UHMWPE Nanocomposite Coatings Reinforced with Alumina (Al2O3) Nanoparticles for Tribological Applications

Influence of Diabase Filler on the Structure and Tribological Properties of Coatings Based on Ultrahigh Molecular Weight Polyethylene

This article presents the results of a study of a composite coating made of ultrahigh molecular weight polyethylene (UHMWPE) with a diabase filler obtained by flame spraying. Diabase of 10 wt.%, 20 wt.%, 30 wt.% and 40 wt.% was chosen as a filler. The polymer coating was applied to the St3 metal substrate using temperature control in a conventional flame spraying process. The coating was studied using scanning electron microscopy, X-ray phase analysis, infrared spectroscopy, abrasive wear resistance, microhardness testing and determination of the friction coefficient. It has been shown that diabases do not have a negative effect on the initial chemical structure of UHMWPE and it is not subjected to destruction during flame spraying. The introduction of diabase into the composition of UHMWPE with a content of 10-40% of the total mass does not adversely affect the crystalline structure of the coating. It has been established that with an increase in the volume of the diabase filler, the wear resistance of the composite coating based on UHMWPE increases. It has been determined that with the addition of diabase, the microhardness of the coatings increases.

Preparation and characterization of UHMWPE reinforced with polyester fibers for artificial cervical disc replacement (ACDR)

The purpose of this paper is to report on the preparation and improvement of a biocomposite material made from ultra-high molecular weight polyethylene for the replacement of natural discs. Such replacements are necessary due to intervertebral disc degradation as humans age, which can cause persistent pain due to nerve compression and high friction between vertebrae that can lead to vertebral corrosion. The material was shown to have excellent mechanical properties such as low coefficient of friction, and biocompatibility; however, it degraded with time due to wear failure. Moreover, The wear resistance was related to many factors, such as toughness.In the methodology of the current study, UHMWPE is reinforced with different percent of polyester (2, 4, 6, 8, 10%) to improve the mechanical properties of the polymer disc, thus enhancing its toughness and providing its high bearing ability for the load.The findings revealed that the tensile strength and modulus of elasticity improved by 43.415% and 34.286%, respectively, with the 6% polyester fibers due to the excellent entanglement between the matrix and reinforcing phase. The other mechanical properties, such as flexural strength and modulus, impact strength, fracture toughness, and compression strength, were also enhanced in this study. The highest value at 6% polyester fiber was found to be due to good bonding and adhesion between the polymer and polyester fibers. The Fourier Transformation Spectroscopy (FTIR) showed a shift on some peaks.The originality of this work is that the improvements due to the new bio-composite polymers for artificial implant cervical discs can open many applications in future for these materials.

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 (R_f: 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.

Nanostructured Coatings: Review on Processing Techniques, Corrosion Behaviour and Tribological Performance

Corrosion and tribology are surface phenomena. Modifying surfaces of materials without resorting to altering their bulk properties is an effective route to alleviate corrosion, friction and wear, encountered in engineering applications. With the advancements in the field of nanotechnology, surface protective coatings with nanomaterials can be readily developed to explore their functionality in mitigating chemical/physical damage of surfaces. Surface protection enhances performance and operating lifetimes of industrial machinery components. This review presents insights on various types of recently developed nanostructured coatings, their synthesis routes, corrosion behaviour and tribological performance. It provides the state-of-the-art information on the development of nanostructured coatings, namely, ceramic coatings, metallic coatings and nanocomposite coatings with metal and polymer matrices. Biomimetic approaches in making nanostructured coatings and challenges encountered in the development of nanostructured coatings are highlighted.

Depolymerization of Waste Plastic Using Bubble Column for Nano Alumina Blended Coating

In this study, we aimed to figure out how the depolymerization of polyethylene terephthalate produces monomers, dimers, trimers, and other oligomers of bis (2-hydroxyethyl) terephthalate. Polymerization was achieved in a bubble column reactor with 0.05 wt% 40–50 nm magnesium oxide nanoparticle as a catalyst. A bubble column reactor was used to perform the recycling process at the boiling point of ethylene glycol and atmospheric pressure. Depolymerized polyethylene terephthalate (DPET) was mixed with poly(methyl methacrylate) and reinforced with 1% Nano Al2O3. The nanoparticles acted as a composite coating in low carbon steel protection. Adhesion strength and mechanical and structural properties were investigated for the composite, and the average coating thickness was 28.39 µm. The results showed that the hardness and adhesion forces between the substrate and composite coating increased with an increase in the amounts of DPET and nano-Al2O3 per polymer resin. On the other hand, the thermal conductivity of the composite coating decreased with the addition of DPET because of an increase in the end chain movement in the composite coating induced by the retardant and an increase in cross-linking force. Furthermore, the bubble column demonstrated outstanding heat and mass transfer phenomena that reduced the reaction time to just 40 min for complete depolymerzation and also reduced energy consumption.

Effect of Nanofillers on Tribological Properties of Polymer Nanocomposites: A Review on Recent Development

Polymer nanocomposites with enhanced performances are becoming a trend in the current research field, overcoming the limitations of bulk polymer and meeting the demands of market and society in tribological applications. Polytetrafluoroethylene, poly(ether ether ketone) and ultrahigh molecular weight polyethylene are the most popular polymers in recent research on tribology. Current work comprehensively reviews recent advancements of polymer nanocomposites in tribology. The influence of different types of nanofiller, such as carbon-based nanofiller, silicon-based nanofiller, metal oxide nanofiller and hybrid nanofiller, on the tribological performance of thermoplastic and thermoset nanocomposites is discussed. Since the tribological properties of polymer nanocomposites are not intrinsic but are dependent on sliding conditions, direct comparison between different types of nanofiller or the same nanofiller of different morphologies and structures is not feasible. Friction and wear rate are normalized to indicate relative improvement by different fillers. Emphasis is given to the effect of nanofiller content and surface modification of nanofillers on friction, wear resistance, wear mechanism and transfer film formation of its nanocomposites. Limitations from the previous works are addressed and future research on tribology of polymer nanocomposites is proposed.

Recent Advances in UHMWPE/UHMWPE Nanocomposite/UHMWPE Hybrid Nanocomposite Polymer Coatings for Tribological Applications: A Comprehensive Review

In the recent past, polymer coatings have gained the attention of many researchers due to their low cost, their ability to be coated easily on different substrates, low friction and good anti-corrosion properties. Various polymers such as polytetrafluroethylene (PTFE), polyether ether ketone (PEEK), polymethylmethacrylate (PMMA), polyurethane (PU), polyamide (PA), epoxy and ultra-high molecular weight polytheylene (UHMWPE) have been used to develop these coatings to modify the surfaces of different components to protect them from wear and corrosion. However, among all these polymers, UHMWPE stands out as a tribologist’s polymer due to its low friction and high wear resistance. These coatings have found their way into applications ranging from microelectro mechanical systems (MEMS) to demanding tribological applications such as bearings and biomedical applications. Despite its excellent tribological properties, UHMWPE suffers from limitations such as low load bearing capacity and low thermal stability. To overcome these challenges researchers have developed various routes such as developing UHMWPE composite and hybrid composite coatings with several types of nano/micro fillers, developing composite films system and developing dual film systems. The present paper is an effort to summarize these various routes adopted by different researchers to improve the tribological performance of UHMWPE coatings.

Hybrid Self-Reinforced Composite Materials Based on Ultra-High Molecular Weight Polyethylene

The properties of hybrid self-reinforced composite (SRC) materials based on ultra-high molecular weight polyethylene (UHMWPE) were studied. The hybrid materials consist of two parts: an isotropic UHMWPE layer and unidirectional SRC based on UHMWPE fibers. Hot compaction as an approach to obtaining composites allowed melting only the surface of each UHMWPE fiber. Thus, after cooling, the molten UHMWPE formed an SRC matrix and bound an isotropic UHMWPE layer and the SRC. The single-lap shear test, flexural test, and differential scanning calorimetry (DSC) analysis were carried out to determine the influence of hot compaction parameters on the properties of the SRC and the adhesion between the layers. The shear strength increased with increasing hot compaction temperature while the preserved fibers' volume decreased, which was proved by the DSC analysis and a reduction in the flexural modulus of the SRC. The increase in hot compaction pressure resulted in a decrease in shear strength caused by lower remelting of the fibers' surface. It was shown that the hot compaction approach allows combining UHMWPE products with different molecular, supramolecular, and structural features. Moreover, the adhesion and mechanical properties of the composites can be varied by the parameters of hot compaction.

Characterization and corrosion resistance of ultra-high molecular weight polyethylene composite coatings reinforced with tungsten carbide particles in hydrochloric acid medium

Ultra-high molecular weight polyethylene (UHMWPE) composite coatings reinforced with different concentrations (1, 3, 6, and 9 wt%) of submicron tungsten carbide (WC) particles were synthesized using electrostatic sprayed method, characterized and evaluated for corrosion resistance in 1 m HCl electrolytic solution. Results showed that the mechanical properties and adhesion strength of the coatings improved with the increasing WC content to an optimum loading of 6 wt%. These properties slightly dropped when the WC content was further increased to 9 wt% due to agglomeration of the WC particles. Furthermore, both the potentiodynamic polarization test and electrochemical impedance spectroscopy measurement confirmed the high corrosion protection efficiency of the UHMWPE/WC composite coatings over the pristine UHMWPE coating to a minimum of 80% improvement. The 1 wt% WC reinforced UHMWPE coating exhibited the highest corrosion resistance due to better dispersion of the WC particles in the matrix.