHMWPE is disseminated, and there is a lack of a comprehensive source for the research community to access information on the subject matter. Here we provide an overview of recent developments and core challenges in the surface modification/functionalization/irradiation of UHMWPE and apply these findings to the case study of UHMWPE for ACL repair.

Investigation of the Mechanical Properties of Flax/Jute/UHMWPE Reinforced Melamine Formaldehyde Composites Using Cone Beam Computed Tomography

ABSTRACT The research on natural fiber-reinforced composites has seen a rapid increase in recent years. The present study aims to further enhance the knowledge of composites by analyzing the mechanical properties of natural fiber-reinforced composites with flax and jute fibers. The properties of a composite are compared with those of a synthetic reinforcement like ultrahigh molecular weight polyethylene (UHMWPE). Melamine formaldefghyde (MF) is employed as a matrix for the preparation of composites. Fabrication is performed with eight layers of each fabric type to produce composite panels of 4 mm thickness. Composites are fabricated using a combination of hand lay-up and temperature-induced compression molding techniques. Mechanical characteristics, particularly, flexural, interlaminar shear, and impact strength, are investigated. Flax-reinforced composites with a flexural strength of 36 MPa, an interlaminar shear strength of 3.5 MPa, and an impact strength of 11.57 kJ/m2 fared better than jute and ultrahigh molecular weight polyethylene composites, signifying the superiority of flax fiber composites. The application of a nondestructive technique like cone-beam computed tomography provided further insight into the failure mechanisms of the composites. Scanning electron microscopy images of the impact specimens revealed failure mechanisms like fiber breakage, fibers shearing and splitting, matrix cracks, voids, and delamination.

Dynamical Young's Modulus and Internal Friction in Ultra-High Molecular Weight Polyethylene Composites

This work is devoted to the acoustic spectroscopy investigation of self-reinforced ultra-high molecular weight polyethylene composites made of pressed unidirectional sheets stacked orthogonally to each other. The studied samples demonstrate excellent mechanical properties in a wide temperature range from –5 °C to 50 °C. The relative change in the modulus of longitudinal elasticity for all samples in the studied temperature range did not exceed 1.6%. Depending on pressure value that is used at the stage of fabrication, the studied samples demonstrated dynamic Young's modulus values up to 17.8 GPa and internal friction up to 16∙10–2. Quasi-static mechanical properties are measured using the specimens of various shapes by tensile test. The values of Young's modulus, determined in the elastic part of the tension curves, reach 16.9 GPa.