Search Results (86)

Polyetheretherketone (PEEK) is a high-performance thermoplastic polymer widely recognized for its distinct mechanical strength, chemical resistance, and biocompatibility. These characteristics make it suitable for a wide range of applications, particularly in medical, aerospace, chemical, and electronics fields. Conventional processing techniques, such as 3D printing, molding, and extrusion, are widely employed for PEEK fabrication. This review critically examines recent advancements in PEEK research, with an emphasis on additive manufacturing techniques that are expanding its applications in the medical field. We provide an in-depth analysis of PEEK’s intrinsic properties, diverse processing methods, and current challenges that hinder its wider adoption. In addition to evaluating PEEK’s performance, this review compares it with alternative biomaterials—such as titanium and ultra-high molecular weight polyethylene (UHMWPE)—to explore its advantages and limitations in biomedical applications. Furthermore, this review discusses cost considerations, regulatory constraints, long-term clinical performance challenges, and failure modes that are essential for validating and ensuring the reliability of PEEK in clinical use. By synthesizing the recent literature, particularly from the last decade, this review highlights the significant potential of PEEK and underscores ongoing research efforts aimed at overcoming its limitations, paving the way for its broader implementation in advanced technological applications. Full article

The polymer composite frost-resistant rubber–UHMWPE (ultra-high molecular weight polyethylene) has simultaneously damping, anti-wear and anti-friction properties. To use it in seals operating in northern climatic conditions, it is necessary to study the effect of climatic aging on mechanical, strength and tribological properties of the composite. In this study, climatic aging of rubber and UHMWPE separately was made at testing ground in Yakutsk (Russia), as well as accelerated thermal aging of the composite in laboratory conditions. Comparison of the results of climatic and laboratory aging showed that climatic aging has a negative effect on the properties of both rubber and UHMWPE. Accelerated aging, on the contrary, leads to an improvement in the anti-friction properties of the composite with a small (about 10 percent) increase in its stiffness. Thus, with prolonged use in friction units, the composite should be protected from radiation and ozone. Full article

The ballistic performance of fiber-reinforced polymer composites (FRPC) is influenced by the adhesive’s mechanical properties, such as stiffness, toughness, and energy dissipation. However, the specific contributions of these properties remain unclear. This study explores how varying the hard segment (HS) content in water-based polyurethane (WPU) impacts the thermal, mechanical, and ballistic performance of FRPCs. By increasing HS content, the storage modulus and tensile strength of WPU improved, while elongation at break decreased, transitioning the adhesive from soft and ductile to rigid and brittle. Quasi-static tests, ballistic experiments, and SEM analysis were conducted on UHMWPE fiber-reinforced WPU-HS% composites. Results reveal that adhesives with high hardness and modulus hinder fiber deformation, reducing energy dissipation and causing severe delamination, which diminishes ballistic performance. Conversely, soft and ductile adhesives allow deformation alongside fibers during bullet impact, suppress delamination, and absorb more kinetic energy while transferring load. Among the tested formulations, WPU with 45% HS content exhibited the best balance of mechanical properties, achieving the most significant improvement in ballistic performance by enhancing energy absorption and minimizing damage. This study establishes a clear relationship between WPU properties and composite protective behavior, providing insights for designing high-performance ballistic materials. Full article

Ultrahigh molecular weight polymers display outstanding properties and have great application potential. However, the traditional polymerization methods have inevitable disadvantages that challenge the green synthesis of ultrahigh molecular weight polymers. The paper achieved an ultrahigh molecular weight poly (trifluoroethyl methacrylate) via a novel polymerization and discussed the mechanistic, kinetic, and experimental aspects. The combination of palladium nanoparticles with ethyl 2-bromopropionate has been identified as an exceedingly efficient system for initiating the polymerization of trifluoroethyl methacrylate. An ultrahigh molecular weight poly (trifluoroethyl methacrylate) with a number-average molecular weight up to 3.03 × 10⁶ Da has been synthesized at a feeding molar ratio of [poly (trifluoroethyl methacrylate)]/[ethyl 2-bromopropionate]/[palladium nanoparticles] = 3.95 × 10⁴:756:1 at 70 °C. The reaction orders concerning palladium nanoparticles, ethyl 2-bromopropionate, and poly (trifluoroethyl methacrylate) were determined to be 0.59, 0.34, and 1.38, respectively. By analyzing a series of characterizations, we verified that the polymerization of poly (trifluoroethyl methacrylate) was initiated by the ethyl 2-bromopropionate residue radicals, which were generated from the interaction between palladium nanoparticles and ethyl 2-bromopropionate. The comparatively large size of the palladium nanoparticles provided a barrier to chain-growing radicals, promoting the synthesis of ultrahigh molecular weight polymers. Full article

The paper presents the production of thermoplastic starch (TPS) mixtures using potato starch and two types of plasticizers: glycerol and sorbitol. The effects of plasticizers, citric acid, organically modified montmorillonite clay nanofiller (OMMT) and an additive based on ultrahigh molecular weight siloxane polymer on the structure and physical–mechanical and thermal properties of TPS samples were analysed. Starch mixtures plasticized with glycerol were obtained, where the starch/glycerol mass ratio was 70:30, as well as starch mixtures plasticized with glycerol and sorbitol, with a starch/glycerol/sorbitol mass ratio of 60:20:20. The starch gelatinization process to obtain TPS was carried out in a Brabender Plasti-Corder internal mixer at 120 °C, with a mixing speed of 30–80 rpm, for 10 min. The obtained results indicate that by adding 2% (weight percentage) of citric acid to the TPS mixtures, there is an improvement in the physical–mechanical properties, as well as structural changes that can indicate both cross-linking reactions by esterification in stages and depolymerisation reactions. The sample of TPS plasticized with glycerol, which contains OMMT, shows an increase in tensile strength by 34.4%, compared to the control sample. Full article

The impact resistance of layered polymer structures using polyvinyl butyral (PVB) in combination with Kevlar^® fabric and ultra-high molecular weight polyethylene (UHMWPE) were fabricated and tested. Methods of wet impregnation and hot-press impregnation and consolidation of fabric with PVB and UHMWPE were used to manufacture multilayer constructs. All sandwich constructs were fixed to the surface of ballistic clay and subject to a free drop-weight test with a conical impactor having a small contact area. All tests were made at the same impact energy of 9.3 J and velocity of 2.85 m/s. The change in the resistance force was recorded using a piezoelectric force sensor at the time intervals of 40 μs. Using experimental force–time history, the change in the impactor’s velocity, the depth of impactor penetration, the energy transformation at various stages of impactor interaction with the sample, and other parameters were obtained. Three indicators were considered as the main criteria for the effectiveness of a sample’s resistance to impact: (1) minimum deformation, bulging, of the panel backside at the moment of impact, (2) minimum absorption of impact energy per areal density, and (3) minimal or, better yet, no destruction of structural integrity. Under the tested conditions, the rigid Kevlar–PVB–Kevlar sandwich at the frontside and relatively soft but flexible UHMWPE–Kevlar–UHMWPE layers in the middle helped to localize and absorb impact energy, while the backside Kevlar–PVB–Kevlar sandwich minimized local bulging providing the best overall performance. The front layer damage area was very shallow and less than two impactor tip diameters. The backside bulging was also less than in any other tested configurations. Full article

This review explores the use of Ultra-High Molecular Weight Polyethylene (UHMWPE) fiber cloth as an innovative solution for the repair and reinforcement of concrete structures. UHMWPE is a polymer formed from a very large number of repeated ethylene (C₂H₄) units with higher molecular weight and long-chain crystallization than normal high-density polyethylene. With its superior tensile strength, elongation, and energy absorption capabilities, UHMWPE emerges as a promising alternative to traditional reinforcement materials like glass and carbon fibers. The paper reviews existing literature on fiber-reinforced polymer (FRP) applications in concrete repair in general, highlighting the unique benefits and potential of UHMWPE fiber cloth compared to other commonly used methods of strengthening concrete structures, such as enlarging concrete sections, near-surface embedded reinforcement, and externally bonded steel plate or other FRPs. Despite the scarcity of experimental data on UHMWPE for concrete repair, this review underscores its feasibility and calls for further research to fully harness its capabilities in civil engineering applications. Full article

In this study, the tribological properties of nanocomposites based on ultra-high molecular weight polyethylene (UHMWPE) filled with nano-CuO and 2-mercaptobenzothiazole (CuO/MBT) in mass ratios of 1:1 and 2:1 were investigated. In the supramolecular structure of UHMWPE nanocomposites, spherulites of several hundred micrometers in size are formed. The density of UHMWPE nanocomposites slightly increases relative to the pure polymer, reaching a maximum at 2 wt.% CuO/MBT in both ratios. The Shore D hardness and compressive stress of the UHMWPE nanocomposites showed an improvement of 5–6% and 23–35%, respectively. The wear resistance and coefficient of friction of UHMWPE nanocomposites were tested using a pin-on-disk configuration under dry friction conditions on #45 steel and on P320 sandpaper. It was shown that the wear rate of UHMWPE nanocomposites filled with 2 wt.% CuO/MBT decreased by ~3.2 times compared to the pure polymer, and the coefficient of friction remained at the level of the polymer matrix. Abrasive wear showed an improvement in UHMWPE nanocomposites filled with 1 wt.% CuO/MBT compared to the polymer matrix and other samples. The worn surfaces of the polymer composites after dry friction were examined by scanning electron microscopy and IR spectroscopy. The formation of secondary structures in the form of tribofilms that protect the material from wear was demonstrated. Due to this, the wear mechanism of UHMWPE nanocomposites is transformed from adhesive to fatigue wear. The developed materials, due to improved mechanical and tribological properties, can be used as parts in friction units of machines and equipment. Full article

The effect of particle size and oxidation degree of new carbon microfillers, based on coal pitch (CP) and petroleum pitch (PET) cokes, on the structure as well as thermal, mechanical, and electrical properties of the composites based on ultrahigh molecular weight polyethylene (UHMWPE) was investigated. The composites studied have a segregated structure of filler particle distribution in the UHMWPE matrix. It was found that composite with smaller CP grain fraction has the highest Young’s modulus and electrical conductivity compared to the other composites studied, which can be the result of a large contribution of flake-shaped particles. Additionally, conductivity of this composite turned out to be similar to composites with well-known carbon nanofillers, such as graphene, carbon black, and CNTs. Additionally, the relationship between electrical conductivity and Young’s modulus values of composites studied was revealed, which indicates that electrical conductivity is very sensitive to the structure of the filler phase in the polymer matrix. In general, it was established that the properties, especially the electrical conductivity, of the composites studied strongly depends on the size, shape, and oxidative treatment of CP and PET filler particles, and that the CP coke of appropriately small particle sizes and flake shape has significant potential as a conductive filler for polymer composites. Full article

The development of catalysts has significantly advanced the progress of polyolefin materials. In particular, group 4 (Ti, Zr, Hf) non-metallocene catalysts ligated with [N,N] bidentate ligand(s) have garnered increasing attention in the field of olefin polymerization due to their structurally stability and exceptional polymerization behaviors. Ligands containing nitrogen donors are diverse and at the core of many highly active catalysts. They mainly include amidine, guanidinato, diamine, and various N-heterocyclic ligands, which can be used to obtain a series of new polyolefin materials, such as ultrahigh molecular weight polyethylene (UHWMPE), olefin copolymers (ethylene/norbornene and ethylene/α-olefin) with high incorporations, and high isotactic or syndiotactic polypropylene after coordination with group 4 metals and activation by cocatalysts. Herein, we focus on the advancements and applications of this field over the past two decades, and introduce the catalyst precursors with [N,N] ligand(s), involving the effects of ligand structure, cocatalyst selection, and polymerization conditions on the catalytic activity and polymer properties. Full article

Preparing a friction pair “polymer-metal” using improved polymeric composites is contemplated a complicated task due to the inert surface of the polymer. Gluing polymer composites with improved mechanical and tribological properties on metals and saving their unique properties at the same time is considered the best way to prepare slide bearing products based on polymer/metal. In this work, ultraviolet initiation is used after a process of mixed acid pre-treatment. The surface of highly oriented films based on ultra-high molecular weight polyethylene (UHMWPE)/graphene nanoplatelets (GNP) is grafted with nanocellulose. The grafting treatment is analyzed using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and contact angle measurements. Mechanical T-peel tests showed that the peel strength for the treated UHMWPE films increased by three times, up to 1.9 kg/cm, in comparison to the untreated films. The tensile strength of the treated UHMWPE films decreased by about 6% to 788 MPa. Tribological tests showed that the values of both friction coefficient and wear intensity of the treated UHMWPE films were increased insignificantly, which were 0.172 and 15.43 µm/m·m², respectively. The prepared adhesive tape based on UHMWPE films, which can withstand a weight of up to 6 kg per 1 cm² of the bonded surface, has a low coefficient of friction, high wear resistance, and high strength, and is considered a promising material for preparing slide bearing products. Full article

The novel ultra-high molecular weight polypropylene (UHMWPP) as a dispersed component was melt blended with conventional high-density polyethylene (PE) and maleic anhydride grafted-polyethylene (mPE) in different proportions through a kneader. Ultra-high molecular weight polypropylene is a high-performance polymer material that has excellent mechanical properties and toughness compared to other polymers. Mechanical, thermal, and rheological properties were presented for various UHMWPP loadings, and correlations between mechanical and rheological properties were examined. Optimal comprehensive mechanical properties are achieved when the UHMWPP content reaches approximately 50 wt%, although the elongation properties do not match those of pure PE or mPE. However, it is worth noting that the elongation properties of these blends did not match those of PE or mPE. Particularly, for the PE/UHMWPP blends, a significant drop in tensile strength was observed as the UHMWPP content decreased (from 30.24 MPa for P50U50 to 13.12 MPa for P90U10). In contrast, the mPE/UHMWPP blends demonstrated only minimal changes in tensile strength (ranging from 29 MPa for mP50U50 to 24.64 MPa for mP90U10) as UHMWPP content varied. The storage modulus of the PE/UHMWPP blends increased drastically with the UHMWPP content due to the UHMWPP chain entanglements and rigidity. Additionally, we noted a substantial reduction in the melt index of the blend system when the UHMWPP content exceeded 10% by weight. Full article

Polymers and their processing by engineering production technologies (injection, molding or additive manufacturing) are increasingly being used. Polymers used in engineering production technologies are constantly being developed and their properties are being improved. Granulometry, X-ray, FTIR and TGA were used to characterize polymer samples. Determination of the fire parameters of powder samples of polyamide (PA) 12, polypropylene, and ultra-high molecular weight (UHMW) polyethylene is the subject of the current article. An explosive atmosphere can be created by the powder form of these polymer materials, and introduction of preventive safeguards to ensure safety is required for their use. Although the fire parameters of these basic types of polymers are available in databases (e.g., GESTIS-DustEx), our results showed that one of the samples used (polypropylene) was not flammable and thus is safe for use in terms of explosiveness. Two samples were flammable and explosive. The lower explosive limit was 30 g·m⁻³ (PA12) and 60 g·m⁻³ (UHMW polyethylene). The maximum explosion pressure of the samples was 6.47 (UHMW polyethylene) and 6.76 bar (PA12). The explosion constant, K_st, of the samples was 116.6 bar·m·s⁻¹ (PA12) and 97.1 bar·m·s⁻¹ (UHMW polyethylene). Therefore, when using polymers in production technologies, it is necessary to know their fire parameters, and to design effective explosion prevention (e.g., ventilation, explosive-proof material, etc.) measures for flammable and explosive polymers. Full article

This study investigates the impact of a binary filler on the physicomechanical and tribological properties, as well as structure, of polymeric composite materials based on ultra-high-molecular-weight polyethylene. The organic modifier—2-mercaptobenzothiazole and wollastonite particles synthesized from two different systems (modeled and derived from waste) were used as the binary filler. The synthesis of wollastonite was carried out in the complex model system (CaSO₄·2H₂O–SiO₂·nH₂O–KOH–H₂O) and from technogenic waste (borogypsum). It was demonstrated that the introduction of the binary filler made it possible to obtain an optimal combination of mechanical and tribological properties. It was found that during the wear of polymeric composite materials loaded with organic fillers, the fillers migrate to the friction surface, providing a shield against abrasive wear of the steel counterface. Due to the modification of ultra-high-molecular-weight polyethylene by 2-mercaptobenzothiazole, the interdiffusion of polymeric matrix macromolecules and interphase coupling with wollastonite particles improve. The 2-mercaptobenzothiazole organic compound used as the filler facilitates the relaxation processes within the composite under external loads. Full article

Polymer composites are a class of material that are gaining a lot of attention in demanding tribological applications due to the ability of manipulating their performance by changing various factors, such as processing parameters, types of fillers, and operational parameters. Hence, a number of samples under different conditions need to be repeatedly produced and tested in order to satisfy the requirements of an application. However, with the advent of a new field of triboinformatics, which is a scientific discipline involving computer technology to collect, store, analyze, and evaluate tribological properties, we presently have access to a variety of high-end tools, such as various machine learning (ML) techniques, which can significantly aid in efficiently gauging the polymer’s characteristics without the need to invest time and money in a physical experimentation. The development of an accurate model specifically for predicting the properties of the composite would not only cheapen the process of product testing, but also bolster the production rates of a very strong polymer combination. Hence, in the current study, the performance of five different machine learning (ML) techniques is evaluated for accurately predicting the tribological properties of ultrahigh molecular-weight polyethylene (UHMWPE) polymer composites reinforced with silicon carbide (SiC) nanoparticles. Three input parameters, namely, the applied pressure, holding time, and the concentration of SiCs, are considered with the specific wear rate (SWR) and coefficient of friction (COF) as the two output parameters. The five techniques used are support vector machines (SVMs), decision trees (DTs), random forests (RFs), k-nearest neighbors (KNNs), and artificial neural networks (ANNs). Three evaluation statistical metrics, namely, the coefficient of determination (R²-value), mean absolute error (MAE), and root mean square error (RMSE), are used to evaluate and compare the performances of the different ML techniques. Based upon the experimental dataset, the SVM technique was observed to yield the lowest error rates—with the RMSE being 2.09 × 10⁻⁴ and MAE being 2 × 10⁻⁴ for COF and for SWR, an RMSE of 2 × 10⁻⁴ and MAE of 1.6 × 10⁻⁴ were obtained—and highest R²-values of 0.9999 for COF and 0.9998 for SWR. The observed performance metrics shows the SVM as the most reliable technique in predicting the tribological properties—with an accuracy of 99.99% for COF and 99.98% for SWR—of the polymer composites. Full article